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1
Siegfried, Matthew R., Robert L. Hawley und John F. Burkhart. „High-Resolution Ground-Based GPS Measurements Show Intercampaign Bias in ICESat Elevation Data Near Summit, Greenland“. IEEE Transactions on Geoscience and Remote Sensing 49, Nr. 6 (September 2011): 3393–400. http://dx.doi.org/10.1109/tgrs.2011.2127483.
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The Geoscience Laser Altimeter System (GLAS) aboard the National Aeronautics and Space Administration's Ice, Cloud, and land Elevation Satellite (ICESat) collected data from early 2003 to late 2009 with the specific goal of measuring ice-surface elevation changes. While the precision of GLAS instrumentation has been studied over its intended target (ice), its accuracy has only been robustly estimated using independent (terrestrial nonlaser) methods over salt flats. Here, we perform repeat high-precision Global Positioning System (GPS) surveys under four passes of ICESat track 0412 (campaigns L3I, L3J, L2D, and L2E) to compare directly GLAS elevation data footprints to a coincident GPS ground truth near Summit, Greenland. Analysis and comparison of GLAS data with GPS data show a campaign-dependent elevation bias ranging from -0.112 ±0.030 m (L3J) to 0.121 ± 0.071 m (L2E). Although uncorrected reflectance values and field observations both indicate that forward scattering of the laser signal through the atmosphere accounts for the anomalously negative L3J bias, the biases of all campaigns studied are within the instrument's goal accuracy of ±0.15 m. However, our analysis shows a campaign dependence in the bias, which may propagate through estimates of mass balance. The error introduced from intercampaign biases illustrates the importance of long-term independent validation experiments of satellite altimetry data over ice sheets.
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Gibertini, Giuseppe, Silvano Rezzonico, Marco Rossetti und Alex Zanotti. „Experimental Investigation of Helicopter Noise While Approaching an Elevated Helipad“. Aerospace 10, Nr. 8 (09.08.2023): 701. http://dx.doi.org/10.3390/aerospace10080701.
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The present paper describes a test campaign performed to investigate the noise footprint emitted by a helicopter in an idealised urban context, reproducing the approach to an elevated helipad. The test campaign was performed in Politecnico di Milano’s anechoic chamber and was finalised to investigate the effects produced only by helicopter noise. The set up consisted of a two-blade main rotor helicopter model and an aluminium rectangular prism model reproducing the landing building. Ground observer perceptions were recorded by means of a surface microphone and a realistic landing trajectory was approximated as a succession of fixed point measurements. Collected data were analysed through acoustic spectra and sound maps. Spectra were used to comprehend physical phenomena, such as reflection, diffraction and shielding, and to analyse the different contributions of helicopter noise. A sound map analysis enabled us to obtain a global perspective of the involved phenomena and to understand th extent to which people close to a building are stressed by a helicopter approaching an elevated urban helipad. Moreover, the experimental database, obtained over a free geometry, can be considered a useful tool for the validation of aeroacoustic solvers with different levels of fidelity.
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Tihanyi, Viktor, Tamás Tettamanti, Mihály Csonthó, Arno Eichberger, Dániel Ficzere, Kálmán Gangel, Leander B. Hörmann et al. „Motorway Measurement Campaign to Support R&D Activities in the Field of Automated Driving Technologies“. Sensors 21, Nr. 6 (19.03.2021): 2169. http://dx.doi.org/10.3390/s21062169.
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A spectacular measurement campaign was carried out on a real-world motorway stretch of Hungary with the participation of international industrial and academic partners. The measurement resulted in vehicle based and infrastructure based sensor data that will be extremely useful for future automotive R&D activities due to the available ground truth for static and dynamic content. The aim of the measurement campaign was twofold. On the one hand, road geometry was mapped with high precision in order to build Ultra High Definition (UHD) map of the test road. On the other hand, the vehicles—equipped with differential Global Navigation Satellite Systems (GNSS) for ground truth localization—carried out special test scenarios while collecting detailed data using different sensors. All of the test runs were recorded by both vehicles and infrastructure. The paper also showcases application examples to demonstrate the viability of the collected data having access to the ground truth labeling. This data set may support a large variety of solutions, for the test and validation of different kinds of approaches and techniques. As a complementary task, the available 5G network was monitored and tested under different radio conditions to investigate the latency results for different measurement scenarios. A part of the measured data has been shared openly, such that interested automotive and academic parties may use it for their own purposes.
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Manni, Mattia, Alessia Di Giuseppe, Alessandro Petrozzi, Andrea Nicolini, Federico Rossi und Franco Cotana. „High-reflective Mulching Membrane for a Sustainable Development: Monitoring Campaign“. E3S Web of Conferences 197 (2020): 08012. http://dx.doi.org/10.1051/e3sconf/202019708012.
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Modern agriculture techniques are responsible for the production of large volumes of greenhouse gases that represent the main cause of climate change. At the same time, agricultural activities are negatively affected by climate change effects, showing a reduction in productivity. Within this framework, the present study aims at investigating the effectiveness of an innovative high-reflective mulching membrane that can be exploited in the agricultural sector to mitigate its environmental impact. It consists of a mulching membrane coupled to an irrigation system, and painted with bright pigments on the side facing the skydome. This technology was used in food crop farming in the experimental field in Perugia. Sensors for monitoring solar irradiation, rainwater recovery, and phenological parameters were installed. Data collected during the monitoring campaign conducted in summer demonstrated that the high-reflective membrane was capable to increase the ground solar reflectance up to 0.60, while avoiding the utilization of potable water and water from the aquifer to irrigate the crops. An acceleration of the photosynthesis processes was also observed along with an increment in the productivity: tomatoes grew up to 20% more in weight.
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Marzahn, P., und R. Ludwig. „On the derivation of soil surface roughness from multi parametric PolSAR data and its potential for hydrological modeling“. Hydrology and Earth System Sciences 13, Nr. 3 (18.03.2009): 381–94. http://dx.doi.org/10.5194/hess-13-381-2009.
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Abstract. The potential of multi parametric polarimetric SAR (PolSAR) data for soil surface roughness estimation is investigated and its potential for hydrological modeling is evaluated. The study utilizes microwave backscatter collected from the DEMMIN test site in the North East of Germany during the AgriSAR 2006 campaign using fully polarimetric L-band E-SAR data. In addition to various measurements of soil physical properties, soil surface roughness was measured extensively using photogrammetric image matching techniques for ground truthing. The resulting micro-DSMs are analyzed to correlate a soil surface roughness index to three well established polarimetric roughness estimators. Good results are obtained for Re[ρRRLL] vs. RMS Height for areas with a polarimetric alpha angel α<40°, which is thus used to produce multi temporal roughness data of the test site. The proposed roughness inversion scheme showed sufficiently accurate results (RMSE=0.1) to allow for a first order assessment of soil-hydrological parameters (soil porosity, void ratio), which are crucial for the initialization and operation of hydrological surface models. While uncertainties remain, the dependency of soil bulk density parameters from surface roughness can be shown and thus highlights the potential of the retrieval approach for hydrological model applications.
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Sikand, M., J. Koskulics, K. Stamnes, B. Hamre, J. J. Stamnes und R. P. Lawson. „Estimation of Mixed-Phase Cloud Optical Depth and Position Using In Situ Radiation and Cloud Microphysical Measurements Obtained from a Tethered-Balloon Platform“. Journal of the Atmospheric Sciences 70, Nr. 1 (01.01.2013): 317–29. http://dx.doi.org/10.1175/jas-d-12-063.1.
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Abstract Microphysical and radiative measurements in boundary layer mixed-phase clouds (MPCs), consisting of ice crystals and liquid droplets, have been analyzed. These cloud measurements were collected during a May–June 2008 tethered-balloon campaign in Ny-Ålesund, Norway, located at 78.9°N, 11.9°E in the High Arctic. The instruments deployed on the tethered-balloon platform included a radiometer, a cloud particle imager (CPI), and a meteorological package. To analyze the data, a radiative transfer model (RTM) was constructed with two cloud layers—consistent with the CPI data—embedded in a background Rayleigh scattering atmosphere. The mean intensities estimated from the radiometer measurements on the balloon were used in conjunction with the RTM to quantify the vertical structure of the MPC system, while the downward irradiances measured by an upward-looking ground-based radiometer were used to constrain the total cloud optical depth. The time series of radiometer and CPI data obtained while profiling the cloud system was used to estimate the time evolution of the liquid water and ice particle optical depths as well as the vertical location of the two cloud layers.
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Marzahn, P., und R. Ludwig. „On the derivation of soil surface roughness from multi parametric PolSAR data and its potential for hydrological modelling“. Hydrology and Earth System Sciences Discussions 5, Nr. 6 (28.11.2008): 3383–418. http://dx.doi.org/10.5194/hessd-5-3383-2008.
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Abstract. The potential of multi parametric polarimetric SAR (PolSAR) data for soil surface roughness estimation is investigated and its potential for hydrological modeling is evaluated. The study utilizes microwave backscatter collected from the DEMMIN test-site in the north-east of Germany during the AgriSAR 2006 campaign using fully polarimetric L-Band E-SAR data. In addition to various measurements of soil physical properties, soil surface roughness was measured extensively using photogrammetric image matching techniques for ground truthing. The resulting micro-DEMs are analyzed to correlate soil surface roughness indices to three well established polarimetric roughness estimators. Good results are obtained for Re[ρRRLL] vs. RMS Height, which is thus used to produce multi-temporal roughness maps of the test site. The spatial quality of maps is limited due to the fact that the presence and growth of particular plants is affecting the derivation process significantly. However, roughness derivation for bare soil surfaces is sufficiently accurate to allow for an first order assessment of soil-hydrological parameters (soil porosity, void ratio, micro depression storage capacity), which are crucial for the initialization and operation of hydrological surface models. While uncertainties remain, the dependency of soil bulk parameters from surface roughness can be shown and thus highlights the potential of the retrieval approach for hydrological model applications.
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Aloysius, M., M. Mohan, K. Parameswaran, S. K. George und P. R. Nair. „Aerosol transport over the Gangetic basin during ISRO-GBP land campaign-II“. Annales Geophysicae 26, Nr. 3 (26.03.2008): 431–40. http://dx.doi.org/10.5194/angeo-26-431-2008.
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Abstract. MODIS (Moderate Resolution Imaging Spectroradiometer) Level-3 aerosol optical depth (AOD) data and NCEP (National Centre for Environmental Prediction) reanalysis winds were incorporated into an aerosol flux continuity equation, for a quantitative assessment of the sources of aerosol generation over the Ganga basin in the winter month of December 2004. Preliminary analysis on the aerosol distribution and wind fields showed wind convergence to be an important factor which, supported by the regional topography, confines aerosols in a long band over the Indo Gangetic plain (IGP) stretching from the west of the Thar desert into the Head-Bay-of-Bengal. The prevailing winds of the season carry the aerosols from Head-Bay-of-Bengal along the east coast as far as the southern tip of the peninsular India. A detailed examination of MODIS data revealed significant day-to-day variations in aerosol loading in localised pockets over the central and eastern parts of the Indo Gangetic plain during the second half of December, with AOD values even exceeding unity. Aerosols over the Ganga basin were dominated by fine particles (geometric mean radius ~0.05–0.1μm) while those over the central and western India were dominated by large particles (geometric mean radius ~0.3–0.7μ). Before introducing it into the flux equation, the MODIS derived AOD was validated through a comparison with the ground-based measurements collected at Kharagpur and Kanpur; two stations located over the Ganga basin. The strength of the aerosol generation computed using the flux equation indicated the existence of aerosol sources whose locations almost coincided with the concentration of thermal power plants. The quantitative agreement between the source strength and the power plant concentration, with a correlation coefficient 0.85, pointed to thermal power plants as substantial contributors to the high aerosol loading over the Ganga Basin in winter. The layout of aerosol sources also nearly matched the spatial distribution of the Respirable Suspended Particulate Matter (RSPM), derived from the Central Pollution Control Board (CPCB) data, lending additional support to our inference.
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Xueref-Remy, I., C. Messager, D. Filippi, P. Nedelec, M. Ramonet, J. D. Paris und P. Ciais. „Variability and budget of CO<sub>2</sub> in Europe: analysis of the CAATER airborne campaigns – Part 1: Observed variability“. Atmospheric Chemistry and Physics Discussions 10, Nr. 2 (26.02.2010): 5665–716. http://dx.doi.org/10.5194/acpd-10-5665-2010.
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Abstract. Atmospheric airborne measurements of CO2 are very well-suited to estimate the time varying distribution of carbon sources and sinks at the regional scale. We present here an analysis of two cross-European airborne campaigns that have been carried out on 23–26 May 2001 (CAATER 1) and 2–3 October 2002 (CAATER 2) over Western Europe. The area covered during CAATER 1 (respectively CAATER 2) was comprised between longitude 4° W to 14° E and latitude 44° N to 52° N (respectively longitude 1° E to 17° E and latitude 46° N to 52° N). High precision in-situ CO2, CO and Radon 222 measurements have been recorded. Flasks samples have been collected during both campaigns to cross-validate the in-situ data. During CAATER 1 (respectively CAATER 2), the mean CO2 concentration was 370.1±4 ppm (respectively 371.7±5 ppm). A HYSPLIT backtrajectories analysis shows that during CAATER 1, dominant winds were blowing from the north-west. In the planetary boundary layer (PBL) airmasses got contaminated over Benelux and Western Germany by pollution from these high urbanized areas, reaching about 380 ppm. Air masses passing over rural areas are depleted in CO2 because of the photosynthesis activity of the land cover vegetation, as low as 355 ppm. During CAATER 2, the backtrajectory analysis shows that airmasses were distributed among the 4 sectors. Airmasses got enriched in CO2 and CO when passing above polluted spots in Germany but also in Poland, as these countries are known to hold part of the most polluting plants based on coal consumption, the so-called "dirty thirty" from WWF. Simultaneous measurements of in-situ CO2 and CO combined to backtrajectories helped us to discriminate the role of fossil fuel emissions from over CO2 sources. The ΔCO/ΔCO2 ratios (R2=0.33 to 0.88, slopes=2.42 to 10.37), calculated for polluted airmasses originating from different countries/regions, matched quite well national inventories, showing that the airborne measurements can help to identify the role of fossil fuel sources even several days/hundreds of kms further in the PBL. CO2 observations have been compared to surrounding ground stations measurements, confirming that the stations located near the ground (ex. CBW, WES, HUN) are representative of the local scale, while those located in the free troposphere (FT) are representative of atmospheric CO2 on a regional scale of a few hundred kilometers (ex. CMN). Stations located several 100 km away measure CO2 concentrations different from a few ppm, indicating the existence of a gradient of a few ppm in the free troposphere. Observations at stations located on top of small mountains (ex. SCH, PUY) match or not the airborne data whether they sample air from the FT or air coming up from the valley. Finally, the analysis of the CO2 vertical variability conducted on the 14 profiles recorded per campaign shows that is at least 5 to 8 times higher in the PBL (4 ppm and 5.7 ppm for CAATER 1 and CAATER 2, respectively) than in the FT (0.5 ppm and 1.1 ppm for CAATER 1 and CAATER 2, respectively). The CO2 jump between the PBL and the FT equals 3.7 ppm for the first campaign and −0.3 ppm for the second campaign. A very striking zonal CO2 gradient of about 11 ppm could be observed in the mid-troposphere during CAATER 2, with higher concentrations in the West than in the East. This gradient could originate from differences in atmospheric mixing, ground emission rates or a earlier beginning of the Fall in the west. More airborne campaigns are currently under analysis in the framework of the CARBOEUROPE-IP project to better assess the role of these different hypothesis. In a companion paper (Xueref-Remy et al., 2010), a comparison of vertical profiles from observations and several modeling frameworks is conducted for both campaigns. An attempt to calculate CO2 fluxes during CAATER 1 using CO2 and Radon-222 observations and modeling tools is also carried out.
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Arthur, Dan K., Sonia Lasher-Trapp, Ayman Abdel-Haleem, Nicholas Klosterman und David S. Ebert. „A New Three-Dimensional Visualization System for Combining Aircraft and Radar Data and Its Application to RICO Observations“. Journal of Atmospheric and Oceanic Technology 27, Nr. 5 (01.05.2010): 811–28. http://dx.doi.org/10.1175/2009jtecha1395.1.
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Abstract The analysis of diverse datasets from meteorological field campaigns often involves the use of separate 1D or combined 2D plots from various applications, making the determination of spatial and temporal relationships and correlations among these data, and the overall synthesis of information, extremely challenging. Presented here is a new 3D visualization tool, the Aircraft and Radar Data Collocation and Analysis in 3D (ARCA3D), that can combine data collected from different sources and at different scales, utilizing advanced visualization and user interface techniques, which allows for easier comparison and synthesis of such disparate data. The 3D tool is demonstrated with aircraft-based microphysical probe data and ground-based dual-polarization radar data all collected during the Rain in Cumulus over the Ocean (RICO) field campaign. The 3D volumes of radar data can be interactively selected and quantitatively probed, while aircraft-measured variables can be viewed along the aircraft track plotted within the 3D radar volumes or plotted as time series within regions of interest relative to the radar echoes. The greatest benefits of the new software, the 3D viewing of large radar and aircraft datasets with user-driven controls, are difficult to communicate here in a static, 2D written medium, but the application of the tool toward a research problem is presented to elucidate the impacts of these benefits. The ARCA3D software is used to investigate the possible role of giant aerosol particles in the development of precipitation in trade wind cumuli. The temporal trends in the spatial location of the maximum differential reflectivity echoes within the clouds are examined with respect to the ambient giant aerosol number concentration and the measured cloud-base droplet number concentrations on 10 days. The results indicate that in trade wind cumuli of sufficient depth, giant aerosol may determine the original location of the earliest differential reflectivity maximum echo, and thus the first raindrops when present in higher number concentrations. However, when the giant aerosol are less plentiful, the number of cloud droplets activated above the cloud base may also play a role in determining the location of the earliest maximum differential reflectivity echo, and thus the earliest raindrops, in these trade wind cumuli.
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Xueref-Remy, I., C. Messager, D. Filippi, M. Pastel, P. Nedelec, M. Ramonet, J. D. Paris und P. Ciais. „Variability and budget of CO<sub>2</sub> in Europe: analysis of the CAATER airborne campaigns – Part 1: Observed variability“. Atmospheric Chemistry and Physics 11, Nr. 12 (20.06.2011): 5655–72. http://dx.doi.org/10.5194/acp-11-5655-2011.
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Abstract. Atmospheric airborne measurements of CO2 are very well suited for estimating the time-varying distribution of carbon sources and sinks at the regional scale due to the large geographical area covered over a short time. We present here an analysis of two cross-European airborne campaigns carried out on 23–26 May 2001 (CAATER-1) and 2–3 October 2002 (CAATER-2) over Western Europe. The area covered during CAATER-1 and CAATER-2 was 4° W to 14° E long; 44° N to 52° N lat and 1° E to 17° E long; 46° N to 52° N lat respectively. High precision in situ CO2, CO and Radon 222 measurements were recorded. Flask samples were collected during both campaigns to cross-validate the in situ data. During CAATER-1 and CAATER-2, the mean CO2 concentration was 370.1 ± 4.0 (1-σ standard deviation) ppm and 371.7 ± 5.0 (1-σ) ppm respectively. A HYSPLIT back-trajectories analysis shows that during CAATER 1, northwesterly winds prevailed. In the planetary boundary layer (PBL) air masses became contaminated over Benelux and Western Germany by emissions from these highly urbanized areas, reaching about 380 ppm. Air masses passing over rural areas were depleted in CO2 because of the photosynthesis activity of the vegetation, with observations as low as 355 ppm. During CAATER-2, the back-trajectory analysis showed that air masses were distributed among the 4 sectors. Air masses were enriched in CO2 and CO over anthropogenic emission spots in Germany but also in Poland, as these countries have part of the most CO2-emitting coal-based plants in Europe. Simultaneous measurements of in situ CO2 and CO combined with back-trajectories helped us to distinguish between fossil fuel emissions and other CO2 sources. The ΔCO/ΔCO2 ratios (R2 = 0.33 to 0.88, slopes = 2.42 to 10.37), calculated for anthropogenic-influenced air masses over different countries/regions matched national inventories quite well, showing that airborne measurements can help to identify the origin of fossil fuel emissions in the PBL even when distanced by several days/hundreds of kms from their sources. We have compared airborne CO2 observations to nearby ground station measurements and thereby, confirmed that measurements taken in the lower few meters of the PBL (low-level ground stations) are representative of the local scale, while those located in the free troposphere (FT) (moutain stations) are representative of atmospheric CO2 regionally on a scale of a few hundred kilometers. Stations located several 100 km away from each other differ from a few ppm in their measurements indicating the existence of a gradient within the free troposphere. Observations at stations located on top of small mountains may match the airborne data if the sampled air comes from the FT rather than coming up from the valley. Finally, the analysis of the CO2 vertical variability conducted on the 14 profiles recorded in each campaign shows a variability at least 5 to 8 times higher in the PBL (the 1-σ standard deviation associated to the CO2 mean of all profiles within the PBL is 4.0 ppm and 5.7 ppm for CAATER-1 and CAATER-2, respectively) than in the FT (within the FT, 1-σ is 0.5 ppm and 1.1 ppm for CAATER-1 and CAATER-2, respectively). The CO2 jump between the PBL and the FT equals 3.7 ppm for the first campaign and −0.3 ppm for the second campaign. A very striking zonal CO2 gradient of about 11 ppm was observed in the mid-PBL during CAATER-2, with higher concentrations in the west than in the east. This gradient may originate from differences in atmospheric mixing, ground emission rates or Autumn's earlier start in the west. More airborne campaigns are currently under analysis in the framework of the CARBOEUROPE-IP project to better assess the likelihood of these different hypotheses. In a companion paper (Xueref-Remy et al., 2011, Part 2), a comparison of vertical profiles from observations and several modeling frameworks was conducted for both campaigns.
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Krishnamoorthy, Siddharth, Daniel Bowman, Emalee Hough, Zach Yap, John D. Wilding, Jamey Jacob, Brian R. Elbing et al. „Development of balloon-based seismology for venus through earth-analog experiments and simulations“. Journal of the Acoustical Society of America 153, Nr. 3_supplement (01.03.2023): A278. http://dx.doi.org/10.1121/10.0018837.
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Balloon-based seismology through the study of low-frequency seismo-acoustic signals (infrasound) has gained acceptance as a viable way to study seismic activity on Venus. Balloon-based barometers have the potential to detect and characterize atmospheric waves launched by venusquakes and volcanic eruptions while offering substantially longer instrument lifetimes in the Venus middle atmosphere, where temperature and pressure are significantly more benign (0–100°C, ∼1 atm) as compared to the surface (>460 °C, ∼90 atm). One of the major challenges in performing balloon-based seismology on Venus is the absence of ground-truth data for event identification and discrimination. To address this challenge, our activities are aimed at building a catalog of terrestrial balloon-recorded infrasound signals of geophysical provenance, using which signal predictions can be extended to Venus and the detectability of events can be analyzed. We will highlight our recently concluded Balloon-based Acoustic Seismology Study (BASS) flight campaign, which served as Earth-analog experiments for Venus balloon-based seismology. Data collected were used to validate seismo-acoustic simulation tools, which are being expanded to include the Venus atmosphere. These tools will used to generate predictions of infrasound signals from geophysical events on Venus. We will also provide perspective on directions for future instrument development for Venus balloon flights.
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Behrendt, Andreas, Volker Wulfmeyer, Hans-Stefan Bauer, Thorsten Schaberl, Paolo Di Girolamo, Donato Summa, Christoph Kiemle et al. „Intercomparison of Water Vapor Data Measured with Lidar during IHOP_2002. Part I: Airborne to Ground-Based Lidar Systems and Comparisons with Chilled-Mirror Hygrometer Radiosondes“. Journal of Atmospheric and Oceanic Technology 24, Nr. 1 (01.01.2007): 3–21. http://dx.doi.org/10.1175/jtech1924.1.
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Abstract The water vapor data measured with airborne and ground-based lidar systems during the International H2O Project (IHOP_2002), which took place in the Southern Great Plains during 13 May–25 June 2002 were investigated. So far, the data collected during IHOP_2002 provide the largest set of state-of-the-art water vapor lidar data measured in a field campaign. In this first of two companion papers, intercomparisons between the scanning Raman lidar (SRL) of the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) and two airborne systems are discussed. There are 9 intercomparisons possible between SRL and the differential absorption lidar (DIAL) of Deutsches Zentrum für Luft- und Raumfahrt (DLR), while there are 10 intercomparisons between SRL and the Lidar Atmospheric Sensing Experiment (LASE) of the NASA Langley Research Center. Mean biases of (−0.30 ± 0.25) g kg−1 or −4.3% ± 3.2% for SRL compared to DLR DIAL (DLR DIAL drier) and (0.16 ± 0.31) g kg−1 or 5.3% ± 5.1% for SRL compared to LASE (LASE wetter) in the height range of 1.3–3.8 km above sea level (450–2950 m above ground level at the SRL site) were found. Putting equal weight on the data reliability of the three instruments, these results yield relative bias values of −4.6%, −0.4%, and +5.0% for DLR DIAL, SRL, and LASE, respectively. Furthermore, measurements of the Snow White (SW) chilled-mirror hygrometer radiosonde were compared with lidar data. For the four comparisons possible between SW radiosondes and SRL, an overall bias of (−0.27 ± 0.30) g kg−1 or −3.2% ± 4.5% of SW compared to SRL (SW drier) again for 1.3–3.8 km above sea level was found. Because it is a challenging effort to reach an accuracy of humidity measurements down to the ∼5% level, the overall results are very satisfactory and confirm the high and stable performance of the instruments and the low noise errors of each profile.
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Clark, Jodie, und Sen Chiao. „A Case Study of Stratospheric Ozone Transport to the Northern San Francisco Bay Area and Sacramento Valley during CABOTS 2016“. Journal of Applied Meteorology and Climatology 58, Nr. 12 (Dezember 2019): 2675–97. http://dx.doi.org/10.1175/jamc-d-18-0322.1.
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AbstractThe California Baseline Ozone Transport Study (CABOTS) was a major air quality study that collected ozone measurements aloft between mid-May and mid-August of 2016. Aircraft measurements, ground-based lidar measurements, and balloon-borne ozonesondes collected precise upper-air ozone measurements across the central and Southern California valley. Utilizing daily ozonesonde data from Bodega Bay, California, and Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), reanalysis data for 25 July to 14 August 2016, three stratospheric intrusion events are identified over Northern California influencing air masses above Bodega Bay and Sacramento simultaneously. Calculated percent daily changes in afternoon ozonesonde observations indicate increasing ozone concentrations from the point of likely stratospheric air injection with the arrival of higher potential vorticity, confirmed by ensemble back trajectories. An analysis of the onsite surface monitoring ozone data indicates ozone increases in the observations for dates of plausible low-level stratospheric air influence. Further, a comparison of Bodega Bay surface ozone observations and 14 Sacramento Valley nonattainment zone surface sites show that the surface ozone observed at the higher-elevation surface sites in the lower Sierra Nevada foothills were positively correlated with elevated ozone captured by the ozonesondes within the lowest 0.5–1 km. The strongest correlations observed (~0.61) were between elevated Bodega Bay ozonesonde data and the Placerville (~612 m) afternoon surface ozone data, an indication that these regions separated by 200 km would be influence by the same ozone source. A comparison of daily changes in afternoon ozone show that the two locales often experience similar daily ozone increases or decreases. While this study leads to a basic quantification of stratospheric influence on surface ozone in the Sacramento nonattainment zone, a future campaign that examines ozone and winds aloft at both locales is suggested to improve the quantification of stratospheric ozone.
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Babić, Karmen, Bianca Adler, Norbert Kalthoff, Hendrik Andersen, Cheikh Dione, Fabienne Lohou, Marie Lothon und Xabier Pedruzo-Bagazgoitia. „The observed diurnal cycle of low-level stratus clouds over southern West Africa: a case study“. Atmospheric Chemistry and Physics 19, Nr. 2 (31.01.2019): 1281–99. http://dx.doi.org/10.5194/acp-19-1281-2019.
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Abstract. This study presents the first detailed observational analysis of the complete diurnal cycle of stratiform low-level clouds (LLC) and involved atmospheric processes over southern West Africa (SWA). The data used here were collected during the comprehensive DACCIWA (Dynamics-Aerosol-Chemistry-Cloud-Interactions in West Africa) ground-based campaign, which aimed at monitoring LLC characteristics and capturing the wide range of atmospheric conditions related to the West African monsoon flow. In this study, in situ and remote sensing measurements from the supersite near Savè (Benin) collected during a typical day, which is characterized by the onset of a nocturnal low-level jet (NLLJ) and the formation of LLC, are analyzed. The associated dynamic and thermodynamic conditions allow the identification of five different phases related to the LLC diurnal cycle: the stable, jet, stratus I, stratus II, and convective phases. The analysis of relative humidity tendency shows that cooling is a dominant process for LLC formation, which leads to a continuous increase in relative humidity at a maximum rate of 6 % h−1, until finally saturation is reached and LLC form with a cloud-base height near the height of NLLJ maximum. Results of heat budget analysis illustrate that horizontal cold-air advection, related to the maritime inflow, which brings the cool maritime air mass and a prominent NLLJ wind profile, has the dominant role in the observed strong cooling of −1.2 K h−1 during the jet phase. The contribution from horizontal cold advection is quantified to be up to 68 %, while radiative cooling and sensible heat flux divergence both contribute 16 % to the observed heat budget below the NLLJ maximum. After the LLC form (stratus phases I and II), turbulent mixing is an important factor leading to the cooling below the cloud base, while strong radiative cooling at the cloud top helps to maintain thick stratus.
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Senff, Christoph, Andrew Langford, Raul Alvarez, Tim Bonin, Alan Brewer, Aditya Choukulkar, Guillaume Kirgis et al. „Entrainment and Mixing of Transported Ozone Layers: Implications for Surface Air Quality in the Western U.S.“ EPJ Web of Conferences 237 (2020): 03012. http://dx.doi.org/10.1051/epjconf/202023703012.
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Recently, two air quality campaigns were conducted in the southwestern United States to study the impact of transported ozone, stratospheric intrusions, and fire emissions on ground-level ozone concentrations. The California Baseline Ozone Transport Study (CABOTS) took place in May – August 2016 covering the central California coast and San Joaquin Valley, and the Fires, Asian, and Stratospheric Transport Las Vegas Ozone Study (FAST-LVOS) was conducted in the greater Las Vegas, Nevada area in May – June 2017. During these studies, nearly 1000 hours of ozone and aerosol profile data were collected with the NOAA TOPAZ lidar. A Doppler wind lidar and a radar wind profiler provided continuous observations of atmospheric turbulence, horizontal winds, and mixed layer height. These measurements allowed us to directly observe the degree to which ozone transport layers aloft were entrained into the boundary layer and to quantify the resulting impact on surface ozone levels. Mixed layer heights in the San Joaquin Valley during CABOTS were generally below 1 km above ground level (AGL), while boundary layer heights in Las Vegas during FAST-LVOS routinely exceeded 3 km AGL and occasionally reached up to 4.5 km AGL. Consequently, boundary layer entrainment was more often observed during FAST-LVOS, while most elevated ozone layers passed untapped over the San Joaquin Valley during CABOTS.
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Billault-Roux, Anne-Claire, und Alexis Berne. „Integrated water vapor and liquid water path retrieval using a single-channel radiometer“. Atmospheric Measurement Techniques 14, Nr. 4 (08.04.2021): 2749–69. http://dx.doi.org/10.5194/amt-14-2749-2021.
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Abstract. Microwave radiometers are widely used for the retrieval of liquid water path (LWP) and integrated water vapor (IWV) in the context of cloud and precipitation studies. This paper presents a new site-independent retrieval algorithm for LWP and IWV, relying on a single-frequency 89 GHz ground-based radiometer. A statistical approach is used based on a neural network, which is trained and tested on a synthetic dataset constructed from radiosonde profiles worldwide. In addition to 89 GHz brightness temperature, the input features include surface measurements of temperature, pressure, and humidity, as well as geographical information and, when available, estimates of IWV and LWP from reanalysis data. An analysis of the algorithm is presented to assess its accuracy, the impact of the various input features, its sensitivity to radiometer calibration, and its stability across geographical locations. While 89 GHz brightness temperature is crucial to LWP retrieval, it only moderately contributes to IWV estimation, which is more constrained by the additional input features. The algorithm is shown to be quite robust, although its accuracy is inevitably lower than that obtained with state-of-the-art multi-channel radiometers, with a relative error of 18 % for LWP (in cloudy cases with LWP >30 g m−2) and 6.5 % for IWV. The highest accuracy is obtained in midlatitude environments with a moderately moist climate, which are more represented in the training dataset. The new method is then implemented and evaluated on real data that were collected during a field deployment in Switzerland and during the ICE-POP 2018 campaign in South Korea.
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Herzfeld, Ute C., Matthew Lawson, Thomas Trantow und Thomas Nylen. „Airborne Validation of ICESat-2 ATLAS Data over Crevassed Surfaces and Other Complex Glacial Environments: Results from Experiments of Laser Altimeter and Kinematic GPS Data Collection from a Helicopter over a Surging Arctic Glacier (Negribreen, Svalbard)“. Remote Sensing 14, Nr. 5 (27.02.2022): 1185. http://dx.doi.org/10.3390/rs14051185.
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The topic of this paper is the airborne evaluation of ICESat-2 Advanced Topographic Laser Altimeter System (ATLAS) measurement capabilities and surface-height-determination over crevassed glacial terrain, with a focus on the geodetical accuracy of geophysical data collected from a helicopter. To obtain surface heights over crevassed and otherwise complex ice surface, ICESat-2 data are analyzed using the density-dimension algorithm for ice surfaces (DDA-ice), which yields surface heights at the nominal 0.7 m along-track spacing of ATLAS data. As the result of an ongoing surge, Negribreen, Svalbard, provided an ideal situation for the validation objectives in 2018 and 2019, because many different crevasse types and morphologically complex ice surfaces existed in close proximity. Airborne geophysical data, including laser altimeter data (profilometer data at 905 nm frequency), differential Global Positioning System (GPS), Inertial Measurement Unit (IMU) data, on-board-time-lapse imagery and photographs, were collected during two campaigns in summers of 2018 and 2019. Airborne experiment setup, geodetical correction and data processing steps are described here. To date, there is relatively little knowledge of the geodetical accuracy that can be obtained from kinematic data collection from a helicopter. Our study finds that (1) Kinematic GPS data collection with correction in post-processing yields higher accuracies than Real-Time-Kinematic (RTK) data collection. (2) Processing of only the rover data using the Natural Resources Canada Spatial Reference System Precise Point Positioning (CSRS-PPP) software is sufficiently accurate for the sub-satellite validation purpose. (3) Distances between ICESat-2 ground tracks and airborne ground tracks were generally better than 25 m, while distance between predicted and actual ICESat-2 ground track was on the order of 9 m, which allows direct comparison of ice-surface heights and spatial statistical characteristics of crevasses from the satellite and airborne measurements. (4) The Lasertech Universal Laser System (ULS), operated at up to 300 m above ground level, yields full return frequency (400 Hz) and 0.06–0.08 m on-ice along-track spacing of height measurements. (5) Cross-over differences of airborne laser altimeter data are −0.172 ± 2.564 m along straight paths, which implies a precision of approximately 2.6 m for ICESat-2 validation experiments in crevassed terrain. (6) In summary, the comparatively light-weight experiment setup of a suite of small survey equipment mounted on a Eurocopter (Helicopter AS-350) and kinematic GPS data analyzed in post-processing using CSRS-PPP leads to high accuracy repeats of the ICESat-2 tracks. The technical results (1)–(6) indicate that direct comparison of ice-surface heights and crevasse depths from the ICESat-2 and airborne laser altimeter data is warranted. Numerical evaluation of height comparisons utilizes spatial surface roughness measures. The final result of the validation is that ICESat-2 ATLAS data, analyzed with the DDA-ice, facilitate surface-height determination over crevassed terrain, in good agreement with airborne data, including spatial characteristics, such as surface roughness, crevasse spacing and depth, which are key informants on the deformation and dynamics of a glacier during surge.
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Jurin, Suzana, und Daniela Kružić. „Cognitive framing through political catchwords“. Ars & Humanitas 14, Nr. 1 (23.06.2020): 89–103. http://dx.doi.org/10.4312/ars.14.1.89-103.
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The Croatian political scene is undergoing radical changes. Since the 2016 parliamentary election, the left-wing has gradually lost ground. One of the key roles in the political process is played by the media, which influence the voters and their choices. In this paper we analysed written texts collected during the 2016 election campaign. Among the most prominent Croatian newspapers the left-wing Novi list and the right-wing Večernji list are chosen as the focal publications. We conducted a text linguistic analysis of the political catchword (phrase, slogan) and its role in creating the political opinions of voters. The analysis provided data about the verbal, nonverbal and paraverbal text segments. These phenomena were abstracted as communicational-pragmatic and language-stylistic entities which are necessary for the successful cognitive framing of the political opinions of the public. In order to create and frame political opinions, the text producer uses subtle persuasive messages. Furthermore, at the content-related level of the text structure analysis, the communicative intention of the producer is shown, while the text function analysis shows the most common text indicators used to transmit the desired content and identifies a potential persuasive message “hidden” in the words. As a result, the number of catchwords published in line with each newspaper’s own political orientation is slightly higher than that of the other option, which shows that political neutrality is lacking in the Croatian media.
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Weide Luiz, Eduardo, und Stephanie Fiedler. „Spatiotemporal observations of nocturnal low-level jets and impacts on wind power production“. Wind Energy Science 7, Nr. 4 (22.07.2022): 1575–91. http://dx.doi.org/10.5194/wes-7-1575-2022.
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Abstract. A challenge of an energy system that nowadays more strongly depends on wind power generation is the spatial and temporal variability in winds. Nocturnal low-level jets (NLLJs) are typical wind phenomena defined as a maximum in the vertical profile of the horizontal wind speed. A NLLJ has typical core heights of 50–500 m a.g.l. (above ground level), which is in the height range of most modern wind turbines. This study presents NLLJ analyses based on new observations from Doppler wind lidars. The aim is to characterize the temporal and spatial variability in NLLJs on the mesoscale and to quantify their impacts on wind power generation. The data were collected during the Field Experiment on Submesoscale Spatio-Temporal Variability (FESSTVaL) campaign from June to August 2020 in Lindenberg and Falkenberg (Germany), located at about 6 km from each other. Both sites have seen NLLJs in about 70 % of the nights with half of them lasting for more than 3 h. Events longer than 6 h occurred more often simultaneously at both sites than shorter events, indicating the mesoscale character of very long NLLJs. Very short NLLJs of less than 1 h occurred more often in Lindenberg than Falkenberg, indicating more local influences on the wind profile. We discussed different meteorological mechanisms for NLLJ formation and linked NLLJ occurrences to synoptic weather patterns. There were positive and negative impacts of NLLJs on wind power that we quantified based on the observational data. NLLJs increased the mean power production by up to 80 % and were responsible for about 25 % of the power potential during the campaign. However, the stronger shear in the rotor layer during NLLJs can also have negative impacts. The impacts of NLLJs on wind power production depended on the relative height between the wind turbine and the core of the NLLJ. For instance, the mean increase in the estimated power production during NLLJ events was about 30 % higher for a turbine at 135 m a.g.l. compared to one at 94 m a.g.l. Our results imply that long NLLJs have an overall stronger impact on the total power production, while short events are primarily relevant as drivers for power ramps.
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Nikolakopoulos, Konstantinos G., Aggeliki Kyriou, Ioannis K. Koukouvelas, Nikolaos Tomaras und Epameinondas Lyros. „UAV, GNSS, and InSAR Data Analyses for Landslide Monitoring in a Mountainous Village in Western Greece“. Remote Sensing 15, Nr. 11 (31.05.2023): 2870. http://dx.doi.org/10.3390/rs15112870.
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Areas in Western Greece are particularly prone to landslides. Usually triggered by earthquakes or intense rainfalls, they cause damage to infrastructure (roads, bridges, etc.) and human properties. Hence, there is an urgent need for the implementation of monitoring and landslide prevention methodologies. In the last years, Unmanned Aerial Vehicles (UAVs), Global Navigation Satellite Systems (GNSS), and Interferometric SAR (InSAR) techniques have been applied for landslide mapping and monitoring. The current study focuses on the systematic and long-term analysis of a landslide that occurred in Ano Kerassovo village, within the region of Western Greece. To precisely measure the current evolution of the landslide, we performed repetitive UAV campaigns in conjunction with corresponding GNSS surveys, covering a time period between February 2021 and April 2023. The identification of surface modification was based on a change detection approach between the generated point clouds. The results are validated through GNSS measurements and field observations. Added to this, we collected archived Persistent Scatterer Interferometry (PSI) measurements derived from the European Ground Motion Service (EGMS) to extend the observation period and gain a more complete understanding of the phenomenon. It is proven that archived PSI measurements can be used as an indicator of possible landslide initialization points and for small-scale large coverage investigations, while UAVs and GNSS data can precisely identify the microscale deformations (centimeter scale).
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Porcacchia, Leonardo, P. E. Kirstetter, J. J. Gourley, V. Maggioni, B. L. Cheong und M. N. Anagnostou. „Toward a Polarimetric Radar Classification Scheme for Coalescence-Dominant Precipitation: Application to Complex Terrain“. Journal of Hydrometeorology 18, Nr. 12 (01.12.2017): 3199–215. http://dx.doi.org/10.1175/jhm-d-17-0016.1.
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Abstract Accurate quantitative precipitation estimation over mountainous basins is of great importance because of their susceptibility to natural hazards. It is generally difficult to obtain reliable precipitation information over complex areas because of the scarce coverage of ground observations, the limited coverage from operational radar networks, and the high elevation of the study sites. Warm-rain processes have been observed in several flash flood events in complex terrain regions. While they lead to high rainfall rates from precipitation growth due to collision–coalescence of droplets in the cloud liquid layer, their characteristics are often difficult to identify. X-band mobile dual-polarization radars located in complex terrain areas provide fundamental information at high-resolution and at low atmospheric levels. This study analyzes a dataset collected in North Carolina during the 2014 Integrated Precipitation and Hydrology Experiment (IPHEx) field campaign over a mountainous basin where the NOAA/National Severe Storm Laboratory’s X-band polarimetric radar (NOXP) was deployed. Polarimetric variables are used to isolate collision–coalescence microphysical processes. This work lays the basis for classification algorithms able to identify coalescence-dominant precipitation by merging the information coming from polarimetric radar measurements. The sensitivity of the proposed classification scheme is tested with different rainfall-rate retrieval algorithms and compared to rain gauge observations. Results show the inadequacy of rainfall estimates when coalescence identification is not taken into account. This work highlights the necessity of a correct classification of collision–coalescence processes, which can lead to improvements in quantitative precipitation estimation. Future studies will aim at generalizing this scheme by making use of spaceborne radar data.
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Schäfer, Michael, Eike Bierwirth, André Ehrlich, Evelyn Jäkel, Frank Werner und Manfred Wendisch. „Directional, horizontal inhomogeneities of cloud optical thickness fields retrieved from ground-based and airbornespectral imaging“. Atmospheric Chemistry and Physics 17, Nr. 3 (15.02.2017): 2359–72. http://dx.doi.org/10.5194/acp-17-2359-2017.
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Abstract. Clouds exhibit distinct horizontal inhomogeneities of their optical and microphysical properties, which complicate their realistic representation in weather and climate models. In order to investigate the horizontal structure of cloud inhomogeneities, 2-D horizontal fields of optical thickness (τ) of subtropical cirrus and Arctic stratus are investigated with a spatial resolution of less than 10 m. The 2-D τ-fields are derived from (a) downward (transmitted) solar spectral radiance measurements from the ground beneath four subtropical cirrus and (b) upward (reflected) radiances measured from aircraft above 10 Arctic stratus. The data were collected during two field campaigns: (a) Clouds, Aerosol, Radiation, and tuRbulence in the trade wind regime over BArbados (CARRIBA) and (b) VERtical Distribution of Ice in Arctic clouds (VERDI). One-dimensional and 2-D autocorrelation functions, as well as power spectral densities, are derived from the retrieved τ-fields. The typical spatial scale of cloud inhomogeneities is quantified for each cloud case. Similarly, the scales at which 3-D radiative effects influence the radiance field are identified. In most of the investigated cloud cases considerable cloud inhomogeneities with a prevailing directional structure are found. In these cases, the cloud inhomogeneities favour a specific horizontal direction, while across this direction the cloud is of homogeneous character. The investigations reveal that it is not sufficient to quantify horizontal cloud inhomogeneities using 1-D inhomogeneity parameters; 2-D parameters are necessary.
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Hruška, J., T. Adão, L. Pádua, N. Guimarães, E. Peres, R. Morais und J. J. Sousa. „EVALUATION OF MACHINE LEARNING TECHNIQUES IN VINE LEAVES DISEASE DETECTION: A PRELIMINARY CASE STUDY ON FLAVESCENCE DORÉE“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W8 (21.08.2019): 151–56. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w8-151-2019.
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<p><strong>Abstract.</strong> Vine culture is influenced by many factors, such as the weather, soil or topography, which are triggers to phytosanitary issues. Among them are some diseases, that are responsible for major economic losses that can, however, be managed with timely interventions in the field, viable of leading to effective results by preventing damage propagation. While not all symptoms might present a visible evidence, hyperspectral sensors can tackle this aspect with their ability for measuring hundreds of continuously sparse bands that range beyond the eye-perceptible spectrum. Having such research line in mind in this work, a hyperspectral sensor was applied to analyse the spectral status of vine leaves samples, collected in three chronologically distinct campaigns, while costly and destructive laboratory methods were used to track Flavescence Dorée (FD) in the same samples, for a ground truth information. Regarding data processing, machine learning approaches were used, in which several classifiers were selected to detect FD in vine leaves hyperspectral images. The goal was to evaluate and find most suitable classifier for this task.</p>
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Petters, Markus D. „Revisiting matrix-based inversion of scanning mobility particle sizer (SMPS) and humidified tandem differential mobility analyzer (HTDMA) data“. Atmospheric Measurement Techniques 14, Nr. 12 (21.12.2021): 7909–28. http://dx.doi.org/10.5194/amt-14-7909-2021.
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Abstract. Tikhonov regularization is a tool for reducing noise amplification during data inversion. This work introduces RegularizationTools.jl, a general-purpose software package for applying Tikhonov regularization to data. The package implements well-established numerical algorithms and is suitable for systems of up to ∼ 1000 equations. Included is an abstraction to systematically categorize specific inversion configurations and their associated hyperparameters. A generic interface translates arbitrary linear forward models defined by a computer function into the corresponding design matrix. This obviates the need to explicitly write out and discretize the Fredholm integral equation, thus facilitating fast prototyping of new regularization schemes associated with measurement techniques. Example applications include the inversion involving data from scanning mobility particle sizers (SMPSs) and humidified tandem differential mobility analyzers (HTDMAs). Inversion of SMPS size distributions reported in this work builds upon the freely available software DifferentialMobilityAnalyzers.jl. The speed of inversion is improved by a factor of ∼ 200, now requiring between 2 and 5 ms per SMPS scan when using 120 size bins. Previously reported occasional failure to converge to a valid solution is reduced by switching from the L-curve method to generalized cross-validation as the metric to search for the optimal regularization parameter. Higher-order inversions resulting in smooth, denoised reconstructions of size distributions are now included in DifferentialMobilityAnalyzers.jl. This work also demonstrates that an SMPS-style matrix-based inversion can be applied to find the growth factor frequency distribution from raw HTDMA data while also accounting for multiply charged particles. The outcome of the aerosol-related inversion methods is showcased by inverting multi-week SMPS and HTDMA datasets from ground-based observations, including SMPS data obtained at Bodega Marine Laboratory during the CalWater 2/ACAPEX campaign and co-located SMPS and HTDMA data collected at the US Department of Energy observatory located at the Southern Great Plains site in Oklahoma, USA. Results show that the proposed approaches are suitable for unsupervised, nonparametric inversion of large-scale datasets as well as inversion in real time during data acquisition on low-cost reduced-instruction-set architectures used in single-board computers. The included software implementation of Tikhonov regularization is freely available, general, and domain-independent and thus can be applied to many other inverse problems arising in atmospheric measurement techniques and beyond.
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Burkhardt, J., C. R. Flechard, F. Gresens, M. Mattsson, P. A. C. Jongejan, J. W. Erisman, T. Weidinger, R. Meszaros, E. Nemitz und M. A. Sutton. „Modelling the dynamic chemical interactions of atmospheric ammonia with leaf surface wetness in a managed grassland canopy“. Biogeosciences 6, Nr. 1 (13.01.2009): 67–84. http://dx.doi.org/10.5194/bg-6-67-2009.
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Abstract. Ammonia exchange fluxes between grassland and the atmosphere were modelled on the basis of stomatal compensation points and leaf surface chemistry, and compared with measured fluxes during the GRAMINAE intensive measurement campaign in spring 2000 near Braunschweig, Germany. Leaf wetness and dew chemistry in grassland were measured together with ammonia fluxes and apoplastic NH4+ and H+ concentration, and the data were used to apply, validate and further develop an existing model of leaf surface chemistry and ammonia exchange. Foliar leaf wetness which is known to affect ammonia fluxes may be persistent after the end of rainfall, or sustained by recondensation of water vapour originating from the ground or leaf transpiration, so measured leaf wetness values were included in the model. pH and ammonium concentrations of dew samples collected from grass were compared to modelled values. The measurement period was divided into three phases: a relatively wet phase followed by a dry phase in the first week before the grass was cut, and a second drier week after the cut. While the first two phases were mainly characterised by ammonia deposition and occasional short emission events, regular events of strong ammonia emissions were observed during the post-cut period. A single-layer resistance model including dynamic cuticular and stomatal exchange could describe the fluxes well before the cut, but after the cut the stomatal compensation points needed to numerically match measured fluxes were much higher than the ones measured by bioassays, suggesting another source of ammonia fluxes. Considerably better agreement both in the direction and the size range of fluxes were obtained when a second layer was introduced into the model, to account for the large additional ammonia source inherent in the leaf litter at the bottom of the grass canopy. Therefore, this was found to be a useful extension of the mechanistic dynamic chemistry model by keeping the advantage of requiring relatively little site-specific information.
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Ninh Nguyen, Gia, und Thi Thu Hong Ho. „Interplay between subjective norm, emotions, and purchase intention towards foreign brands: Evidence from Vietnam“. Innovative Marketing 18, Nr. 1 (10.02.2022): 79–93. http://dx.doi.org/10.21511/im.18(1).2022.07.
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Understanding the mechanisms through which social groups impact consumers’ purchase decisions is of particular interest to scholars and practitioners. The purpose of this study is to contribute to the cognitive-affective model by examining the roles of the subjective norm and its contingency factors in the cognitive-affective model and the indigenous consumers’ purchase intention towards a foreign footwear brand. The validity of the model is tested using data collected from 257 Vietnamese consumers. The results of PLS-SEM and SPSS Macro PROCESS reveal that subjective norm positively influences the emotional value (β = 0.219, p = 0.002) and perceived quality (β = 0.239, p = 0.000) for the foreign brand. In addition, face consciousness positively moderates the indirect effects of subjective norm on purchase intention through emotional value (β = 0.08; LLCI = 0.02; ULCI = 0.13) while the moderating effect of perceived behavioral control is significantly negative (β = –0.1074; LLCI = -0.182; ULCI = –0.05). In conclusion, this study can offer insight into the roles of social groups and their contingency factors in the cognitive-affective model and purchase intention. On this ground, managers of foreign brands are advised to focus on the impacts of social groups in their marketing campaigns, together with underlining the social status and superbness of their offerings to attract new consumers. Acknowledgment We would like to thank the University of Finance-Marketing for their funding.
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Malbéteau, Yoann, Stephen Parkes, Bruno Aragon, Jorge Rosas und Matthew McCabe. „Capturing the Diurnal Cycle of Land Surface Temperature Using an Unmanned Aerial Vehicle“. Remote Sensing 10, Nr. 9 (05.09.2018): 1407. http://dx.doi.org/10.3390/rs10091407.
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Characterizing the land surface temperature (LST) and its diurnal cycle is important in understanding a range of surface properties, including soil moisture status, evaporative response, vegetation stress and ground heat flux. While remote-sensing platforms present a number of options to retrieve this variable, there are inevitable compromises between the resolvable spatial and temporal resolution. For instance, the spatial resolution of geostationary satellites, which can provide sub-hourly LST, is often too coarse (3 km) for many applications. On the other hand, higher-resolution polar orbiting satellites are generally infrequent in time, with return intervals on the order of weeks, limiting their capacity to capture surface dynamics. With recent developments in the application of unmanned aerial vehicles (UAVs), there is now the opportunity to collect LST measurements on demand and at ultra-high spatial resolution. Here, we detail the collection and analysis of a UAV-based LST dataset, with the purpose of examining the diurnal surface temperature response: something that has not been possible from traditional satellite platforms at these scales. Two separate campaigns were conducted over a bare desert surface in combination with either Rhodes grass or a recently harvested maize field. In both cases, thermal imagery was collected between 0800 and 1700 local solar time. The UAV-based diurnal cycle was consistent with ground-based measurements, with a mean correlation coefficient and root mean square error (RMSE) of 0.99 and 0.68 °C, respectively. LST retrieved over the grass surface presented the best results, with an RMSE of 0.45 °C compared to 0.67 °C for the single desert site and 1.28 °C for the recently harvested maize surface. Even considering the orders of magnitude difference in scale, an exploratory analysis comparing retrievals of the UAV-based diurnal cycle with METEOSAT geostationary data yielded pleasing results (R = 0.98; RMSE = 1.23 °C). Overall, our analysis revealed a diurnal range over the desert and maize surfaces of ~20 °C and ~17 °C respectively, while the grass showed a reduced amplitude of ~12 °C. Considerable heterogeneity was observed over the grass surface at the peak of the diurnal cycle, which was likely indicative of the varying crop water status. To our knowledge, this study presents the first spatially varying analysis of the diurnal LST captured at ultra-high resolution, from any remote platform. Our findings highlight the considerable potential to utilize UAV-based retrievals to enhance investigations across multi-disciplinary studies in agriculture, hydrology and land-atmosphere investigations.
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Ehrlich, André, Eike Bierwirth, Larysa Istomina und Manfred Wendisch. „Combined retrieval of Arctic liquid water cloud and surface snow properties using airborne spectral solar remote sensing“. Atmospheric Measurement Techniques 10, Nr. 9 (04.09.2017): 3215–30. http://dx.doi.org/10.5194/amt-10-3215-2017.
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Abstract. The passive solar remote sensing of cloud properties over highly reflecting ground is challenging, mostly due to the low contrast between the cloud reflectivity and that of the underlying surfaces (sea ice and snow). Uncertainties in the retrieved cloud optical thickness τ and cloud droplet effective radius reff, C may arise from uncertainties in the assumed spectral surface albedo, which is mainly determined by the generally unknown effective snow grain size reff, S. Therefore, in a first step the effects of the assumed snow grain size are systematically quantified for the conventional bispectral retrieval technique of τ and reff, C for liquid water clouds. In general, the impact of uncertainties of reff, S is largest for small snow grain sizes. While the uncertainties of retrieved τ are independent of the cloud optical thickness and solar zenith angle, the bias of retrieved reff, C increases for optically thin clouds and high Sun. The largest deviations between the retrieved and true original values are found with 83 % for τ and 62 % for reff, C. In the second part of the paper a retrieval method is presented that simultaneously derives all three parameters (τ, reff, C, reff, S) and therefore accounts for changes in the snow grain size. Ratios of spectral cloud reflectivity measurements at the three wavelengths λ1 = 1040 nm (sensitive to reff, S), λ2 = 1650 nm (sensitive to τ), and λ3 = 2100 nm (sensitive to reff, C) are combined in a trispectral retrieval algorithm. In a feasibility study, spectral cloud reflectivity measurements collected by the Spectral Modular Airborne Radiation measurement sysTem (SMART) during the research campaign Vertical Distribution of Ice in Arctic Mixed-Phase Clouds (VERDI, April/May 2012) were used to test the retrieval procedure. Two cases of observations above the Canadian Beaufort Sea, one with dense snow-covered sea ice and another with a distinct snow-covered sea ice edge are analysed. The retrieved values of τ, reff, C, and reff, S show a continuous transition of cloud properties across snow-covered sea ice and open water and are consistent with estimates based on satellite data. It is shown that the uncertainties of the trispectral retrieval increase for high values of τ, and low reff, S but nevertheless allow the effective snow grain size in cloud-covered areas to be estimated.
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Ayikwa, Lutete Christian, Johan W. De Jager und Dion Van Zyl. „Validating the Theory of Planned Behavior Model Extended to Social Marketing Behavioral Enhancers Using Structural Equation Modeling“. Social Marketing Quarterly 26, Nr. 4 (28.08.2020): 276–96. http://dx.doi.org/10.1177/1524500420951593.
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Background: This study addresses the HIV/AIDS epidemic that constitutes a major health issue in South Africa, the country most burdened by the virus in the world. Focus of the Article: It is an empirical study that investigates predictive behavioral patterns between traditional components of the theory of planned behavior and the previously identified social marketing behavioral enhancers and intentions to perform preventative sexual behaviors promoted under the Abstinence, Being faithful, and Condomize campaign. Research Question: The main question this study attempts to answer is: Is it relevant to increase the theory of planned behavior components by incorporating the social marketing behavioral enhancers’ variables to design programs that successfully influence individuals to adhere to the preventative sexual behaviors? Importance to the Social Marketing Field: Results will tell social marketers, through design programs fighting the spread of the HIV set within a theory of planned behavior theoretical framework, which of the social marketing behavioral enhancers are worth integrating into their model to induce behavioral change. Methods: Theory of planned behavior models extended to social marketing behavioral enhancers for abstinence, faithfulness, and condom use were used as theoretical frameworks to test how well they are good fits of the empirically manifested structural models. Gauteng was chosen, because three of the five metropolitan municipalities with a HIV prevalence greater than 10% are located in this province. Data were collected by means of questionnaires administered to a sample chosen randomly, using a multi-stage stratification method. A quota was determined for each suburb or city considered according to the size of its population compared to the overall Gauteng population to ensure representativeness of the study’s sample. Results: The study’s theoretical frameworks fitted the data well, but results also revealed insignificant causal relationships between HIV/AIDS knowledge and all Abstinence–Being faithful–Condomize intentions. Similarly, no predictive relationships were found between accessibility to HIV/AIDS information and intention to use condoms, while attitudes toward abstinence and condom use were insignificant with their respective intentions. However, their positive correlations with predictive variables suggest that they influence intentions indirectly. Recommendation for Research: Researchers are invited to conduct further studies to test the model in a different context. Indeed, this study does not investigate whether relationships between HIV/AIDS knowledge, accessibility to HIV/AIDS information, and attitudes toward abstinence and condom use would remain insignificant or that it could not change over time in a research ground other than Gauteng. Opportunities should be explored to augment the traditional theory of planned behavior components by variables other than the social marketing behavioral enhancers, in order to build a more robust model that will incorporate more significant factors to design successful programs. Limitations: Collecting data from only one province constitutes a limitation in terms of drawing conclusions for the whole South African population.
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Demir, Ibrahim, Helen Conover, Witold F. Krajewski, Bong-Chul Seo, Radosław Goska, Yubin He, Michael F. McEniry, Sara J. Graves und Walter Petersen. „Data-Enabled Field Experiment Planning, Management, and Research Using Cyberinfrastructure“. Journal of Hydrometeorology 16, Nr. 3 (27.05.2015): 1155–70. http://dx.doi.org/10.1175/jhm-d-14-0163.1.
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Abstract In the spring of 2013, NASA conducted a field campaign known as Iowa Flood Studies (IFloodS) as part of the Ground Validation (GV) program for the Global Precipitation Measurement (GPM) mission. The purpose of IFloodS was to enhance the understanding of flood-related, space-based observations of precipitation processes in events that transpire worldwide. NASA used a number of scientific instruments such as ground-based weather radars, rain and soil moisture gauges, stream gauges, and disdrometers to monitor rainfall events in Iowa. This article presents the cyberinfrastructure tools and systems that supported the planning, reporting, and management of the field campaign and that allow these data and models to be accessed, evaluated, and shared for research. The authors describe the collaborative informatics tools, which are suitable for the network design, that were used to select the locations in which to place the instruments. How the authors used information technology tools for instrument monitoring, data acquisition, and visualizations after deploying the instruments and how they used a different set of tools to support data analysis and modeling after the campaign are also explained. All data collected during the campaign are available through the Global Hydrology Resource Center (GHRC), a NASA Distributed Active Archive Center (DAAC).
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Geerts, Bart, Binod Pokharel, Katja Friedrich, Daniel Breed, Roy Rasmussen, Yang Yang, Qun Miao, Samuel Haimov, Bruce Boe und Evan Kalina. „The AgI Seeding Cloud Impact Investigation (ASCII) campaign 2012: overview and preliminary results“. Journal of Weather Modification 45, Nr. 1 (30.03.2013): 24–43. http://dx.doi.org/10.54782/jwm.v45i1.121.
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The ASCII campaign was conducted in early 2012 over the Sierra Madre, a Continental Divide range in Wyoming, to examine cloud microphysical changes resulting from the ground-based injection of silver iodide (AgI) into shallow orographic clouds. The campaign included a dual-polarization Doppler-On-Wheels radar on the mountain pass, the University of Wyoming King Air aircraft with profiling mm-wave radar and polarization backscatter lidar, two Ka-band profiling radars, one upstream of the AgI generators, and one downstream, and a number of instruments on the ground to characterize the cloud liquid water content and the in situ snow particle characteristics. The experimental design supported both simultaneous (upstream/ downstream) and non-simultaneous (before/ during) comparisons, in order to tease out the impact of glaciogenic seeding on cloud and precipitation. Unfortunately, suitably cold cloud base temperatures rarely occurred during the campaign. Nevertheless, profiling radar data collected on flights with a no-seeding period followed by a seeding period, as well as simultaneous ground-based profiling radar data, indicate that under suitable conditions AgI seeding can significantly increase radar reflectivity in the boundary layer, and thus snowfall rate near the ground.
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Klebe, D. I., R. D. Blatherwick und V. R. Morris. „Ground-based all-sky mid-infrared and visible imagery for purposes of characterizing cloud properties“. Atmospheric Measurement Techniques Discussions 6, Nr. 4 (29.08.2013): 7985–8019. http://dx.doi.org/10.5194/amtd-6-7985-2013.
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Abstract. This paper describes the All Sky Infrared Visible Analyzer (ASIVA), a multi-purpose visible and infrared sky imaging and analysis instrument whose primary function is to provide radiometrically calibrated imagery in the mid-infrared (mid-IR) atmospheric window. This functionality enables the determination of diurnal hemispherical cloud fraction (HCF) and estimates of sky/cloud temperature from which one can derive estimates of cloud emissivity and cloud height. This paper describes the calibration methods and performance of the ASIVA instrument with particular emphasis on data products being developed for the meteorological community. Data presented here were collected during a field campaign conducted at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Climate Research Facility from 21 May to 27 July 2009. The purpose of this campaign was to determine the efficacy of IR technology in providing reliable nighttime HCF data. Significant progress has been made in the analysis of the campaign data over the past several years and the ASIVA has proven to be an excellent instrument for determining HCF as well as several other important cloud properties.
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Klebe, D. I., R. D. Blatherwick und V. R. Morris. „Ground-based all-sky mid-infrared and visible imagery for purposes of characterizing cloud properties“. Atmospheric Measurement Techniques 7, Nr. 2 (24.02.2014): 637–45. http://dx.doi.org/10.5194/amt-7-637-2014.
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Abstract. This paper describes the All Sky Infrared Visible Analyzer (ASIVA), a multi-purpose visible and infrared sky imaging and analysis instrument whose primary function is to provide radiometrically calibrated imagery in the mid-infrared (mid-IR) atmospheric window. This functionality enables the determination of diurnal fractional sky cover and estimates of sky/cloud temperature from which one can derive estimates of sky/cloud emissivity and cloud height. This paper describes the calibration methods and performance of the ASIVA instrument with particular emphasis on data products being developed for the meteorological community. Data presented here were collected during the Solmirus' ASIVA campaign conducted at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Climate Research Facility from 21 May to 27 July 2009. The purpose of this campaign was to determine the efficacy of IR technology in providing reliable nighttime sky cover data. Significant progress has been made in the analysis of the campaign data over the past several years and the ASIVA has proven to be an excellent instrument for determining sky cover as well as the potential for determining sky/cloud temperature, sky/cloud emissivity, precipitable water vapor (PWV), and ultimately cloud height.
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Lee, SeungJae, SunGu Lee und Dongryeol Ryu. „Ground-based data from wheat cropping fields in Australia for development of soil moisture retrieval algorithm using satelliteimages“. GEO DATA 2, Nr. 2 (31.12.2020): 1–4. http://dx.doi.org/10.22761/dj2020.2.2.001.
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Soil moisture is an important data which can be used for crop growth estimation, drought prediction, irrigation, and development of hydrological model. However, it is difficult to obtain soil moisture data from inaccessible area or very large area using only general field campaign. For this reason, many soil moisture retrieval algorithms have been developed based on satellite remote sensing technique. It should be noted that both satellite images and ground-based data for the region of interest are required to effectively develop the soil moisture retrieval algorithm using satellite images. Thus, Korea aerospace research institute, KARI, have collected ground-based data containing soil moisture, soil temperature, and crop height in collaboration with the university of Melbourne from wheat cropping fields in Australia which are suitable for the development of soil moisture retrieval algorithm. The ground-based data was collected from wheat cropping fields containing various types of soils for about 7 months from May 2019 to November 2019.
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Silvestri, Malvina, Federico Rabuffi, Antonino Pisciotta, Massimo Musacchio, Iole Diliberto, Claudia Spinetti, Valerio Lombardo, Laura Colini und Maria Buongiorno. „Analysis of Thermal Anomalies in Volcanic Areas Using Multiscale and Multitemporal Monitoring: Vulcano Island Test Case“. Remote Sensing 11, Nr. 2 (11.01.2019): 134. http://dx.doi.org/10.3390/rs11020134.
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Surface temperatures derived by 208 ASTER and L8 satellite imagery were analysed to test multiscale and multitemporal capability through available sets of thermal data to support the volcanic monitoring of Vulcano Island in Italy. The analysis of thermal historical series derived by ASTER and L8 shows that two are the main thermally active areas: La Fossa crater and the mud pool of Fangaia. In this work we aimed to assess the correlation between the satellite-retrieved temperatures with those measured during the daytime ground field campaign conducted within the same time period and, in particular cases, simultaneously. Moreover, nighttime data acquired by an airborne and field campaign were processed with the same methodology applied to satellite data for a multiscale approach verification. Historical meteorological data acquired from a weather station were also considered. Statistically significant correlations were observed between nighttime acquisitions and meteorological data. Correlations were also significant for temperature measured during the airborne campaign, while differences up to 50% with daytime acquisition during the ground field campaigns were observed. The analysis of the results suggests that within nighttime data acquisition, differences between satellite-derived temperatures and ground temperature measurements are considerably reduced; therefore nighttime data acquisition is recommended to detect thermal anomalies.
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Billault-Roux, Anne-Claire, Jacopo Grazioli, Julien Delanoë, Susana Jorquera, Nicolas Pauwels, Nicolas Viltard, Audrey Martini et al. „ICE GENESIS: Synergetic Aircraft and Ground-Based Remote Sensing and In Situ Measurements of Snowfall Microphysical Properties“. Bulletin of the American Meteorological Society 104, Nr. 2 (Februar 2023): E367—E388. http://dx.doi.org/10.1175/bams-d-21-0184.1.
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Abstract An international field experiment took place in the Swiss Jura in January 2021 as a milestone of the European ICE GENESIS project (www.ice-genesis.eu/), which aims to better measure, understand, and model the ice/snow particle properties and mechanisms responsible for icing of rotor-craft and aircraft. The field campaign was designed to collect observations of clouds and snowfall at a prescribed range of temperatures (−10° to +2°C). The suite of in situ and remote sensing instruments included airborne probes and imagers on board a SAFIRE ATR-42 aircraft, able to sample liquid and ice particles from the micron to the millimeter size range, as well as icing sensors and cameras. Two 95 GHz Doppler cloud radars were installed on the SAFIRE ATR-42, while six Doppler weather radars operating at frequencies ranging from 10 to 95 GHz (and one lidar) were ground based. An operational polarimetric weather radar in nearby France (Montancy) complements the coverage. Finally, observations of standard meteorological variables as well as high-resolution pictures of falling snowflakes from a multiangle snowflake camera were collected at the ground level. The campaign showed its full potential during five (multihourly) flights where precipitation was monitored from cloud to ground. The originality of this campaign resides in the targeted specific temperature range for snowfall and in the synchronization between the ground-based remote sensing and the aircraft trajectories designed to maximize the collection of in situ observations within the column above the radar systems.
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Bell, Tyler M., Petra M. Klein, Julie K. Lundquist und Sean Waugh. „Remote-sensing and radiosonde datasets collected in the San Luis Valley during the LAPSE-RATE campaign“. Earth System Science Data 13, Nr. 3 (15.03.2021): 1041–51. http://dx.doi.org/10.5194/essd-13-1041-2021.
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Abstract. In July 2018, the International Society for Atmospheric Research using Remotely piloted Aircraft (ISARRA) hosted a flight week to showcase the role remotely piloted aircraft systems (RPASs) can have in filling the atmospheric data gap. This campaign was called Lower Atmospheric Process Studies at Elevation – a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE). In support of this campaign, ground-based remote and in situ systems were also deployed for the campaign. The University of Oklahoma deployed the Collaborative Lower Atmospheric Mobile Profiling System (CLAMPS), the University of Colorado deployed two Doppler wind lidars, and the National Severe Storms Laboratory deployed a mobile mesonet with the ability to launch radiosondes. This paper focuses on the data products from these instruments that result in profiles of the atmospheric state. The data are publicly available in the Zenodo LAPSE-RATE community portal (https://zenodo.org/communities/lapse-rate/, 19 January 2021). The profile data discussed are available at https://doi.org/10.5281/zenodo.3780623 (Bell and Klein, 2020), https://doi.org/10.5281/zenodo.3780593 (Bell et al., 2020b), https://doi.org/10.5281/zenodo.3727224 (Bell et al., 2020a), https://doi.org/10.5281/zenodo.3738175 (Waugh, 2020b), https://doi.org/10.5281/zenodo.3720444 (Waugh, 2020a), and https://doi.org/10.5281/zenodo.3698228 (Lundquist et al., 2020).
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Hasanov, V. „Morphogenetic Diagnostics and Nomenclature of Alluvial-Meadow Soils in the Subtropical Semiarid Area, Floodplain of the Kur River, Azerbaijan“. Bulletin of Science and Practice, Nr. 10 (15.10.2022): 85–95. http://dx.doi.org/10.33619/2414-2948/83/10.
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The aim of this study was to evaluate morphologic features, diagnostic qualifiers and enhance classification of alluvial-meadow soils in the floodplain of the Kur River within Azerbaijan. For this purpose, several soil pits were placed in the representative test areas and multiple soil samples collected within field campaigns (2014–2015). Based on the field and laboratory test data, the detailed soil maps of the test areas were compiled, and diversity of alluvial-meadow soils was classified as suborders (subtypes): alluvial-meadow primitive; alluvial-meadow layered (flaggy); alluvial-meadow dark and alluvial-meadow irrigated. It was found out that in the floodplains, local soil variability was predominantly attributed to not only alluvial sediments, but also water table, mineralization rate and salt content of underground water as well flood water play an important role. The mineralization of ground water is weak (1.40–3.70 g/l) and the concentration of hydro-carbonates (HCO3−) varies from 0.56 to 0.92 g/l. No salinization indication found in the profile of alluvial-meadow primitive and alluvial-meadow layered soils, while weak concentration (solid content = 0.40–0.54%) was found at a depth of 80–150 cm in the alluvial-meadow dark soil. Unlike other subtypes, alluvial-meadow dark soil is characterized with the higher biomass (green weight of top = 41.5 cwt/ha and green weight of underground = 142.3 cwt/ha), high mobility of humus substances with predominance of the 1st fraction of humin (20.0–28.1%) and fulvic acids (14.6–22.3%). The ratio of Cha : Cfa reaches 1.18–1.32. For the alluvial-meadow irrigated soil, the second fraction of humin acid (9.3–10.2%) and total content of humin acid ranges from 45.6 to 50.3%. The ratio of Cha : Cfa is larger (1.37–1.50). Depending on the lithology of alluvial sediments, the content of SiO2and R2O3 varies in the ranges of 53.0–57.2% and 9,6–26,0%, respectively. For the alluvial-meadow dark soil, decomposition of alum silicates in alkaline hydrolysis is typical (8.7–9.0). The content of SiO2and R2O3 varies between 47.8 and 50.6 %, and 19.7 and 21.6%, respectively. In the topsoil, of the irrigated soils in associated to washing out the content of Ca and CaO content (12.2–13.1%) increases in deeper horizons.
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Seo, Bong-Chul, Witold F. Krajewski, Felipe Quintero, Mohamed ElSaadani, Radoslaw Goska, Luciana K. Cunha, Brenda Dolan et al. „Comprehensive Evaluation of the IFloodS Radar Rainfall Products for Hydrologic Applications“. Journal of Hydrometeorology 19, Nr. 11 (01.11.2018): 1793–813. http://dx.doi.org/10.1175/jhm-d-18-0080.1.
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Abstract This study describes the generation and testing of a reference rainfall product created from field campaign datasets collected during the NASA Global Precipitation Measurement (GPM) mission Ground Validation Iowa Flood Studies (IFloodS) experiment. The study evaluates ground-based radar rainfall (RR) products acquired during IFloodS in the context of building the reference rainfall product. The purpose of IFloodS was not only to attain a high-quality ground-based reference for the validation of satellite rainfall estimates but also to enhance understanding of flood-related rainfall processes and the predictability of flood forecasting. We assessed the six RR estimates (IFC, Q2, CSU-DP, NWS-DP, Stage IV, and Q2-Corrected) using data from rain gauge and disdrometer networks that were located in the broader field campaign area of central and northeastern Iowa. We performed the analyses with respect to time scales ranging from 1 h to the entire campaign period in order to compare the capabilities of each RR product and to characterize the error structure at scales that are frequently used in hydrologic applications. The evaluation results show that the Stage IV estimates perform superior to other estimates, demonstrating the need for gauge-based bias corrections of radar-only products. This correction should account for each product’s algorithm-dependent error structure that can be used to build unbiased rainfall products for the campaign reference. We characterized the statistical error structures (e.g., systematic and random components) of each RR estimate and used them for the generation of a campaign reference rainfall product. To assess the hydrologic utility of the reference product, we performed hydrologic simulations driven by the reference product over the Turkey River basin. The comparison of hydrologic simulation results demonstrates that the campaign reference product performs better than Stage IV in streamflow generation.
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Fu, D., K. A. Walker, R. L. Mittermeier, K. Strong, K. Sung, H. Fast, P. F. Bernath et al. „Simultaneous atmospheric measurements using two Fourier transform infrared spectrometers at the Polar Environment Atmospheric Research Laboratory during spring 2006, and comparisons with the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer“. Atmospheric Chemistry and Physics Discussions 8, Nr. 2 (13.03.2008): 5305–58. http://dx.doi.org/10.5194/acpd-8-5305-2008.
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Abstract. The 2006 Canadian Arctic ACE (Atmospheric Chemistry Experiment) Validation Campaign collected measurements at the Polar Environment Atmospheric Research Laboratory (PEARL, 80.05° N, 86.42° W, 610 m above sea level) at Eureka, Canada from 17 February to 31 March 2006. Two of the ten instruments involved in the campaign, both Fourier transform spectrometers (FTSs), were operated simultaneously, recording atmospheric solar absorption spectra. The first instrument was an ABB Bomem DA8 high-resolution infrared FTS. The second instrument was the Portable Atmospheric Research Interferometric Spectrometer for the Infrared (PARIS-IR), the ground-based version of the satellite-borne FTS on the ACE satellite (ACE-FTS). From the measurements collected by these two ground-based instruments, total column densities of seven stratospheric trace gases (O3, HNO3, NO2, HCl, HF, NO, and ClONO2 were retrieved using the optimal estimation method and these results were compared. Since the two instruments sampled the same portions of atmosphere by synchronizing observations during the campaign, the biases in retrieved columns from the two spectrometers represent the instrumental differences. These differences were consistent with those seen in previous FTS intercomparison studies. Partial column results from the ground-based spectrometers were also compared with partial columns derived from ACE-FTS version 2.2 (including updates for O3, HDO and N2O5 profiles and the differences found were consistent with the other validation comparison studies for the ACE-FTS version 2.2 data products. Column densities of O3, HCl, ClONO2, and HNO3 from the three FTSs were normalized with respect to HF and used to probe the time evolution of the chemical constituents in the atmosphere over Eureka during spring 2006.
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Banda, Francesco, Mauro Mariotti d’Alessandro und Stefano Tebaldini. „Ground and Volume Decomposition as a Proxy for AGB from P-Band SAR Data“. Remote Sensing 12, Nr. 2 (10.01.2020): 240. http://dx.doi.org/10.3390/rs12020240.
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In this work, the role of volume scattering obtained from ground and volume decomposition of P-band synthetic aperture radar (SAR) data as a proxy for biomass is investigated. The analysis here presented originates from the BIOMASS L2 activities, part of which were focused on strengthening the physical foundations of the SAR-based retrieval of forest above-ground biomass (AGB). A critical analysis of the observed strong correlation between tomographic intensity and AGB is done in order to propose simplified AGB proxies to be used during the interferometric phase of BIOMASS. In particular, the aim is to discuss whether, and to what extent, volume scattering obtained from ground/volume decomposition can provide a reasonable alternative to tomography. To do this, both are tested on P-band data collected at Paracou during the TropiSAR campaign and cross-validated against in-situ AGB measurements. Results indicate that volume backscattered power as obtained by ground/volume decomposition is weakly correlated to AGB, notwithstanding different solutions for volume scattering are tested, and support the conclusion that forest structure actually plays a non-negligible role in AGB retrieval in dense tropical forests.
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Karnezi, Eleni, Liine Heikkinen, Markku Kulmala und Spyros N. Pandis. „Simulating Atmospheric Organic Aerosol in the Boreal Forest Using Its Volatility-Oxygen Content Distribution“. Atmosphere 14, Nr. 5 (22.04.2023): 763. http://dx.doi.org/10.3390/atmos14050763.
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Various parameterizations of organic aerosol (OA) formation and its subsequent evolution in the two-dimensional Volatility Basis Set (2D-VBS) framework are evaluated using ground measurements collected in the 2013 PEGASOS field campaign in the boreal forest station of Hyytiälä in southern Finland. A number of chemical aging schemes that performed well in the polluted environment of the Po Valley in Italy during the PEGASOS 2012 campaign are examined, taking into account various functionalization and fragmentation pathways for biogenic and anthropogenic OA components. All seven aging schemes considered have satisfactory results, consistent with the ground measurements. Despite their differences, these schemes predict similar contributions of the various OA sources and formation pathways for the periods examined. The highest contribution comes from biogenic secondary OA (bSOA), as expected, contributing 40–63% depending on the modeling scheme. Anthropogenic secondary OA (aSOA) is predicted to contribute 11–18% of the total OA, while SOA from intermediate-volatility compounds (SOA-iv) oxidation contributes another 18–27%. The fresh primary OA (POA) contributes 4%, while the SOA resulting from the oxidation of the evaporated semivolatile POA (SOA-sv) varies between 4 and 6%. Finally, 5–6% is predicted to be due to long-range transport from outside the modeling domain.
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Palo, S. E., M. E. Hagan, C. E. Meek, R. A. Vincent, M. D. Burrage, C. McLandress, S. J. Franke et al. „An intercomparison between the GSWM, UARS, and ground based radar observations: a case-study in January 1993“. Annales Geophysicae 15, Nr. 9 (30.09.1997): 1123–41. http://dx.doi.org/10.1007/s00585-997-1123-x.
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Abstract. The Global-Scale Wave Model (GSWM) is a steady-state two-dimensional linearized model capable of simulating the solar tides and planetary waves. In an effort to understand the capabilities and limitations of the GSWM throughout the upper mesosphere and thermosphere a comparative analysis with observational data is presented. A majority of the observational data used in this study was collected during the World Day campaign which ran from 20 January to 30 January 1993. During this campaign data from 18 ground-based observational sites across the globe and two instruments located on the UARS spacecraft were analyzed. Comparisons of these data with the simulations from the GSWM indicate that the GSWM results are in reasonable agreement with the observations. However, there are a number of cases where the agreement is not particularly good. One such instance is for the semidiurnal tide in the northern hemisphere, where the GSWM estimates may exceed observations by 50% . Through a number of numerical simulations, it appears that this discrepancy may be due to the eddy diffusivity profiles used by the GSWM. Other differences relating to the diurnal tide and the quasi-two-day wave are presented and discussed. Additionally, a discussion on the biases and aliasing difficulties which may arise in the observational data is also presented.
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de Boer, Gijs, Adam Houston, Jamey Jacob, Phillip B. Chilson, Suzanne W. Smith, Brian Argrow, Dale Lawrence et al. „Data generated during the 2018 LAPSE-RATE campaign: an introduction and overview“. Earth System Science Data 12, Nr. 4 (11.12.2020): 3357–66. http://dx.doi.org/10.5194/essd-12-3357-2020.
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Abstract. Unmanned aircraft systems (UASs) offer innovative capabilities for providing new perspectives on the atmosphere, and therefore atmospheric scientists are rapidly expanding their use, particularly for studying the planetary boundary layer. In support of this expansion, from 14 to 20 July 2018 the International Society for Atmospheric Research using Remotely piloted Aircraft (ISARRA) hosted a community flight week, dubbed the Lower Atmospheric Profiling Studies at Elevation – a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE; de Boer et al., 2020a). This field campaign spanned a 1-week deployment to Colorado's San Luis Valley, involving over 100 students, scientists, engineers, pilots, and outreach coordinators. These groups conducted intensive field operations using unmanned aircraft and ground-based assets to develop comprehensive datasets spanning a variety of scientific objectives, including a total of nearly 1300 research flights totaling over 250 flight hours. This article introduces this campaign and lays the groundwork for a special issue on the LAPSE-RATE project. The remainder of the special issue provides detailed overviews of the datasets collected and the platforms used to collect them. All of the datasets covered by this special issue have been uploaded to a LAPSE-RATE community set up at the Zenodo data archive (https://zenodo.org/communities/lapse-rate/, last access: 3 December 2020).
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Dehnavi, S., und Y. Maghsoudi. „A HYBRID METHOD IN VEGETATION HEIGHT ESTIMATION USING POLINSAR IMAGES OF CAMPAIGN BIOSAR“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-1-W5 (10.12.2015): 141–46. http://dx.doi.org/10.5194/isprsarchives-xl-1-w5-141-2015.
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Recently, there have been plenty of researches on the retrieval of forest height by PolInSAR data. This paper aims at the evaluation of a hybrid method in vegetation height estimation based on L-band multi-polarized air-borne SAR images. The SAR data used in this paper were collected by the airborne E-SAR system. The objective of this research is firstly to describe each interferometry cross correlation as a sum of contributions corresponding to single bounce, double bounce and volume scattering processes. Then, an ESPIRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) algorithm is implemented, to determine the interferometric phase of each local scatterer (ground and canopy). Secondly, the canopy height is estimated by phase differencing method, according to the RVOG (Random Volume Over Ground) concept. The applied model-based decomposition method is unrivaled, as it is not limited to specific type of vegetation, unlike the previous decomposition techniques. In fact, the usage of generalized probability density function based on the nth power of a cosine-squared function, which is characterized by two parameters, makes this method useful for different vegetation types. Experimental results show the efficiency of the approach for vegetation height estimation in the test site.
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Bonet-Solà, Daniel, Ester Vidaña-Vila und Rosa Ma Alsina-Pagès. „Analysis and Acoustic Event Classification of Environmental Data Collected in a Citizen Science Project“. International Journal of Environmental Research and Public Health 20, Nr. 4 (19.02.2023): 3683. http://dx.doi.org/10.3390/ijerph20043683.
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Citizen science can serve as a tool to obtain information about changes in the soundscape. One of the challenges of citizen science projects is the processing of data gathered by the citizens, to obtain conclusions. As part of the project Sons al Balcó, authors aim to study the soundscape in Catalonia during the lockdown due to the COVID-19 pandemic and afterwards and design a tool to automatically detect sound events as a first step to assess the quality of the soundscape. This paper details and compares the acoustic samples of the two collecting campaigns of the Sons al Balcó project. While the 2020 campaign obtained 365 videos, the 2021 campaign obtained 237. Later, a convolutional neural network is trained to automatically detect and classify acoustic events even if they occur simultaneously. Event based macro F1-score tops 50% for both campaigns for the most prevalent noise sources. However, results suggest that not all the categories are equally detected: the percentage of prevalence of an event in the dataset and its foregound-to-background ratio play a decisive role.
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Figueras i Ventura, Jordi, Nicolau Pineda, Nikola Besic, Jacopo Grazioli, Alessandro Hering, Oscar A. van der Velde, David Romero et al. „Polarimetric radar characteristics of lightning initiation and propagating channels“. Atmospheric Measurement Techniques 12, Nr. 5 (27.05.2019): 2881–911. http://dx.doi.org/10.5194/amt-12-2881-2019.
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Abstract. In this paper we present an analysis of a large dataset of lightning and polarimetric weather radar data collected in the course of a lightning measurement campaign that took place in the summer of 2017 in the area surrounding Säntis, in the northeastern part of Switzerland. For this campaign and for the first time in the Alps, a lightning mapping array (LMA) was deployed. The main objective of the campaign was to study the atmospheric conditions leading to lightning production with a particular focus on the lightning discharges generated due to the presence of the 124 m tall Säntis telecommunications tower. In this paper we relate LMA very high frequency (VHF) sources data with co-located radar data in order to characterise the main features (location, timing, polarimetric signatures, etc.) of both the flash origin and its propagation path. We provide this type of analysis first for all of the data and then we separate the datasets into intra-cloud and cloud-to-ground flashes (and within this category positive and negative flashes) and also upward lightning. We show that polarimetric weather radar data can be helpful in determining regions where lightning is more likely to occur but that lightning climatology and/or knowledge of the orography and man-made structures is also relevant.
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Piters, A. J. M., K. F. Boersma, M. Kroon, J. C. Hains, M. Van Roozendael, F. Wittrock, N. Abuhassan et al. „The Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI): design, execution, and early results“. Atmospheric Measurement Techniques Discussions 4, Nr. 5 (16.09.2011): 5935–6005. http://dx.doi.org/10.5194/amtd-4-5935-2011.
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Abstract. From June to July 2009 more than thirty different in-situ and remote sensing instruments from all over the world participated in the Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI). The campaign took place at KNMI's Cabauw Experimental Site for Atmospheric Research in the Netherlands. Its main objectives were to determine the accuracy of state-of-the-art ground-based measurement techniques for the detection of atmospheric nitrogen dioxide (both in-situ and remote sensing), and to investigate their usability in satellite data validation. The expected outcomes are recommendations regarding the operation and calibration of such instruments, retrieval settings, and observation strategies for the use in ground-based networks for air quality monitoring and satellite data validation. Twenty-four optical spectrometers participated in the campaign, of which twenty-one had the capability to scan different elevation angles consecutively, the so-called Multi-axis DOAS systems, thereby collecting vertical profile information, in particular for nitrogen dioxide and aerosol. Various in-situ samplers simultaneously characterized the variability of atmospheric trace gases and the physical properties of aerosol particles. A large data set of continuous measurements of these atmospheric constituents has been collected under various meteorological conditions and air pollution levels. Together with the permanent measurement capability at the Cabauw site characterizing the meteorological state of the atmosphere, the CINDI campaign provided a comprehensive observational data set of atmospheric constituents in a highly polluted region of the world during summertime. First detailed comparisons performed with the CINDI data show that slant column measurements of NO2, O4 and HCHO with MAX-DOAS agree within 5 to 15%, vertical profiles of NO2 derived from several independent instruments agree within 25%, and MAX-DOAS aerosol optical thickness agrees within 20–30% with AERONET data. For the in-situ NO2 instrument using a molybdenum converter, a bias was found as large as 5 ppbv during day time, when compared to the other in-situ instruments using photolytic converters.
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Piters, A. J. M., K. F. Boersma, M. Kroon, J. C. Hains, M. Van Roozendael, F. Wittrock, N. Abuhassan et al. „The Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI): design, execution, and early results“. Atmospheric Measurement Techniques 5, Nr. 2 (27.02.2012): 457–85. http://dx.doi.org/10.5194/amt-5-457-2012.
Der volle Inhalt der QuelleAnnotation:
Abstract. From June to July 2009 more than thirty different in-situ and remote sensing instruments from all over the world participated in the Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI). The campaign took place at KNMI's Cabauw Experimental Site for Atmospheric Research (CESAR) in the Netherlands. Its main objectives were to determine the accuracy of state-of-the-art ground-based measurement techniques for the detection of atmospheric nitrogen dioxide (both in-situ and remote sensing), and to investigate their usability in satellite data validation. The expected outcomes are recommendations regarding the operation and calibration of such instruments, retrieval settings, and observation strategies for the use in ground-based networks for air quality monitoring and satellite data validation. Twenty-four optical spectrometers participated in the campaign, of which twenty-one had the capability to scan different elevation angles consecutively, the so-called Multi-axis DOAS systems, thereby collecting vertical profile information, in particular for nitrogen dioxide and aerosol. Various in-situ samplers and lidar instruments simultaneously characterized the variability of atmospheric trace gases and the physical properties of aerosol particles. A large data set of continuous measurements of these atmospheric constituents has been collected under various meteorological conditions and air pollution levels. Together with the permanent measurement capability at the CESAR site characterizing the meteorological state of the atmosphere, the CINDI campaign provided a comprehensive observational data set of atmospheric constituents in a highly polluted region of the world during summertime. First detailed comparisons performed with the CINDI data show that slant column measurements of NO2, O4 and HCHO with MAX-DOAS agree within 5 to 15%, vertical profiles of NO2 derived from several independent instruments agree within 25% of one another, and MAX-DOAS aerosol optical thickness agrees within 20–30% with AERONET data. For the in-situ NO2 instrument using a molybdenum converter, a bias was found as large as 5 ppbv during day time, when compared to the other in-situ instruments using photolytic converters.