Academic literature on the topic 'CIMEL sun photometer'
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Journal articles on the topic "CIMEL sun photometer"
1
Barreto, A., E. Cuevas, B. Damiri, P. M. Romero, and F. Almansa. "Column water vapor determination in night period with a lunar photometer prototype." Atmospheric Measurement Techniques 6, no. 8 (August 29, 2013): 2159–67. http://dx.doi.org/10.5194/amt-6-2159-2013.
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Abstract. In this paper we present the preliminary results of atmospheric column-integrated precipitable water vapor (PWV) obtained with a new Lunar Cimel photometer (LC) at the high mountain Izaña Observatory in the period July–August 2011. We have compared quasi-simultaneous nocturnal PWV from LC with PWV from a Global Positioning System (GPS) receiver and nighttime radiosondes (RS92). LC data have been calibrated using the Lunar Langley method (LLM). We complemented this comparative study using quasi-simultaneous daytime PWV from Cimel AERONET (CA), GPS and RS92. Comparison of daytime PWV from CA shows differences between GPS and RS92 up to 0.18 cm. Two different filters, with and approximate bandwidth of 10 nm and central wavelengths at 938 nm (Filter#1) and 937 nm (Filter#2), were mounted onto the LC. Filter#1 is currently used in operational AERONET sun photometers. PWV obtained with LC-Filter#1 showed an overestimation above 0.18 and 0.25 cm compared to GPS and RS92, respectively, and root-mean-square errors (RMSEs) up to 0.27 cm and 0.24 cm, respectively. Filter#2, with a reduced out-of-band radiation, showed very low differences compared with the same references (≤ 0.05 cm) and RMSE values ≤ 0.08 cm in the case of GPS precise orbits. These results demonstrate the ability of the new lunar photometer to obtain accurate and continuous PWV measurements at night, and the remarkable influence of the filter's transmissivity response to PWV determination at nighttime. The use of enhanced bandpass filters in lunar photometry, which is affected by more important inaccuracies than sun photometry, is necessary to infer PWV with similar precision to AERONET.
2
Estellés, V., M. Campanelli, T. J. Smyth, M. P. Utrillas, and J. A. Martínez-Lozano. "Evaluation of the new ESR network software for the retrieval of direct sun products from CIMEL CE318 and PREDE POM01 sun-sky radiometers." Atmospheric Chemistry and Physics 12, no. 23 (December 5, 2012): 11619–30. http://dx.doi.org/10.5194/acp-12-11619-2012.
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Abstract. The European Skynet Radiometers network (EuroSkyRad or ESR) has been recently established as a research network of European PREDE sun-sky radiometers. Moreover, ESR is federated with SKYNET, an international network of PREDE sun-sky radiometers mostly present in East Asia. In contrast to SKYNET, the European network also integrates users of the CIMEL CE318 sky–sun photometer. Keeping instrumental duality in mind, a set of open source algorithms has been developed consisting of two modules for (1) the retrieval of direct sun products (aerosol optical depth, wavelength exponent and water vapor) from the sun extinction measurements; and (2) the inversion of the sky radiance to derive other aerosol optical properties such as size distribution, single scattering albedo or refractive index. In this study we evaluate the ESR direct sun products in comparison with the AERosol RObotic NETwork (AERONET) products. Specifically, we have applied the ESR algorithm to a CIMEL CE318 and PREDE POM simultaneously for a 4-yr database measured at the Burjassot site (Valencia, Spain), and compared the resultant products with the AERONET direct sun measurements obtained with the same CIMEL CE318 sky–sun photometer. The comparison shows that aerosol optical depth differences are mostly within the nominal uncertainty of 0.003 for a standard calibration instrument, and fall within the nominal AERONET uncertainty of 0.01–0.02 for a field instrument in the spectral range 340 to 1020 nm. In the cases of the Ångström exponent and the columnar water vapor, the differences are lower than 0.02 and 0.15 cm, respectively. Therefore, we present an open source code program that can be used with both CIMEL and PREDE sky radiometers and whose results are equivalent to AERONET and SKYNET retrievals.
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Carrer, Dominique, Catherine Meurey, Olivier Hagolle, Guillaume Bigeard, Alexandre Paci, Jean-Marie Donier, Gilles Bergametti, et al. "Casual Rerouting of AERONET Sun/Sky Photometers: Toward a New Network of Ground Measurements Dedicated to the Monitoring of Surface Properties?" Remote Sensing 13, no. 16 (August 4, 2021): 3072. http://dx.doi.org/10.3390/rs13163072.
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This paper presents an innovative method for observing vegetation health at a very high spatial resolution (~5 × 5 cm) and low cost by upgrading an existing Aerosol RObotic NETwork (AERONET) ground station dedicated to the observation of aerosols in the atmosphere. This study evaluates the capability of a sun/sky photometer to perform additional surface reflectance observations. The ground station of Toulouse, France, which belongs to the AERONET sun/sky photometer network, is used for this feasibility study. The experiment was conducted for a 5-year period (between 2016 and 2020). The sun/sky photometer was mounted on a metallic structure at a height of 2.5 m, and the acquisition software was adapted to add a periodical (every hour) ground-observation scenario with the sun/sky photometer observing the surface instead of being inactive. Evaluation is performed by using a classical metric characterizing the vegetation health: the normalized difference vegetation index (NDVI), using as reference the satellite NDVI derived from a Sentinel-2 (S2) sensor at 10 × 10 m resolution. Comparison for the 5-year period showed good agreement between the S2 and sun/sky photometer NDVIs (i.e., bias = 0.004, RMSD = 0.082, and R = 0.882 for a mean value of S2A NDVI around 0.6). Discrepancies could have been due to spatial-representativeness issues (of the ground measurement compared to S2), the differences between spectral bands, and the quality of the atmospheric correction applied on S2 data (accuracy of the sun/sky photometer instrument was better than 0.1%). However, the accuracy of the atmospheric correction applied on S2 data in this station appeared to be of good quality, and no dependence on the presence of aerosols was observed. This first analysis of the potential of the CIMEL CE318 sun/sky photometer to monitor the surface is encouraging. Further analyses need to be carried out to estimate the potential in different AERONET stations. The occasional rerouting of AERONET stations could lead to a complementary network of surface reflectance observations. This would require an update of the software, and eventual adaptations of the measurement platforms to the station environments. The additional cost, based on the existing AERONET network, would be quite limited. These new surface measurements would be interesting for measurements of vegetation health (monitoring of NDVI, and also of other vegetation indices such as the leaf area and chlorophyll indices), for validation and calibration exercise purposes, and possibly to refine various scientific algorithms (i.e., algorithms dedicated to cloud detection or the AERONET aerosol retrieval algorithm itself). CIMEL is ready to include the ground scenario used in this study in all new sun/sky photometers.
4
Toledano, Carlos, Benjamín Torres, Cristian Velasco-Merino, Dietrich Althausen, Silke Groß, Matthias Wiegner, Bernadett Weinzierl, et al. "Sun photometer retrievals of Saharan dust properties over Barbados during SALTRACE." Atmospheric Chemistry and Physics 19, no. 23 (December 2, 2019): 14571–83. http://dx.doi.org/10.5194/acp-19-14571-2019.
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Abstract. The Saharan Aerosol Long-Range Transport and Aerosol–Cloud-Interaction Experiment (SALTRACE) was devoted to the investigation of Saharan dust properties over the Caribbean. The campaign took place in June–July 2013. A wide set of ground-based and airborne aerosol instrumentation was deployed at the island of Barbados for a comprehensive experiment. Several sun photometers performed measurements during this campaign: two AERONET (Aerosol Robotic Network) Cimel sun photometers and the Sun and Sky Automatic Radiometer (SSARA). The sun photometers were co-located with the ground-based multi-wavelength lidars BERTHA (Backscatter Extinction lidar Ratio Temperature Humidity profiling Apparatus) and POLIS (Portable Lidar System). Aerosol properties derived from direct sun and sky radiance observations are analyzed, and a comparison with the co-located lidar and in situ data is provided. The time series of aerosol optical depth (AOD) allows identifying successive dust events with short periods in between in which the marine background conditions were observed. The moderate aerosol optical depth in the range of 0.3 to 0.6 was found during the dust periods. The sun photometer infrared channel at the 1640 nm wavelength was used in the retrieval to investigate possible improvements to aerosol size retrievals, and it was expected to have a larger sensitivity to coarse particles. The comparison between column (aerosol optical depth) and surface (dust concentration) data demonstrates the connection between the Saharan Air Layer and the boundary layer in the Caribbean region, as is shown by the synchronized detection of the successive dust events in both datasets. However the differences of size distributions derived from sun photometer data and in situ observations reveal the difficulties in carrying out a column closure study.
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Kruczyk, Michał, and Tomasz Liwosz. "Integrated Precipitable Water Vapour Measurements At Polish Polar Station Hornsund From GPS Observations Verified By Aerological Techniques." Reports on Geodesy and Geoinformatics 98, no. 1 (July 1, 2015): 1–17. http://dx.doi.org/10.2478/rgg-2015-0001.
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AbstractWe present results of the comparison of integrated precipitable water measurements from GPS solution and aerological techniques: CIMEL-318 sun-photometer and radiosoundings (RAOB). Integrated Precipitable Water (IPW) - important meteorological parameter is derived from GPS tropospheric solutions by known procedure for GPS station at Polish Polar Station, Hornsund (Svalbard). The relation between 2 m temperature and the mean temperature of atmosphere above, used to convert from wet part of tropospheric delay (ZWD) to IPW, has been derived using local radiosonde data at Ny Alesund. Sunphotometer data have been provided by AERONET. Quality of dedicated tropospheric solutions has been verified by comparison with EPN tropospheric combined product. Several IPW comparisons and analyses lead to determination of systematic difference between techniques: GPS IPW and sunphotometer data (not present in case of RAOBs). IPW measured by CIMEL is on average 5% bigger (0.5 mm) than IPW from GPS. This bias changes seasonally and is a function of atmospheric temperature what signals some systematic deficiencies in solar photometry as IPW retrieval technique. CIMEL IPW show some temperature dependent bias also in relation to radiosoundings.
6
Barreto, A., E. Cuevas, M. J. Granados-Muñoz, L. Alados-Arboledas, P. M. Romero, J. Gröbner, N. Kouremeti, et al. "The new sun-sky-lunar Cimel CE318-T multiband photometer – a comprehensive performance evaluation." Atmospheric Measurement Techniques Discussions 8, no. 10 (October 28, 2015): 11077–138. http://dx.doi.org/10.5194/amtd-8-11077-2015.
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Abstract. This paper presents the new photometer CE318-T, able to perform daytime and nighttime photometric measurements using the sun and the moon as light source. Therefore, this new device permits to extract a complete cycle of diurnal aerosol and water vapor measurements valuable to enhance atmospheric monitoring. In this study we have found significantly higher triplets precision when comparing the CE318-T master and the Cimel AErosol RObotic NETwork (AERONET) master (CE318-AERONET) triplets as a result of the new CE318-T tracking system. Regarding the instrument calibration, a new methodology to transfer the calibration from a master (Sun Ratio technique) is presented and discussed. It allows us to reduce the previous complexities inherent to nocturnal calibration. A quantitative estimation of CE318-T AOD uncertainty by means of error propagation theory during daytime revealed AOD uncertainties (uDAOD) for Langley-calibrated instruments similar to the expected values for other reference instruments (0.002–0.009). We have also found uDAOD values similar to the values reported in sun photometry for field instruments (~ 0.015). In the case of nighttime period, the CE318-T estimated uncertainty (uNAOD) is dependent not only on the calibration technique but also on illumination conditions and the instrumental noise. These values range from 0.011–0.019 for Lunar Langley calibrated instruments to 0.012–0.021 for instruments calibrated using the Sun Ratio technique. A subsequent performance evaluation including CE318-T and collocated measurements from independent reference instruments has served to assess the CE318-T performance as well as to confirm its estimated uncertainty. Daytime AOD evaluation performed at Izaña station from March to June 2014, encompassed measurements from a reference CE318-T, a CE318-AERONET master, a Precision Filter Radiometer (PFR) and a Precision SpectroRadiometer (PSR) prototype, reporting low AOD discrepancies between the four instruments (up to 0.006). The nocturnal AOD evaluation was performed using CE318-T and star photometer collocated measurements and also by means of a day/night coherence transition test using the master CE318-T and the CE318 daytime data from the CE318-AERONET master. Results showed low discrepancies with star photometer at 870 and 500 nm channels (≤ 0.013) and differences with AERONET daytime data (1 h after and before sunset and sunrise) in agreement with the estimated uNAOD values at all illumination conditions in case of channels within the visible spectral range, and only for high moon's illumination conditions in case of near infrared channels. Precipitable water vapor (PWV) validation showed a good agreement between CE318-T and Global Navigation Satellite System (GNSS) PWV values for all illumination conditions, within the expected precision for sun photometry. Finally, two case studies have been included to highlight the ability of the new CE318-T to capture the diurnal cycle of aerosols and water vapor as well as short-term atmospheric variations, critical for climate studies.
7
Barreto, A., E. Cuevas, B. Damiri, P. M. Romero, and F. Almansa. "Column water vapor determination in night period with a lunar photometer prototype." Atmospheric Measurement Techniques Discussions 6, no. 1 (January 22, 2013): 767–93. http://dx.doi.org/10.5194/amtd-6-767-2013.
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Abstract. In this paper we present the preliminary results of atmospheric column integrated water vapor (PWV) obtained with a new Lunar Cimel photometer (LC) at the high mountain Izaña Observatory in the period July–August, 2011. We have compared nocturnal PWV from LC with PWV from a Global Positioning System (GPS) receiver and nighttime radiosondes (RS92). LC data have been calibrated using the Lunar Langley Method (LLM). We complemented this comparative study using quasi-simultaneous daytime PWV from Cimel AERONET (CA), GPS and RS92. Comparison of daytime PWV from CA shows differences against GPS and RS92 up to 0.18 cm. Two different filters, with and approximate bandwidth of 10 nm and central wavelengths at 938 nm (Filter#1) and 937 nm (Filter#2), were mounted into the LC. Filter#1 is currently used in operational AERONET sunphotometers. PWV obtained with LC-Filter#1 showed an overestimation above 0.18 and 0.25 cm compared to GPS and RS92, respectively, meanwhile Filter#2, with a reduced out-of-band radiation, showed very low differences compared with the same references (≤0.03 cm). These results demonstrate the ability of the new lunar photometer to obtain accurate and continuous PWV measurements at night in addition to the notably influence of the filter's transmissivity response on PWV determination at nighttime. The use of enhanced bandpass filters in lunar photometry, which is affected by more important inaccuracies than sun-photometry, is necessary to infer PWV with similar precision than AERONET.
8
Kazadzis, S., N. Kouremeti, V. Amiridis, A. Arola, and E. Gerasopoulos. "Aerosol absorption retrieval at ultraviolet wavelengths in a complex environment." Atmospheric Measurement Techniques Discussions 5, no. 5 (September 21, 2012): 6991–7023. http://dx.doi.org/10.5194/amtd-5-6991-2012.
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Abstract. We have combined sun and sky radiance measurements from a CIMEL sun-photometer and total and diffuse UV irradiance measurements with a multi-filter rotating shadow-band radiometer (UVMFR), in order to calculate aerosol absorption properties (single scattering albedo) in the UV range, for a 10 month period in Athens, Greece. The aerosol extinction optical thickness measured by the CIMEL instrument has been used for the inter-calibration of the UVMFR. The measurements from both instruments were used as input to a radiative transfer model and the single scattering albedo (SSA) for 368 nm and 332 nm has been calculated. The SSA values at these wavelengths, together with synchronous SSA, CIMEL-derived, retrievals at 440 nm, show a mean of 0.88, 0.86 and 0.80, with lowest values (higher absorption) towards lower wavelengths. In addition, noticeable diurnal variations of the SSA in all wavelengths are revealed, with amplitudes in the order of 0.05. Higher SSA wavelength dependence is found for cases of lower Ångström exponents and also an SSA decrease with decreasing extinction optical depth, suggesting an effect of the different aerosol composition.
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Barreto, África, Emilio Cuevas, María-José Granados-Muñoz, Lucas Alados-Arboledas, Pedro M. Romero, Julian Gröbner, Natalia Kouremeti, et al. "The new sun-sky-lunar Cimel CE318-T multiband photometer – a comprehensive performance evaluation." Atmospheric Measurement Techniques 9, no. 2 (February 24, 2016): 631–54. http://dx.doi.org/10.5194/amt-9-631-2016.
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Abstract. This paper presents the new photometer CE318-T, able to perform daytime and night-time photometric measurements using the sun and the moon as light source. Therefore, this new device permits a complete cycle of diurnal aerosol and water vapour measurements valuable to enhance atmospheric monitoring to be extracted. In this study we have found significantly higher precision of triplets when comparing the CE318-T master instrument and the Cimel AErosol RObotic NETwork (AERONET) master (CE318-AERONET) triplets as a result of the new CE318-T tracking system. Regarding the instrument calibration, two new methodologies to transfer the calibration from a reference instrument using only daytime measurements (Sun Ratio and Sun-Moon gain factor techniques) are presented and discussed. These methods allow the reduction of the previous complexities inherent to nocturnal calibration. A quantitative estimation of CE318-T AOD uncertainty by means of error propagation theory during daytime revealed AOD uncertainties (uDAOD) for Langley-calibrated instruments similar to the expected values for other reference instruments (0.002–0.009). We have also found uDAOD values similar to the values reported in sun photometry for field instruments ( ∼ 0.015). In the case of the night-time period, the CE318-T-estimated standard combined uncertainty (uNAOD) is dependent not only on the calibration technique but also on illumination conditions and the instrumental noise. These values range from 0.011–0.018 for Lunar Langley-calibrated instruments to 0.012–0.021 for instruments calibrated using the Sun Ratio technique. In the case of moon-calibrated instruments using the Sun-Moon gain factor method and sun-calibrated using the Langley technique, we found uNAOD ranging from 0.016 to 0.017 (up to 0.019 in 440 nm channel), not dependent on any lunar irradiance model.A subsequent performance evaluation including CE318-T and collocated measurements from independent reference instruments has served to assess the CE318-T performance as well as to confirm its estimated uncertainty. Daytime AOD evaluation, performed at Izaña station from March to June 2014, encompassed measurements from a reference CE318-T, a CE318-AERONET master instrument, a Precision Filter Radiometer (PFR) and a Precision Spectroradiometer (PSR) prototype, reporting low AOD discrepancies between the four instruments (up to 0.006). The nocturnal AOD evaluation was performed using CE318-T- and star-photometer-collocated measurements and also by means of a day/night coherence transition test using the CE318-T master instrument and the CE318 daytime data from the CE318-AERONET master instrument. Results showed low discrepancies with the star photometer at 870 and 500 nm channels ( ≤ 0.013) and differences with AERONET daytime data (1 h after and before sunset and sunrise) in agreement with the estimated uNAOD values at all illumination conditions in the case of channels within the visible spectral range, and only for high moon's illumination conditions in the case of near-infrared channels.Precipitable water vapour (PWV) validation showed a good agreement between CE318-T and Global Navigation Satellite System (GNSS) PWV values for all illumination conditions, within the expected precision for sun photometry.Finally, two case studies have been included to highlight the ability of the new CE318-T to capture the diurnal cycle of aerosols and water vapour as well as short-term atmospheric variations, critical for climate studies.
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Landulfo, Eduardo, Alexandros Papayannis, Ani Sobral Torres, Sandro Toshio Uehara, Lucila Maria Viola Pozzetti, Caio Alencar de Matos, Patricia Sawamura, Walter Morinobu Nakaema, and Wellington de Jesus. "A Four-Year Lidar–Sun Photometer Aerosol Study at São Paulo, Brazil." Journal of Atmospheric and Oceanic Technology 25, no. 8 (August 1, 2008): 1463–68. http://dx.doi.org/10.1175/2007jtecha984.1.
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Abstract A backscattering lidar system, the first of this kind in Brazil, has been used to provide the vertical profile of the aerosol backscatter coefficient at 532 nm up to an altitude of 4–6 km above sea level (ASL), in a suburban area in the city of São Paulo. The lidar system has been operational since September 2001. The lidar data products were obtained in a 4-yr period (2001–04) and concerned the aerosol optical thickness (AOT), the aerosol backscattering and extinction coefficients at 532 nm, cloud properties (cloud base, thickness), planetary boundary layer (PBL) heights, aerosol layering, and the structure and dynamics of the lower troposphere. The lidar data are presented and analyzed in synergy with AOT measurements obtained by a Cimel sun-tracking photometer in the visible spectral region, not only to validate the lidar data but also to provide an input value of the so-called extinction-to-backscatter ratio [lidar ratio (LR)]. A correlation between the lidar data and the data obtained by a Cimel sun-tracking photometer [belonging to the Aerosol Robotic Network (AERONET)] is being made to set a temporal database of those data that were collected concomitantly and to cross correlate the information gathered by each instrument. The sun photometer data are used to provide AOT values at selected wavelengths and thus to derive the Ångström exponent (AE) values, single scattering albedo (SSA) and phase function values, and LR values. The analysis of these data showed an important trend in the seasonal signature of the LR indicating a change of the predominant type of aerosol between the dry and wet seasons. Thus, during the wet season the LR lidar values are greater (50–60 sr), which indicates that larger absorption by the aerosols takes place during this period. The corresponding AE values range between 1.3 and 2 for both periods.
Dissertations / Theses on the topic "CIMEL sun photometer"
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Bigala, Thomas Aquinas. "Aerosol loading over the South African Highveld." Thesis, 2009. http://hdl.handle.net/10539/6846.
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The Highveld region of South Africa contributes substantially to the aerosol loading
over southern Africa because of its importance as an industrial, mining and farming
base. Aerosols affect climate by absorbing or reflecting incoming solar radiation, and
by affecting cloud microphysics, cloud albedo and precipitation. The physical and
optical properties of industrial/urban aerosols over the Highveld region of
South Africa were analysed during a 32-day winter sampling period (21 May to
21 June) in 2002; a 32-day summer sampling period (21 October to 21 November) in
2002, and a second 32-day winter sampling period (19 May to 19 June) in 2003.
Synoptic circulation systems were examined in as far as they affect the horizontal
transport of aerosols over the Highveld region. Measurements of aerosol optical
thickness (AOT) from the ground to the top of the atmosphere and aerosol size
distribution characteristics over the Highveld region were taken using hand-held
hazemeters and a CIMEL sun photometer. The AOT observed over the region during
the winter 2002 and 2003 sampling periods and during the summer 2002 sampling
period indicated high turbidity. In the 2002 winter sampling period, the AOT530nm
ranged between 0.05 to 0.7 with an average of 0.14. In the 2002 summer sampling
period, the AOT530nm ranged between 0.05 to 0.6, with an average of 0.24. In the
2003 winter sampling period, the AOT500nm ranged between 0.06 to 0.6, with an
average of 0.21. The Ångström exponent value had a wide range, 0.8 to 2.4 in the 2002 winter and summer sampling periods and also in the 2003 winter sampling
period, indicating that a range of particle sizes was present over the Highveld region.
The Ångström exponent values obtained were derived from the influences of Aeolian
dust, coarse-mode industrial particles and, to a small extent, fine-mode biomassburning
aerosols. Case studies, based on trajectory analysis and meteorology of the
sampling area, were made of the aerosols emanating from the township sites during
each of the three sampling periods to observe the build-up and dispersion of aerosols
at that time.
Conference papers on the topic "CIMEL sun photometer"
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Evgenieva, Tsvetina, Ilko Iliev, Nikolay Kolev, Piotr Sobolewski, Aleksander Pieterczuk, Brent Holben, and Ivan Kolev. "Optical characteristics of aerosol determined by Cimel, Prede, and Microtops II sun photometers over Belsk, Poland." In 15th International School on Quantum Electronics: Laser Physics and Applications, edited by Tanja Dreischuh, Elena Taskova, Ekaterina Borisova, and Alexander Serafetinides. SPIE, 2008. http://dx.doi.org/10.1117/12.822507.
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Flynn, Connor J., Jens Redemann, Beat Schmid, Steve Dunagan, Roy R. Johnson, Yohei Shinozuka, John M. Livingston, et al. "Design and Characterization of the 4STAR Sun-Sky Spectrometer with Results from 4-Way Intercomparison of 4STAR, AATS-14, Prede, and Cimel Photometers at Mauna Loa Observatory." In Hyperspectral Imaging and Sensing of the Environment. Washington, D.C.: OSA, 2009. http://dx.doi.org/10.1364/hisense.2009.htuc4.
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