Pour voir les autres types de publications sur ce sujet consultez le lien suivant : Long duration stratospheric–.
Articles de revues sur le sujet « Long duration stratospheric– »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleurs articles de revues pour votre recherche sur le sujet « Long duration stratospheric– ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les articles de revues sur diverses disciplines et organisez correctement votre bibliographie.
1
Ovarlez, Joëlle, et Michèle Forichon. « Stratospheric Wind Velocity Determination from Long Duration Balloon Flights ». Journal of Applied Meteorology 29, no 10 (octobre 1990) : 1068–71. http://dx.doi.org/10.1175/1520-0450(1990)029<1068:swvdfl>2.0.co;2.
Texte intégral
2
Leroux, Mathilde, et Vincent Noel. « Investigating long-term changes in polar stratospheric clouds above Antarctica during past decades : a temperature-based approach using spaceborne lidar detections ». Atmospheric Chemistry and Physics 24, no 10 (31 mai 2024) : 6433–54. http://dx.doi.org/10.5194/acp-24-6433-2024.
Texte intégralRésumé :
Abstract. Polar stratospheric clouds play a significant role in the seasonal thinning of the ozone layer by facilitating the activation of stable chlorine and bromine reservoirs into reactive radicals, as well as prolonging the ozone depletion by removing HNO3 and H2O from the stratosphere by sedimentation. In a context of climate change, the cooling of the lower polar stratosphere could enhance polar stratospheric cloud (PSC) formation and by consequence cause more ozone depletion. There is thus a need to document the evolution of the PSC cover to better understand its impact on the ozone layer. In this article we present a statistical model based on the analysis of the CALIPSO (Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations) PSC product from 2006 to 2020. The model predicts the daily regionally averaged PSC density by pressure level derived from stratospheric temperatures. Applied to stratospheric temperatures from the CALIPSO PSC product, our model reproduces observed and interannual variations in PSC density well between 10 and 150 hPa over the 2006–2020 period. The model reproduces the PSC seasonal progression well, even during disruptive events like stratospheric sudden warmings, except for years characterized by volcanic eruptions. We also apply our model to gridded temperatures from Modern Era Retrospective analysis for Research and Application (MERRA-2) reanalyses over the complete South Pole region to evaluate changes in PSC season duration over the 1980–2021 period. We find that over the 1980–2000 period, the PSC season gets significantly longer between 30 and 150 hPa. Lengthening of the PSC season from 22 d (30–50 hPa) to 32 d (100–150 hPa) is possibly related to volcanic eruptions occurring over this period. Over 1980–2021, we find that the PSC season gets significantly longer between 30 and 100 hPa, but due to biases in MERRA-2 temperatures, the reliability of these trends is hard to evaluate.
3
Peters, Dieter, Andrea Schneidereit et Alexey Karpechko. « Enhanced Stratosphere/Troposphere Coupling During Extreme Warm Stratospheric Events with Strong Polar-Night Jet Oscillation ». Atmosphere 9, no 12 (29 novembre 2018) : 467. http://dx.doi.org/10.3390/atmos9120467.
Texte intégralRésumé :
Extreme warm stratospheric events during polar winters from ERA-Interim reanalysis and CMIP5-ESM-LR runs were separated by duration and strength of the polar-night jet oscillation (PJO) using a high statistical confidence level of three standard deviations (strong-PJO events). With a composite analysis, we demonstrate that strong-PJO events show a significantly stronger downward propagating signal in both, northern annular mode (NAM) and zonal mean zonal wind anomaly in the stratosphere in comparison with non-PJO events. The lower stratospheric EP-flux-divergence difference in ERA-Interim was stronger in comparison to long-term CMIP5-ESM-LR runs (by a factor of four). This suggests that stratosphere–troposphere coupling is stronger in ERA-Interim than in CMIP5-ESM-LR. During the 60 days following the central date (CD), the Arctic oscillation signal was more intense during strong-PJO events than during non-PJO events in ERA-Interim data in comparison to CMIP5-ESM-LR runs. During the 15-day phase after CD, strong PJO events had a significant increase in stratospheric ozone, upper tropospheric zonally asymmetric impact, and a regional surface impact in ERA-Interim. Finally, we conclude that the applied high statistical threshold gives a clearer separation of extreme warm stratospheric events into strong-PJO events and non-PJO events including their different downward propagating NAM signal and tropospheric impacts.
4
Liu, Sitong, Shuyu Zhou, Jinggang Miao, Hai Shang, Yuxuan Cui et Ying Lu. « Autonomous Trajectory Planning Method for Stratospheric Airship Regional Station-Keeping Based on Deep Reinforcement Learning ». Aerospace 11, no 9 (13 septembre 2024) : 753. http://dx.doi.org/10.3390/aerospace11090753.
Texte intégralRésumé :
The stratospheric airship, as a near-space vehicle, is increasingly utilized in scientific exploration and Earth observation due to its long endurance and regional observation capabilities. However, due to the complex characteristics of the stratospheric wind field environment, trajectory planning for stratospheric airships is a significant challenge. Unlike lower atmospheric levels, the stratosphere presents a wind field characterized by significant variability in wind speed and direction, which can drastically affect the stability of the airship’s trajectory. Recent advances in deep reinforcement learning (DRL) have presented promising avenues for trajectory planning. DRL algorithms have demonstrated the ability to learn complex control strategies autonomously by interacting with the environment. In particular, the proximal policy optimization (PPO) algorithm has shown effectiveness in continuous control tasks and is well suited to the non-linear, high-dimensional problem of trajectory planning in dynamic environments. This paper proposes a trajectory planning method for stratospheric airships based on the PPO algorithm. The primary contributions of this paper include establishing a continuous action space model for stratospheric airship motion; enabling more precise control and adjustments across a broader range of actions; integrating time-varying wind field data into the reinforcement learning environment; enhancing the policy network’s adaptability and generalization to various environmental conditions; and enabling the algorithm to automatically adjust and optimize flight paths in real time using wind speed information, reducing the need for human intervention. Experimental results show that, within its wind resistance capability, the airship can achieve long-duration regional station-keeping, with a maximum station-keeping time ratio (STR) of up to 0.997.
5
de Bernardis, P., et S. Masi. « Precision CMB measurements with long-duration stratospheric balloons : activities in the Arctic ». Proceedings of the International Astronomical Union 8, S288 (août 2012) : 208–13. http://dx.doi.org/10.1017/s1743921312016894.
Texte intégralRésumé :
AbstractWe report on the activities preparing long duration stratospheric flights, suitable for CMB (Cosmic Microwave Background) measurements, in the Arctic region. We focus on pathfinder flights, and on two forthcoming experiments to be flown from Longyearbyen (Svalbard islands): the OLIMPO Sunyaev-Zeldovich spectrometer, and the Large-Scale Polarization Explorer (LSPE).
6
Olschewski, Friedhelm, Christian Monte, Albert Adibekyan, Max Reiniger, Berndt Gutschwager, Joerg Hollandt et Ralf Koppmann. « A large-area blackbody for in-flight calibration of an infrared interferometer deployed on board a long-duration balloon for stratospheric research ». Atmospheric Measurement Techniques 11, no 8 (14 août 2018) : 4757–62. http://dx.doi.org/10.5194/amt-11-4757-2018.
Texte intégralRésumé :
Abstract. The deployment of the imaging Fourier Transform Spectrometer GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) on board a long-duration balloon for stratospheric research requires a blackbody for in-flight calibration in order to provide traceability to the International Temperature Scale (ITS-90) to ensure comparability with the results of other experiments and over time. GLORIA, which has been deployed onboard various research aircraft such as the Russian M55 Geophysica or the German HALO in the past, shall also be used for detailed atmospheric measurements in the stratosphere up to 40 km altitude. The instrument uses a two-dimensional detector array and an imaging optics with a large aperture diameter of 36 mm and an opening angle of 4.07∘ × 4.07∘ for infrared limb observations. To overfill the field of view (FOV) of the instrument, a large-area blackbody radiation sources (125 mm × 125 mm) is required for in-flight calibration. In order to meet the requirements regarding the scientific goals of the GLORIA missions, the radiance temperature of the blackbody calibration source has to be determined to better than 100 mK and the spatial temperature uniformity shall be better than 150 mK. As electrical resources on board a stratospheric balloon are very limited, the latent heat of the phase change of a eutectic material is utilized for temperature stabilization of the calibration source, such that the blackbody has a constant temperature of about −32 ∘C corresponding to a typical temperature observed in the stratosphere. The Institute for Atmospheric and Environmental Research at the University of Wuppertal designed and manufactured a prototype of the large-area blackbody for in-flight calibration of an infrared interferometer deployed on board a long-duration balloon for stratospheric research. This newly developed calibration source was tested under lab conditions as well as in a climatic and environmental test chamber in order to verify its performance especially under flight conditions. At the PTB (Physikalisch-Technische Bundesanstalt), the German national metrology institute, the spatial radiance distribution of the blackbody was determined and traceability to the International Temperature Scale (ITS-90) has been assured. In this paper the design and performance of the balloon-borne blackbody (BBB) is presented.
7
Iarocci, A., P. Benedetti, F. Caprara, A. Cardillo, F. Di Felice, G. Di Stefano, P. Drakøy et al. « PEGASO : An ultra light long duration stratospheric payload for polar regions flights ». Advances in Space Research 42, no 10 (novembre 2008) : 1633–40. http://dx.doi.org/10.1016/j.asr.2007.05.079.
Texte intégral
8
Tockert, C. « Concept for an open-neck stratospheric balloon with long-duration flight capability ». Advances in Space Research 13, no 2 (février 1993) : 119–22. http://dx.doi.org/10.1016/0273-1177(93)90284-i.
Texte intégral
9
Akita, Daisuke. « Feasibility study of a sea-anchored stratospheric balloon for long-duration flights ». Advances in Space Research 50, no 4 (août 2012) : 508–15. http://dx.doi.org/10.1016/j.asr.2012.05.002.
Texte intégral
10
Fesen, Robert, et Yorke Brown. « A method for establishing a long duration, stratospheric platform for astronomical research ». Experimental Astronomy 39, no 3 (23 mai 2015) : 475–93. http://dx.doi.org/10.1007/s10686-015-9459-9.
Texte intégral
11
Ji, Xinzhe, Kangwen Sun, Haoquan Liang, Xiao Guo, Xixiang Yang et Chuan Shan. « Energy management in hybrid energy system for long-duration stratospheric airship mission ». Energy 324 (juin 2025) : 136021. https://doi.org/10.1016/j.energy.2025.136021.
Texte intégral
12
Ndarana, Thando, Mary-Jane Bopape, Darryn Waugh et Liesl Dyson. « The Influence of the Lower Stratosphere on Ridging Atlantic Ocean Anticyclones over South Africa ». Journal of Climate 31, no 15 (août 2018) : 6175–87. http://dx.doi.org/10.1175/jcli-d-17-0832.1.
Texte intégralRésumé :
The link between Rossby wave breaking and ridging Atlantic Ocean anticyclones in the South African domain is examined using NCEP–DOE AMIP-II reanalysis data. A simple composite analysis, which used the duration of ridging events as a basis of averaging, reveals that ridging anticyclones are coupled with Rossby wave breaking at levels higher than the dynamical tropopause. Lower-stratospheric PV anomalies extend to the surface, thus coupling the ridging highs with the lower stratosphere. The anomaly extending from the 70-hPa level to the surface contributes to a southward extension of the surface negative anomaly over the Namibian coast, which induces a cyclonic flow, causing the ridging anticyclone to take a bean-like shape. The surface positive anomaly induces the internal anticyclonic flow within the large-scale pressure system, causing the ridging end to break off and amalgamate with the Indian Ocean high pressure system. Lower-stratospheric Rossby wave breaking lasts for as long as the ridging process, suggesting that the former is critical to the longevity of the latter by maintaining and keeping the vertical coupling intact.
13
Jones, William C. « Precision CMB Measurements from Long Duration Stratospheric Balloons : Towards B-modes and Inflation ». Proceedings of the International Astronomical Union 8, S288 (août 2012) : 53–60. http://dx.doi.org/10.1017/s1743921312016675.
Texte intégralRésumé :
AbstractObservations of the Cosmic Microwave Background (CMB) have played a leading role in establishing an understanding of the structure and evolution of the Universe on the largest scales. This achievement has been enabled by a series of extremely successful experiments, coupled with the simplicity of the relationship between the cosmological theory and data. Antarctic experiments, including both balloon-borne telescopes and instruments at the South Pole, have played a key role in realizing the scientific potential of the CMB, from the characterization of the temperature anisotropies to the detection and study of the polarized component. Current and planned Antarctic long duration balloon experiments will extend this heritage of discovery to test theories of cosmic genesis through sensitive polarized surveys of the millimeter-wavelength sky. In this paper we will review the pivotal role that Antarctic balloon borne experiments have played in transforming our understanding of the Universe, and describe the scientific goals and technical approach of current and future missions.
14
Knudsen, B. M., J. M. Rosen, N. T. Kjome et A. T. Whitten. « Comparison of analyzed stratospheric temperatures and calculated trajectories with long-duration balloon data ». Journal of Geophysical Research : Atmospheres 101, no D14 (1 août 1996) : 19137–45. http://dx.doi.org/10.1029/96jd01163.
Texte intégral
15
Hertzog, Albert, M. Joan Alexander et Riwal Plougonven. « On the Intermittency of Gravity Wave Momentum Flux in the Stratosphere ». Journal of the Atmospheric Sciences 69, no 11 (1 novembre 2012) : 3433–48. http://dx.doi.org/10.1175/jas-d-12-09.1.
Texte intégralRésumé :
Abstract In this article, long-duration balloon and spaceborne observations, and mesoscale numerical simulations are used to study the intermittency of gravity waves in the lower stratosphere above Antarctica and the Southern Ocean; namely, the characteristics of the gravity wave momentum-flux probability density functions (pdfs) obtained with these three datasets are described. The pdfs consistently exhibit long tails associated with the occurrence of rare and large-amplitude events. The pdf tails are even longer above mountains than above oceanic areas, which is in agreement with previous studies of gravity wave intermittency in this region. It is moreover found that these rare, large-amplitude events represent the main contribution to the total momentum flux during the winter regime of the stratospheric circulation. In contrast, the wave intermittency significantly decreases when stratospheric easterlies develop in late spring and summer. It is also shown that, except above mountainous areas in winter, the momentum-flux pdfs tend to behave like lognormal distributions. Monte Carlo simulations are undertaken to examine the role played by critical levels in influencing the shape of momentum-flux pdfs. In particular, the study finds that the lognormal shape may result from the propagation of a wave spectrum into a varying background wind field that generates the occurrence of frequent critical levels.
16
Masi, Silvia, A. Coppolecchia, E. Battistelli, P. de Bernardis, F. Columbro, G. D’Alessandro, L. Lamagna, A. Paiella, F. Piacentini et G. Presta. « Balloon-borne Cosmic Microwave Background experiments ». EPJ Web of Conferences 209 (2019) : 01046. http://dx.doi.org/10.1051/epjconf/201920901046.
Texte intégralRésumé :
Stratospheric balloon experiments play a unique role in current Cosmic Microwave Background (CMB) studies. CMB research has entered a precision phase, harvesting the detailed properties of its anisotropy, polarization and spectrum, at incredible precision levels. These measurements, however, require careful monitoring and subtraction of local backgrounds, produced by the earth atmosphere and the interstellar medium. High frequencies (larger than 180 GHz) are crucial for the measurements of interstellar dust contamination, but are degraded by atmospheric emission and its fluctuations, even in the best (cold and dry) sites on earth. For this reason, new balloon-borne missions, exploiting long-duration and ultra-long duration stratospheric flights, are being developed in several laboratories worldwide. These experiments have the double purpose of qualifying instrumentation and validating methods to be used on satellite missions, and produce CMB science at a relatively fast pace, synergically to ground-based CMB observatories.
17
Maruca, Bennett A., Raffaele Marino, David Sundkvist, Niharika H. Godbole, Stephane Constantin, Vincenzo Carbone et Herb Zimmerman. « Overview of and first observations from the TILDAE High-Altitude Balloon Mission ». Atmospheric Measurement Techniques 10, no 4 (26 avril 2017) : 1595–607. http://dx.doi.org/10.5194/amt-10-1595-2017.
Texte intégralRésumé :
Abstract. Though the presence of intermittent turbulence in the stratosphere has been well established, much remains unknown about it. In situ observations of this phenomenon, which have provided the greatest details of it, have mostly been achieved via sounding balloons (i.e., small balloons which burst at peak altitude) carrying constant-temperature hot-wire anemometers (CTAs). The Turbulence and Intermittency Long-Duration Atmospheric Experiment (TILDAE) was developed to test a new paradigm for stratospheric observations. Rather than flying on a sounding balloon, TILDAE was incorporated as an add-on experiment to the payload of a NASA long-duration balloon mission that launched in January 2016 from McMurdo Station, Antarctica. Furthermore, TILDAE's key instrument was a sonic anemometer, which (relative to a CTA) provides better-calibrated measurements of wind velocity and a more robust separation of velocity components. During the balloon's ascent, TILDAE's sonic anemometer provided atmospheric measurements up to an altitude of about 18 km, beyond which the ambient air pressure was too low for the instrument to function properly. Efforts are currently underway to scientifically analyze these observations of small-scale fluctuations in the troposphere, tropopause, and stratosphere and to develop strategies for increasing the maximum operating altitude of the sonic anemometer.
18
Hertzog, Albert, Philippe Cocquerez, René Guilbon, Jean-Noël Valdivia, Stéphanie Venel, Claude Basdevant, Gillian Boccara et al. « Stratéole/Vorcore—Long-duration, Superpressure Balloons to Study the Antarctic Lower Stratosphere during the 2005 Winter ». Journal of Atmospheric and Oceanic Technology 24, no 12 (1 décembre 2007) : 2048–61. http://dx.doi.org/10.1175/2007jtecha948.1.
Texte intégralRésumé :
Abstract In September and October 2005, the Stratéole/Vorcore campaign flew 27 superpressure balloons from McMurdo, Antarctica, into the stratospheric polar vortex. Long-duration flights were successfully achieved, 16 of those flights lasting for more than 2 months. Most flights were terminated because they flew out of the authorized flight domain or because of energy shortage in the gondola. The atmospheric pressure (1-Pa precision) was measured every minute during the flights, whereas air temperature observations (0.25-K accuracy) and balloon positions (absolute GPS observations, 10-m accuracy) were obtained every 15 min. Fifteen-minute-averaged horizontal velocities of the wind were deduced from the successive balloon positions with a corresponding accuracy ≲0.1 m s−1. The collected dataset (more than 150 000 independent observations) provides a thorough high-resolution sampling of the polar lower stratosphere in the Southern Hemisphere from its wintertime state up to the establishment of the summer circulation in December–January. Most of the balloons stayed inside the vortex until its final breakdown, although a few were ejected toward the midlatitudes in November during filamention events associated with an increase in planetary wave activity. The balloons behaved as quasi-Lagrangian tracers during the first part of the campaign (quiescent vortex) and after the vortex breakdown in early December. Large-amplitude mountain gravity waves were detected over the Antarctic Peninsula and caused one flight termination associated with the sudden burst in the balloon superpressure.
19
Schofield, R., L. M. Avallone, L. E. Kalnajs, A. Hertzog, I. Wohltmann et M. Rex. « First quasi-Lagrangian in-situ measurements of Antarctic Polar springtime ozone : observed ozone loss rates from the Concordiasi long-duration balloon campaign ». Atmospheric Chemistry and Physics Discussions 14, no 16 (1 septembre 2014) : 22245–72. http://dx.doi.org/10.5194/acpd-14-22245-2014.
Texte intégralRésumé :
Abstract. We present ozone measurements made using state-of-the-art ultraviolet photometers onboard three long-duration stratospheric balloons launched as part of the Concordiasi campaign in austral spring 2010. Ozone loss rates calculated by matching air-parcels sampled at different times and places during the polar spring are in agreement with rates previously derived from ozonesonde measurements, for the vortex-average, ranging between 2–7 ppbv (sunlit h)−1 or 25–110 ppbv per day. However, the geographical coverage of these long-duration stratospheric balloon platforms provides new insights into the temporal and spatial patterns of ozone loss over Antarctica. Very large ozone loss rates of up to 200 ppbv day−1 (16 ppbv (sunlit h)−1) are observed for airmasses that are down-wind of the Antarctic Peninsula and/or over the East Antarctic region. The ozone loss rate maximum downstream of the Antarctic Peninsula region is consistent with high PSC occurrence from Calipso and large ClO abundances from MLS satellite observations for 12–22 September 2010.
20
Schofield, R., L. M. Avallone, L. E. Kalnajs, A. Hertzog, I. Wohltmann et M. Rex. « First quasi-Lagrangian in situ measurements of Antarctic Polar springtime ozone : observed ozone loss rates from the Concordiasi long-duration balloon campaign ». Atmospheric Chemistry and Physics 15, no 5 (5 mars 2015) : 2463–72. http://dx.doi.org/10.5194/acp-15-2463-2015.
Texte intégralRésumé :
Abstract. We present ozone measurements made using state-of-the-art ultraviolet photometers onboard three long-duration stratospheric balloons launched as part of the Concordiasi campaign in austral spring 2010. Ozone loss rates calculated by matching air parcels sampled at different times and places during the polar spring are in agreement with rates previously derived from ozonesonde measurements, for the vortex average, ranging between 2 and 7 ppbv per sunlit hour or between 25 and 110 ppbv per day. However, the geographical coverage of these long-duration stratospheric balloon platforms provides new insights into the temporal and spatial patterns of ozone loss over Antarctica. Very large ozone loss rates of up to 230 ppbv per day (16 ppbv per sunlit hour) are observed for air masses that are downwind of the Antarctic Peninsula and/or over the East Antarctic region. The ozone loss rate maximum downstream of the Antarctic Peninsula region is consistent with high PSC occurrence from CALIPSO and large ClO abundances from MLS satellite observations for 12–22 September 2010, and with a chemical box model simulation using JPL 2011 kinetics with full chlorine activation.
21
Hertzog, A., C. Basdevant, F. Vial et C. R. Mechoso. « The accuracy of stratospheric analyses in the northern hemisphere inferred from long-duration balloon flights ». Quarterly Journal of the Royal Meteorological Society 130, no 597 (31 janvier 2004) : 607–26. http://dx.doi.org/10.1256/qj.03.76.
Texte intégral
22
Keil, Michael, Matt Heun, John Austin, William Lahoz, Guang Ping Lou et Alan O'Neill. « The use of long-duration balloon data to determine the accuracy of stratospheric analyses and forecasts ». Journal of Geophysical Research : Atmospheres 106, no D10 (1 mai 2001) : 10299–312. http://dx.doi.org/10.1029/2000jd900420.
Texte intégral
23
Gaskin, J. A., I. S. Smith et W. V. Jones. « Introduction ». Journal of Astronomical Instrumentation 03, no 02 (novembre 2014) : 1403001. http://dx.doi.org/10.1142/s2251171714030019.
Texte intégralRésumé :
In 1783, the Montgolfier brothers ushered in a new era of transportation and exploration when they used hot air to drive an un-tethered balloon to an altitude of ~2 km. Made of sackcloth and held together with cords, this balloon challenged the way we thought about human travel, and it has since evolved into a robust platform for performing novel science and testing new technologies. Today, high-altitude balloons regularly reach altitudes of 40 km, and they can support payloads that weigh more than 3000 kg. Long-duration balloons can currently support mission durations lasting ~55 days, and developing balloon technologies (i.e. Super-Pressure Balloons) are expected to extend that duration to 100 days or longer; competing with satellite payloads. This relatively inexpensive platform supports a broad range of science payloads, spanning multiple disciplines (astrophysics, heliophysics, planetary and earth science). Applications extending beyond traditional science include testing new technologies for eventual space-based application and stratospheric airships for planetary applications.
24
Wang, Xuwei, Zhaojie Li et Yanlei Zhang. « Model for Predicting the Operating Temperature of Stratospheric Airship Solar Cells with a Support Vector Machine ». Energies 14, no 5 (24 février 2021) : 1228. http://dx.doi.org/10.3390/en14051228.
Texte intégralRésumé :
The stratospheric airship is a kind of aircraft that completely relies on the cycle of photovoltaic energy systems to achieve long duration flight. The accurate estimation of the operating temperature of solar cell modules on stratospheric airship is extremely important for the design of photovoltaics system (PV system), the output power calculation of PV system, and the calculation of energy balance. However, the related study has been rarely reported. A support vector machine prediction method based on particle swarm optimization algorithm (PSO-SVM) was established to predict the operating temperature of solar cell modules on stratospheric airship. The PSO algorithm was used to dynamically optimize the SVM’s parameters between the operating temperature of the solar cell modules and the measured data such as atmospheric pressure, solar radiation intensity, flight speed, and ambient temperature. The operating temperature data of the two sets of solar cell modules measured in the flight test were used to verify the accuracy of the temperature prediction model, and the prediction results were compared with a back propagation neural network (BPNN) method and the simulation results calculated by COMSOL Multiphysics of COMSOL, Inc., Columbus, MA, USA. The results shown that the PSO-SVM model realized the accurate prediction of the operating temperature of solar cell modules on stratospheric airship, which can guide the design of PV system, the output power calculation of PV system, and the calculation of energy balance.
25
Romeo, Giovanni, Pasquale Adobbato, Simone Bacci, Giuseppe Di Stefano, Alessandro Iarocci, Amedeo Lepore, Massimo Mari et al. « HERMES : A Data and Specimens Transporter from the Stratosphere to the Ground—The First Experimental Flight ». Drones 7, no 5 (5 mai 2023) : 308. http://dx.doi.org/10.3390/drones7050308.
Texte intégralRésumé :
Large stratospheric balloons are the easiest access to near space. Large long duration balloons (LDBs) can float in the stratosphere for weeks collecting measurements (e.g., astrophysical or geophysical data) or samples (e.g., contaminants, volcanic ash, micrometeorites). The recovery of data media and samples is a common problem in this type of experiment because direct radio communication becomes useless when the balloon crosses the horizon, and satellite links are too slow and expensive. For this reason, physical recovery of the payload is mandatory to obtain experimental results, which is a difficult task, especially in polar regions. The goal of HERMES (HEmera Returning MESsenger) is to allow researchers to obtain experimental data prior to payload recovery. HERMES is a system equipped with an autonomous glider capable of physically transporting data and samples from the stratosphere to a recovery point on the ground. The glider is installed on the balloon payload via a remotely controlled release system and is connected to the main computer to store a copy of the scientific data and to receive the geographic coordinates of the recovery point. This allows scientists to obtain experimental results before recovering the payload. The article describes HERMES and the first experimental flight of the entire system, which was conducted at Esrange Space Center (Kiruna, Sweden) in July 2022.
26
Qu, Yi, Sheng Wang, Hui Feng et Qiang Liu. « Geometry Optimization of Stratospheric Pseudolite Network for Navigation Applications ». Electronics 13, no 12 (19 juin 2024) : 2397. http://dx.doi.org/10.3390/electronics13122397.
Texte intégralRésumé :
A stratospheric pseudolite (SP) is a pseudolite installed on a stratospheric airship. A stratospheric pseudolite network (SPN) is composed of multiple SPs, which shows promising potential in navigation applications because of its station-keeping capability, long service duration, and flexible deployment. Most traditional research about SPN geometry optimization has centered on geometric dilution of precision (GDOP). However, previous research rarely dealt with the topic of how SPN geometry configuration not only affects its GDOP, but also affects its energy balance. To obtain an optimal integrated performance, this paper employs the proportion of energy consumption in energy production as an indicator to assess SPN energy status and designs a composite indicator including GDOP and energy status to assess SPN geometry performance. Then, this paper proposes an SPN geometry optimization algorithm based on gray wolf optimization. Furthermore, this paper implements a series of simulations with an SPN composed of six SPs in a specific service area. Simulations show that the proposed algorithm can obtain SPN geometry solutions with good GDOP and energy balance performance. Also, simulations show that in the supposed scenarios and the specific area, a higher SP altitude can improve both GDOP and energy balance, while a lower SP latitude can improve SPN energy status.
27
Gurubaran, Subramanian, Manu Shanmugam, Kaliappan Jawahar, Kaliappan Emperumal, Prasanna Mahavarkar et Suneel Kumar Buduru. « A high-altitude balloon experiment to probe stratospheric electric fields from low latitudes ». Annales Geophysicae 35, no 2 (3 février 2017) : 189–201. http://dx.doi.org/10.5194/angeo-35-189-2017.
Texte intégralRésumé :
Abstract. The Earth's electrical environment hosts a giant electrical circuit, often referred to as the global electric circuit (GEC), linking the various sources of electrical generators located in the lower atmosphere, the ionosphere and the magnetosphere. The middle atmosphere (stratosphere and mesosphere) has been traditionally believed to be passively transmitting electric fields generated elsewhere. Some observations have reported anomalously large electric fields at these altitudes, and the scientific community has had to revisit the earlier hypothesis time and again. At stratospheric altitudes and especially at low latitudes, horizontal electric fields are believed to be of ionospheric origin. Though measurements of these fields from a balloon platform are challenging because of their small magnitudes (around a few mV m−1), a suitably designed long-duration balloon experiment capable of detecting such small fields can provide useful information on the time evolution of ionospheric electric fields, which is otherwise possible only using radar or satellite in situ measurements. We present herein details of one such experiment, BEENS (Balloon Experiment on the Electrodynamics of Near Space), carried out from a low-latitude site in India. The instrument package for this experiment is comprised of four deployable booms for measurements of horizontal electric fields and one inclined boom for vertical electric field measurements, all equipped with conducting spheres at the tip. The experiment was conducted from Hyderabad (17.5° N, 78.6° E) during the post-midnight hours on 14 December 2013. In spite of a few shortcomings we report herein, a noticeable feature of the observations has been the detection of horizontal electric fields of ∼ 5 mV m−1 at the stratospheric altitudes of ∼ 35 km.
28
Borchi, F., J. P. Pommereau, A. Garnier et M. Pinharanda. « Evaluation of SHADOZ sondes, HALOE and SAGE II ozone profiles at the tropics from SAOZ UV-Vis remote measurements onboard long duration balloons ». Atmospheric Chemistry and Physics Discussions 4, no 5 (2 septembre 2004) : 4945–97. http://dx.doi.org/10.5194/acpd-4-4945-2004.
Texte intégralRésumé :
Abstract. Long series of ozone profiles from 6 to 28 km at the Southern Tropics have been obtained from solar occultation measurements at twilight using a SAOZ spectrometer borne by long duration balloons. Two flights have been performed from Bauru in Brazil both in the summer, in February and March 2001 and 2003, from where the balloons are moving westward at almost constant latitude (20°±5° S). The flight in 2001 passed right over Reunion Island where the SAOZ measurements could be compared to those of both tropospheric and stratospheric ozone lidars. In the stratosphere, compared to that of SAOZ, the measurements of the SHADOZ ozonesondes network, and the HALOE and SAGE II instruments in orbit are found a little noisier (2–3% for SAGE II, 3–4% for HALOE, 4–5% for the sondes), and of insignificant or small high biased (SAGE II). No differences in altitude could be found between SAOZ and SAGE II at all levels, and HALOE above 22 km. But the ozonesondes appear to be systematically displaced upwards by some 400–700 m at all levels, and the HALOE profiles do show an increasing altitude bias at decreasing altitude below 22 km. In the upper troposphere, the SAOZ measurements are found consistent with those of the sondes at Reunion Island and high biased on average over the Western Pacific, at American Samoa and Fiji. Compared to SAOZ, SAGE II shows a 50–60% low bias similar to that already found with the ozonesondes, and a 2–2.5 times larger zonal variability, suggesting a degradation of its precision below the tropopause. Finally, the unrealistic large offsets and variability in the HALOE data compared to all others suggest that its measurements are no reliable in the tropical troposphere below 17 km.
29
Ovarlez, Joëlle. « Stratospheric water vapor measurement in the tropical zone by means of a frost point hygrometer on board long-duration balloons ». Journal of Geophysical Research 96, no D8 (1991) : 15541. http://dx.doi.org/10.1029/91jd01215.
Texte intégral
30
Lecouffe, Audrey, Sophie Godin-Beekmann, Andrea Pazmiño et Alain Hauchecorne. « Evolution of the intensity and duration of the Southern Hemisphere stratospheric polar vortex edge for the period 1979–2020 ». Atmospheric Chemistry and Physics 22, no 6 (31 mars 2022) : 4187–200. http://dx.doi.org/10.5194/acp-22-4187-2022.
Texte intégralRésumé :
Abstract. The intensity and position of the Southern Hemisphere stratospheric polar vortex edge is evaluated as a function of equivalent latitude over the period 1979–2020 on three isentropic levels (475, 550, and 675 K) from ECMWF ERA-Interim reanalysis. The study also includes an analysis of the onset and breakup dates of the polar vortex, which are determined from wind thresholds (e.g., 15.2, 20, and 25 m s−1) along the vortex edge. The vortex edge is stronger in late winter, during September–October–November, with the period of strongest intensity occurring later at the lowermost level. During the same period, we observe a lower variability of the edge position. A long-term increase in the vortex edge intensity and break-up date is observed during 1979–1999, linked to the increase in the ozone hole. A long-term decrease in the vortex onset date related to the 25 m s−1 wind threshold is also observed at 475 K during this period. The solar cycle and to a lower extent the quasi-biennial oscillation (QBO) and El Niño–Southern Oscillation (ENSO) modulate the interannual evolution of the strength of the vortex edge and the vortex breakup dates. A stronger vortex edge and longer vortex duration are observed in solar minimum (minSC) years, with the QBO and ENSO further modulating the solar cycle influence, especially at 475 and 550 K: during west QBO (wQBO) phases, the difference between vortex edge intensity for minSC and maxSC years is smaller than during east QBO (eQBO) phases. The polar vortex edge is stronger and lasts longer for maxSC/wQBO years than for maxSC/eQBO years. ENSO has a weaker impact but the vortex edge is somewhat stronger during cold ENSO phases for both minSC and maxSC years.
31
Flemming, J., A. Inness, L. Jones, H. J. Eskes, V. Huijnen, M. G. Schultz, O. Stein, D. Cariolle, D. Kinnison et G. Brasseur. « Forecasts and assimilation experiments of the Antarctic ozone hole 2008 ». Atmospheric Chemistry and Physics 11, no 5 (3 mars 2011) : 1961–77. http://dx.doi.org/10.5194/acp-11-1961-2011.
Texte intégralRésumé :
Abstract. The 2008 Antarctic ozone hole was one of the largest and most long-lived in recent years. Predictions of the ozone hole were made in near-real time (NRT) and hindcast mode with the Integrated Forecast System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). The forecasts were carried out both with and without assimilation of satellite observations from multiple instruments to provide more realistic initial conditions. Three different chemistry schemes were applied for the description of stratospheric ozone chemistry: (i) a linearization of the ozone chemistry, (ii) the stratospheric chemical mechanism of the Model of Ozone and Related Chemical Tracers, version 3, (MOZART-3) and (iii) the relaxation to climatology as implemented in the Transport Model, version 5, (TM5). The IFS uses the latter two schemes by means of a two-way coupled system. Without assimilation, the forecasts showed model-specific shortcomings in predicting start time, extent and duration of the ozone hole. The assimilation of satellite observations from the Microwave Limb Sounder (MLS), the Ozone Monitoring Instrument (OMI), the Solar Backscattering Ultraviolet radiometer (SBUV-2) and the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) led to a significant improvement of the forecasts when compared with total columns and vertical profiles from ozone sondes. The combined assimilation of observations from multiple instruments helped to overcome limitations of the ultraviolet (UV) sensors at low solar elevation over Antarctica. The assimilation of data from MLS was crucial to obtain a good agreement with the observed ozone profiles both in the polar stratosphere and troposphere. The ozone analyses by the three model configurations were very similar despite the different underlying chemistry schemes. Using ozone analyses as initial conditions had a very beneficial but variable effect on the predictability of the ozone hole over 15 days. The initialized forecasts with the MOZART-3 chemistry produced the best predictions of the increasing ozone hole whereas the linear scheme showed the best results during the ozonehole closure.
32
Hertzog, Albert, Gillian Boccara, Robert A. Vincent, François Vial et Philippe Cocquerez. « Estimation of Gravity Wave Momentum Flux and Phase Speeds from Quasi-Lagrangian Stratospheric Balloon Flights. Part II : Results from the Vorcore Campaign in Antarctica ». Journal of the Atmospheric Sciences 65, no 10 (octobre 2008) : 3056–70. http://dx.doi.org/10.1175/2008jas2710.1.
Texte intégralRésumé :
The stratospheric gravity wave field in the Southern Hemisphere is investigated by analyzing observations collected by 27 long-duration balloons that flew between September 2005 and February 2006 over Antarctica and the Southern Ocean. The analysis is based on the methods introduced by Boccara et al. in a companion paper. Special attention is given to deriving information useful to gravity wave drag parameterizations employed in atmospheric general circulation models. The balloon dataset is used to map the geographic variability of gravity wave momentum fluxes in the lower stratosphere. This flux distribution is found to be very heterogeneous with the largest time-averaged value (28 mPa) observed above the Antarctic Peninsula. This value exceeds by a factor of ∼10 the overall mean momentum flux measured during the balloon campaign. Zonal momentum fluxes were predominantly westward, whereas meridional momentum fluxes were equally northward and southward. A local enhancement of southward flux is nevertheless observed above Adélie Land and is attributed to waves generated by katabatic winds, for which the signature is otherwise rather small in the balloon observations. When zonal averages are performed, oceanic momentum fluxes are found to be of similar magnitude to continental values (2.5–3 mPa), stressing the importance of nonorographic gravity waves over oceans. Last, gravity wave intermittency is investigated. Mountain waves appear to be significantly more sporadic than waves observed above the ocean.
33
Kalnajs, Lars E., Sean M. Davis, J. Douglas Goetz, Terry Deshler, Sergey Khaykin, Alex St. Clair, Albert Hertzog, Jerome Bordereau et Alexey Lykov. « A reel-down instrument system for profile measurements of water vapor, temperature, clouds, and aerosol beneath constant-altitude scientific balloons ». Atmospheric Measurement Techniques 14, no 4 (6 avril 2021) : 2635–48. http://dx.doi.org/10.5194/amt-14-2635-2021.
Texte intégralRésumé :
Abstract. The tropical tropopause layer (TTL; 14–18.5 km) is the gateway for most air entering the stratosphere, and therefore processes within this layer have an outsized influence in determining global stratospheric ozone and water vapor concentrations. Despite the importance of this layer there are few in situ measurements with the necessary detail to resolve the fine-scale processes within this region. Here, we introduce a novel platform for high-resolution in situ profiling that lowers and retracts a suspended instrument package beneath drifting long-duration balloons in the tropics. During a 100 d circumtropical flight, the instrument collected over a hundred 2 km profiles of temperature, water vapor, and aerosol at 1 m resolution, yielding unprecedented geographic sampling and vertical resolution. The instrument system integrates proven sensors for water vapor, temperature, pressure, and cloud and aerosol particles with an innovative mechanical reeling and control system. A technical evaluation of the system performance demonstrated the feasibility of this new measurement platform for future missions with minor modifications. Six instruments planned for two upcoming field campaigns are expected to provide over 4000 profiles through the TTL, quadrupling the number of high-resolution aircraft and balloon profiles collected to date. These and future measurements will provide the necessary resolution to diagnose the importance of competing mechanisms for the transport of water vapor across the TTL.
34
Friedrich, Leon S., Adrian J. McDonald, Gregory E. Bodeker, Kathy E. Cooper, Jared Lewis et Alexander J. Paterson. « A comparison of Loon balloon observations and stratospheric reanalysis products ». Atmospheric Chemistry and Physics 17, no 2 (19 janvier 2017) : 855–66. http://dx.doi.org/10.5194/acp-17-855-2017.
Texte intégralRésumé :
Abstract. Location information from long-duration super-pressure balloons flying in the Southern Hemisphere lower stratosphere during 2014 as part of X Project Loon are used to assess the quality of a number of different reanalyses including National Centers for Environmental Prediction Climate Forecast System version 2 (NCEP-CFSv2), European Centre for Medium-Range Weather Forecasts (ERA-Interim), NASA Modern Era Retrospective-Analysis for Research and Applications (MERRA), and the recently released MERRA version 2. Balloon GPS location information is used to derive wind speeds which are then compared with values from the reanalyses interpolated to the balloon times and locations. All reanalysis data sets accurately describe the winds, with biases in zonal winds of less than 0.37 m s−1 and meridional biases of less than 0.08 m s−1. The standard deviation on the differences between Loon and reanalyses zonal winds is latitude-dependent, ranging between 2.5 and 3.5 m s−1, increasing equatorward. Comparisons between Loon trajectories and those calculated by applying a trajectory model to reanalysis wind fields show that MERRA-2 wind fields result in the most accurate simulated trajectories with a mean 5-day balloon–reanalysis trajectory separation of 621 km and median separation of 324 km showing significant improvements over MERRA version 1 and slightly outperforming ERA-Interim. The latitudinal structure of the trajectory statistics for all reanalyses displays marginally lower mean separations between 15 and 35° S than between 35 and 55° S, despite standard deviations in the wind differences increasing toward the equator. This is shown to be related to the distance travelled by the balloon playing a role in the separation statistics.
35
Li, Ying, Gottfried Kirchengast, Marc Schwärz, Florian Ladstädter et Yunbin Yuan. « Monitoring sudden stratospheric warmings using radio occultation : a new approach demonstrated based on the 2009 event ». Atmospheric Measurement Techniques 14, no 3 (26 mars 2021) : 2327–43. http://dx.doi.org/10.5194/amt-14-2327-2021.
Texte intégralRésumé :
Abstract. We introduce a new method to detect and monitor sudden stratospheric warming (SSW) events using Global Navigation Satellite System (GNSS) radio occultation (RO) data at high northern latitudes and demonstrate it for the well-known January–February 2009 event. We first construct RO temperature, density, and bending angle anomaly profiles and estimate vertical-mean anomalies in selected altitude layers. These mean anomalies are then averaged into a daily updated 5∘ latitude × 20∘ longitude grid over 50–90∘ N. Based on the gridded mean anomalies, we employ the concept of threshold exceedance areas (TEAs), the geographic areas wherein the anomalies exceed predefined threshold values such as 40 K or 40 %. We estimate five basic TEAs for selected altitude layers and thresholds and use them to derive primary-, secondary-, and trailing-phase TEA metrics to detect SSWs and to monitor in particular their main-phase (primary- plus secondary-phase) evolution on a daily basis. As an initial setting, the main phase requires daily TEAs to exceed 3×106 km2, based on which main-phase duration, area, and overall event strength are recorded. Using the January–February 2009 SSW event for demonstration, and employing RO data plus cross-evaluation data from analysis fields of the European Centre for Medium-Range Weather Forecasts (ECMWF), we find the new approach has strong potential for detecting and monitoring SSW events. The primary-phase metric shows a strong SSW emerging on 20 January, reaching a maximum on 23 January and fading by 30 January. On 22–23 January, temperature anomalies over the middle stratosphere exceeding 40 K cover an area of more than 10×106 km2. The geographic tracking of the SSW showed that it was centered over east Greenland, covering Greenland entirely and extending from western Iceland to eastern Canada. The secondary- and trailing-phase metrics track the further SSW development, where the thermodynamic anomaly propagated downward and was fading with a transient upper stratospheric cooling, spanning until the end of February and beyond. Given the encouraging demonstration results, we expect the method to be very suitable for long-term monitoring of how SSW characteristics evolve under climate change and polar vortex variability, using both RO and reanalysis data.
36
Flemming, J., A. Inness, L. Jones, H. J. Eskes, V. Huijnen, M. G. Schultz, O. Stein, D. Cariolle, D. Kinnison et G. Brasseur. « Forecasts and assimilation experiments of the Antarctic Ozone Hole 2008 ». Atmospheric Chemistry and Physics Discussions 10, no 4 (9 avril 2010) : 9173–217. http://dx.doi.org/10.5194/acpd-10-9173-2010.
Texte intégralRésumé :
Abstract. The 2008 Antarctic ozone hole was one of the largest and most long-lived in recent years. Predictions of the ozone hole were made in near-real time (NRT) and hindcast mode with the Integrated Forecast System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). The forecasts were carried out both with and without assimilation of satellite observations from multiple instruments to provide more realistic initial conditions. Three different chemistry schemes were applied for the description of stratospheric ozone chemistry: (i) a linearization of the ozone chemistry, (ii) the stratospheric chemical mechanism of the MOZART-3 chemical transport model (CTM) and (iii) the relaxation to a climatology as implemented in the TM5 CTM. The IFS uses the latter two schemes by means of a two-way coupled system. Without assimilation, the forecasts showed model-specific shortcomings in predicting start time, extent and duration of the ozone hole. The assimilation of satellite observations from the Microwave Limb Sounder (MLS), the Ozone Monitoring Instrument (OMI), the Solar Backscattering Ultraviolet radiometer (SBUV-2) and the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) led to a significant improvement of the forecasts when compared with total columns and vertical profiles from ozone sondes. The combined assimilation of observations from multiple instruments helped to overcome limitations of the ultraviolet (UV) sensors at low solar elevation over Antarctica. The assimilation of data from MLS was crucial to obtain a good agreement with the observed ozone profiles both in the polar stratosphere and troposphere. The ozone analyses by the three model configurations were very similar despite the different underlying chemistry schemes. During the chemically instigated development of the ozone hole, differences quickly developed in the initialized forecasts by the different schemes. The predictions of the ozone-hole closure, which is driven mainly by dynamical processes, benefited from the initialization over a much longer forecast length. The characteristics of the individual chemistry schemes became apparent after the third forecast day but the forecasts were still close to the respective analyses. The initialization with ozone analyses was beneficial up to at least 15 days.
37
Arteta, J., V. Marécal et E. D. Rivière. « Regional modelling of tracer transport by tropical convection – Part 1 : Sensitivity to convection parameterization ». Atmospheric Chemistry and Physics Discussions 9, no 2 (4 mars 2009) : 5889–928. http://dx.doi.org/10.5194/acpd-9-5889-2009.
Texte intégralRésumé :
Abstract. The general objective of this series of papers is to evaluate long duration limited area simulations with idealised tracers as a tool to assess tracer transport in chemistry-transport models (CTMs). In this first paper, we analyse the results of six simulations using different convection parameterizations. The simulations are using the Grell and Dévényi (2002) mass-flux framework for the convection parameterization with different closures (Grell=GR, Arakawa-Shubert=AS, Kain-Fritch=KF, Low omega=LO, Moisture convergence=MC) and an ensemble parameterization (EN) based on the other five closures. The simulations are run for one month during the SCOUT-O3 field campaign lead from Darwin (Australia) and have a 60 km horizontal resolution and a fine vertical resolution in the upper troposphere/lower stratosphere. Meteorological results are compared with satellite products, radiosoundings and SCOUT-O3 aircraft campaign data. They show that the model is generally in good agreement with the measurements with less variability in the model. Except for the precipitation field the differences between the six simulations are small with respect to the differences with the meteorological observations. The comparison with TRMM rainrates shows that the six simulations have two different behaviours with the EN, AS and KF parameterizations (Group 1) providing better rain fields than LO, MC and GR (Group 2). The vertical distribution of tropospheric tracers is very different for the two groups showing significantly more transport into the TTL for Group 1 related to the larger average values of the upward velocities. Nevertheless the low values for the Group 1 fluxes at and above the cold point level indicate that the model does not simulate significant overshooting. For stratospheric tracers, the differences between the two groups of parameterizations are small indicating that the downward transport from the stratosphere is more related to the turbulent mixing parameterization than to the convection parameterization.
38
Li, Ying, Gottfried Kirchengast, Marc Schwaerz et Yunbin Yuan. « Monitoring sudden stratospheric warmings under climate change since 1980 based on reanalysis data verified by radio occultation ». Atmospheric Chemistry and Physics 23, no 2 (24 janvier 2023) : 1259–84. http://dx.doi.org/10.5194/acp-23-1259-2023.
Texte intégralRésumé :
Abstract. We developed a new approach to monitor sudden stratospheric warming (SSW) events under climate change since 1980 based on reanalysis data verified by radio occultation data. We constructed gridded daily mean temperature anomalies from the input fields at different vertical resolutions (basic-case full resolution, cross-check with reanalysis at 10 stratospheric standard pressure levels or 10 and 50 hPa levels only) and employed the concept of threshold exceedance areas (TEAs), the geographic areas wherein the anomalies exceed predefined thresholds (such as 30 K), to monitor the phenomena. We derived main-phase TEAs, representing combined middle- and lower-stratospheric warming, to monitor SSWs on a daily basis. Based on the main-phase TEAs, three key metrics, including main-phase duration, area, and strength, are estimated and used for the detection and classification of SSW events. An SSW is defined to be detected if the main-phase warming lasts at least 6 d. According to the strength, SSW events are classified into minor, major, and extreme. An informative 42 winters' SSW climatology (1980–2021) was developed, including the three key metrics as well as onset date, maximum-warming-anomaly location, and other valuable SSW characterization information. The results and validation against previous studies underpin that the new method is robust for SSW detection and monitoring and that it can be applied to any quality-assured reanalysis, observational and model temperature data that cover the polar region and winter timeframes of interest, either using high-vertical-resolution input data (preferable basic case), coarser standard-pressure-levels resolution, or (at least) 10 and 50 hPa pressure level data. Within the 42 winters, 43 SSW events were detected for the basic case, yielding a frequency of about 1 event per year. In the 1990s, where recent studies showed gaps, we detected several events. Over 95 % of event onset dates occurred in deep winter (December–January–February timeframe, about 50 % in January), and more than three-quarters have their onset location over northern Eurasia and the adjacent polar ocean. Regarding long-term change, we found a statistically significant increase in the duration of SSW main-phase warmings of about 5(±2) d over the climate change period from the 1980s to the 2010s, raising the average duration by nearly 50 % from about 10 d to 15 d and inducing an SSW strength increase of about 40(±25) million km2 days from about 100 to 140 million km2 days. The results are robust (consistent within uncertainties) across the use of different input data resolutions. They can hence be used as a reference for further climate-change-related studies and as a valuable basis for studying SSW impacts and links to other weather and climate phenomena, such as changes in polar-vortex dynamics and in mid-latitude extreme weather.
39
Ocampo, Jonna, Hailey Barker, Kelly C. Rice et Mariola J. Ferraro. « Impact of payload shielding on Enterobacter cloacae viability and proteomic profile : Insights from a stratospheric weather balloon flight experiment ». Gravitational and Space Research 12, no 1 (1 janvier 2024) : 64–76. http://dx.doi.org/10.2478/gsr-2024-0005.
Texte intégralRésumé :
Abstract Enterobacter cloacae, a gram-negative bacterium commonly found in the human gut microbiota, poses potential health risks to astronauts in the unique environment of space flight. This study investigated the effects of payload shielding on E. cloacae in a short-duration, student-initiated, weather balloon flight experiment. Faraday fabric-based payload shielding did not impact the viability of the balloon flight samples. However, murine macrophage infection assays showed that shielded balloon flight E. cloacae had significantly improved intracellular survival compared to unshielded E. cloacae. Proteomic analysis demonstrated distinct profiles in shielded and unshielded samples, with a differential abundance of proteins involved in diverse biological processes. Specifically, decreased abundance of proteins involved in chemotaxis, DNA repair, replication, transcription, peptidoglycan synthesis, and proteolysis were observed in the Faraday fabric-based payload-shielded samples. In contrast, proteins associated with protein translation, transport, tricarboxylic acid cycle, fatty acid biosynthesis, and amino acid metabolism were increased in shielded conditions. This experiment provides a framework for which future long-duration balloon flight experiments can be designed, and the findings provide initial insights into the impact of payload shielding on E. cloacae physiology. Understanding the impact of the stratosphere on human gut microbiota is important for preserving human health during future space flight missions.
40
Arteta, J., V. Marécal et E. D. Rivière. « Regional modelling of tracer transport by tropical convection – Part 1 : Sensitivity to convection parameterization ». Atmospheric Chemistry and Physics 9, no 18 (24 septembre 2009) : 7081–100. http://dx.doi.org/10.5194/acp-9-7081-2009.
Texte intégralRésumé :
Abstract. The general objective of this series of papers is to evaluate long duration limited area simulations with idealised tracers as a tool to assess tracer transport in chemistry-transport models (CTMs). In this first paper, we analyse the results of six simulations using different convection closures and parameterizations. The simulations are using the Grell and Dévényi (2002) mass-flux framework for the convection parameterization with different closures (Grell = GR, Arakawa-Shubert = AS, Kain-Fritch = KF, Low omega = LO, Moisture convergence = MC) and an ensemble parameterization (EN) based on the other five closures. The simulations are run for one month during the SCOUT-O3 field campaign lead from Darwin (Australia). They have a 60 km horizontal resolution and a fine vertical resolution in the upper troposphere/lower stratosphere. Meteorological results are compared with satellite products, radiosoundings and SCOUT-O3 aircraft campaign data. They show that the model is generally in good agreement with the measurements with less variability in the model. Except for the precipitation field, the differences between the six simulations are small on average with respect to the differences with the meteorological observations. The comparison with TRMM rainrates shows that the six parameterizations or closures have similar behaviour concerning convection triggering times and locations. However, the 6 simulations provide two different behaviours for rainfall values, with the EN, AS and KF parameterizations (Group 1) modelling better rain fields than LO, MC and GR (Group 2). The vertical distribution of tropospheric tracers is very different for the two groups showing significantly more transport into the TTL for Group 1 related to the larger average values of the upward velocities. Nevertheless the low values for the Group 1 fluxes at and above the cold point level indicate that the model does not simulate significant overshooting. For stratospheric tracers, the differences between the two groups are small indicating that the downward transport from the stratosphere is more related to the turbulent mixing parameterization than to the convection parameterization.
41
Boccara, Gillian, Albert Hertzog, Robert A. Vincent et François Vial. « Estimation of Gravity Wave Momentum Flux and Phase Speeds from Quasi-Lagrangian Stratospheric Balloon Flights. Part I : Theory and Simulations ». Journal of the Atmospheric Sciences 65, no 10 (octobre 2008) : 3042–55. http://dx.doi.org/10.1175/2008jas2709.1.
Texte intégralRésumé :
A methodology for estimating gravity wave characteristics from quasi-Lagrangian observations provided by long-duration, superpressure balloon flights in the stratosphere is reviewed. Wavelet analysis techniques are used to detect gravity wave packets in observations of pressure, temperature, and horizontal velocity. An emphasis is put on the estimation of gravity wave momentum fluxes and intrinsic phase speeds, which are generally poorly known on global scales in the atmosphere. The methodology is validated using Monte Carlo simulations of time series that mimic the balloon measurements, including the uncertainties associated with each of the meteorological parameters. While the azimuths of the wave propagation direction are accurately retrieved, the momentum fluxes are generally slightly underestimated, especially when wave packets overlap in the time–frequency domain, or for short-period waves. A proxy is derived to estimate by how much momentum fluxes are reduced by the analysis. Retrievals of intrinsic phase speeds are less accurate, especially for low phase speed waves. A companion paper (Part II) implements the methodology to observations gathered during the Vorcore campaign that took place in Antarctica between September 2005 and February 2006.
42
Arteta, J., V. Marécal et E. D. Rivière. « Regional modelling of tracer transport by tropical convection – Part 2 : Sensitivity to model resolutions ». Atmospheric Chemistry and Physics Discussions 9, no 2 (4 mars 2009) : 5929–65. http://dx.doi.org/10.5194/acpd-9-5929-2009.
Texte intégralRésumé :
Abstract. The general objective of this series of two papers is to evaluate long duration limited-area simulations with idealised tracers as a tool to assess the tracer transport in chemistry-transport models (CTMs). In this second paper we analyse the results of three simulations using different horizontal and vertical resolutions against meteorological observations and their impact on idealized tracer transport. The reference simulation (REF) uses a 60 km horizontal resolution and 300 m vertically in the upper troposphere/lower stratosphere (UTLS). A 20 km horizontal resolution simulation (HR) is run as well as a simulation (CVR) with 850 m vertical resolution in the UTLS. The simulations are run for one month during the SCOUT-O3 field campaign. The Falcon and Geophysica aircraft data and the TRMM rainrate estimates have been used to evaluate the simulations. They show that the HR configuration gives generally a better agreement with the measurements than the REF simulation, the CVR simulation giving generally the worst results. The vertical distribution of the tropospheric tracers for the simulations has a similar shape with a 15 km altitude maximum of 0.4 ppbv for REF, 1.2 for HR and 0.04 for CVR. This is related to the dynamics produced by the three simulations that leads to larger values of the upward velocities on average for HR and lower for CVR compared to REF. The HR provides more frequent overshoots over the cold point dynamical barrier than REF and CVR. For the stratospheric tracers the differences between the three simulations are small. The diurnal cycle of the fluxes of all tracers in the TTL (Tropical Tropopause Layer) exhibits a maximum linked to the maximum of convective activity that is particularly well marked in the HR simulation. The largest integrated fluxes are found for tropospheric tracers in HR.
43
Arteta, J., V. Marécal et E. D. Rivière. « Regional modelling of tracer transport by tropical convection – Part 2 : Sensitivity to model resolutions ». Atmospheric Chemistry and Physics 9, no 18 (24 septembre 2009) : 7101–14. http://dx.doi.org/10.5194/acp-9-7101-2009.
Texte intégralRésumé :
Abstract. The general objective of this series of two papers is to evaluate long duration limited-area simulations with idealised tracers as a possible tool to assess the tracer transport in chemistry-transport models (CTMs). In this second paper we analyse the results of three simulations using different horizontal and vertical resolutions. The goal is to study the impact of the model spatial resolution on convective transport of idealized tracer in the tropics. The reference simulation (REF) uses a 60 km horizontal resolution and 300 m vertically in the upper troposphere/lower stratosphere (UTLS). A 20 km horizontal resolution simulation (HR) is run as well as a simulation with 850 m vertical resolution in the UTLS (CVR). The simulations are run for one month during the SCOUT-O3 field campaign. Aircraft data, TRMM rainrate estimates and radiosoundings have been used to evaluate the simulations. They show that the HR configuration gives generally a better agreement with the measurements than the REF simulation. The CVR simulation gives generally the worst results. The vertical distribution of the tropospheric tracers for the simulations has a similar shape with a ~15 km altitude maximum for the 6h-lifetime tracer of 0.4 ppbv for REF, 1.2 for HR and 0.04 for CVR. These differences are related to the dynamics produced by the three simulations that leads to larger values of the upward velocities on average for HR and lower for CVR compared to REF. HR simulates more frequent and stronger convection leading to enhanced fluxes compared to REF and higher detrainment levels compared to CVR. HR provides also occasional overshoots over the cold point dynamical barrier. For the stratospheric tracers the differences between the three simulations are small. The diurnal cycle of the fluxes of all tracers in the Tropical Tropopause Layer exhibits a maximum linked to the maximum of convective activity.
44
Schmidt, Anja, et Benjamin A. Black. « Reckoning with the Rocky Relationship Between Eruption Size and Climate Response : Toward a Volcano-Climate Index ». Annual Review of Earth and Planetary Sciences 50, no 1 (31 mai 2022) : 627–61. http://dx.doi.org/10.1146/annurev-earth-080921-052816.
Texte intégralRésumé :
Volcanic eruptions impact climate, subtly and profoundly. The size of an eruption is only loosely correlated with the severity of its climate effects, which can include changes in surface temperature, ozone levels, stratospheric dynamics, precipitation, and ocean circulation. We review the processes—in magma chambers, eruption columns, and the oceans, biosphere, and atmosphere—that mediate the climate response to an eruption. A complex relationship between eruption size, style, duration, and the subsequent severity of the climate response emerges. We advocate for a new, consistent metric, the Volcano-Climate Index, to categorize climate response to eruptions independent of eruption properties and spanning the full range of volcanic activity, from brief explosive eruptions to long-lasting flood basalts. A consistent metric for categorizing the climate response to eruptions that differ in size, style, and duration is critical for establishing the relationshipbetween the severity and the frequency of such responses aiding hazard assessments, and furthering understanding of volcanic impacts on climate on timescales of years to millions of years. ▪ We review the processes driving the rocky relationship between eruption size and climate response and propose a Volcano-Climate Index. ▪ Volcanic eruptions perturb Earth's climate on a range of timescales, with key open questions regarding how processes in the magmatic system, eruption column, and atmosphere shape the climate response to volcanism. ▪ A Volcano-Climate Index will provide information on the volcano-climate severity-frequency distribution, analogous to earthquake hazards. ▪ Understanding of the frequency of specific levels of volcanic climate effects will aid hazard assessments, planning, and mitigation of societal impacts.
45
Bevan, Suzanne, Adrian Luckman, Harry Hendon et Guomin Wang. « The 2020 Larsen C Ice Shelf surface melt is a 40-year record high ». Cryosphere 14, no 10 (27 octobre 2020) : 3551–64. http://dx.doi.org/10.5194/tc-14-3551-2020.
Texte intégralRésumé :
Abstract. Along with record-breaking summer air temperatures at an Antarctic Peninsula meteorological station in February 2020, the Larsen C ice shelf experienced an exceptionally long and extensive 2019/2020 melt season. We use a 40-year time series of passive and scatterometer satellite microwave data, which are sensitive to the presence of liquid water in the snow pack, to reveal that the extent and duration of melt observed on the ice shelf in the austral summer of 2019/2020 was the greatest on record. We find that unusual perturbations to Southern Hemisphere modes of atmospheric flow, including a persistently positive Indian Ocean Dipole in the spring and a very rare Southern Hemisphere sudden stratospheric warming in September 2019, preceded the exceptionally warm Antarctic Peninsula summer. It is likely that teleconnections between the tropics and southern high latitudes were able to bring sufficient heat via the atmosphere and ocean to the Antarctic Peninsula to drive the extreme Larsen C Ice Shelf melt. The record-breaking melt of 2019/2020 brought to an end the trend of decreasing melt that had begun in 1999/2000, will reinitiate earlier thinning of the ice shelf by depletion of the firn air content, and probably affected a much greater region than Larsen C Ice Shelf.
46
Monteiro Estvāo, Diogo Miguel. « Production of UV-B screens and changes in photosynthetic efficiency in Antarctic Nostoc commune colonies and a lichen Xanthoria elegans depend on a dose and duration of UV-B stress ». Czech Polar Reports 5, no 1 (1 janvier 2015) : 55–68. http://dx.doi.org/10.5817/cpr2015-1-6.
Texte intégralRésumé :
The survival of non-vascular autotrophs in the extreme polar conditions and the principles of their high tolerance to extreme physical factors have been intriguing scientists in last decades. Therefore, this study focuses on the capacity of production of UV-B screening pigments in two model Antarctic species, one algal lichen, and colony of a cyanobacterium. Dose-dependent activation of protective mechanisms of Antarctic cyanobacterium (Nostoc commune) and algal lichen (Xanthoria elegans), synthesis of UV-B screening compounds in particular, were studied together with the changes in photosynthetic efficiency induced by a background photosynthetically active radiation (PAR) supplemented with UV-B radiation. The samples were exposed to different doses of UV-B (280–320 nm), low (0.7 W m-2), medium (1.5 W m-2) and high (3.0 W m-2) for 5 days. Untreated samples (control) were shielded from UV-B radiation during experiment. Chlorophyll fluorescence parameters and secondary UV-B protective metabolites were analysed in the intervals of 24 h, 48 h and 120 h. Amount of UV-B screening pigments was measured spectrophotometrically using several specific wavelengths in UV-B absorption range. Results showed that if exposed to a low dose of UV-B radiation or a short-term treatment, both species exhibited an increase in UV-B screening pigments to protect the lichen photobiont against UV-B damage. However, if exposed to a high dose of UV-B radiation or a long-term treatment, a decrease of UV-B screening compounds occured. This implies that Antarctic lichen and cyanobacterium can protect themselves against an increase of stress factors ranging within physiological limits, like e.g. increased synthesis of UV-B screening compounds thanks to a thinning of the ozone layer and consequent increase in UV radiation doses incident on Antarctic terrestrial ecosystems. Nevertheless, the likely increased UV-B radiation due to more intense depletion of stratospheric ozone layer may lead to alterations in UV-B tolerance in Antarctic lichens in future.
47
Malaterre, P. « Long duration balloon flights in the middle stratosphere ». Advances in Space Research 13, no 2 (février 1993) : 107–14. http://dx.doi.org/10.1016/0273-1177(93)90282-g.
Texte intégral
48
Jones, G. O. L., M. A. Clilverd, P. J. Espy, S. Chew, D. C. Fritts et D. M. Riggin. « An alternative explanation of PMSE-like scatter in MF radar data ». Annales Geophysicae 22, no 8 (7 septembre 2004) : 2715–22. http://dx.doi.org/10.5194/angeo-22-2715-2004.
Texte intégralRésumé :
Abstract. There have been reports in the literature that spaced-antenna MF radars may provide a source of data on Polar Mesospheric Summer Echoes (PMSE). Even though the expected scatter from PMSE at MF frequencies is very much weaker than at VHF, the wide distribution of sites and long duration of data sets for MF radar systems could provide valuable information about the occurrence of PMSE. This paper tests whether there is any evidence of PMSE in the profiles derived using the MF radar at Rothera, Antarctica, one of the few such radars at high southern latitudes. Over a year of data during 1997/1998 has been analysed for the occurrence of persistent features around midday in the altitude range 60-95km. Criteria were chosen to test the likelihood that some of the narrow peaks in the power profiles were manifestations of electron density structures associated with PMSE. Although a small number of persistent features were seen at altitudes of 80-85km that are typically associated with PMSE, there was no seasonality in their occurrence. A detailed analysis of specific days showed that two peaks were often seen with altitude separations consistent with the vertical wavelength of the diurnal tide. Persistent features were also detected at altitudes of 70km and 90km during the winter months, thus showing a quite different seasonality to that of PMSE. An estimate of the turbulence caused by the breaking of gravity waves that have propagated up from the lower atmosphere shows that at Rothera significant energy is deposited near 80km during summer, and near 70 and 90km during winter. This seasonal variability is driven by the screening effect of stratospheric winds, and it appears that breaking gravity wave dynamics, rather than PMSE phenomena, can explain many of the localised altitude features in the MF radar data.
49
Cao, Bing, Jennifer S. Haase, Michael J. Murphy, M. Joan Alexander, Martina Bramberger et Albert Hertzog. « Equatorial waves resolved by balloon-borne Global Navigation Satellite System radio occultation in the Strateole-2 campaign ». Atmospheric Chemistry and Physics 22, no 23 (5 décembre 2022) : 15379–402. http://dx.doi.org/10.5194/acp-22-15379-2022.
Texte intégralRésumé :
Abstract. Current climate models have difficulty representing realistic wave–mean flow interactions, partly because the contribution from waves with fine vertical scales is poorly known. There are few direct observations of these waves, and most models have difficulty resolving them. This observational challenge cannot be addressed by satellite or sparse ground-based methods. The Strateole-2 long-duration stratospheric superpressure balloons that float with the horizontal wind on constant-density surfaces provide a unique platform for wave observations across a broad range of spatial and temporal scales. For the first time, balloon-borne Global Navigation Satellite System (GNSS) radio occultation (RO) is used to provide high-vertical-resolution equatorial wave observations. By tracking navigation signal refractive delays from GPS satellites near the horizon, 40–50 temperature profiles were retrieved daily, from balloon flight altitude (∼20 km) down to 6–8 km altitude, forming an orthogonal pattern of observations over a broad area (±400–500 km) surrounding the flight track. The refractivity profiles show an excellent agreement of better than 0.2 % with co-located radiosonde, spaceborne COSMIC-2 RO, and reanalysis products. The 200–500 m vertical resolution and the spatial and temporal continuity of sampling make it possible to extract properties of Kelvin waves and gravity waves with vertical wavelengths as short as 2–3 km. The results illustrate the difference in the Kelvin wave period (20 vs. 16 d) in the Lagrangian versus ground-fixed reference and as much as a 20 % difference in amplitude compared to COSMIC-2, both of which impact estimates of momentum flux. A small dataset from the extra Galileo, GLONASS, and BeiDou constellations demonstrates the feasibility of nearly doubling the sampling density in planned follow-on campaigns when data with full equatorial coverage will contribute to a better estimate of wave forcing on the quasi-biennial oscillation (QBO) and improved QBO representation in models.
50
Cohn, Stephen A., Terry Hock, Philippe Cocquerez, Junhong Wang, Florence Rabier, David Parsons, Patrick Harr et al. « Driftsondes : Providing In Situ Long-Duration Dropsonde Observations over Remote Regions ». Bulletin of the American Meteorological Society 94, no 11 (1 novembre 2013) : 1661–74. http://dx.doi.org/10.1175/bams-d-12-00075.1.
Texte intégralRésumé :
Constellations of driftsonde systems— gondolas floating in the stratosphere and able to release dropsondes upon command— have so far been used in three major field experiments from 2006 through 2010. With them, high-quality, high-resolution, in situ atmospheric profiles were made over extended periods in regions that are otherwise very difficult to observe. The measurements have unique value for verifying and evaluating numerical weather prediction models and global data assimilation systems; they can be a valuable resource to validate data from remote sensing instruments, especially on satellites, but also airborne or ground-based remote sensors. These applications for models and remote sensors result in a powerful combination for improving data assimilation systems. Driftsondes also can support process studies in otherwise difficult locations—for example, to study factors that control the development or decay of a tropical disturbance, or to investigate the lower boundary layer over the interior Antarctic continent. The driftsonde system is now a mature and robust observing system that can be combined with flight-level data to conduct multidisciplinary research at heights well above that reached by current research aircraft. In this article we describe the development and capabilities of the driftsonde system, the exemplary science resulting from its use to date, and some future applications.