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Journal articles on the topic 'Stratosphere research'
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1
Wang, Dongxiang, and Iwona S. Stachlewska. "Stratospheric Smoke Properties Based on Lidar Observations in Autumn 2017 Over Warsaw." EPJ Web of Conferences 237 (2020): 02033. http://dx.doi.org/10.1051/epjconf/202023702033.
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Smoke layers in the stratosphere were observed during autumn 2017 using PollyXT-UW Raman lidar at the European Aerosol Research Lidar Network in the frame of the Aerosol Cloud and Trace Gases Research Infrastructure, i.e. the EARLINET-ACTRIS site in Warsaw, Poland. The analysis was focused on discriminating very weak signatures of smoke layers in the stratosphere and investigating their optical properties. Preliminary results are presented and discussed. A decrease of the lidar-derived stratospheric aerosol optical depth contribution to the total optical depth was detected after the stratospheric smoke particles circled Northern Hemisphere.
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Shao, Min, Yansong Bao, George P. Petropoulos, and Hongfang Zhang. "A Two-Season Impact Study of Radiative Forced Tropospheric Response to Stratospheric Initial Conditions Inferred From Satellite Radiance Assimilation." Climate 7, no. 9 (September 18, 2019): 114. http://dx.doi.org/10.3390/cli7090114.
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This study investigated the impacts of stratospheric temperatures and their variations on tropospheric short-term weather forecasting using the Advanced Research Weather Research and Forecasting (WRF-ARW) system with real satellite data assimilation. Satellite-borne microwave stratospheric temperature measurements up to 1 mb, from the Advanced Microwave Sounding Unit-A (AMSU-A), the Advanced Technology Microwave Sounder (ATMS), and the Special Sensor microwave Imager/Sounder (SSMI/S), were assimilated into the WRF model over the continental U.S. during winter and summer 2015 using the community Gridpoint Statistical Interpolation (GSI) system. Adjusted stratospheric temperature related to upper stratospheric ozone absorption of short-wave (SW) radiation further lead to vibration in downward SW radiation in winter predictions and overall reduced with a maximum of 5.5% reduction of downward SW radiation in summer predictions. Stratospheric signals in winter need 48- to 72-h to propagate to the lower troposphere while near-instant tropospheric response to the stratospheric initial conditions are observed in summer predictions. A schematic plot illustrated the physical processes of the coupled stratosphere and troposphere related to radiative processes. Our results suggest that the inclusion of the entire stratosphere and better representation of the upper stratosphere are important in regional NWP systems in short-term forecasts.
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Wu, Zheng, and Thomas Reichler. "Variations in the Frequency of Stratospheric Sudden Warmings in CMIP5 and CMIP6 and Possible Causes." Journal of Climate 33, no. 23 (December 2020): 10305–20. http://dx.doi.org/10.1175/jcli-d-20-0104.1.
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AbstractThe climatological frequency of stratospheric sudden warming events (SSWs) is an important dynamical characteristic of the extratropical stratosphere. However, modern climate models have difficulties in simulating this frequency, with many models either considerably under- or overestimating the observational estimates. Past research has found that models with a higher upper lid tend to simulate a higher and more realistic number of SSWs. The present study revisits this issue and investigates causes for biases in the simulated SSW frequency from the CMIP5 and CMIP6 models. It is found that variations in the frequency are closely related to 1) the strength of the polar vortex and 2) the upward-propagating wave activity in the stratosphere. While it is difficult to explain the variations in the polar vortex strength from the available model output, the stratospheric wave activity is influenced by different aspects of the climatological mean state of the atmosphere in the lower stratosphere. We further find that models with a finer vertical resolution in the stratosphere are overall more realistic: vertical resolution is associated with a smaller cold bias above the extratropical tropopause, more upward-propagating wave activity in the lower stratosphere, and a higher frequency of SSWs. We conclude that not only a high model lid but also a fine vertical resolution in the stratosphere is important for simulating the dynamical variability of the stratosphere.
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Ekhwan Toriman, Mohd, Musa Garba Abdullahi, Mohd Khairul Amri Kamarudin, Roslan Umar, Aliyu Muhammad Nalado, and Md Firoz Khan. "Trends Analysis of Ozone Hole Annual Records Using SBUV Data Version 8.6 (1979 to 2017 Datasets)." International Journal of Engineering & Technology 7, no. 3.14 (July 25, 2018): 30. http://dx.doi.org/10.14419/ijet.v7i3.14.16858.
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Ozone is the triatomic of oxygen forms within the Earth's atmosphere from the ultraviolet dissociation of oxygen molecules, within tropical stratosphere. It is conveyed toward the extratropics through the Brewer-Dobson circulation (BDC), generating a layer in the stratosphere known as a protective ozone layer. The data from NASA and NOAA measurements of ozone shows that the ozone layer has stopped deteriorating across the world; nonetheless no strong intensification has been detected at latitudes amongst 60° S and 60° N in the outer the Polar Regions within 60° to 90°.In this study, the evidence of the ozone hole from satellite measurements, and evidence that ozone within the lower stratosphere at the amid of 60° S and 60° N has continuous to decline after the Montreal Protocol. This study explained that, upper stratospheric ozone is improving; the recent descending trend in the lower stratosphere prevails, consequential in a descending trend in stratospheric ozone amongst 60° S and 60° N. The trend indicated that by 2060 to 2080, the ozone hole is expecting to have complete heal. Hence, the details for the continual decrease of ozone in the lower stratosphere are not clear; this study models do not prescribe these trends, and thus is a gap for another research.
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Akhil Raj, Sivan Thankamani, Madineni Venkat Ratnam, Daggumati Narayana Rao, and Boddam Venkata Krishna Murthy. "Long-term trends in stratospheric ozone, temperature, and water vapor over the Indian region." Annales Geophysicae 36, no. 1 (January 29, 2018): 149–65. http://dx.doi.org/10.5194/angeo-36-149-2018.
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Abstract. We have investigated the long-term trends in and variabilities of stratospheric ozone, water vapor and temperature over the Indian monsoon region using the long-term data constructed from multi-satellite (Upper Atmosphere Research Satellite (UARS MLS and HALOE, 1993–2005), Aura Microwave Limb Sounder (MLS, 2004–2015), Sounding of the Atmosphere using Broadband Emission Radiometry (SABER, 2002–2015) on board TIMED (Thermosphere Ionosphere Mesosphere Energetics Dynamics)) observations covering the period 1993–2015. We have selected two locations, namely, Trivandrum (8.4∘ N, 76.9∘ E) and New Delhi (28∘ N, 77∘ E), covering northern and southern parts of the Indian region. We also used observations from another station, Gadanki (13.5∘ N, 79.2∘ E), for comparison. A decreasing trend in ozone associated with NOx chemistry in the tropical middle stratosphere is found, and the trend turned to positive in the upper stratosphere. Temperature shows a cooling trend in the stratosphere, with a maximum around 37 km over Trivandrum (−1.71 ± 0.49 K decade−1) and New Delhi (−1.15 ± 0.55 K decade−1). The observed cooling trend in the stratosphere over Trivandrum and New Delhi is consistent with Gadanki lidar observations during 1998–2011. The water vapor shows a decreasing trend in the lower stratosphere and an increasing trend in the middle and upper stratosphere. A good correlation between N2O and O3 is found in the middle stratosphere (∼ 10 hPa) and poor correlation in the lower stratosphere. There is not much regional difference in the water vapor and temperature trends. However, upper stratospheric ozone trends over Trivandrum and New Delhi are different. The trend analysis carried out by varying the initial year has shown significant changes in the estimated trend. Keywords. Atmospheric composition and structure (middle atmosphere – composition and chemistry; troposphere – composition and chemistry) – meteorology and atmospheric dynamics (climatology)
6
Taguchi, Masakazu. "Predictability of stratospheric sudden warming and vortex intensification and their effects on the troposphere." Impact 2020, no. 3 (May 13, 2020): 14–16. http://dx.doi.org/10.21820/23987073.2020.3.14.
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The atmosphere of the Earth is composed of several different layers that extend out into space. The layer that occupies between the first 9 and 17 km from the Earth's surface is the troposphere, where most of our weather occurs. The stratosphere extends above it up to about 50 km altitude. Associate Professor Masakazu Taguchi at the Department of Earth Science, Aichi University of Education in Japan, is currently focusing his research on understanding the dynamical interaction between the extratropical stratosphere and troposphere and the role of stratospheric variations in the weather and climate.
7
Urban, J., M. Pommier, D. P. Murtagh, M. L. Santee, and Y. J. Orsolini. "Nitric acid in the stratosphere based on Odin observations from 2001 to 2009 – Part 1: A global climatology." Atmospheric Chemistry and Physics 9, no. 18 (September 23, 2009): 7031–44. http://dx.doi.org/10.5194/acp-9-7031-2009.
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Abstract. The Sub-Millimetre Radiometer (SMR) on board the Odin satellite, launched in February 2001, observes thermal emissions of stratospheric nitric acid (HNO3) originating from the Earth limb in a band centred at 544.6 GHz. Height-resolved measurements of the global distribution of nitric acid in the stratosphere were performed approximately on two observation days per week. An HNO3 climatology based on more than 7 years of observations from August 2001 to April 2009 covering the vertical range between typically ~19 and 45 km (~1.5–60 hPa or ~500–1800 K in terms of potential temperature) was created. The study highlights the spatial and seasonal variation of nitric acid in the stratosphere, characterised by a pronounced seasonal cycle at middle and high latitudes with maxima during late fall and minima during spring, strong denitrification in the lower stratosphere of the Antarctic polar vortex during winter (the irreversible removal of NOy by the sedimentation of cloud particles containing HNO3), as well as large quantities of HNO3 formed every winter at high-latitudes in the middle and upper stratosphere. A strong inter-annual variability is observed in particular at high latitudes. A comparison with a stratospheric HNO3 climatology, based on over 7 years of UARS/MLS (Upper Atmosphere Research Satellite/Microwave Limb Sounder) measurements from the 1990s, shows good consistency and agreement of the main morphological features in the potential temperature range ~465 to ~960 K, if the different characteristics of the data sets such as the better altitude resolution of Odin/SMR as well as the slightly different altitude ranges are considered. Odin/SMR reaches higher up and UARS/MLS lower down in the stratosphere. An overview from 1991 to 2009 of stratospheric nitric acid is provided (with a short gap between 1998 and 2001), if the global measurements of both experiments are taken together.
8
Schanz, A., K. Hocke, N. Kämpfer, S. Chabrillat, A. Inness, M. Palm, J. Notholt, I. Boyd, A. Parrish, and Y. Kasai. "The diurnal variation in stratospheric ozone from the MACC reanalysis, the ERA-Interim reanalysis, WACCM and Earth observation data: characteristics and intercomparison." Atmospheric Chemistry and Physics Discussions 14, no. 23 (December 22, 2014): 32667–708. http://dx.doi.org/10.5194/acpd-14-32667-2014.
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Abstract. In this study we compare the diurnal variation in stratospheric ozone derived from free-running simulations of the Whole Atmosphere Community Climate Model (WACCM) and from reanalysis data of the atmospheric service MACC (Monitoring Atmospheric Composition and Climate) which both use a similar stratospheric chemistry module. We find good agreement between WACCM and the MACC reanalysis for the diurnal ozone variation in the high-latitude summer stratosphere based on photochemistry. In addition, we consult the ozone data product of the ERA-Interim reanalysis. The ERA-Interim reanalysis ozone system with its long-term ozone parametrization can not capture these diurnal variations in the upper stratosphere that are due to photochemistry. The good dynamics representations, however, reflects well dynamically induced ozone variations in the lower stratosphere. For the high-latitude winter stratosphere we describe a novel feature of diurnal variation in ozone where changes of up to 46.6% (3.3 ppmv) occur in monthly mean data. For this effect good agreement between the ERA-Interim reanalysis and the MACC reanalysis suggest quite similar diurnal advection processes of ozone. The free-running WACCM model seriously underestimates the role of diurnal advection processes at the polar vortex at the two tested resolutions. The intercomparison of the MACC reanalysis and the ERA-Interim reanalysis demonstrates how global reanalyses can benefit from a chemical representation held by a chemical transport model. The MACC reanalysis provides an unprecedented description of the dynamics and photochemistry of the diurnal variation of stratospheric ozone which is of high interest for ozone trend analysis and research on atmospheric tides. We confirm the diurnal variation in ozone at 5 hPa by observations of the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) experiment and selected sites of the Network for Detection of Atmospheric Composition Change (NDACC). The latter give valuable insight even to diurnal variation of ozone in the polar winter stratosphere.
9
Haarig, Moritz, Holger Baars, Albert Ansmann, Ronny Engelmann, Kevin Ohneiser, Cristofer Jimenez, Dietrich Althausen, et al. "Wildfire Smoke in the Stratosphere Over Europe–First Measurements of Depolarization and Lidar Ratios at 355, 532, and 1064 nm." EPJ Web of Conferences 237 (2020): 02036. http://dx.doi.org/10.1051/epjconf/202023702036.
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Canadian wildfire smoke was detected in the troposphere and lower stratosphere over Europe in August and September 2017. Lidar measurements from various stations of the European Aerosol Research Lidar Network (EARLINET) observed the stratospheric smoke layer. Triple-wavelength (355, 532, and 1064 nm) lidar measurements of the depolarization and the lidar ratio are reported from Leipzig, Germany. The particle linear depolarization ratio of the wildfire smoke in the stratosphere had an exceptional strong wavelength dependence reaching from 0.22 at 355 nm, to 0.18 at 532 nm, and 0.04 at 1064 nm. The lidar ratio increased with wavelength from 40±16 sr at 355 nm, to 66±12 sr at 532 nm, and 92±27 sr at 1064 nm. The development of the stratospheric smoke plume over several months was studied by long-term lidar measurements in Cyprus. The stratospheric smoke layers increased in altitude up to 24 km height.
10
Cairo, F., J. P. Pommereau, K. S. Law, H. Schlager, A. Garnier, F. Fierli, M. Ern, et al. "An overview of the SCOUT-AMMA stratospheric aircraft, balloons and sondes campaign in West Africa, August 2006: rationale, roadmap and highlights." Atmospheric Chemistry and Physics Discussions 9, no. 5 (September 23, 2009): 19713–81. http://dx.doi.org/10.5194/acpd-9-19713-2009.
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Abstract. A multi-platform field measurement campaign involving aircraft and balloons took place over West Africa between 26 July and 25 August 2006, in the frame of the concomitant AMMA Special Observing Period and SCOUT-O3 African tropical activities. Specifically aiming at sampling the upper troposphere and lower stratosphere, the high-altitude research aircraft M55 Geophysica was deployed in Ouagadougou (12.3° N, 1.7° W), Burkina Faso, in conjunction with the German D-20 Falcon, while a series of stratospheric balloon and sonde flights were conducted from Niamey (13.5° N, 2.0° E), Niger. The stratospheric aircraft and balloon flights intended to gather experimental evidence for a better understanding of large scale transport, assessing the effect of lightning on NOx production, and studying the impact of intense mesoscale convective systems on water, aerosol, dust and chemical species in the upper troposphere and lower stratosphere. The M55 Geophysica carried out five local and four transfer flights between southern Europe and the Sahel and back, while eight stratospheric balloons and twenty-nine sondes were flown from Niamey. These experiments allowed a characterization of the tropopause and lower stratosphere of the region. We provide here an overview of the campaign activities together with a description of the general meteorological situation during the flights and a summary of the observations accomplished.
11
Khosrawi, Farahnaz, Oliver Kirner, Björn-Martin Sinnhuber, Sören Johansson, Michael Höpfner, Michelle L. Santee, Lucien Froidevaux, et al. "Denitrification, dehydration and ozone loss during the 2015/2016 Arctic winter." Atmospheric Chemistry and Physics 17, no. 21 (November 1, 2017): 12893–910. http://dx.doi.org/10.5194/acp-17-12893-2017.
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Abstract. The 2015/2016 Arctic winter was one of the coldest stratospheric winters in recent years. A stable vortex formed by early December and the early winter was exceptionally cold. Cold pool temperatures dropped below the nitric acid trihydrate (NAT) existence temperature of about 195 K, thus allowing polar stratospheric clouds (PSCs) to form. The low temperatures in the polar stratosphere persisted until early March, allowing chlorine activation and catalytic ozone destruction. Satellite observations indicate that sedimentation of PSC particles led to denitrification as well as dehydration of stratospheric layers. Model simulations of the 2015/2016 Arctic winter nudged toward European Centre for Medium-Range Weather Forecasts (ECMWF) analysis data were performed with the atmospheric chemistry–climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC) for the Polar Stratosphere in a Changing Climate (POLSTRACC) campaign. POLSTRACC is a High Altitude and Long Range Research Aircraft (HALO) mission aimed at the investigation of the structure, composition and evolution of the Arctic upper troposphere and lower stratosphere (UTLS). The chemical and physical processes involved in Arctic stratospheric ozone depletion, transport and mixing processes in the UTLS at high latitudes, PSCs and cirrus clouds are investigated. In this study, an overview of the chemistry and dynamics of the 2015/2016 Arctic winter as simulated with EMAC is given. Further, chemical–dynamical processes such as denitrification, dehydration and ozone loss during the 2015/2016 Arctic winter are investigated. Comparisons to satellite observations by the Aura Microwave Limb Sounder (Aura/MLS) as well as to airborne measurements with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) performed aboard HALO during the POLSTRACC campaign show that the EMAC simulations nudged toward ECMWF analysis generally agree well with observations. We derive a maximum polar stratospheric O3 loss of ∼ 2 ppmv or 117 DU in terms of column ozone in mid-March. The stratosphere was denitrified by about 4–8 ppbv HNO3 and dehydrated by about 0.6–1 ppmv H2O from the middle to the end of February. While ozone loss was quite strong, but not as strong as in 2010/2011, denitrification and dehydration were so far the strongest observed in the Arctic stratosphere in at least the past 10 years.
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Hurwitz, M. M., P. A. Newman, L. D. Oman, and A. M. Molod. "Response of the Antarctic Stratosphere to Two Types of El Niño Events." Journal of the Atmospheric Sciences 68, no. 4 (April 1, 2011): 812–22. http://dx.doi.org/10.1175/2011jas3606.1.
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Abstract This study is the first to identify a robust El Niño–Southern Oscillation (ENSO) signal in the Antarctic stratosphere. El Niño events between 1979 and 2009 are classified as either conventional “cold tongue” events (positive SST anomalies in the Niño-3 region) or “warm pool” events (positive SST anomalies in the Niño-4 region). The 40-yr ECMWF Re-Analysis (ERA-40), NCEP, and Modern Era Retrospective–Analysis for Research and Applications (MERRA) meteorological reanalyses are used to show that the Southern Hemisphere stratosphere responds differently to these two types of El Niño events. Consistent with previous studies, cold tongue events do not impact temperatures in the Antarctic stratosphere. During warm pool El Niño events, the poleward extension and increased strength of the South Pacific convergence zone favor an enhancement of planetary wave activity during September–November. On average, these conditions lead to higher polar stratospheric temperatures and a weakening of the Antarctic polar jet in November and December, as compared with neutral ENSO years. The phase of the quasi-biennial oscillation (QBO) modulates the stratospheric response to warm pool El Niño events; the strongest planetary wave driving events are coincident with the easterly phase of the QBO.
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Newman, Paul A. "Preserving Earth’s Stratosphere." Mechanical Engineering 120, no. 10 (October 1, 1998): 88–91. http://dx.doi.org/10.1115/1.1998-oct-5.
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This article discusses that ozone levels in the Arctic and Antarctic should begin to recover due to reductions in chlorofluorocarbon production, but greenhouse warming may exacerbate losses of the gas in the polar region. It is important to understand the life cycle of ozone molecules because it plays such a vital role in screening harmful ultraviolet radiation. The concentrations of certain gases, such as these highly reactive chlorine compounds, have a critical effect on ozone levels. The chlorine found in the stratosphere comes principally from chlorofluorocarbons (CFC). A CFC release becomes well mixed throughout the troposphere in about one year. The CFCs, which enter the stratosphere from the tropical upper-troposphere region, have been measured by the Cryogenic Limb Array Etalon Spectrometer on the Upper Atmosphere Research Satellite (UARS). Recent research has suggested that greenhouse warming may lead to significant cooling of the polar region. If so, this cooling may exacerbate ozone losses despite decreasing chlorine and bromine levels.
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Fadnavis, S., and G. Beig. "Decadal solar effects on temperature and ozone in the tropical stratosphere." Annales Geophysicae 24, no. 8 (September 13, 2006): 2091–103. http://dx.doi.org/10.5194/angeo-24-2091-2006.
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Abstract. To investigate the effects of decadal solar variability on ozone and temperature in the tropical stratosphere, along with interconnections to other features of the middle atmosphere, simultaneous data obtained from the Halogen Occultation Experiment (HALOE) aboard the Upper Atmospheric Research Satellite (UARS) and the Stratospheric Aerosol and Gas Experiment II (SAGE II) aboard the Earth Radiation Budget Satellite (ERBS) during the period 1992–2004 have been analyzed using a multifunctional regression model. In general, responses of solar signal on temperature and ozone profiles show good agreement for HALOE and SAGE~II measurements. The inferred annual-mean solar effect on temperature is found to be positive in the lower stratosphere (max 1.2±0.5 K / 100 sfu) and near stratopause, while negative in the middle stratosphere. The inferred solar effect on ozone is found to be significant in most of the stratosphere (2±1.1–4±1.6% / 100 sfu). These observed results are in reasonable agreement with model simulations. Solar signals in ozone and temperature are in phase in the lower stratosphere and they are out of phase in the upper stratosphere. These inferred solar effects on ozone and temperature are found to vary dramatically during some months, at least in some altitude regions. Solar effects on temperature are found to be negative from August to March between 9 mb–3 mb pressure levels while solar effects on ozone are maximum during January–March near 10 mb in the Northern Hemisphere and 5 mb–7 mb in the Southern Hemisphere.
15
Ivy, Diane J., Casey Hilgenbrink, Doug Kinnison, R. Alan Plumb, Aditi Sheshadri, Susan Solomon, and David W. J. Thompson. "Observed Changes in the Southern Hemispheric Circulation in May." Journal of Climate 30, no. 2 (January 2017): 527–36. http://dx.doi.org/10.1175/jcli-d-16-0394.1.
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Much research has focused on trends in the Southern Hemispheric circulation in austral summer (December–February) in the troposphere and stratosphere, whereas changes in other seasons have received less attention. Here the seasonality and structure of observed changes in tropospheric and stratospheric winds, temperature, and ozone over the Southern Hemisphere are examined. It is found that statistically significant trends similar to those of the Antarctic summer season are also observed since 1979 in austral fall, particularly May, and are strongest over the Pacific sector of the hemisphere. Evidence is provided for a significant shift in the position of the jet in May over the Pacific, and it is shown that the strengthening and shifting of the jet has rendered the latitudinal distribution of upper-tropospheric zonal wind more bimodal. The Antarctic ozone hole has cooled the lower stratosphere and strengthened the polar vortex. While the mechanism and timing are not fully understood, the ozone hole has been identified as a key driver of the summer season tropospheric circulation changes in several previous observational and modeling studies. It is found here that significant ozone depletion and associated polar cooling also occur in the lowermost stratosphere and tropopause region through austral fall, with spatial patterns that are coincident with the observed changes in stratospheric circulation. It is also shown that radiatively driven temperature changes associated with the observed ozone depletion in May represent a substantial portion of the observed May cooling in the lowermost stratosphere, suggesting a potential for contribution to the circulation changes.
16
Miyagawa, K., I. Petropavlovskikh, R. D. Evans, C. Long, J. Wild, G. L. Manney, and W. H. Daffer. "Long-term changes in the upper stratospheric ozone at Syowa, Antarctica." Atmospheric Chemistry and Physics 14, no. 8 (April 17, 2014): 3945–68. http://dx.doi.org/10.5194/acp-14-3945-2014.
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Abstract. Analyses of stratospheric ozone data determined from Dobson–Umkehr measurements since 1977 at the Syowa (69.0° S, 39.6° E), Antarctica, station show a significant decrease in ozone at altitudes higher than that of the 4 hPa pressure level during the 1980s and 1990s. Ozone values over Syowa have remained low since 2001. The time series of upper stratospheric ozone from the homogenized NOAA SBUV (Solar Backscatter Ultraviolet Instrument)(/2) 8.6 overpass data (±4°, 24 h) are in qualitative agreement with those from the Syowa station data. Ozone recovery during the austral spring over the Syowa station appears to be slower than predicted by the equivalent effective stratospheric chlorine (EESC) curve. The long-term changes in the station's equivalent latitude (indicative of vortex size/position in winter and spring) are derived from MERRA (Modern Era Retrospective-analysis for Research and Applications) reanalyses at ~ 2 and ~ 50 hPa. These data are used to attribute some of the upper and middle stratospheric ozone changes to the changes in vortex position relative to the station's location. In addition, high correlation of the Southern Hemisphere annular mode (SAM) with polar upper stratospheric ozone during years of maximum solar activity points toward a strong relationship between the strength of the Brewer–Dobson circulation and the polar stratospheric ozone recovery. In the lower stratosphere, ozone recovery attributable to CFCs (chlorofluorocarbons) is still not definitive, whereas the recovery of the upper stratosphere is slower than predicted. Further research indicates that dynamical and other chemical changes in the atmosphere are delaying detection of recovery over this station.
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Cairo, F., J. P. Pommereau, K. S. Law, H. Schlager, A. Garnier, F. Fierli, M. Ern, et al. "An introduction to the SCOUT-AMMA stratospheric aircraft, balloons and sondes campaign in West Africa, August 2006: rationale and roadmap." Atmospheric Chemistry and Physics 10, no. 5 (March 3, 2010): 2237–56. http://dx.doi.org/10.5194/acp-10-2237-2010.
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Abstract. A multi-platform field measurement campaign involving aircraft and balloons took place over West Africa between 26 July and 25 August 2006, in the frame of the concomitant AMMA Special Observing Period and SCOUT-O3 African tropical activities. Specifically aiming at sampling the upper troposphere and lower stratosphere, the high-altitude research aircraft M55 Geophysica was deployed in Ouagadougou (12.3° N, 1.7° W), Burkina Faso, in conjunction with the German D-20 Falcon, while a series of stratospheric balloons and sonde flights were conducted from Niamey (13.5° N, 2.0° E), Niger. Altogether, these measurements were intended to provide experimental evidence for a better understanding of large scale transport, assessing the effect of lightning on NOx production, and studying the impact of intense mesoscale convective systems on water, aerosol, dust and chemical species in the upper troposphere and lower stratosphere. The M55 Geophysica carried out five local and four transfer flights between southern Europe and the Sahel and back, while eight stratospheric balloons and twenty-nine sondes were flown from Niamey. These experiments allowed a characterization of the tropopause and lower stratosphere of the region. The paper provides an overview of SCOUT-AMMA campaign activities together with a description of the meteorology of the African monsoon and the situation prevailing during the flights and a brief summary of the observations accomplished.
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Wang, T., A. E. Dessler, M. R. Schoeberl, W. J. Randel, and J. E. Kim. "The impact of temperature vertical structure on trajectory modeling of stratospheric water vapor." Atmospheric Chemistry and Physics 15, no. 6 (March 31, 2015): 3517–26. http://dx.doi.org/10.5194/acp-15-3517-2015.
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Abstract. Lagrangian trajectories driven by reanalysis meteorological fields are frequently used to study water vapor (H2O) in the stratosphere, in which the tropical cold-point temperatures regulate the amount of H2O entering the stratosphere. Therefore, the accuracy of temperatures in the tropical tropopause layer (TTL) is of great importance for understanding stratospheric H2O abundances. Currently, most reanalyses, such as the NASA MERRA (Modern Era Retrospective – analysis for Research and Applications), only provide temperatures with ~ 1.2 km vertical resolution in the TTL, which has been argued to miss finer vertical structure in the tropopause and therefore introduce uncertainties in our understanding of stratospheric H2O. In this paper, we quantify this uncertainty by comparing the Lagrangian trajectory prediction of H2O using MERRA temperatures on standard model levels (traj.MER-T) to those using GPS temperatures at finer vertical resolution (traj.GPS-T), and those using adjusted MERRA temperatures with finer vertical structures induced by waves (traj.MER-Twave). It turns out that by using temperatures with finer vertical structure in the tropopause, the trajectory model more realistically simulates the dehydration of air entering the stratosphere. But the effect on H2O abundances is relatively minor: compared with traj.MER-T, traj.GPS-T tends to dry air by ~ 0.1 ppmv, while traj.MER-Twave tends to dry air by 0.2–0.3 ppmv. Despite these differences in absolute values of predicted H2O and vertical dehydration patterns, there is virtually no difference in the interannual variability in different runs. Overall, we find that a tropopause temperature with finer vertical structure has limited impact on predicted stratospheric H2O.
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Bohlinger, P., B. M. Sinnhuber, R. Ruhnke, and O. Kirner. "Radiative and dynamical contributions to past and future Arctic stratospheric temperature trends." Atmospheric Chemistry and Physics 14, no. 3 (February 13, 2014): 1679–88. http://dx.doi.org/10.5194/acp-14-1679-2014.
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Abstract. Arctic stratospheric ozone depletion is closely linked to the occurrence of low stratospheric temperatures. There are indications that cold winters in the Arctic stratosphere have been getting colder, raising the question if and to what extent a cooling of the Arctic stratosphere may continue into the future. We use meteorological reanalyses from the European Centre for Medium Range Weather Forecasts (ECMWF) ERA-Interim and NASA's Modern-Era Retrospective-Analysis for Research and Applications (MERRA) for the past 32 yr together with calculations of the chemistry-climate model (CCM) ECHAM/MESSy Atmospheric Chemistry (EMAC) and models from the Chemistry-Climate Model Validation (CCMVal) project to infer radiative and dynamical contributions to long-term Arctic stratospheric temperature changes. For the past three decades the reanalyses show a warming trend in winter and cooling trend in spring and summer, which agree well with trends from the Radiosonde Innovation Composite Homogenization (RICH) adjusted radiosonde data set. Changes in winter and spring are caused by a corresponding change of planetary wave activity with increases in winter and decreases in spring. During winter the increase of planetary wave activity is counteracted by a residual radiatively induced cooling. Stratospheric radiatively induced cooling is detected throughout all seasons, being highly significant in spring and summer. This means that for a given dynamical situation, according to ERA-Interim the annual mean temperature of the Arctic lower stratosphere has been cooling by −0.41 ± 0.11 K decade−1 at 50 hPa over the past 32 yr. Calculations with state-of-the-art models from CCMVal and the EMAC model qualitatively reproduce the radiatively induced cooling for the past decades, but underestimate the amount of radiatively induced cooling deduced from reanalyses. There are indications that this discrepancy could be partly related to a possible underestimation of past Arctic ozone trends in the models. The models project a continued cooling of the Arctic stratosphere over the coming decades (2001–2049) that is for the annual mean about 40% less than the modeled cooling for the past, due to the reduction of ozone depleting substances and the resulting ozone recovery. This projected cooling in turn could offset between 15 and 40% of the Arctic ozone recovery.
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Weigel, K., L. Hoffmann, G. Günther, F. Khosrawi, F. Olschewski, P. Preusse, R. Spang, F. Stroh, and M. Riese. "A stratospheric intrusion at the subtropical jet over the Mediterranean Sea: air-borne remote sensing observations and model results." Atmospheric Chemistry and Physics Discussions 12, no. 3 (March 20, 2012): 7793–827. http://dx.doi.org/10.5194/acpd-12-7793-2012.
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Abstract. Remote sensing measurements from the Cryogenic Infrared Spectrometers and Telescope for the Atmosphere – New Frontiers (CRISTA-NF) during a flight on 29 July 2006 are presented. This flight is part of the AMMA-SCOUT-O3 measurement campaign, where CRISTA-NF was deployed on the high-flying research aircraft M55-Geophysica. The flight path was located over Italy and the Mediterranean Sea and crossed over the subtropical jet twice. Measurements of temperature, and the volume mixing ratios of water vapor (H2O), ozone (O3), nitric acid (HNO3) and peroxyacetyl nitrate (PAN) are available with a vertical resolution of up to 500 m between about 6 to 21 km altitude. CRISTA-NF observes these trace gases simultaneously and provides a quasi-2D view of the transition region between the troposphere and the stratosphere. The observation of these different trace gases allows to determine the origin of air masses in the stratosphere or troposphere. As expected, higher abundances are found where the main source of the trace gases is located: in the stratosphere for O3 and in the troposphere for H2O and PAN. Tracer-tracer correlations between O3 and PAN are used to identify mixed tropospheric and lowermost stratospheric air at the subtropical jet and around the thermal tropopause north of the jet. An intrusion of stratospheric air into the troposphere associated with the subtropical jet is found in the CRISTA-NF observations. The observations indicate that the intrusion is connected to a tropopause fold which is not resolved in the ECMWF analysis data. The intrusion was reproduced in a simulation with the Chemical Lagrangian Model of the Stratosphere (CLaMS). This work discusses the nature of the observed processes at the subtropical jet based on the CRISTA-NF observations and the CLaMS simulation.
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Keith, David W., Debra K. Weisenstein, John A. Dykema, and Frank N. Keutsch. "Stratospheric solar geoengineering without ozone loss." Proceedings of the National Academy of Sciences 113, no. 52 (December 12, 2016): 14910–14. http://dx.doi.org/10.1073/pnas.1615572113.
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Injecting sulfate aerosol into the stratosphere, the most frequently analyzed proposal for solar geoengineering, may reduce some climate risks, but it would also entail new risks, including ozone loss and heating of the lower tropical stratosphere, which, in turn, would increase water vapor concentration causing additional ozone loss and surface warming. We propose a method for stratospheric aerosol climate modification that uses a solid aerosol composed of alkaline metal salts that will convert hydrogen halides and nitric and sulfuric acids into stable salts to enable stratospheric geoengineering while reducing or reversing ozone depletion. Rather than minimizing reactive effects by reducing surface area using high refractive index materials, this method tailors the chemical reactivity. Specifically, we calculate that injection of calcite (CaCO3) aerosol particles might reduce net radiative forcing while simultaneously increasing column ozone toward its preanthropogenic baseline. A radiative forcing of −1 W⋅m−2, for example, might be achieved with a simultaneous 3.8% increase in column ozone using 2.1 Tg⋅y−1 of 275-nm radius calcite aerosol. Moreover, the radiative heating of the lower stratosphere would be roughly 10-fold less than if that same radiative forcing had been produced using sulfate aerosol. Although solar geoengineering cannot substitute for emissions cuts, it may supplement them by reducing some of the risks of climate change. Further research on this and similar methods could lead to reductions in risks and improved efficacy of solar geoengineering methods.
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Oelhaf, Hermann, Björn-Martin Sinnhuber, Wolfgang Woiwode, Harald Bönisch, Heiko Bozem, Andreas Engel, Andreas Fix, et al. "POLSTRACC: Airborne Experiment for Studying the Polar Stratosphere in a Changing Climate with the High Altitude and Long Range Research Aircraft (HALO)." Bulletin of the American Meteorological Society 100, no. 12 (December 1, 2019): 2634–64. http://dx.doi.org/10.1175/bams-d-18-0181.1.
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Abstract The Polar Stratosphere in a Changing Climate (POLSTRACC) mission employed the German High Altitude and Long Range Research Aircraft (HALO). The payload comprised an innovative combination of remote sensing and in situ instruments. The in situ instruments provided high-resolution observations of cirrus and polar stratospheric clouds (PSCs), a large number of reactive and long-lived trace gases, and temperature at the aircraft level. Information above and underneath the aircraft level was achieved by remote sensing instruments as well as dropsondes. The mission took place from 8 December 2015 to 18 March 2016, covering the extremely cold late December to early February period and the time around the major warming in the beginning of March. In 18 scientific deployments, 156 flight hours were conducted, covering latitudes from 25° to 87°N and maximum altitudes of almost 15 km, and reaching potential temperature levels of up to 410 K. Highlights of results include 1) new aspects of transport and mixing in the Arctic upper troposphere–lower stratosphere (UTLS), 2) detailed analyses of special dynamical features such as tropopause folds, 3) observations of extended PSCs reaching sometimes down to HALO flight levels at 13–14 km, 4) observations of particulate NOy and vertical redistribution of gas-phase NOy in the lowermost stratosphere (LMS), 5) significant chlorine activation and deactivation in the LMS along with halogen source gas observations, and 6) the partitioning and budgets of reactive chlorine and bromine along with a detailed study of the efficiency of ClOx/BrOx ozone loss cycle. Finally, we quantify—based on our results—the ozone loss in the 2015/16 winter and address the question of how extraordinary this Arctic winter was.
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Fan, Z. Q., Z. Sheng, H. Q. Shi, X. H. Zhang, and C. J. Zhou. "A Characterization of the Quality of the Stratospheric Temperature Distributions from SABER based on Comparisons with COSMIC Data." Journal of Atmospheric and Oceanic Technology 33, no. 11 (November 2016): 2401–13. http://dx.doi.org/10.1175/jtech-d-16-0085.1.
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AbstractGlobal stratospheric temperature measurement is an important field in the study of climate and weather. Dynamic and radiative coupling between the stratosphere and troposphere has been demonstrated in a number of studies over the past decade or so. However, studies of the stratosphere were hampered by a shortage of observation data before satellite technology was used in atmospheric sounding. Now, the data from the Thermosphere, Ionosphere, Mesosphere Energetics, and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) observations make it easier to study the stratosphere. The precision and accuracy of TIMED/SABER satellite soundings in the stratosphere are analyzed in this paper using refraction error data and temperature data obtained from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) radio occultation sounding system and TIMED/SABER temperature data between April 2006 and December 2009. The results show high detection accuracy of TIMED/SABER satellite soundings in the stratosphere. The temperature standard deviation (STDV) errors of SABER are mostly in the range from of 0–3.5 K. At 40 km the STDV error is usually less than 1 K, which means that TIMED/SABER temperature is close to the real atmospheric temperature at this height. The distributions of SABER STDV errors follow a seasonal variation: they are approximately similar in the months that belong to the same season. As the weather situation is complicated and fickle, the distribution of SABER STDV errors is most complex at the equator. The results in this paper are consistent with previous research and can provide further support for application of the SABER’s temperature data.
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Son, Seok-Woo, Sukyoung Lee, and Steven B. Feldstein. "Intraseasonal Variability of the Zonal-Mean Extratropical Tropopause Height." Journal of the Atmospheric Sciences 64, no. 2 (February 1, 2007): 608–20. http://dx.doi.org/10.1175/jas3855.1.
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Abstract The physical processes that drive the fluctuations of the extratropical tropopause height are examined with the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis data. A composite zonal-mean heat budget analysis for the Northern Hemisphere winter shows that fluctuations in the extratropical tropopause height result not only from a warming of the troposphere but also from an even stronger cooling of the lower stratosphere. While the tropospheric warming is caused by a poleward eddy heat transport associated with baroclinic eddies, the stratospheric cooling is driven primarily by planetary-scale waves. The results from analyses of synoptic- and planetary-scale eddy kinetic energy and Eliassen–Palm fluxes are consistent with the planetary waves first gaining their energy within the troposphere, and then propagating vertically into the stratosphere. For the Southern Hemisphere, while lower-stratospheric temperature anomalies still play an important role for the fluctuations in the tropopause height, the temperature anomalies are accounted for primarily by a poleward eddy heat transport associated with synoptic-scale eddies, and by diabatic heating. These results indicate that, although the height of the extratropical tropopause is modulated by baroclinic eddies, which is consistent with existing theories, the amount of the modulation is highly influenced by stratospheric processes.
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Filus, Michal T., Elliot L. Atlas, Maria A. Navarro, Elena Meneguz, David Thomson, Matthew J. Ashfold, Lucy J. Carpenter, Stephen J. Andrews, and Neil R. P. Harris. "Transport of short-lived halocarbons to the stratosphere over the Pacific Ocean." Atmospheric Chemistry and Physics 20, no. 2 (January 31, 2020): 1163–81. http://dx.doi.org/10.5194/acp-20-1163-2020.
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Abstract. The effectiveness of transport of short-lived halocarbons to the upper troposphere and lower stratosphere remains an important uncertainty in quantifying the supply of ozone-depleting substances to the stratosphere. In early 2014, a major field campaign in Guam in the western Pacific, involving UK and US research aircraft, sampled the tropical troposphere and lower stratosphere. The resulting measurements of CH3I, CHBr3 and CH2Br2 are compared here with calculations from a Lagrangian model. This methodology benefits from an updated convection scheme that improves simulation of the effect of deep convective motions on particle distribution within the tropical troposphere. We find that the observed CH3I, CHBr3 and CH2Br2 mixing ratios in the tropical tropopause layer (TTL) are consistent with those in the boundary layer when the new convection scheme is used to account for convective transport. More specifically, comparisons between modelled estimates and observations of short-lived CH3I indicate that the updated convection scheme is realistic up to the lower TTL but is less good at reproducing the small number of extreme convective events in the upper TTL. This study consolidates our understanding of the transport of short-lived halocarbons to the upper troposphere and lower stratosphere by using improved model calculations to confirm consistency between observations in the boundary layer, observations in the TTL and atmospheric transport processes. Our results support recent estimates of the contribution of short-lived bromocarbons to the stratospheric bromine budget.
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Davis, Sean M., Michaela I. Hegglin, Masatomo Fujiwara, Rossana Dragani, Yayoi Harada, Chiaki Kobayashi, Craig Long, et al. "Assessment of upper tropospheric and stratospheric water vapor and ozone in reanalyses as part of S-RIP." Atmospheric Chemistry and Physics 17, no. 20 (October 26, 2017): 12743–78. http://dx.doi.org/10.5194/acp-17-12743-2017.
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Abstract. Reanalysis data sets are widely used to understand atmospheric processes and past variability, and are often used to stand in as "observations" for comparisons with climate model output. Because of the central role of water vapor (WV) and ozone (O3) in climate change, it is important to understand how accurately and consistently these species are represented in existing global reanalyses. In this paper, we present the results of WV and O3 intercomparisons that have been performed as part of the SPARC (Stratosphere–troposphere Processes and their Role in Climate) Reanalysis Intercomparison Project (S-RIP). The comparisons cover a range of timescales and evaluate both inter-reanalysis and observation-reanalysis differences. We also provide a systematic documentation of the treatment of WV and O3 in current reanalyses to aid future research and guide the interpretation of differences amongst reanalysis fields.The assimilation of total column ozone (TCO) observations in newer reanalyses results in realistic representations of TCO in reanalyses except when data coverage is lacking, such as during polar night. The vertical distribution of ozone is also relatively well represented in the stratosphere in reanalyses, particularly given the relatively weak constraints on ozone vertical structure provided by most assimilated observations and the simplistic representations of ozone photochemical processes in most of the reanalysis forecast models. However, significant biases in the vertical distribution of ozone are found in the upper troposphere and lower stratosphere in all reanalyses.In contrast to O3, reanalysis estimates of stratospheric WV are not directly constrained by assimilated data. Observations of atmospheric humidity are typically used only in the troposphere, below a specified vertical level at or near the tropopause. The fidelity of reanalysis stratospheric WV products is therefore mainly dependent on the reanalyses' representation of the physical drivers that influence stratospheric WV, such as temperatures in the tropical tropopause layer, methane oxidation, and the stratospheric overturning circulation. The lack of assimilated observations and known deficiencies in the representation of stratospheric transport in reanalyses result in much poorer agreement amongst observational and reanalysis estimates of stratospheric WV. Hence, stratospheric WV products from the current generation of reanalyses should generally not be used in scientific studies.
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Tretkoff, Ernie. "Research Spotlight: Conditions in the stratosphere influence the ionosphere." Eos, Transactions American Geophysical Union 91, no. 25 (June 22, 2010): 228. http://dx.doi.org/10.1029/eo091i025p00228-03.
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Froidevaux, L., J. Anderson, H. J. Wang, R. A. Fuller, M. J. Schwartz, M. L. Santee, N. J. Livesey, et al. "Global OZone Chemistry And Related trace gas Data records for the Stratosphere (GOZCARDS): methodology and sample results with a focus on HCl, H<sub>2</sub>O, and O<sub>3</sub>." Atmospheric Chemistry and Physics 15, no. 18 (September 24, 2015): 10471–507. http://dx.doi.org/10.5194/acp-15-10471-2015.
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Abstract. We describe the publicly available data from the Global OZone Chemistry And Related trace gas Data records for the Stratosphere (GOZCARDS) project and provide some results, with a focus on hydrogen chloride (HCl), water vapor (H2O), and ozone (O3). This data set is a global long-term stratospheric Earth system data record, consisting of monthly zonal mean time series starting as early as 1979. The data records are based on high-quality measurements from several NASA satellite instruments and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on SCISAT. We examine consistency aspects between the various data sets. To merge ozone records, the time series are debiased relative to SAGE II (Stratospheric Aerosol and Gas Experiments) values by calculating average offsets versus SAGE II during measurement overlap periods, whereas for other species the merging derives from an averaging procedure during overlap periods. The GOZCARDS files contain mixing ratios on a common pressure–latitude grid, as well as standard errors and other diagnostics; we also present estimates of systematic uncertainties in the merged products. Monthly mean temperatures for GOZCARDS were also produced, based directly on data from the Modern-Era Retrospective analysis for Research and Applications. The GOZCARDS HCl merged product comes from the Halogen Occultation Experiment (HALOE), ACE-FTS and lower-stratospheric Aura Microwave Limb Sounder (MLS) data. After a rapid rise in upper-stratospheric HCl in the early 1990s, the rate of decrease in this region for 1997–2010 was between 0.4 and 0.7 % yr−1. On 6–8-year timescales, the rate of decrease peaked in 2004–2005 at about 1 % yr−1, and it has since levelled off, at ~ 0.5 % yr−1. With a delay of 6–7 years, these changes roughly follow total surface chlorine, whose behavior versus time arises from inhomogeneous changes in the source gases. Since the late 1990s, HCl decreases in the lower stratosphere have occurred with pronounced latitudinal variability at rates sometimes exceeding 1–2 % yr−1. Recent short-term tendencies of lower-stratospheric and column HCl vary substantially, with increases from 2005 to 2010 for northern midlatitudes and deep tropics, but decreases (increases) after 2011 at northern (southern) midlatitudes. For H2O, the GOZCARDS product covers both stratosphere and mesosphere, and the same instruments as for HCl are used, along with Upper Atmosphere Research Satellite (UARS) MLS stratospheric H2O data (1991–1993). We display seasonal to decadal-type variability in H2O from 22 years of data. In the upper mesosphere, the anticorrelation between H2O and solar flux is now clearly visible over two full solar cycles. Lower-stratospheric tropical H2O has exhibited two periods of increasing values, followed by fairly sharp drops (the well-documented 2000–2001 decrease and a recent drop in 2011–2013). Tropical decadal variability peaks just above the tropopause. Between 1991 and 2013, both in the tropics and on a near-global basis, H2O has decreased by ~ 5–10 % in the lower stratosphere, but about a 10 % increase is observed in the upper stratosphere and lower mesosphere. However, such tendencies may not represent longer-term trends. For ozone, we used SAGE I, SAGE II, HALOE, UARS and Aura MLS, and ACE-FTS data to produce a merged record from late 1979 onward, using SAGE II as the primary reference. Unlike the 2 to 3 % increase in near-global column ozone after the late 1990s reported by some, GOZCARDS stratospheric column O3 values do not show a recent upturn of more than 0.5 to 1 %; long-term interannual column ozone variations from GOZCARDS are generally in very good agreement with interannual changes in merged total column ozone (Version 8.6) data from SBUV instruments. A brief mention is also made of other currently available, commonly formatted GOZCARDS satellite data records for stratospheric composition, namely those for N2O and HNO3.
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Wallington, T. J., J. H. Seinfeld, and J. R. Barker. "100 Years of Progress in Gas-Phase Atmospheric Chemistry Research." Meteorological Monographs 59 (January 1, 2019): 10.1–10.52. http://dx.doi.org/10.1175/amsmonographs-d-18-0008.1.
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Abstract Remarkable progress has occurred over the last 100 years in our understanding of atmospheric chemical composition, stratospheric and tropospheric chemistry, urban air pollution, acid rain, and the formation of airborne particles from gas-phase chemistry. Much of this progress was associated with the developing understanding of the formation and role of ozone and of the oxides of nitrogen, NO and NO2, in the stratosphere and troposphere. The chemistry of the stratosphere, emerging from the pioneering work of Chapman in 1931, was followed by the discovery of catalytic ozone cycles, ozone destruction by chlorofluorocarbons, and the polar ozone holes, work honored by the 1995 Nobel Prize in Chemistry awarded to Crutzen, Rowland, and Molina. Foundations for the modern understanding of tropospheric chemistry were laid in the 1950s and 1960s, stimulated by the eye-stinging smog in Los Angeles. The importance of the hydroxyl (OH) radical and its relationship to the oxides of nitrogen (NO and NO2) emerged. The chemical processes leading to acid rain were elucidated. The atmosphere contains an immense number of gas-phase organic compounds, a result of emissions from plants and animals, natural and anthropogenic combustion processes, emissions from oceans, and from the atmospheric oxidation of organics emitted into the atmosphere. Organic atmospheric particulate matter arises largely as gas-phase organic compounds undergo oxidation to yield low-volatility products that condense into the particle phase. A hundred years ago, quantitative theories of chemical reaction rates were nonexistent. Today, comprehensive computer codes are available for performing detailed calculations of chemical reaction rates and mechanisms for atmospheric reactions. Understanding the future role of atmospheric chemistry in climate change and, in turn, the impact of climate change on atmospheric chemistry, will be critical to developing effective policies to protect the planet.
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Froidevaux, L., J. Anderson, H. J. Wang, R. A. Fuller, M. J. Schwartz, M. L. Santee, N. J. Livesey, et al. "Global OZone Chemistry And Related Datasets for the Stratosphere (GOZCARDS): methodology and sample results with a focus on HCl, H<sub>2</sub>O, and O<sub>3</sub>." Atmospheric Chemistry and Physics Discussions 15, no. 5 (March 2, 2015): 5849–957. http://dx.doi.org/10.5194/acpd-15-5849-2015.
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Abstract. We describe the publicly available dataset from the Global OZone Chemistry And Related Datasets for the Stratosphere (GOZCARDS) project, and provide some results, with a~focus on hydrogen chloride (HCl), water vapor (H2O), and ozone (O3). This dataset is a global long-term stratospheric Earth System Data Record (ESDR), consisting of monthly zonal mean time series starting as early as 1979. The data records are based on high quality measurements from several NASA satellite instruments and ACE-FTS on SCISAT. We examine consistency aspects between the various datasets. To merge ozone records, the time series are debiased by calculating average offsets with respect to SAGE II during periods of measurement overlap, whereas for other species, the merging derives from an averaging procedure based on overlap periods. The GOZCARDS files contain mixing ratios on a common pressure/latitude grid, as well as standard errors and other diagnostics; we also present estimates of systematic uncertainties in the merged products. Monthly mean temperatures for GOZCARDS were also produced, based directly on data from the Modern-Era Retrospective analysis for Research and Applications (MERRA). The GOZCARDS HCl merged product comes from HALOE, ACE-FTS and (for the lower stratosphere) Aura MLS data. After a~rapid rise in upper stratospheric HCl in the early 1990s, the rate of decrease in this region for 1997–2010 was between 0.4 and 0.7% yr−1. On shorter timescales (6 to 8 years), the rate of decrease peaked in 2004–2005 at about 1% yr−1, and has since levelled off, at ~0.5 yr−1. With a delay of 6–7 years, these changes roughly follow total surface chlorine, whose behavior vs. time arises from inhomogeneous changes in the source gases. Since the late 1990s, HCl decreases in the lower stratosphere have occurred with pronounced latitudinal variability at rates sometimes exceeding 1–2 yr−1. There has been a significant reversal in the changes of lower stratospheric HCl abundances and columns for 2005–2010, in particular at northern midlatitudes and in the deep tropics, where short-term increases are observed. However, lower stratospheric HCl tendencies appear to be reversing after about 2011, with (short-term) decreases at northern midlatitudes and some increasing tendencies at southern midlatitudes. For GOZCARDS H2O, covering the stratosphere and mesosphere, the same instruments as for HCl are used, along with UARS MLS stratospheric H2O data (1991–1993). We display seasonal to decadal-type variability in H2O from 22 years of data. In the upper mesosphere, the anti-correlation between H2O and solar flux is now clearly visible over two full solar cycles. Lower stratospheric tropical H2O has exhibited two periods of increasing values, followed by fairly sharp drops, the well-documented 2000–2001 decrease, and another recent decrease in 2011–2013. Tropical decadal variability peaks just above the tropopause. Between 1991 and 2013, both in the tropics and on a near-global basis, H2O has decreased by ~ 5–10% in the lower stratosphere, but about a 10% increase is observed in the upper stratosphere and lower mesosphere. However, recent tendencies may not hold for the long-term, and the addition of a few years of data can significantly modify trend results. For ozone, we used SAGE I, SAGE II, HALOE, UARS and Aura MLS, and ACE-FTS data to produce a~merged record from late 1979 onward, using SAGE II as the primary reference for aligning (debiasing) the other datasets. Other adjustments were needed in the upper stratosphere to circumvent temporal drifts in SAGE II O3 after June 2000, as a result of the (temperature-dependent) data conversion from a density/altitude to a mixing ratio/pressure grid. Unlike the 2 to 3% increase in near-global column ozone after the late 1990s reported by some, GOZCARDS stratospheric column O3 values do not show a recent upturn of more than 0.5 to 1%; continuing studies of changes in global ozone profiles, as well as ozone columns, are warranted. A brief mention is also made of other currently available, commonly-formatted GOZCARDS satellite data records for stratospheric composition, namely those for N2O and HNO3.
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Xu, Xin, Ming Xue, Miguel A. C. Teixeira, Jianping Tang, and Yuan Wang. "Parameterization of Directional Absorption of Orographic Gravity Waves and Its Impact on the Atmospheric General Circulation Simulated by the Weather Research and Forecasting Model." Journal of the Atmospheric Sciences 76, no. 11 (October 30, 2019): 3435–53. http://dx.doi.org/10.1175/jas-d-18-0365.1.
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Abstract In this work, a new parameterization scheme is developed to account for the directional absorption of orographic gravity waves (OGWs) using elliptical mountain-wave theory. The vertical momentum transport of OGWs is addressed separately for waves with different orientations through decomposition of the total wave momentum flux (WMF) into individual wave components. With the new scheme implemented in the Weather Research and Forecasting (WRF) Model, the impact of directional absorption of OGWs on the general circulation in boreal winter is studied for the first time. The results show that directional absorption can change the vertical distribution of OGW forcing, while maintaining the total column-integrated forcing. In general, directional absorption inhibits wave breaking in the lower troposphere, producing weaker orographic gravity wave drag (OGWD) there and transporting more WMF upward. This is because directional absorption can stabilize OGWs by reducing the local wave amplitude. Owing to the increased WMF from below, the OGWD in the upper troposphere at midlatitudes is enhanced. However, in the stratosphere of mid- to high latitudes, the OGWD is still weakened due to greater directional absorption occurring there. Changes in the distribution of midlatitude OGW forcing are found to weaken the tropospheric jet locally and enhance the stratospheric polar night jet remotely. The latter occurs as the adiabatic warming (associated with the OGW-induced residual circulation) is increased at midlatitudes and suppressed at high latitudes, giving rise to stronger thermal contrast. Resolved waves are likely to contribute to the enhancement of polar stratospheric winds as well, because their upward propagation into the high-latitude stratosphere is suppressed.
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Matthias, V., P. Hoffmann, A. Manson, C. Meek, G. Stober, P. Brown, and M. Rapp. "The impact of planetary waves on the latitudinal displacement of sudden stratospheric warmings." Annales Geophysicae 31, no. 8 (August 9, 2013): 1397–415. http://dx.doi.org/10.5194/angeo-31-1397-2013.
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Abstract. The Northern Hemispheric winter is disturbed by large scale variability mainly caused by Planetary Waves (PWs), which interact with the mean flow and thus result in Sudden Stratospheric Warmings (SSWs). The effects of a SSW on the middle atmosphere are an increase of stratospheric and a simultaneous decrease of mesospheric temperature as well as a wind reversal to westward wind from the mesosphere to the stratosphere. In most cases these disturbances are strongest at polar latitudes, get weaker toward the south and vanish at mid-latitudes around 50° to 60° N as for example during the winter 2005/06. However, other events like in 2009, 2010 and 2012 show a similar or even stronger westward wind at mid- than at polar latitudes either in the mesosphere or in the stratosphere during the SSW. This study uses local meteor and MF-radar measurements, global satellite observations from the Microwave Limb Sounder (MLS) and assimilated model data from MERRA (Modern-ERA Retrospective analysis for research and Applications). We compare differences in the latitudinal structure of the zonal wind, temperature and PW activity between a "normal" event, where the event in 2006 was chosen representatively, and the latitudinal displaced events in 2009, 2010 and 2012. A continuous westward wind band between the pole and 20° N is observed during the displaced events. Furthermore, distinctive temperature differences at mid-latitudes occur before the displaced warmings compared to 2006 as well as a southward extended stratospheric warming afterwards. These differences between the normal SSW in 2006 and the displaced events in 2009, 2010 and 2012 are linked to an increased PW activity between 30° N and 50° N and the changed stationary wave flux in the stratosphere around the displaced events compared to 2006.
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Shaw, Tiffany A., Judith Perlwitz, Nili Harnik, Paul A. Newman, and Steven Pawson. "The Impact of Stratospheric Ozone Changes on Downward Wave Coupling in the Southern Hemisphere*." Journal of Climate 24, no. 16 (August 15, 2011): 4210–29. http://dx.doi.org/10.1175/2011jcli4170.1.
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Abstract The impact of stratospheric ozone changes on downward wave coupling between the stratosphere and troposphere in the Southern Hemisphere is investigated using a suite of Goddard Earth Observing System chemistry–climate model (GEOS CCM) simulations. Downward wave coupling occurs when planetary waves reflected in the stratosphere impact the troposphere. In reanalysis data, the climatological coupling occurs from September to December when the stratospheric basic state has a well-defined high-latitude meridional waveguide in the lower stratosphere that is bounded above by a reflecting surface, called a bounded wave geometry. Reanalysis data suggests that downward wave coupling during November–December has increased during the last three decades. The GEOS CCM simulation of the recent past captures the main features of downward wave coupling in the Southern Hemisphere. Consistent with the Modern Era Retrospective-Analysis for Research and Application (MERRA) dataset, wave coupling in the model maximizes during October–November when there is a bounded wave geometry configuration. However, the wave coupling in the model is stronger than in the MERRA dataset, and starts earlier and ends later in the seasonal cycle. The late season bias is caused by a bias in the timing of the stratospheric polar vortex breakup. Temporal changes in stratospheric ozone associated with past depletion and future recovery significantly impact downward wave coupling in the model. During the period of ozone depletion, the spring bounded wave geometry, which is favorable for downward wave coupling, extends into early summer, due to a delay in the vortex breakup date, and leads to increased downward wave coupling during November–December. During the period of ozone recovery, the stratospheric basic state during November–December shifts from a spring configuration back to a summer configuration, where waves are trapped in the troposphere, and leads to a decrease in downward wave coupling. Model simulations with chlorine fixed at 1960 values and increasing greenhouse gases show no significant changes in downward wave coupling and confirm that the changes in downward wave coupling in the model are caused by ozone changes. The results reveal a new mechanism wherein stratospheric ozone changes can affect the tropospheric circulation.
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Zhang, Xin Li, Yun An Hu, and Di Liu. "The Research on Height Control of Airship with Constant Flying Speed." Applied Mechanics and Materials 644-650 (September 2014): 875–78. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.875.
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The PID control scheme of airship with fixed flying high is studied in allusion to pitch channel nonlinear model of a class of stratosphere airship in this paper. The traditional PID control law is designed aim at the fixed high flight control of airship. The detailed simulation analysis is presented. It indicates that the airship can realize the fixed high flight in the range of 1000 meters. When flying high increase further, PID control scheme is not reasonable because instruction is too large. At the same time, the speed of engine has large influence on PID control scheme. The research of paper has good technical reference value for design and experiments of stratosphere airship.
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Bernet, Leonie, Thomas von Clarmann, Sophie Godin-Beekmann, Gérard Ancellet, Eliane Maillard Barras, René Stübi, Wolfgang Steinbrecht, Niklaus Kämpfer, and Klemens Hocke. "Ground-based ozone profiles over central Europe: incorporating anomalous observations into the analysis of stratospheric ozone trends." Atmospheric Chemistry and Physics 19, no. 7 (April 3, 2019): 4289–309. http://dx.doi.org/10.5194/acp-19-4289-2019.
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Abstract. Observing stratospheric ozone is essential to assess whether the Montreal Protocol has succeeded in saving the ozone layer by banning ozone depleting substances. Recent studies have reported positive trends, indicating that ozone is recovering in the upper stratosphere at mid-latitudes, but the trend magnitudes differ, and uncertainties are still high. Trends and their uncertainties are influenced by factors such as instrumental drifts, sampling patterns, discontinuities, biases, or short-term anomalies that may all mask a potential ozone recovery. The present study investigates how anomalies, temporal measurement sampling rates, and trend period lengths influence resulting trends. We present an approach for handling suspicious anomalies in trend estimations. For this, we analysed multiple ground-based stratospheric ozone records in central Europe to identify anomalous periods in data from the GROund-based Millimetre-wave Ozone Spectrometer (GROMOS) located in Bern, Switzerland. The detected anomalies were then used to estimate ozone trends from the GROMOS time series by considering the anomalous observations in the regression. We compare our improved GROMOS trend estimate with results derived from the other ground-based ozone records (lidars, ozonesondes, and microwave radiometers), that are all part of the Network for the Detection of Atmospheric Composition Change (NDACC). The data indicate positive trends of 1 % decade−1 to 3 % decade−1 at an altitude of about 39 km (3 hPa), providing a confirmation of ozone recovery in the upper stratosphere in agreement with satellite observations. At lower altitudes, the ground station data show inconsistent trend results, which emphasize the importance of ongoing research on ozone trends in the lower stratosphere. Our presented method of a combined analysis of ground station data provides a useful approach to recognize and to reduce uncertainties in stratospheric ozone trends by considering anomalies in the trend estimation. We conclude that stratospheric trend estimations still need improvement and that our approach provides a tool that can also be useful for other data sets.
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Weigel, K., L. Hoffmann, G. Günther, F. Khosrawi, F. Olschewski, P. Preusse, R. Spang, F. Stroh, and M. Riese. "A stratospheric intrusion at the subtropical jet over the Mediterranean Sea: air-borne remote sensing observations and model results." Atmospheric Chemistry and Physics 12, no. 18 (September 20, 2012): 8423–38. http://dx.doi.org/10.5194/acp-12-8423-2012.
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Abstract. Remote sensing measurements from the Cryogenic Infrared Spectrometers and Telescope for the Atmosphere – New Frontiers (CRISTA-NF) during a flight on 29 July 2006 are presented. This flight is part of the AMMA-SCOUT-O3 measurement campaign, where CRISTA-NF was deployed on the high-flying research aircraft M55-Geophysica. The flight path was located over Italy and the Mediterranean Sea and crossed over the subtropical jet twice. Measurements of temperature, and the volume mixing ratios of water vapor (H2O), ozone (O3), nitric acid (HNO3) and peroxyacetyl nitrate (PAN) are available with a vertical resolution of up to 500 m between about 6 to 21 km altitude. CRISTA-NF observes these trace gases simultaneously and provides a quasi-2-D view of the transition region between the troposphere and the stratosphere. The observation of these different trace gases allows to determine tropospheric and stratospheric air masses. As expected, higher abundances are found where the main source of the trace gases is located: in the stratosphere for O3 and in the troposphere for H2O and PAN. Tracer-tracer correlations between O3 and PAN are used to identify the mixed tropospheric and lowermost stratospheric air at the subtropical jet and around the thermal tropopause north of the jet. An intrusion of stratospheric air into the troposphere associated with the subtropical jet is found in the CRISTA-NF observations. The observations indicate that the intrusion is connected to a tropopause fold which is not resolved in the ECMWF analysis data. The intrusion was reproduced in a simulation with the Chemical Lagrangian Model of the Stratosphere (CLaMS). The CLaMS simulation shows, that the lowermost stratospheric air masses in the intrusion where transported along the the subtropical jet. The tropospheric air masses around the intrusion originate from the vicinity of the Asian monsoon anticyclone. This work discusses the nature of the observed processes at the subtropical jet based on the CRISTA-NF observations and the CLaMS simulation.
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Revell, Laura E., Andrea Stenke, Beiping Luo, Stefanie Kremser, Eugene Rozanov, Timofei Sukhodolov, and Thomas Peter. "Impacts of Mt Pinatubo volcanic aerosol on the tropical stratosphere in chemistry–climate model simulations using CCMI and CMIP6 stratospheric aerosol data." Atmospheric Chemistry and Physics 17, no. 21 (November 7, 2017): 13139–50. http://dx.doi.org/10.5194/acp-17-13139-2017.
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Abstract. To simulate the impacts of volcanic eruptions on the stratosphere, chemistry–climate models that do not include an online aerosol module require temporally and spatially resolved aerosol size parameters for heterogeneous chemistry and aerosol radiative properties as a function of wavelength. For phase 1 of the Chemistry-Climate Model Initiative (CCMI-1) and, later, for phase 6 of the Coupled Model Intercomparison Project (CMIP6) two such stratospheric aerosol data sets were compiled, whose functional capability and representativeness are compared here. For CCMI-1, the SAGE-4λ data set was compiled, which hinges on the measurements at four wavelengths of the SAGE (Stratospheric Aerosol and Gas Experiment) II satellite instrument and uses ground-based lidar measurements for gap-filling immediately after the 1991 Mt Pinatubo eruption, when the stratosphere was too optically opaque for SAGE II. For CMIP6, the new SAGE-3λ data set was compiled, which excludes the least reliable SAGE II wavelength and uses measurements from CLAES (Cryogenic Limb Array Etalon Spectrometer) on UARS, the Upper Atmosphere Research Satellite, for gap-filling following the Mt Pinatubo eruption instead of ground-based lidars. Here, we performed SOCOLv3 (Solar Climate Ozone Links version 3) chemistry–climate model simulations of the recent past (1986–2005) to investigate the impact of the Mt Pinatubo eruption in 1991 on stratospheric temperature and ozone and how this response differs depending on which aerosol data set is applied. The use of SAGE-4λ results in heating and ozone loss being overestimated in the tropical lower stratosphere compared to observations in the post-eruption period by approximately 3 K and 0.2 ppmv, respectively. However, less heating occurs in the model simulations based on SAGE-3λ, because the improved gap-filling procedures after the eruption lead to less aerosol loading in the tropical lower stratosphere. As a result, simulated tropical temperature anomalies in the model simulations based on SAGE-3λ for CMIP6 are in excellent agreement with MERRA and ERA-Interim reanalyses in the post-eruption period. Less heating in the simulations with SAGE-3λ means that the rate of tropical upwelling does not strengthen as much as it does in the simulations with SAGE-4λ, which limits dynamical uplift of ozone and therefore provides more time for ozone to accumulate in tropical mid-stratospheric air. Ozone loss following the Mt Pinatubo eruption is overestimated by up to 0.1 ppmv in the model simulations based on SAGE-3λ, which is a better agreement with observations than in the simulations based on SAGE-4λ. Overall, the CMIP6 stratospheric aerosol data set, SAGE-3λ, allows SOCOLv3 to more accurately simulate the post-Pinatubo eruption period.
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Kaufmann, M., J. Blank, T. Guggenmoser, J. Ungermann, A. Engel, M. Ern, F. Friedl-Vallon, et al. "Retrieval of three-dimensional small-scale structures in upper-tropospheric/lower-stratospheric composition as measured by GLORIA." Atmospheric Measurement Techniques 8, no. 1 (January 9, 2015): 81–95. http://dx.doi.org/10.5194/amt-8-81-2015.
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Abstract. The three-dimensional quantification of small-scale processes in the upper troposphere and lower stratosphere is one of the challenges of current atmospheric research and requires the development of new measurement strategies. This work presents the first results from the newly developed Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) obtained during the ESSenCe (ESa Sounder Campaign) and TACTS/ESMVal (TACTS: Transport and composition in the upper troposphere/lowermost stratosphere, ESMVal: Earth System Model Validation) aircraft campaigns. The focus of this work is on the so-called dynamics-mode data characterized by a medium-spectral and a very-high-spatial resolution. The retrieval strategy for the derivation of two- and three-dimensional constituent fields in the upper troposphere and lower stratosphere is presented. Uncertainties of the main retrieval targets (temperature, O3, HNO3, and CFC-12) and their spatial resolution are discussed. During ESSenCe, high-resolution two-dimensional cross-sections have been obtained. Comparisons to collocated remote-sensing and in situ data indicate a good agreement between the data sets. During TACTS/ESMVal, a tomographic flight pattern to sense an intrusion of stratospheric air deep into the troposphere was performed. It was possible to reconstruct this filament at an unprecedented spatial resolution of better than 500 m vertically and 20 × 20 km horizontally.
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Dreessen, Joel. "A Sea Level Stratospheric Ozone Intrusion Event Induced within a Thunderstorm Gust Front." Bulletin of the American Meteorological Society 100, no. 7 (July 2019): 1259–75. http://dx.doi.org/10.1175/bams-d-18-0113.1.
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AbstractOzone from a stratospheric intrusion (SI) reached sea level in association with a thunderstorm gust front during the predawn hours of 16 April 2018. The event caused surface ozone concentration increases of 30 to more than 50 ppbv in a matter of minutes in a band from approximately Richmond, Virginia, to Philadelphia, Pennsylvania. Peak hourly ozone concentrations reached 74 ppbv in northeastern Maryland despite absent photochemistry and ongoing convective activity. An intense jet stream with velocities >80 kt (41 m s−1) less than 1 km above ground level was observed associated with a deepening cyclone. Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), showed a filament of ozone with concentrations greater than 90 ppbv extending downward from the stratosphere to the lower troposphere. This SI filament became collocated with an ongoing severe squall line, and stratospheric ozone was transported directly to sea level when entrained into the squall-line gust front. Weather radar and in situ observations confirmed surface ozone increased with the thunderstorm gust front, while a concurrent reduction in carbon monoxide confirmed air within the gust front had stratospheric origins. While rare, such coupling events are important to troposphere–stratosphere exchanges and in overall atmospheric chemistry and climate. This may be the first event of its type and magnitude documented.
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Voigt, C., H. Schlager, B. P. Luo, A. Dörnbrack, A. Roiger, P. Stock, J. Curtius, et al. "Nitric acid trihydrate (NAT) formation at low NAT supersaturations." Atmospheric Chemistry and Physics Discussions 4, no. 6 (December 23, 2004): 8579–607. http://dx.doi.org/10.5194/acpd-4-8579-2004.
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Abstract. A polar stratospheric cloud (PSC) was observed on 6 February 2003 in the Arctic stratosphere by in-situ measurements onboard the high-altitude research aircraft Geophysica. Low number densities (~10−4 cm−3) of nitric acid (HNO3) containing particles – probably NAT – with diameters up to 6 µm were measured at altitudes between 18 and 20 km. These particles have the potential to grow further and to remove HNO3 from the stratosphere, thereby enhancing polar ozone loss. Interestingly, the NAT particles formed in less than a day at temperatures T>TNAT−3.5 K, just slightly below the NAT equilibrium temperature TNAT. This unique measurement of PSC formation at extremely low NAT saturation ratios (SNAT≤11) constrains current NAT nucleation theories. In particular, NAT formation on ice can for certain be excluded. Conversely, we suggest that meteoritic particles may be favorable candidates for triggering nucleation of NAT at the observed low number densities.
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Kozubek, M., P. Krizan, and J. Lastovicka. "Northern Hemisphere stratospheric winds in higher midlatitudes: longitudinal distribution and long-term trends." Atmospheric Chemistry and Physics 15, no. 4 (February 27, 2015): 2203–13. http://dx.doi.org/10.5194/acp-15-2203-2015.
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Abstract. The Brewer–Dobson circulation (mainly meridional circulation) is very important for stratospheric ozone dynamics and thus for the overall state of the stratosphere. There are some indications that the meridional circulation in the stratosphere could be longitudinally dependent, which would have an impact on the ozone distribution. Therefore, we analyse here the meridional component of the stratospheric wind at northern middle latitudes to study its longitudinal dependence. The analysis is based on the NCEP/NCAR-1 (National Centers for Environmental Prediction and the National Center for Atmospheric Research), MERRA (Modern Era-Retrospective Analysis) and ERA-Interim (European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis Interim) reanalysis data. The well-developed two-core structure of strong but opposite meridional winds, one in each hemisphere at 10 hPa at higher northern middle latitudes, and a less pronounced five-core structure at 100 hPa are identified. In the central areas of the two-core structure the meridional and zonal wind magnitudes are comparable. The two-core structure at 10 hPa is almost identical for all three different reanalysis data sets in spite of the different time periods covered. The two-core structure is not associated with tides. However, the two-core structure at the 10 hPa level is related to the Aleutian pressure high at 10 hPa. Zonal wind, temperature and the ozone mixing ratio at 10 hPa also exhibit the effect of the Aleutian high, which thus affects all parameters of the Northern Hemisphere middle stratosphere. Long-term trends in the meridional wind in the "core" areas are significant at the 99% level. Trends of meridional winds are negative during the period of ozone depletion development (1970–1995), while they are positive after the ozone trend turnaround (1996–2012). Meridional wind trends are independent of the sudden stratospheric warming (SSW) occurrence and the quasi-biennial oscillation (QBO) phase. The influence of the 11-year solar cycle on stratospheric winds has been identified only during the west phase of QBO. The well-developed two-core structure in the meridional wind illustrates the limitations of application of the zonal mean concept in studying stratospheric circulation.
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Roiger, A., H. Schlager, A. Schäfler, H. Huntrieser, M. Scheibe, H. Aufmhoff, O. R. Cooper, et al. "In-situ observation of Asian pollution transported into the Arctic lowermost stratosphere." Atmospheric Chemistry and Physics Discussions 11, no. 5 (May 31, 2011): 16265–310. http://dx.doi.org/10.5194/acpd-11-16265-2011.
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Abstract. On a research flight on 10 July 2008, the German research aircraft Falcon sampled an air mass with unusually high carbon monoxide (CO), peroxyacetyl nitrate (PAN) and water vapour (H2O) mixing ratios in the Arctic lowermost stratosphere. The air mass was encountered twice at an altitude of 11.3 km, ~800 m above the dynamical tropopause. In-situ measurements of ozone, NO, and NOy indicate that this layer was a mixed air mass containing both air from the troposphere and stratosphere. Backward trajectory and Lagrangian particle dispersion model analysis suggest that the Falcon sampled the top of a polluted air mass originating from the coastal regions of East Asia. The anthropogenic pollution plume experienced strong up-lift in a warm conveyor belt (WCB) located over the Russian east-coast. Subsequently the Asian air mass was transported across the North Pole into the sampling area, elevating the local tropopause by up to ~3 km. Mixing with surrounding Arctic stratospheric air most likely took place during the horizontal transport when the tropospheric streamer was stretched into long and narrow filaments. The mechanism illustrated in this study possibly presents an important pathway to transport pollution into the polar tropopause region.
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Roiger, A., H. Schlager, A. Schäfler, H. Huntrieser, M. Scheibe, H. Aufmhoff, O. R. Cooper, et al. "In-situ observation of Asian pollution transported into the Arctic lowermost stratosphere." Atmospheric Chemistry and Physics 11, no. 21 (November 7, 2011): 10975–94. http://dx.doi.org/10.5194/acp-11-10975-2011.
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Abstract. On a research flight on 10 July 2008, the German research aircraft Falcon sampled an air mass with unusually high carbon monoxide (CO), peroxyacetyl nitrate (PAN) and water vapour (H2O) mixing ratios in the Arctic lowermost stratosphere. The air mass was encountered twice at an altitude of 11.3 km, ~800 m above the dynamical tropopause. In-situ measurements of ozone, NO, and NOy indicate that this layer was a mixed air mass containing both air from the troposphere and stratosphere. Backward trajectory and Lagrangian particle dispersion model analysis suggest that the Falcon sampled the top of a polluted air mass originating from the coastal regions of East Asia. The anthropogenic pollution plume experienced strong up-lift in a warm conveyor belt (WCB) located over the Russian east-coast. Subsequently the Asian air mass was transported across the North Pole into the sampling area, elevating the local tropopause by up to ~3 km. Mixing with surrounding Arctic stratospheric air most likely took place during the horizontal transport when the tropospheric streamer was stretched into long and narrow filaments. The mechanism illustrated in this study possibly presents an important pathway to transport pollution into the polar tropopause region.
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Kawatani, Yoshio, Kevin Hamilton, and Shingo Watanabe. "The Quasi-Biennial Oscillation in a Double CO2 Climate." Journal of the Atmospheric Sciences 68, no. 2 (February 1, 2011): 265–83. http://dx.doi.org/10.1175/2010jas3623.1.
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Abstract The effects of anticipated twenty-first-century global climate change on the stratospheric quasi-biennial oscillation (QBO) have been studied using a high-resolution version of the Model for Interdisciplinary Research on Climate (MIROC) atmospheric GCM. This version of the model is notable for being able to simulate a fairly realistic QBO for present-day conditions including only explicitly resolved nonstationary waves. A long control integration of the model was run with observed climatological sea surface temperatures (SSTs) appropriate for the late twentieth century, followed by another integration with increased atmospheric CO2 concentration and SSTs incremented by the projected twenty-first-century warming in a multimodel ensemble of coupled ocean–atmosphere runs that were forced by the Special Report on Emissions Scenarios (SRES) A1B scenario of future atmospheric composition. In the experiment for late twenty-first-century conditions the QBO period becomes longer and QBO amplitude weaker than in the late twentieth-century simulation. The downward penetration of the QBO into the lowermost stratosphere is also curtailed in the late twenty-first-century run. These changes are driven by a significant (30%–40%) increase of the mean upwelling in the equatorial stratosphere, and the effect of this enhanced mean circulation overwhelms counteracting influences from strengthened wave fluxes in the warmer climate. The momentum fluxes associated with waves propagating upward into the equatorial stratosphere do strengthen overall by ∼(10%–15%) in the warm simulation, but the increases are almost entirely in zonal phase speed ranges that have little effect on the stratospheric QBO but that would be expected to have important influences in the mesosphere and lower thermosphere.
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Viciani, Silvia, Alessio Montori, Antonio Chiarugi, and Francesco D’Amato. "A Portable Quantum Cascade Laser Spectrometer for Atmospheric Measurements of Carbon Monoxide." Sensors 18, no. 7 (July 21, 2018): 2380. http://dx.doi.org/10.3390/s18072380.
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Trace gas concentration measurements in the stratosphere and troposphere are critically required as inputs to constrain climate models. For this purpose, measurement campaigns on stratospheric aircraft and balloons are being carried out all over the world, each one involving sensors which are tailored for the specific gas and environmental conditions. This paper describes an automated, portable, mid-infrared quantum cascade laser spectrometer, for in situ carbon monoxide mixing ratio measurements in the stratosphere and troposphere. The instrument was designed to be versatile, suitable for easy installation on different platforms and capable of operating completely unattended, without the presence of an operator, not only during one flight but for the whole period of a campaign. The spectrometer features a small size (80 × 25 × 41 cm3), light weight (23 kg) and low power consumption (85 W typical), without being pressurized and without the need of calibration on the ground or during in-flight operation. The device was tested in the laboratory and in-field during a research campaign carried out in Nepal in summer 2017, onboard the stratospheric aircraft M55 Geophysica. The instrument worked extremely well, without external maintenance during all flights, proving an in-flight sensitivity of 1–2 ppbV with a time resolution of 1 s.
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de Reus, M., S. Borrmann, A. Bansemer, A. J. Heymsfield, R. Weigel, C. Schiller, V. Mitev, et al. "Evidence for ice particles in the tropical stratosphere from in-situ measurements." Atmospheric Chemistry and Physics 9, no. 18 (September 18, 2009): 6775–92. http://dx.doi.org/10.5194/acp-9-6775-2009.
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Abstract. In-situ ice crystal size distribution measurements are presented within the tropical troposphere and lower stratosphere. The measurements were performed using a combination of a Forward Scattering Spectrometer Probe (FSSP-100) and a Cloud Imaging Probe (CIP), which were installed on the Russian high altitude research aircraft M55 "Geophysica" during the SCOUT-O3 campaign in Darwin, Australia. One of the objectives of the campaign was to characterise the Hector convective system, which appears on an almost daily basis during the pre-monsoon season over the Tiwi Islands, north of Darwin. In total 90 encounters with ice clouds, between 10 and 19 km altitude were selected from the dataset and were analysed. Six of these encounters were observed in the lower stratosphere, up to 1.4 km above the local tropopause. Concurrent lidar measurements on board "Geophysica" indicate that these ice clouds were a result of overshooting convection. Large ice crystals, with a maximum dimension up to 400 μm, were observed in the stratosphere. The stratospheric ice clouds included an ice water content ranging from 7.7×10−5 to 8.5×10−4 g m−3 and were observed at ambient relative humidities (with respect to ice) between 75 and 157%. Three modal lognormal size distributions were fitted to the average size distributions for different potential temperature intervals, showing that the shape of the size distribution of the stratospheric ice clouds are similar to those observed in the upper troposphere. In the tropical troposphere the effective radius of the ice cloud particles decreases from 100 μm at about 10 km altitude, to 3 μm at the tropopause, while the ice water content decreases from 0.04 to 10−5 g m−3. No clear trend in the number concentration was observed with altitude, due to the thin and inhomogeneous characteristics of the observed cirrus clouds. The ice water content calculated from the observed ice crystal size distribution is compared to the ice water content derived from two hygrometer instruments. This independent measurement of the ice water content agrees within the combined uncertainty of the instruments for ice water contents exceeding 3×10−4g m−3. Stratospheric residence times, calculated based on gravitational settling, and evaporation rates show that the ice crystals observed in the stratosphere over the Hector storm system had a high potential of humidifying the stratosphere locally. Utilizing total aerosol number concentration measurements from a four channel condensation particle counter during two separate campaigns, it can be shown that the fraction of ice particles to the number of aerosol particles remaining ranges from 1:300 to 1:30 000 for tropical upper tropospheric ice clouds with ambient temperatures below −75°C.
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Lubis, Sandro W., Vered Silverman, Katja Matthes, Nili Harnik, Nour-Eddine Omrani, and Sebastian Wahl. "How does downward planetary wave coupling affect polar stratospheric ozone in the Arctic winter stratosphere?" Atmospheric Chemistry and Physics 17, no. 3 (February 15, 2017): 2437–58. http://dx.doi.org/10.5194/acp-17-2437-2017.
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Abstract. It is well established that variable wintertime planetary wave forcing in the stratosphere controls the variability of Arctic stratospheric ozone through changes in the strength of the polar vortex and the residual circulation. While previous studies focused on the variations in upward wave flux entering the lower stratosphere, here the impact of downward planetary wave reflection on ozone is investigated for the first time. Utilizing the MERRA2 reanalysis and a fully coupled chemistry–climate simulation with the Community Earth System Model (CESM1(WACCM)) of the National Center for Atmospheric Research (NCAR), we find two downward wave reflection effects on ozone: (1) the direct effect in which the residual circulation is weakened during winter, reducing the typical increase of ozone due to upward planetary wave events and (2) the indirect effect in which the modification of polar temperature during winter affects the amount of ozone destruction in spring. Winter seasons dominated by downward wave reflection events (i.e., reflective winters) are characterized by lower Arctic ozone concentration, while seasons dominated by increased upward wave events (i.e., absorptive winters) are characterized by relatively higher ozone concentration. This behavior is consistent with the cumulative effects of downward and upward planetary wave events on polar stratospheric ozone via the residual circulation and the polar temperature in winter. The results establish a new perspective on dynamical processes controlling stratospheric ozone variability in the Arctic by highlighting the key role of wave reflection.
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Fiehn, Alina, Birgit Quack, Helmke Hepach, Steffen Fuhlbrügge, Susann Tegtmeier, Matthew Toohey, Elliot Atlas, and Kirstin Krüger. "Delivery of halogenated very short-lived substances from the west Indian Ocean to the stratosphere during the Asian summer monsoon." Atmospheric Chemistry and Physics 17, no. 11 (June 8, 2017): 6723–41. http://dx.doi.org/10.5194/acp-17-6723-2017.
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Abstract. Halogenated very short-lived substances (VSLSs) are naturally produced in the ocean and emitted to the atmosphere. When transported to the stratosphere, these compounds can have a significant influence on the ozone layer and climate. During a research cruise on RV Sonne in the subtropical and tropical west Indian Ocean in July and August 2014, we measured the VSLSs, methyl iodide (CH3I) and for the first time bromoform (CHBr3) and dibromomethane (CH2Br2), in surface seawater and the marine atmosphere to derive their emission strengths. Using the Lagrangian particle dispersion model FLEXPART with ERA-Interim meteorological fields, we calculated the direct contribution of observed VSLS emissions to the stratospheric halogen burden during the Asian summer monsoon. Furthermore, we compare the in situ calculations with the interannual variability of transport from a larger area of the west Indian Ocean surface to the stratosphere for July 2000–2015. We found that the west Indian Ocean is a strong source for CHBr3 (910 pmol m−2 h−1), very strong source for CH2Br2 (930 pmol m−2 h−1), and an average source for CH3I (460 pmol m−2 h−1). The atmospheric transport from the tropical west Indian Ocean surface to the stratosphere experiences two main pathways. On very short timescales, especially relevant for the shortest-lived compound CH3I (3.5 days lifetime), convection above the Indian Ocean lifts oceanic air masses and VSLSs towards the tropopause. On a longer timescale, the Asian summer monsoon circulation transports oceanic VSLSs towards India and the Bay of Bengal, where they are lifted with the monsoon convection and reach stratospheric levels in the southeastern part of the Asian monsoon anticyclone. This transport pathway is more important for the longer-lived brominated compounds (17 and 150 days lifetime for CHBr3 and CH2Br2). The entrainment of CHBr3 and CH3I from the west Indian Ocean to the stratosphere during the Asian summer monsoon is lower than from previous cruises in the tropical west Pacific Ocean during boreal autumn and early winter but higher than from the tropical Atlantic during boreal summer. In contrast, the projected CH2Br2 entrainment was very high because of the high emissions during the west Indian Ocean cruise. The 16-year July time series shows highest interannual variability for the shortest-lived CH3I and lowest for the longest-lived CH2Br2. During this time period, a small increase in VSLS entrainment from the west Indian Ocean through the Asian monsoon to the stratosphere is found. Overall, this study confirms that the subtropical and tropical west Indian Ocean is an important source region of halogenated VSLSs, especially CH2Br2, to the troposphere and stratosphere during the Asian summer monsoon.
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Olschewski, Friedhelm, Christian Monte, Albert Adibekyan, Max Reiniger, Berndt Gutschwager, Joerg Hollandt, and 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 (August 14, 2018): 4757–62. http://dx.doi.org/10.5194/amt-11-4757-2018.
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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.
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Sheng, Z., J. W. Li, Y. Jiang, S. D. Zhou, and W. L. Shi. "Characteristics of Stratospheric Winds over Jiuquan (41.1°N, 100.2°E) Using Rocketsonde Data in 1967–2004." Journal of Atmospheric and Oceanic Technology 34, no. 3 (March 2017): 657–67. http://dx.doi.org/10.1175/jtech-d-16-0014.1.
Full textAbstract:
AbstractStratospheric winds play a significant role in middle atmosphere dynamics, model research, and carrier rocket experiments. For the first time, 65 sets of rocket sounding experiments conducted at Jiuquan (41.1°N, 100.2°E), China, from 1967 to 2004 are presented to study horizontal wind fields in the stratosphere. At a fixed height, wind speed obeys the lognormal distribution. Seasonal mean winds are westerly in winter and easterly in summer. In spring and autumn, zonal wind directions change from the upper to the lower stratosphere. The monthly zonal mean winds have an annual cycle period with large amplitudes at high altitudes. The correlation coefficients for zonal winds between observations and the Horizontal Wind Model (HWM) with all datasets are 0.7. The MERRA reanalysis is in good agreement with rocketsonde data according to the zonal winds comparison with a coefficient of 0.98. The sudden stratospheric warming is an important contribution to biases in the HWM, because it changes the zonal wind direction in the midlatitudes. Both the model and the reanalysis show dramatic meridional wind differences with the observation data.