Articles | Volume 17, issue 2 
            
                
                    
            
            
            https://doi.org/10.5194/acp-17-793-2017
                    © Author(s) 2017. This work is distributed under 
the Creative Commons Attribution 3.0 License.
                the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/acp-17-793-2017
                    © Author(s) 2017. This work is distributed under 
the Creative Commons Attribution 3.0 License.
                the Creative Commons Attribution 3.0 License.
Tropical temperature variability and Kelvin-wave activity in the UTLS from GPS RO measurements
Barbara Scherllin-Pirscher
CORRESPONDING AUTHOR
                                            
                                    
                                            Wegener Center for Climate and Global Change (WEGC) and Institute for Geophysics, Astrophysics, and Meteorology/Institute
of Physics (IGAM/IP), University of Graz, Graz, Austria
                                        
                                    
                                            Zentralanstalt für Meteorologie und Geodynamik (ZAMG), Vienna, Austria
                                        
                                    William J. Randel
                                            National Center for Atmospheric Research (NCAR), Boulder,
Colorado, USA
                                        
                                    Joowan Kim
                                            National Center for Atmospheric Research (NCAR), Boulder,
Colorado, USA
                                        
                                    
                                            Department of Atmospheric Sciences, Kongju National University, Gongju, Korea
                                        
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                                        Kimberlee Dubé, Daniel Zawada, Adam Bourassa, Doug Degenstein, William Randel, David Flittner, Patrick Sheese, and Kaley Walker
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                                        Matthieu Plu, Barbara Scherllin-Pirscher, Delia Arnold Arias, Rocio Baro, Guillaume Bigeard, Luca Bugliaro, Ana Carvalho, Laaziz El Amraoui, Kurt Eschbacher, Marcus Hirtl, Christian Maurer, Marie D. Mulder, Dennis Piontek, Lennart Robertson, Carl-Herbert Rokitansky, Fritz Zobl, and Raimund Zopp
                                    Nat. Hazards Earth Syst. Sci., 21, 2973–2992, https://doi.org/10.5194/nhess-21-2973-2021, https://doi.org/10.5194/nhess-21-2973-2021, 2021
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                                                Past volcanic eruptions that spread out ash over large areas, like Eyjafjallajökull in 2010, forced the cancellation of thousands of flights and had huge economic consequences.
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                                        Kimberlee Dubé, Adam Bourassa, Daniel Zawada, Douglas Degenstein, Robert Damadeo, David Flittner, and William Randel
                                    Atmos. Meas. Tech., 14, 557–566, https://doi.org/10.5194/amt-14-557-2021, https://doi.org/10.5194/amt-14-557-2021, 2021
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                                    Nat. Hazards Earth Syst. Sci., 20, 1719–1739, https://doi.org/10.5194/nhess-20-1719-2020, https://doi.org/10.5194/nhess-20-1719-2020, 2020
                                    Short summary
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                                                The paper summarizes the set-up and outcome of a volcanic-hazard demonstration exercise, with the goals of assessing and mitigating the impacts of volcanic ash clouds on civil and military aviation. Experts in the field simulated the sequence of procedures for an artificial eruption of the Etna volcano in Italy. The scope of the exercise ranged from the detection of the assumed event to the issuance of early warnings and optimized rerouting of flights.
                                            
                                            
                                        Jiali Luo, Laura L. Pan, Shawn B. Honomichl, John W. Bergman, William J. Randel, Gene Francis, Cathy Clerbaux, Maya George, Xiong Liu, and Wenshou Tian
                                    Atmos. Chem. Phys., 18, 12511–12530, https://doi.org/10.5194/acp-18-12511-2018, https://doi.org/10.5194/acp-18-12511-2018, 2018
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                                                We analyze upper tropospheric CO and O3 using satellite data from limb-viewing (MLS) and nadir-viewing (IASI and OMI) sensors, together with dynamical variables, to examine how the two types of data complement each other in representing the chemical variability associated with the day-to-day dynamical variability in the Asian summer monsoon anticyclone. The results provide new observational evidence of eddy shedding in upper tropospheric CO distribution.
                                            
                                            
                                        Therese Rieckh, Richard Anthes, William Randel, Shu-Peng Ho, and Ulrich Foelsche
                                    Atmos. Meas. Tech., 11, 3091–3109, https://doi.org/10.5194/amt-11-3091-2018, https://doi.org/10.5194/amt-11-3091-2018, 2018
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                                                Water vapor is the most important tropospheric greenhouse gas and is also highly variable in space and time. We study the vertical structure and variability of tropospheric humidity using various observing techniques (GPS radio occultation, radiosondes, Atmospheric Infrared Sounder) and models. Time–height cross sections reveal seasonal biases for different pressure layers. We find that radio occultation humidity has high accuracy and can contribute valuable information in data assimilation.
                                            
                                            
                                        Hallgeir Wilhelmsen, Florian Ladstädter, Barbara Scherllin-Pirscher, and Andrea K. Steiner
                                    Atmos. Meas. Tech., 11, 1333–1346, https://doi.org/10.5194/amt-11-1333-2018, https://doi.org/10.5194/amt-11-1333-2018, 2018
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                                                Tropical atmospheric variability is often described using proxy indices of the Quasi-Biennial Oscillation and the El Niño–Southern Oscillation. We introduce new proxies derived from GNSS radio occultation (RO) satellite measurements. Using the high vertical resolution of the RO temperature fields we obtain altitude-resolved indices which can improve the description of atmospheric variability patterns and can be used in climate studies where a detailed knowledge of these patterns is required.
                                            
                                            
                                        Petr Pisoft, Petr Sacha, Jiri Miksovsky, Peter Huszar, Barbara Scherllin-Pirscher, and Ulrich Foelsche
                                    Atmos. Meas. Tech., 11, 515–527, https://doi.org/10.5194/amt-11-515-2018, https://doi.org/10.5194/amt-11-515-2018, 2018
                                    Short summary
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                                                We revise selected findings regarding utilization of Global Positioning System radio occultation density profiles for analysis of internal gravity waves. The results show that previously published results are valid only for one specific data version only. Using radiosonde profiles, we also analyze a nonhydrostatic component in temperature profiles. The last part presents detailed study on the utilization of density profiles for characterization of the wave field stability.
                                            
                                            
                                        Barbara Angerer, Florian Ladstädter, Barbara Scherllin-Pirscher, Marc Schwärz, Andrea K. Steiner, Ulrich Foelsche, and Gottfried Kirchengast
                                    Atmos. Meas. Tech., 10, 4845–4863, https://doi.org/10.5194/amt-10-4845-2017, https://doi.org/10.5194/amt-10-4845-2017, 2017
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                                                We present a detailed analysis of the latest Wegener Center GPS radio occultation reprocessing (OPSv5.6) output. Knowledge of differences in data quality, as well as of data consistency, is essential when combining data from different missions to a long-term climate record. We compare quality aspects of the various processed satellite missions and present satellite-dependent variations. Temperature data from various satellites are found to be highly consistent within 8 to 25 km.
                                            
                                            
                                        Olga V. Tweedy, Natalya A. Kramarova, Susan E. Strahan, Paul A. Newman, Lawrence Coy, William J. Randel, Mijeong Park, Darryn W. Waugh, and Stacey M. Frith
                                    Atmos. Chem. Phys., 17, 6813–6823, https://doi.org/10.5194/acp-17-6813-2017, https://doi.org/10.5194/acp-17-6813-2017, 2017
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                                                In this study we examined the impact of unprecedented disruption in the wind pattern (the quasi-biennial oscillation, or QBO) in the tropical stratosphere (16–48 km above the ground) on chemicals very important to the stratospheric climate such as ozone (O3). During the 2016 boreal summer, total O3 is lower in the extratropics than during previous QBO cycles due to lifting forced from the disruption. This decrease in O3 led to the increase in surface UV index by 8.5 % compared to the 36 yr mean.
                                            
                                            
                                        Therese Rieckh, Richard Anthes, William Randel, Shu-Peng Ho, and Ulrich Foelsche
                                    Atmos. Meas. Tech., 10, 1093–1110, https://doi.org/10.5194/amt-10-1093-2017, https://doi.org/10.5194/amt-10-1093-2017, 2017
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                                                We use GPS radio occultation (RO) data to investigate the structure and temporal behavior of extremely dry, high-ozone tropospheric air in the tropical western Pacific and compare them to various data sets (research aircraft, radiosonde, infrared sounder, and model reanalyses). All these data sets have limitations. We show that the RO data contribute significant information on the water vapor content. Our results also verify the quality of the reanalyses.
                                            
                                            
                                        Lukas Brunner, Andrea K. Steiner, Barbara Scherllin-Pirscher, and Martin W. Jury
                                    Atmos. Chem. Phys., 16, 4593–4604, https://doi.org/10.5194/acp-16-4593-2016, https://doi.org/10.5194/acp-16-4593-2016, 2016
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                                                Atmospheric blocking refers to persistent high-pressure systems which block the climatological flow at midlatitudes. We explore blocking with observations from GPS radio occultation (RO), a satellite-based remote-sensing system. Using two example cases, we find that RO data robustly capture blocking, highlighting the potential of RO observations to complement models and reanalysis as a basis for blocking research.
                                            
                                            
                                        Hella Garny and William J. Randel
                                    Atmos. Chem. Phys., 16, 2703–2718, https://doi.org/10.5194/acp-16-2703-2016, https://doi.org/10.5194/acp-16-2703-2016, 2016
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                                                We investigate the fate of air that originates in the monsoon region in the upper troposphere, where it was transported to by convection. We find that almost half of the air parcels released in the monsoon region in the upper troposphere reach the stratosphere within 60 days, and most ascend to the tropical lower stratosphere. This suggests that trace gases, including pollutants, that are transported into the stratosphere via the Asian monsoon are in a position to enter the deep stratosphere.
                                            
                                            
                                        Y. Li, G. Kirchengast, B. Scherllin-Pirscher, R. Norman, Y. B. Yuan, J. Fritzer, M. Schwaerz, and K. Zhang
                                    Atmos. Meas. Tech., 8, 3447–3465, https://doi.org/10.5194/amt-8-3447-2015, https://doi.org/10.5194/amt-8-3447-2015, 2015
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                                                We introduce a new dynamic statistical optimization algorithm to initialize ionosphere-corrected bending angles of Global Navigation Satellite System-based radio occultation measurements. The new algorithm is evaluated against the OPSv5.6 algorithm developed by the Wegener Center using both simulated and real observed data. It is found that the algorithm can significantly reduce the random errors of optimized bending angles. The retrieved refractivity and temperature profiles are also benefited.
                                            
                                            
                                        T. Wang, A. E. Dessler, M. R. Schoeberl, W. J. Randel, and J.-E. Kim
                                    Atmos. Chem. Phys., 15, 3517–3526, https://doi.org/10.5194/acp-15-3517-2015, https://doi.org/10.5194/acp-15-3517-2015, 2015
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                                                We investigated the impacts of vertical temperature structures on trajectory simulations of stratospheric dehydration and water vapor by using 1) MERRA temperatures on model levels; 2) GPS temperatures at finer vertical resolutions; and 3) adjusted MERRA temperatures with finer vertical structures induced by waves. We show that despite the fact that temperatures at finer vertical structures tend to dry air by 0.1-0.3ppmv, the interannual variability in different runs is essentially the same.
                                            
                                            
                                        B. Scherllin-Pirscher, S. Syndergaard, U. Foelsche, and K. B. Lauritsen
                                    Atmos. Meas. Tech., 8, 109–124, https://doi.org/10.5194/amt-8-109-2015, https://doi.org/10.5194/amt-8-109-2015, 2015
                            S. Fueglistaler, M. Abalos, T. J. Flannaghan, P. Lin, and W. J. Randel
                                    Atmos. Chem. Phys., 14, 13439–13453, https://doi.org/10.5194/acp-14-13439-2014, https://doi.org/10.5194/acp-14-13439-2014, 2014
                            T. Rieckh, B. Scherllin-Pirscher, F. Ladstädter, and U. Foelsche
                                    Atmos. Meas. Tech., 7, 3947–3958, https://doi.org/10.5194/amt-7-3947-2014, https://doi.org/10.5194/amt-7-3947-2014, 2014
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                                                Radio Occultation (RO) observations featuring high vertical resolution, global availability, and high accuracy were used to investigate global characteristics of the lapse rate tropopause. Climatological tropopause characteristics for the
RO record from 2001 to 2013 extend previous studies on tropopause structure and its temporal variability. Latitudinal and longitudinal variations as well as the annual cycle and inter-annual variability were analyzed for the tropopause altitude and temperature.
                                            
                                            
                                        J. Danzer, U. Foelsche, B. Scherllin-Pirscher, and M. Schwärz
                                    Atmos. Meas. Tech., 7, 2883–2896, https://doi.org/10.5194/amt-7-2883-2014, https://doi.org/10.5194/amt-7-2883-2014, 2014
                            T. Wang, W. J. Randel, A. E. Dessler, M. R. Schoeberl, and D. E. Kinnison
                                    Atmos. Chem. Phys., 14, 7135–7147, https://doi.org/10.5194/acp-14-7135-2014, https://doi.org/10.5194/acp-14-7135-2014, 2014
                            A. E. Bourassa, D. A. Degenstein, W. J. Randel, J. M. Zawodny, E. Kyrölä, C. A. McLinden, C. E. Sioris, and C. Z. Roth
                                    Atmos. Chem. Phys., 14, 6983–6994, https://doi.org/10.5194/acp-14-6983-2014, https://doi.org/10.5194/acp-14-6983-2014, 2014
                            M. Abalos, F. Ploeger, P. Konopka, W. J. Randel, and E. Serrano
                                    Atmos. Chem. Phys., 13, 10787–10794, https://doi.org/10.5194/acp-13-10787-2013, https://doi.org/10.5194/acp-13-10787-2013, 2013
                            M. Abalos, W. J. Randel, D. E. Kinnison, and E. Serrano
                                    Atmos. Chem. Phys., 13, 10591–10607, https://doi.org/10.5194/acp-13-10591-2013, https://doi.org/10.5194/acp-13-10591-2013, 2013
                            J. Danzer, B. Scherllin-Pirscher, and U. Foelsche
                                    Atmos. Meas. Tech., 6, 2169–2179, https://doi.org/10.5194/amt-6-2169-2013, https://doi.org/10.5194/amt-6-2169-2013, 2013
                            K. A. Tereszchuk, D. P. Moore, J. J. Harrison, C. D. Boone, M. Park, J. J. Remedios, W. J. Randel, and P. F. Bernath
                                    Atmos. Chem. Phys., 13, 5601–5613, https://doi.org/10.5194/acp-13-5601-2013, https://doi.org/10.5194/acp-13-5601-2013, 2013
                            A. K. Steiner, D. Hunt, S.-P. Ho, G. Kirchengast, A. J. Mannucci, B. Scherllin-Pirscher, H. Gleisner, A. von Engeln, T. Schmidt, C. Ao, S. S. Leroy, E. R. Kursinski, U. Foelsche, M. Gorbunov, S. Heise, Y.-H. Kuo, K. B. Lauritsen, C. Marquardt, C. Rocken, W. Schreiner, S. Sokolovskiy, S. Syndergaard, and J. Wickert
                                    Atmos. Chem. Phys., 13, 1469–1484, https://doi.org/10.5194/acp-13-1469-2013, https://doi.org/10.5194/acp-13-1469-2013, 2013
                            M. Abalos, W. J. Randel, and E. Serrano
                                    Atmos. Chem. Phys., 12, 11505–11517, https://doi.org/10.5194/acp-12-11505-2012, https://doi.org/10.5194/acp-12-11505-2012, 2012
                            Related subject area
            Subject: Dynamics | Research Activity: Remote Sensing | Altitude Range: Stratosphere | Science Focus: Physics (physical properties and processes)
            
                    
                        
                            
                            
                                     
                                Observational perspective on sudden stratospheric warmings and blocking from Eliassen–Palm fluxes
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Aeolus wind lidar observations of the 2019/2020 quasi-biennial oscillation disruption with comparison to radiosondes and reanalysis
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Convective gravity wave events during summer near 54° N, present in both AIRS and Rayleigh–Mie–Raman (RMR) lidar observations
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Signatures of the Madden–Julian oscillation in middle-atmosphere zonal mean temperature: triggering the interhemispheric coupling pattern
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                The quasi-biennial oscillation (QBO) and global-scale tropical waves in Aeolus wind observations, radiosonde data, and reanalyses
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Vertical structure of the lower-stratospheric moist bias in the ERA5 reanalysis and its connection to mixing processes
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Intermittency of gravity wave potential energies and absolute momentum fluxes derived from infrared limb sounding satellite observations
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                The evolution and dynamics of the Hunga Tonga–Hunga Ha'apai sulfate aerosol plume in the stratosphere
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Stratospheric water vapour and ozone response to the quasi-biennial oscillation disruptions in 2016 and 2020
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                A new methodology for measuring traveling quasi-5-day oscillations during sudden stratospheric warming events based on satellite observations
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                The middle atmospheric meridional circulation for 2002–2012 derived from MIPAS observations
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Stratospheric gravity waves over the mountainous island of South Georgia: testing a high-resolution dynamical model with 3-D satellite observations and radiosondes
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Smoke-charged vortices in the stratosphere generated by wildfires and their behaviour in both hemispheres: comparing Australia 2020 to Canada 2017
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Using a network of temperature lidars to identify temperature biases in the upper stratosphere in ECMWF reanalyses
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Direct inversion of circulation from tracer measurements – Part 2: Sensitivity studies and model recovery tests
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Record low ozone values over the Arctic in boreal spring 2020
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                New insights into Rossby wave packet properties in the extratropical UTLS using GNSS radio occultations
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Superposition of gravity waves with different propagation characteristics observed by airborne and space-borne infrared sounders
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                First measurements of tides in the stratosphere and lower mesosphere by ground-based Doppler microwave wind radiometry
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Gravity waves in the winter stratosphere over the Southern Ocean: high-resolution satellite observations and 3-D spectral analysis
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Comparison of equatorial wave activity in the tropical tropopause layer and stratosphere represented in reanalyses
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Investigation of Arctic middle-atmospheric dynamics using 3 years of H2O and O3 measurements from microwave radiometers at Ny-Ålesund
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Influence of ENSO and MJO on the zonal structure of tropical tropopause inversion layer using high-resolution temperature profiles retrieved from COSMIC GPS Radio Occultation
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                How well do stratospheric reanalyses reproduce high-resolution satellite temperature measurements?
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                First tomographic observations of gravity waves by the infrared limb imager GLORIA
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Shift of subtropical transport barriers explains observed hemispheric asymmetry of decadal trends of age of air
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Exploring gravity wave characteristics in 3-D using a novel S-transform technique: AIRS/Aqua measurements over the Southern Andes and Drake Passage
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                A decadal satellite record of gravity wave activity in the lower stratosphere to study polar stratospheric cloud formation
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Evolution of the eastward shift in the quasi-stationary minimum of the Antarctic total ozone column
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                The major stratospheric final warming in 2016: dispersal of vortex air and termination of Arctic chemical ozone loss
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                The tropical tropopause inversion layer: variability and modulation by equatorial waves
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Satellite observations of middle atmosphere gravity wave absolute momentum flux and of its vertical gradient during recent stratospheric warmings
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Stratospheric gravity waves at Southern Hemisphere orographic hotspots: 2003–2014 AIRS/Aqua observations
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Global temperature response to the major volcanic eruptions in multiple reanalysis data sets
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Reassessment of MIPAS age of air trends and variability
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Enhanced internal gravity wave activity and breaking over the northeastern Pacific–eastern Asian region
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Global distributions of overlapping gravity waves in HIRDLS data
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                The southern stratospheric gravity wave hot spot: individual waves and their momentum fluxes measured by COSMIC GPS-RO
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Methane as a diagnostic tracer of changes in the Brewer–Dobson circulation of the stratosphere
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                The influence of the North Atlantic Oscillation and El Niño–Southern Oscillation on mean and extreme values of column ozone over the United States
                                
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Short vertical-wavelength inertia-gravity waves generated by a jet–front system at Arctic latitudes – VHF radar, radiosondes and numerical modelling
                                
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                A climatology of the diurnal variations in stratospheric and mesospheric ozone over Bern, Switzerland
                                
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Long-term changes in the upper stratospheric ozone at Syowa, Antarctica
                                
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Estimates of turbulent diffusivities and energy dissipation rates from satellite measurements of spectra of stratospheric refractivity perturbations
                                
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Observations of filamentary structures near the vortex edge in the Arctic winter lower stratosphere
                                
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Impact of land convection on temperature diurnal variation in the tropical lower stratosphere inferred from COSMIC GPS radio occultations
                                
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Observation of horizontal winds in the middle-atmosphere between 30° S and 55° N during the northern winter 2009–2010
                                
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Variability in the speed of the Brewer–Dobson circulation as observed by Aura/MLS
                                
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Simultaneous occurrence of polar stratospheric clouds and upper-tropospheric clouds caused by blocking anticyclones in the Southern Hemisphere
                                
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Quantification of structural uncertainty in climate data records from GPS radio occultation
                                
                            
                            
                        
                    
                    
            
        
        Kamilya Yessimbet, Andrea K. Steiner, Florian Ladstädter, and Albert Ossó
                                    Atmos. Chem. Phys., 24, 10893–10919, https://doi.org/10.5194/acp-24-10893-2024, https://doi.org/10.5194/acp-24-10893-2024, 2024
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                                                Major sudden stratospheric warmings (SSWs) and atmospheric blocking can markedly influence winter extratropical surface weather. To study the relationship between SSWs and blocking, we examine dynamic stratosphere–troposphere coupling using vertically highly resolved observations from global navigation satellite system radio occultation for 2007–2019. Our results provide a purely observational view of the evolution of major SSWs, their link to blocking, and their effect on the polar tropopause.
                                            
                                            
                                        Timothy P. Banyard, Corwin J. Wright, Scott M. Osprey, Neil P. Hindley, Gemma Halloran, Lawrence Coy, Paul A. Newman, Neal Butchart, Martina Bramberger, and M. Joan Alexander
                                    Atmos. Chem. Phys., 24, 2465–2490, https://doi.org/10.5194/acp-24-2465-2024, https://doi.org/10.5194/acp-24-2465-2024, 2024
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                                                In 2019/2020, the tropical stratospheric wind phenomenon known as the quasi-biennial oscillation (QBO) was disrupted for only the second time in the historical record. This was poorly forecasted, and we want to understand why. We used measurements from the first Doppler wind lidar in space, Aeolus, to observe the disruption in an unprecedented way. Our results reveal important differences between Aeolus and the ERA5 reanalysis that affect the timing of the disruption's onset and its evolution.
                                            
                                            
                                        Eframir Franco-Diaz, Michael Gerding, Laura Holt, Irina Strelnikova, Robin Wing, Gerd Baumgarten, and Franz-Josef Lübken
                                    Atmos. Chem. Phys., 24, 1543–1558, https://doi.org/10.5194/acp-24-1543-2024, https://doi.org/10.5194/acp-24-1543-2024, 2024
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                                                We use satellite, lidar, and ECMWF data to study storm-related waves that propagate above Kühlungsborn, Germany, during summer. Although these events occur in roughly half of the years of the satellite data we analyzed, we focus our study on two case study years (2014 and 2015). These events could contribute significantly to middle atmospheric circulation and are not accounted for in weather and climate models.
                                            
                                            
                                        Christoph G. Hoffmann, Lena G. Buth, and Christian von Savigny
                                    Atmos. Chem. Phys., 23, 12781–12799, https://doi.org/10.5194/acp-23-12781-2023, https://doi.org/10.5194/acp-23-12781-2023, 2023
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                                                The Madden–Julian oscillation is an important feature of weather in the tropics. Although it is mainly active in the troposphere, we show that it systematically influences the air temperature in the layers above, up to about 100 km altitude and from pole to pole. We have linked this to another known far-reaching process, interhemispheric coupling. This is basic research on atmospheric couplings and variability but might also be of interest for intraseasonal weather forecasting models.
                                            
                                            
                                        Manfred Ern, Mohamadou A. Diallo, Dina Khordakova, Isabell Krisch, Peter Preusse, Oliver Reitebuch, Jörn Ungermann, and Martin Riese
                                    Atmos. Chem. Phys., 23, 9549–9583, https://doi.org/10.5194/acp-23-9549-2023, https://doi.org/10.5194/acp-23-9549-2023, 2023
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                                                Quasi-biennial oscillation (QBO) of the stratospheric tropical winds is an important mode of climate variability but is not well reproduced in free-running climate models. We use the novel global wind observations by the Aeolus satellite and radiosondes to show that the QBO is captured well in three modern reanalyses (ERA-5, JRA-55, and MERRA-2). Good agreement is also found also between Aeolus and reanalyses for large-scale tropical wave modes in the upper troposphere and lower stratosphere.
                                            
                                            
                                        Konstantin Krüger, Andreas Schäfler, Martin Wirth, Martin Weissmann, and George C. Craig
                                    Atmos. Chem. Phys., 22, 15559–15577, https://doi.org/10.5194/acp-22-15559-2022, https://doi.org/10.5194/acp-22-15559-2022, 2022
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                                                A comprehensive data set of airborne lidar water vapour profiles is compared with ERA5 reanalyses for a robust characterization of the vertical structure of the mid-latitude lower-stratospheric moist bias. We confirm a moist bias of up to 55 % at 1.3 km altitude above the tropopause and uncover a decreasing bias beyond. Collocated O3 and H2O observations reveal a particularly strong bias in the mixing layer, indicating insufficiently modelled transport processes fostering the bias.
                                            
                                            
                                        Manfred Ern, Peter Preusse, and Martin Riese
                                    Atmos. Chem. Phys., 22, 15093–15133, https://doi.org/10.5194/acp-22-15093-2022, https://doi.org/10.5194/acp-22-15093-2022, 2022
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                                                Based on data from the HIRDLS and SABER infrared limb sounding satellite instruments, we investigate the intermittency of global distributions of gravity wave (GW) potential energies and GW momentum fluxes in the stratosphere and mesosphere using probability distribution functions (PDFs) and Gini coefficients. We compare GW intermittency in different regions, seasons, and altitudes. These results can help to improve GW parameterizations and the distributions of GWs resolved in models.
                                            
                                            
                                        Bernard Legras, Clair Duchamp, Pasquale Sellitto, Aurélien Podglajen, Elisa Carboni, Richard Siddans, Jens-Uwe Grooß, Sergey Khaykin, and Felix Ploeger
                                    Atmos. Chem. Phys., 22, 14957–14970, https://doi.org/10.5194/acp-22-14957-2022, https://doi.org/10.5194/acp-22-14957-2022, 2022
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                                                The long-duration atmospheric impact of the Tonga eruption in January 2022 is a plume of water and sulfate aerosols in the stratosphere that persisted for more than 6 months. We study this evolution using several satellite instruments and analyse the unusual behaviour of this plume as sulfates and water first moved down rapidly and then separated into two layers. We also report the self-organization in compact and long-lived patches.
                                            
                                            
                                        Mohamadou A. Diallo, Felix Ploeger, Michaela I. Hegglin, Manfred Ern, Jens-Uwe Grooß, Sergey Khaykin, and Martin Riese
                                    Atmos. Chem. Phys., 22, 14303–14321, https://doi.org/10.5194/acp-22-14303-2022, https://doi.org/10.5194/acp-22-14303-2022, 2022
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                                                The quasi-biennial oacillation disruption events in both 2016 and 2020 decreased lower-stratospheric water vapour and ozone. Differences in the strength and depth of the anomalous lower-stratospheric circulation and ozone are due to differences in tropical upwelling and cold-point temperature induced by lower-stratospheric planetary and gravity wave breaking. The differences in water vapour are due to higher cold-point temperature in 2020 induced by Australian wildfire.
                                            
                                            
                                        Zheng Ma, Yun Gong, Shaodong Zhang, Qiao Xiao, Chunming Huang, and Kaiming Huang
                                    Atmos. Chem. Phys., 22, 13725–13737, https://doi.org/10.5194/acp-22-13725-2022, https://doi.org/10.5194/acp-22-13725-2022, 2022
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                                                We present a novel method to measure the amplitudes of traveling quasi-5-day oscillations (Q5DOs) in the middle atmosphere during sudden stratospheric warming events based on satellite observations. Simulations and observations demonstrate that the previously reported traveling Q5DOs might be contaminated by stationary planetary waves (SPWs). The new fitting method is developed by inhibiting the effect of a rapid and large change in SPWs.
                                            
                                            
                                        Thomas von Clarmann, Udo Grabowski, Gabriele P. Stiller, Beatriz M. Monge-Sanz, Norbert Glatthor, and Sylvia Kellmann
                                    Atmos. Chem. Phys., 21, 8823–8843, https://doi.org/10.5194/acp-21-8823-2021, https://doi.org/10.5194/acp-21-8823-2021, 2021
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                                                Measurements of long-lived trace gases (SF6, CFC-11, CFC-12, HCFC-12, CCl4, N2O, CH4, H2O, and CO) performed with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) have been used to infer the stratospheric and mesospheric meridional circulation. The MIPAS data set covers the time period from July 2002 to April 2012. The method used for this purpose was the direct inversion of the two-dimensional continuity equation. Multiannual monthly mean circulation fields are presented.
                                            
                                            
                                        Neil P. Hindley, Corwin J. Wright, Alan M. Gadian, Lars Hoffmann, John K. Hughes, David R. Jackson, John C. King, Nicholas J. Mitchell, Tracy Moffat-Griffin, Andrew C. Moss, Simon B. Vosper, and Andrew N. Ross
                                    Atmos. Chem. Phys., 21, 7695–7722, https://doi.org/10.5194/acp-21-7695-2021, https://doi.org/10.5194/acp-21-7695-2021, 2021
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                                                One limitation of numerical atmospheric models is spatial resolution. For atmospheric gravity waves (GWs) generated over small mountainous islands, the driving effect of these waves on atmospheric circulations can be underestimated. Here we use a specialised high-resolution model over South Georgia island to compare simulated stratospheric GWs to colocated 3-D satellite observations. We find reasonable model agreement with observations, with some GW amplitudes much larger than expected.
                                            
                                            
                                        Hugo Lestrelin, Bernard Legras, Aurélien Podglajen, and Mikail Salihoglu
                                    Atmos. Chem. Phys., 21, 7113–7134, https://doi.org/10.5194/acp-21-7113-2021, https://doi.org/10.5194/acp-21-7113-2021, 2021
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                                                Following the 2020 Australian fires, it was recently discovered that stratospheric wildfire smoke plumes self-organize as anticyclonic vortices that persist for months and rise by 10 km due to the radiative heating from the absorbing smoke. In this study, we show that smoke-charged vortices previously occurred in the aftermath of the 2017 Canadian fires. We use meteorological analysis to characterize this new object in geophysical fluid dynamics, which likely impacts radiation and climate.
                                            
                                            
                                        Graeme Marlton, Andrew Charlton-Perez, Giles Harrison, Inna Polichtchouk, Alain Hauchecorne, Philippe Keckhut, Robin Wing, Thierry Leblanc, and Wolfgang Steinbrecht
                                    Atmos. Chem. Phys., 21, 6079–6092, https://doi.org/10.5194/acp-21-6079-2021, https://doi.org/10.5194/acp-21-6079-2021, 2021
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                                                A network of Rayleigh lidars have been used to infer the upper-stratosphere temperature bias in ECMWF ERA-5 and ERA-Interim reanalyses during 1990–2017. Results show that ERA-Interim exhibits a cold bias of −3 to −4 K between 10 and 1 hPa. Comparisons with ERA-5 found a smaller bias of 1 K which varies between cold and warm between 10 and 3 hPa, indicating a good thermal representation of the atmosphere to 3 hPa. These biases must be accounted for in stratospheric studies using these reanalyses.
                                            
                                            
                                        Thomas von Clarmann and Udo Grabowski
                                    Atmos. Chem. Phys., 21, 2509–2526, https://doi.org/10.5194/acp-21-2509-2021, https://doi.org/10.5194/acp-21-2509-2021, 2021
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                                                The direct inversion of the 2D continuity equation allows us to infer the effective meridional transport velocity of trace gases in the middle stratosphere. This method exploits the information both given by the displacement of patterns in measured trace gas distributions and by the approximate balance between sinks and horizontal as well as vertical advection. The robustness of this method has been tested and characterized using model recovery tests and sensitivity studies.
                                            
                                            
                                        Martin Dameris, Diego G. Loyola, Matthias Nützel, Melanie Coldewey-Egbers, Christophe Lerot, Fabian Romahn, and Michel van Roozendael
                                    Atmos. Chem. Phys., 21, 617–633, https://doi.org/10.5194/acp-21-617-2021, https://doi.org/10.5194/acp-21-617-2021, 2021
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                                                Record low ozone values were observed in March 2020. Dynamical and chemical circumstances leading to low ozone values in spring 2020 are discussed and are compared to similar dynamical conditions in the Northern Hemisphere in 1996/1997 and 2010/2011. 2019/2020 showed an unusual persistent polar vortex with low stratospheric temperatures, which were permanently below 195 K at 50 hPa. This enabled enhanced formation of polar stratospheric clouds and a subsequent clear reduction of total ozone.
                                            
                                            
                                        Robin Pilch Kedzierski, Katja Matthes, and Karl Bumke
                                    Atmos. Chem. Phys., 20, 11569–11592, https://doi.org/10.5194/acp-20-11569-2020, https://doi.org/10.5194/acp-20-11569-2020, 2020
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                                                Rossby wave packet (RWP) dynamics are crucial for weather forecasting, climate change projections and stratosphere–troposphere interactions. Our study is a first attempt to describe RWP behavior in the UTLS with global coverage directly from observations, using GNSS-RO data. Our novel results show an interesting relation of RWP vertical propagation with sudden stratospheric warmings and provide very useful information to improve RWP diagnostics in models and reanalysis.
                                            
                                            
                                        Isabell Krisch, Manfred Ern, Lars Hoffmann, Peter Preusse, Cornelia Strube, Jörn Ungermann, Wolfgang Woiwode, and Martin Riese
                                    Atmos. Chem. Phys., 20, 11469–11490, https://doi.org/10.5194/acp-20-11469-2020, https://doi.org/10.5194/acp-20-11469-2020, 2020
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                                                In 2016, a scientific research flight above Scandinavia acquired various atmospheric data (temperature, gas composition, etc.). Through advanced 3-D reconstruction methods, a superposition of multiple gravity waves was identified. An in-depth analysis enabled the characterisation of these waves as well as the identification of their sources. This work will enable a better understanding of atmosphere dynamics and could lead to improved climate projections.
                                            
                                            
                                        Jonas Hagen, Klemens Hocke, Gunter Stober, Simon Pfreundschuh, Axel Murk, and Niklaus Kämpfer
                                    Atmos. Chem. Phys., 20, 2367–2386, https://doi.org/10.5194/acp-20-2367-2020, https://doi.org/10.5194/acp-20-2367-2020, 2020
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                                                The middle atmosphere (30 to 70 km altitude) is stratified and, despite very strong horizontal winds, there is less mixing between the horizontal layers. An important driver for the energy exchange between the layers in this regime is atmospheric tides, which are waves that are driven by the diurnal cycle of solar heating. We measure these tides in the wind field for the first time using a ground-based passive instrument. Ultimately, such measurements could be used to improve atmospheric models.
                                            
                                            
                                        Neil P. Hindley, Corwin J. Wright, Nathan D. Smith, Lars Hoffmann, Laura A. Holt, M. Joan Alexander, Tracy Moffat-Griffin, and Nicholas J. Mitchell
                                    Atmos. Chem. Phys., 19, 15377–15414, https://doi.org/10.5194/acp-19-15377-2019, https://doi.org/10.5194/acp-19-15377-2019, 2019
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                                                In this study, a 3–D Stockwell transform is applied to AIRS–Aqua satellite observations in the first extended 3–D study of stratospheric gravity waves over the Southern Ocean during winter. A dynamic environment is revealed that contains some of the most intense gravity wave sources on Earth. A particularly striking result is a large–scale meridional convergence of gravity wave momentum flux towards latitudes near 60 °S, something which is not normally considered in model parameterisations.
                                            
                                            
                                        Young-Ha Kim, George N. Kiladis, John R. Albers, Juliana Dias, Masatomo Fujiwara, James A. Anstey, In-Sun Song, Corwin J. Wright, Yoshio Kawatani, François Lott, and Changhyun Yoo
                                    Atmos. Chem. Phys., 19, 10027–10050, https://doi.org/10.5194/acp-19-10027-2019, https://doi.org/10.5194/acp-19-10027-2019, 2019
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                                                Reanalyses are widely used products of meteorological variables, generated using observational data and assimilation systems. We compare six modern reanalyses, with focus on their representation of equatorial waves which are important in stratospheric variability and stratosphere–troposphere exchange. Agreement/spreads among the reanalyses in the spectral properties and spatial distributions of the waves are examined, and satellite impacts on the wave representation in reanalyses are discussed.
                                            
                                            
                                        Franziska Schranz, Brigitte Tschanz, Rolf Rüfenacht, Klemens Hocke, Mathias Palm, and Niklaus Kämpfer
                                    Atmos. Chem. Phys., 19, 9927–9947, https://doi.org/10.5194/acp-19-9927-2019, https://doi.org/10.5194/acp-19-9927-2019, 2019
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                                                The dynamics of the Arctic middle atmosphere above Ny-Ålesund, Svalbard (79° N, 12° E) is investigated using 3 years of H2O and O3 measurements from ground-based microwave radiometers. We found the signals of atmospheric phenomena like sudden stratospheric warmings, polar vortex shifts, effective descent rates of water vapour and periodicities in our data. Additionally, a comprehensive intercomparison is performed with models and measurements from ground-based, in situ and satellite instruments.
                                            
                                            
                                        Noersomadi, Toshitaka Tsuda, and Masatomo Fujiwara
                                    Atmos. Chem. Phys., 19, 6985–7000, https://doi.org/10.5194/acp-19-6985-2019, https://doi.org/10.5194/acp-19-6985-2019, 2019
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                                                Characteristics of static stability (N2) in the tropical tropopause are analyzed using 0.1 km vertical resolution temperature profiles retrieved from COSMIC GNSS-RO. We define the tropopause inversion layer (TIL) by the sharp increase in N2 across the cold point tropopause (CPT) and the thickness of the enhanced peak in N2 just above the CPT. We investigated the TIL at the intraseasonal to interannual timescales above the Maritime Continent and Pacific Ocean with different land–sea distribution.
                                            
                                            
                                        Corwin J. Wright and Neil P. Hindley
                                    Atmos. Chem. Phys., 18, 13703–13731, https://doi.org/10.5194/acp-18-13703-2018, https://doi.org/10.5194/acp-18-13703-2018, 2018
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                                                Reanalyses (RAs) are models which assimilate observations and are widely used as proxies for the true atmospheric state. Here, we resample six leading RAs using the weighting functions of four high-res satellite instruments, allowing a like-for-like comparison. We find that the RAs generally reproduce the satellite data well, except at high altitudes and in the tropics. However, we also find that the RAs more tightly correlate with each other than with observations, even those they assimilate.
                                            
                                            
                                        Isabell Krisch, Peter Preusse, Jörn Ungermann, Andreas Dörnbrack, Stephen D. Eckermann, Manfred Ern, Felix Friedl-Vallon, Martin Kaufmann, Hermann Oelhaf, Markus Rapp, Cornelia Strube, and Martin Riese
                                    Atmos. Chem. Phys., 17, 14937–14953, https://doi.org/10.5194/acp-17-14937-2017, https://doi.org/10.5194/acp-17-14937-2017, 2017
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                                                Using the infrared limb imager GLORIA, the 3-D structure of mesoscale gravity waves in the lower stratosphere was measured for the first time, allowing for a complete 3-D characterization of the waves. This enables the precise determination of the sources of the waves in the mountain regions of Iceland with backward ray tracing. Forward ray tracing shows oblique propagation, an effect generally neglected in global atmospheric models.
                                            
                                            
                                        Gabriele P. Stiller, Federico Fierli, Felix Ploeger, Chiara Cagnazzo, Bernd Funke, Florian J. Haenel, Thomas Reddmann, Martin Riese, and Thomas von Clarmann
                                    Atmos. Chem. Phys., 17, 11177–11192, https://doi.org/10.5194/acp-17-11177-2017, https://doi.org/10.5194/acp-17-11177-2017, 2017
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                                                The discrepancy between modelled and observed 25-year trends of the strength of the stratospheric Brewer–Dobson circulation (BDC) is still not resolved. With our paper we trace the observed hemispheric dipole structure of age of air trends back to natural variability in shorter-term (decadal) time frames. Beyond this we demonstrate that after correction for the decadal natural variability the remaining trend for the first decade of the 21st century is consistent with model simulations.
                                            
                                            
                                        Corwin J. Wright, Neil P. Hindley, Lars Hoffmann, M. Joan Alexander, and Nicholas J. Mitchell
                                    Atmos. Chem. Phys., 17, 8553–8575, https://doi.org/10.5194/acp-17-8553-2017, https://doi.org/10.5194/acp-17-8553-2017, 2017
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                                                We introduce a novel 3-D method of measuring atmospheric gravity waves, based around a 3-D Stockwell transform. Our method lets us measure new properties, including wave intrinsic frequencies and phase and group velocities. We apply it to data from the AIRS satellite instrument over the Southern Andes for two consecutive winters. Our results show clear evidence that the waves measured are primarily orographic in origin, and that their group velocity vectors are focused into the polar night jet.
                                            
                                            
                                        Lars Hoffmann, Reinhold Spang, Andrew Orr, M. Joan Alexander, Laura A. Holt, and Olaf Stein
                                    Atmos. Chem. Phys., 17, 2901–2920, https://doi.org/10.5194/acp-17-2901-2017, https://doi.org/10.5194/acp-17-2901-2017, 2017
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                                                We introduce a 10-year record (2003–2012) of AIRS/Aqua observations of gravity waves in the polar lower stratosphere. The data set was optimized to study the impact of gravity waves on the formation of polar stratospheric clouds (PSCs). We discuss the temporal and spatial patterns of gravity wave activity, validate explicitly resolved small-scale temperature fluctuations in the ECMWF data, and present a survey of gravity-wave-induced PSC formation events using joint AIRS and MIPAS observations.
                                            
                                            
                                        Asen Grytsai, Andrew Klekociuk, Gennadi Milinevsky, Oleksandr Evtushevsky, and Kane Stone
                                    Atmos. Chem. Phys., 17, 1741–1758, https://doi.org/10.5194/acp-17-1741-2017, https://doi.org/10.5194/acp-17-1741-2017, 2017
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                                                Twenty years ago we discovered that the ozone hole shape is asymmetric. This asymmetry is minimum over the Weddell Sea region and maximum over the Ross Sea area. Later we detected that the position of the ozone minimum is shifting east. We have continued to follow this event, and a couple years ago we revealed that the shift is slowing down and starting to move back. We connect all this movement with ozone hole increase; since 2000 the ozone layer has been stabilizing and recently recovering.
                                            
                                            
                                        Gloria L. Manney and Zachary D. Lawrence
                                    Atmos. Chem. Phys., 16, 15371–15396, https://doi.org/10.5194/acp-16-15371-2016, https://doi.org/10.5194/acp-16-15371-2016, 2016
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                                                The 2015/16 Arctic winter stratosphere was the coldest on record through late February, raising the possibility of extensive chemical ozone loss. However, a major final sudden stratospheric warming in early March curtailed ozone destruction. We used Aura MLS satellite trace gas data and MERRA-2 meteorological data to show the details of transport, mixing, and dispersal of chemically processed air during the major final warming, and how these processes limited Arctic chemical ozone loss.
                                            
                                            
                                        Robin Pilch Kedzierski, Katja Matthes, and Karl Bumke
                                    Atmos. Chem. Phys., 16, 11617–11633, https://doi.org/10.5194/acp-16-11617-2016, https://doi.org/10.5194/acp-16-11617-2016, 2016
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                                                This study provides a detailed overview of the daily variability of the tropopause inversion layer (TIL) in the tropics, where TIL research had focused little. The vertical and horizontal structures of this atmospheric layer are described and linked to near-tropopause horizontal wind divergence, the QBO and especially to equatorial waves. Our results increase the knowledge about the observed properties of the tropical TIL, mainly using satellite GPS radio-occultation measurements.
                                            
                                            
                                        Manfred Ern, Quang Thai Trinh, Martin Kaufmann, Isabell Krisch, Peter Preusse, Jörn Ungermann, Yajun Zhu, John C. Gille, Martin G. Mlynczak, James M. Russell III, Michael J. Schwartz, and Martin Riese
                                    Atmos. Chem. Phys., 16, 9983–10019, https://doi.org/10.5194/acp-16-9983-2016, https://doi.org/10.5194/acp-16-9983-2016, 2016
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                                                Sudden stratospheric warmings (SSWs) influence the atmospheric circulation over a large range of altitudes and latitudes. We investigate the global distribution of small-scale gravity waves (GWs) during SSWs as derived from 13 years of satellite observations.
We find that GWs may play an important role for triggering SSWs by preconditioning the polar vortex, as well as during long-lasting vortex recovery phases after SSWs. The GW distribution during SSWs displays strong day-to-day variability.
                                            
                                            
                                        Lars Hoffmann, Alison W. Grimsdell, and M. Joan Alexander
                                    Atmos. Chem. Phys., 16, 9381–9397, https://doi.org/10.5194/acp-16-9381-2016, https://doi.org/10.5194/acp-16-9381-2016, 2016
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                                                We present a 12-year record (2003-2014) of stratospheric gravity wave activity at Southern Hemisphere orographic hotspots as observed by the AIRS/Aqua satellite instrument. We introduce a method to discriminate between gravity waves from orographic or other sources and propose a simple model to predict the occurrence of mountain waves using zonal wind thresholds. The prediction model can help to disentangle upper level wind effects from low level source and other influences.
                                            
                                            
                                        M. Fujiwara, T. Hibino, S. K. Mehta, L. Gray, D. Mitchell, and J. Anstey
                                    Atmos. Chem. Phys., 15, 13507–13518, https://doi.org/10.5194/acp-15-13507-2015, https://doi.org/10.5194/acp-15-13507-2015, 2015
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                                                This paper evaluates the temperature response in the troposphere and the stratosphere to the three major volcanic eruptions between the 1960s and the 1990s by comparing nine reanalysis data sets. It was found that the volcanic temperature response patterns differ among the major eruptions and that in general, more recent reanalysis data sets show a more consistent response pattern.
                                            
                                            
                                        F. J. Haenel, G. P. Stiller, T. von Clarmann, B. Funke, E. Eckert, N. Glatthor, U. Grabowski, S. Kellmann, M. Kiefer, A. Linden, and T. Reddmann
                                    Atmos. Chem. Phys., 15, 13161–13176, https://doi.org/10.5194/acp-15-13161-2015, https://doi.org/10.5194/acp-15-13161-2015, 2015
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                                                Stratospheric circulation is thought to change as a consequence of climate change. Empirical evidence, however, is sparse. In this paper we present latitude- and altitude-resolved trends of the mean age of stratospheric air as derived from SF6 measurements performed by the MIPAS satellite instrument. The mean of the age of stratospheric air is a measure of the intensity of the Brewer-Dobson circulation. In this paper we discuss differences with respect to a preceding analysis by Stiller et al.
                                            
                                            
                                        P. Šácha, A. Kuchař, C. Jacobi, and P. Pišoft
                                    Atmos. Chem. Phys., 15, 13097–13112, https://doi.org/10.5194/acp-15-13097-2015, https://doi.org/10.5194/acp-15-13097-2015, 2015
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                                                In this study, we present a discovery of an internal gravity wave activity and breaking hotspot collocated with an area of anomalously low annual cycle amplitude and specific dynamics in the stratosphere over the Northeastern Pacific/Eastern Asia coastal region. The reasons why this particular IGW activity hotspot was not discovered before nor the specific dynamics of this region pointed out are discussed together with possible consequences on the middle atmospheric dynamics and transport.
                                            
                                            
                                        C. J. Wright, S. M. Osprey, and J. C. Gille
                                    Atmos. Chem. Phys., 15, 8459–8477, https://doi.org/10.5194/acp-15-8459-2015, https://doi.org/10.5194/acp-15-8459-2015, 2015
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                                                Data from the HIRDLS instrument are used to study the numerical variability of gravity waves. Observed distributions are dominated by long-vertical-short-horizontal-wavelength waves, with a similar spectral form at all locations. We further divide our data into subspecies by wavelength, and investigate variation in these subspecies in time and space. We show that the variations associated with particular phenomena arise due to changes in specific parts of the spectrum.
                                            
                                            
                                        N. P. Hindley, C. J. Wright, N. D. Smith, and N. J. Mitchell
                                    Atmos. Chem. Phys., 15, 7797–7818, https://doi.org/10.5194/acp-15-7797-2015, https://doi.org/10.5194/acp-15-7797-2015, 2015
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                                                In nearly all GCMs, unresolved gravity wave (GW) drag may cause the southern stratospheric winter polar vortex to break down too late. Here, we characterise GWs in this region of the atmosphere using GPS radio occultation. We find GWs may propagate into the region from other latitudes. We develop a new quantitative wave identification method to learn about regional wave populations. We also find intense GW momentum fluxes over the southern Andes and Antarctic Peninsula GW hot spot.
                                            
                                            
                                        E. E. Remsberg
                                    Atmos. Chem. Phys., 15, 3739–3754, https://doi.org/10.5194/acp-15-3739-2015, https://doi.org/10.5194/acp-15-3739-2015, 2015
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                                                Time series of the satellite-observed stratospheric tracer, CH4, are analyzed to see whether they indicate a significant trend for the hemispheric Brewer--Dobson circulation (BDC) for 1992-2005.  Trends in CH4 for the lower stratosphere are generally positive and equivalent to those of the troposphere.  However, the Northern Hemisphere BDC is clearly accelerated in the mid-stratosphere (20 to 7hPa). Corresponding trends for the Southern Hemisphere are smaller and less significant.
                                            
                                            
                                        I. Petropavlovskikh, R. Evans, G. McConville, G. L. Manney, and H. E. Rieder
                                    Atmos. Chem. Phys., 15, 1585–1598, https://doi.org/10.5194/acp-15-1585-2015, https://doi.org/10.5194/acp-15-1585-2015, 2015
                            A. Réchou, S. Kirkwood, J. Arnault, and P. Dalin
                                    Atmos. Chem. Phys., 14, 6785–6799, https://doi.org/10.5194/acp-14-6785-2014, https://doi.org/10.5194/acp-14-6785-2014, 2014
                            S. Studer, K. Hocke, A. Schanz, H. Schmidt, and N. Kämpfer
                                    Atmos. Chem. Phys., 14, 5905–5919, https://doi.org/10.5194/acp-14-5905-2014, https://doi.org/10.5194/acp-14-5905-2014, 2014
                            K. Miyagawa, I. Petropavlovskikh, R. D. Evans, C. Long, J. Wild, G. L. Manney, and W. H. Daffer
                                    Atmos. Chem. Phys., 14, 3945–3968, https://doi.org/10.5194/acp-14-3945-2014, https://doi.org/10.5194/acp-14-3945-2014, 2014
                            N. M. Gavrilov
                                    Atmos. Chem. Phys., 13, 12107–12116, https://doi.org/10.5194/acp-13-12107-2013, https://doi.org/10.5194/acp-13-12107-2013, 2013
                            C. Kalicinsky, J.-U. Grooß, G. Günther, J. Ungermann, J. Blank, S. Höfer, L. Hoffmann, P. Knieling, F. Olschewski, R. Spang, F. Stroh, and M. Riese
                                    Atmos. Chem. Phys., 13, 10859–10871, https://doi.org/10.5194/acp-13-10859-2013, https://doi.org/10.5194/acp-13-10859-2013, 2013
                            S. M. Khaykin, J.-P. Pommereau, and A. Hauchecorne
                                    Atmos. Chem. Phys., 13, 6391–6402, https://doi.org/10.5194/acp-13-6391-2013, https://doi.org/10.5194/acp-13-6391-2013, 2013
                            P. Baron, D. P. Murtagh, J. Urban, H. Sagawa, S. Ochiai, Y. Kasai, K. Kikuchi, F. Khosrawi, H. Körnich, S. Mizobuchi, K. Sagi, and M. Yasui
                                    Atmos. Chem. Phys., 13, 6049–6064, https://doi.org/10.5194/acp-13-6049-2013, https://doi.org/10.5194/acp-13-6049-2013, 2013
                            T. Flury, D. L. Wu, and W. G. Read
                                    Atmos. Chem. Phys., 13, 4563–4575, https://doi.org/10.5194/acp-13-4563-2013, https://doi.org/10.5194/acp-13-4563-2013, 2013
                            M. Kohma and K. Sato
                                    Atmos. Chem. Phys., 13, 3849–3864, https://doi.org/10.5194/acp-13-3849-2013, https://doi.org/10.5194/acp-13-3849-2013, 2013
                            A. K. Steiner, D. Hunt, S.-P. Ho, G. Kirchengast, A. J. Mannucci, B. Scherllin-Pirscher, H. Gleisner, A. von Engeln, T. Schmidt, C. Ao, S. S. Leroy, E. R. Kursinski, U. Foelsche, M. Gorbunov, S. Heise, Y.-H. Kuo, K. B. Lauritsen, C. Marquardt, C. Rocken, W. Schreiner, S. Sokolovskiy, S. Syndergaard, and J. Wickert
                                    Atmos. Chem. Phys., 13, 1469–1484, https://doi.org/10.5194/acp-13-1469-2013, https://doi.org/10.5194/acp-13-1469-2013, 2013
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                        Alexander, S. P., Tsuda, T., Kawatani, Y., and Takahashi, M.: Global distribution of atmospheric waves in the equatorial upper troposphere and lower stratosphere: COSMIC observations of wave mean flow interactions, J. Geophys. Res., 113, D24115, https://doi.org/10.1029/2008JD010039, 2008.
                    
                
                        
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                Short summary
                    Tropical temperature variability and associated Kelvin-wave activity are investigated from 10 km to 30 km using 13 years of high-resolution observational data. Strongest temperature variability is found in the tropical tropopause region between about 16 km and 20 km, where peaks of Kelvin-wave activity are irregularly distributed in time. Detailed knowledge of dynamical processes in the tropical tropopause region is an essential part of better understanding climate variability and change.
                    Tropical temperature variability and associated Kelvin-wave activity are investigated from 10 km...
                    
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