Stefan Lossow
Karlsruhe Institute of Technology
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Featured researches published by Stefan Lossow.
Journal of Geophysical Research | 2010
Yvan J. Orsolini; Joachim Urban; Donal P. Murtagh; Stefan Lossow; Varavut Limpasuvan
Using newly analyzed mesospheric water vapor and temperature observations from the Sub-Millimeter Radiometer instrument aboard the Odin research satellite over the period 2001-2009, we present evidence for an anomalously strong descent of dry mesospheric air from the lower mesosphere into the upper stratosphere in the winters of 2004, 2006, and 2009. In the three cases, the descent follows the recovery of the upper stratospheric polar vortex from a major midwinter stratospheric sudden warming. It is also accompanied by the rapid formation of an anomalously warm polar mesospheric layer, i.e., an elevated polar stratopause, near 75 km, and its slower descent to prewarming level (near 1 hPa) over 1.5-2 months. These three winters stand out in the current record of Odin/Sub-Millimeter Radiometer observations started in July 2001.
Journal of Geophysical Research | 2009
Stefan Lossow; Joachim Urban; H. Schmidt; Daniel R. Marsh; Jörg Gumbel; Patrick Eriksson; Donal P. Murtagh
In this paper we present Odin submillimeter radiometer (Odin/SMR) water vapor measurements in the upper mesosphere and lower thermosphere with focus on the polar latitudes in winter. Measurements since 2003 have been compiled to provide a first overview of the water vapor distribution in this altitude range. Our observations show a distinct seasonal increase of the water vapor concentration during winter at a given altitude above 90 km. Above 95 km the observations exhibit the annual water vapor maximum during wintertime. Model simulations from the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA) and the Whole Atmosphere Community Climate Model version 3 (WACCM3) show results that are very similar to the observations. We suggest that the observed increase in water vapor during winter is mainly caused by a combination of upwelling of moister air from lower altitudes and diffusion processes. Distinct interhemispheric differences in the winter water vapor distribution in the upper mesosphere and lower thermosphere can be observed, both in the observations and the model results. The seasonal water vapor increase in the polar regions is much more pronounced in the Southern Hemisphere winter where higher concentrations can be observed. This observation is most likely due to interhemispheric differences in the underlying dynamics and diffusion processes.
Eos, Transactions American Geophysical Union | 2014
Joachim Urban; Stefan Lossow; G. P. Stiller; William G. Read
In 2000 a sudden severe drop in stratospheric water vapor levels interrupted the supposed long-term increase of this greenhouse gas, an important contributor to global warming and climate variability. Satellite sensors observed a recovery in the following years, hidden behind a large variability. More recently, during 2011 and 2012, measurements revealed another severe drop in stratospheric water vapor concentrations.
Journal of Geophysical Research | 2012
Michael H. Stevens; Stefan Lossow; Jens Fiedler; Gerd Baumgarten; F.-J. Lübken; Kristofer Hallgren; Paul Hartogh; Cora E. Randall; Jerry Lumpe; Scott Martin Bailey; Rick Niciejewski; R. R. Meier; John M. C. Plane; Andrew J. Kochenash; Donal P. Murtagh; Christoph R. Englert
The space shuttle launched for the last time on 8 July 2011. As with most shuttle launches, the three main engines injected about 350 t of water vapor between 100 and 115 km off the east coast of the United States during its ascent to orbit. We follow the motion of this exhaust with a variety of satellite and ground-based data sets and find that (1) the shuttle water vapor plume spread out horizontally in all directions over a distance of 3000 to 4000 km in 18 h, (2) a portion of the plume reached northern Europe in 21 h to form polar mesospheric clouds (PMCs) that are brighter than over 99% of all PMCs observed in that region, and (3) the observed altitude dependence of the particle size is reversed with larger particles above smaller particles. We use a one- dimensional cloud formation model initialized with predictions of a plume diffusion model to simulate the unusually bright PMCs. We find that eddy mixing can move the plume water vapor down to the mesopause near 90 km where ice particles can form. If the eddy diffusion coefficient is 400 to 1000 m(2)/s, the predicted integrated cloud brightness is in agreement with both satellite and ground-based observations of the shuttle PMCs. The propellant mass of the shuttle is about 20% of that from all vehicles launched during the northern 2011 PMC season. We suggest that the brightest PMC population near 70 degrees N is formed by space traffic exhaust.
Atmospheric Measurement Techniques | 2016
K. Weigel; A. Rozanov; Faiza Azam; Klaus Bramstedt; Robert Damadeo; K.-U. Eichmann; C. Gebhardt; D. F. Hurst; M. Kraemer; Stefan Lossow; William G. Read; N. Spelten; G. P. Stiller; Kaley A. Walker; M. Weber; Heinrich Bovensmann; J. P. Burrows
The SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) aboard the Envisat satellite provided measurements from August 2002 until April 2012. SCIAMACHY measured the scattered or direct sunlight using different observation geometries. The limb viewing geometry allows the retrieval of water vapour at about 10-25 km height from the near-infrared spectral range (1353-1410 nm). These data cover the upper troposphere and lower stratosphere (UTLS), a region in the atmosphere which is of special interest for a variety of dynamical and chemical processes as well as for the radiative forcing. Here, the latest data version of water vapour (V3.01) from SCIAMACHY limb measurements is presented and validated by comparisons with data sets from other satellite and in situ measurements. Considering retrieval tests and the results of these comparisons, the V3.01 data are reliable from about 11 to 23 km and the best results are found in the middle of the profiles between about 14 and 20 km. Above 20 km in the extra tropics V3.01 is drier than all other data sets. Additionally, for altitudes above about 19 km, the vertical resolution of the retrieved profile is not sufficient to resolve signals with a short vertical structure like the tape recorder. Below 14 km, SCIAMACHY water vapour V3.01 is wetter than most collocated data sets, but the high variability of water vapour in the troposphere complicates the comparison. For 14-20 km height, the expected errors from the retrieval and simulations and the mean differences to collocated data sets are usually smaller than 10 % when the resolution of the SCIAMACHY data is taken into account. In general, the temporal changes agree well with collocated data sets except for the Northern Hemisphere extratropical stratosphere, where larger differences are observed. This indicates a possible drift in V3.01 most probably caused by the incomplete treatment of volcanic aerosols in the retrieval. In all other regions a good temporal stability is shown. In the tropical stratosphere an increase in water vapour is found between 2002 and 2012, which is in agreement with other satellite data sets for overlapping time periods.
Journal of Atmospheric and Solar-Terrestrial Physics | 2017
Yvan J. Orsolini; Varavut Limpasuvan; Kristell Pérot; Patrick J. Espy; R. E. Hibbins; Stefan Lossow; Katarina Raaholt Larsson; Donal P. Murtagh
Using simulations with a whole-atmosphere chemistry-climate model nudged by meteorological analyses, global satellite observations of nitrogen oxide (NO) and water vapour by the Sub-Millimetre Radiometer instrument (SMR), of temperature by the Microwave Limb Sounder (MLS), as well as local radar observations, this study examines the recent major stratospheric sudden warming accompanied by an elevated stratopause event (ESE) that occurred in January 2013. We examine dynamical processes during the ESE, including the role of planetary wave, gravity wave and tidal forcing on the initiation of the descent in the mesosphere-lower thermosphere (MLT) and its continuation throughout the mesosphere and stratosphere, as well as the impact of model eddy diffusion. We analyse the transport of NO and find the model underestimates the large descent of NO compared to SMR observations. We demonstrate that the discrepancy arises abruptly in the MLT region at a time when the resolved wave forcing and the planetary wave activity increase, just before the elevated stratopause reforms. The discrepancy persists despite doubling the model eddy diffusion. While the simulations reproduce an enhancement of the semi-diurnal tide following the onset of the 2013 SSW, corroborating new meteor radar observations at high northern latitudes over Trondheim (63.4°N), the modelled tidal contribution to the forcing of the mean meridional circulation and to the descent is a small portion of the resolved wave forcing, and lags it by about ten days.
Remote Sensing | 2018
Tongmei Wang; Qiong Zhang; Stefan Lossow; Léon Chafik; Camille Risi; Donal P. Murtagh; Abdel Hannachi
Stable Water Isotopologues (SWIs) are important diagnostic tracers for understanding processes in the atmosphere and the global hydrological cycle. Using eight years (2002–2009) of retrievals from Odin/SMR (Sub-Millimetre Radiometer), the global climatological features of three SWIs, H216O, HDO and H218O, the isotopic composition δD and δ18O in the stratosphere are analysed for the first time. Spatially, SWIs are found to increase with altitude due to stratospheric methane oxidation. In the tropics, highly depleted SWIs in the lower stratosphere indicate the effect of dehydration when the air comes through the cold tropopause, while, at higher latitudes, more enriched SWIs in the upper stratosphere during summer are produced and transported to the other hemisphere via the Brewer–Dobson circulation. Furthermore, we found that more H216O is produced over summer Northern Hemisphere and more HDO is produced over summer Southern Hemisphere. Temporally, a tape recorder in H216O is observed in the lower tropical stratosphere, in addition to a pronounced downward propagating seasonal signal in SWIs from the upper to the lower stratosphere over the polar regions. These observed features in SWIs are further compared to SWI-enabled model outputs. This helped to identify possible causes of model deficiencies in reproducing main stratospheric features. For instance, choosing a better advection scheme and including methane oxidation process in a specific model immediately capture the main features of stratospheric water vapor. The representation of other features, such as the observed inter-hemispheric difference of isotopic component, is also discussed.
Atmospheric Chemistry and Physics | 2018
Charlotta Högberg; Stefan Lossow; Ralf Bauer; Kaley A. Walker; Patrick Eriksson; Donal P. Murtagh; Gabriele P. Stiller; Jörg Steinwagner; Qiong Zhang
1Stockholm University, Department of Physical Geography and the Bolin Centre for Climate Research, Svante Arrhenius väg 8, 10691 Stockholm, Sweden. 2Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research, Hermann-von-HelmholtzPlatz 1, 76344 Leopoldshafen, Germany. 3University of Toronto, Department of Physics, 60 St. George Street, Toronto, Ontario M5S 1A7, Canada. 4Chalmers University of Technology, Department of Earth and Space Sciences, Hörsalsvägen 11, 41296 Göteborg, Sweden. 5Max-Planck-Institute for extraterrestrial Physics, Gießenbachstraße 1, 85748 Garching, Germany.
Atmospheric Chemistry and Physics | 2011
Gabriele P. Stiller; T. von Clarmann; F. Haenel; B. Funke; N. Glatthor; U. Grabowski; S. Kellmann; M. Kiefer; A. Linden; Stefan Lossow; M. López-Puertas
Atmospheric Chemistry and Physics | 2013
E. Eckert; T. von Clarmann; M. Kiefer; G. P. Stiller; Stefan Lossow; N. Glatthor; D. A. Degenstein; L. Froidevaux; Sophie Godin-Beekmann; Thierry Leblanc; S. Mcdermid; Maud Pastel; Wolfgang Steinbrecht; D. P. J. Swart; Kaley A. Walker; Peter F. Bernath