Science.gov

Sample records for stratospheric warmings ssws

  1. The Sudden Stratospheric Warming Atlas

    NASA Astrophysics Data System (ADS)

    Sjoberg, J. P.; Butler, A. H.; Seidel, D. J.

    2015-12-01

    Sudden stratospheric warmings (SSWs) are large and rapid temperature increases in the polar stratosphere associated with a complete reversal of the climatological westerly winds in wintertime. These extreme events can have substantial impacts on wintertime surface climate, such as cold air outbreaks over North America and Eurasia, or anomalous warming over Greenland. Here we promote our progress towards a new atlas of historical SSW events and their impacts on the surface. The SSW atlas contains a variety of metrics, time series, maps, and animations for individual SSW events. The atlas will allow users to examine the structure and development of individual SSWs, the variability between events, the surface impacts in temperature and precipitation, and the impacts of SSWs during years with certain tropospheric signatures, like El Niño or La Niña winters.

  2. Defining Sudden Stratospheric Warmings

    NASA Astrophysics Data System (ADS)

    Butler, Amy; Seidel, Dian; Hardiman, Steven; Butchart, Neal; Birner, Thomas; Match, Aaron

    2015-04-01

    The general form of the definition for Sudden Stratospheric Warmings (SSWs) is largely agreed to be a reversal of the temperature gradient and of the zonal circulation polewards of 60° latitude at the 10 hPa level, as developed by the World Meteorological Organization (WMO) in the 1960s and 1970s. However, the details of the definition and its calculation are ambiguous, resulting in inconsistent classifications of SSW events. These discrepancies are problematic for understanding the observed frequency and statistical relationships with SSWs, and for maintaining a robust metric with which to assess wintertime stratospheric variability in observations and climate models. To provide a basis for community-wide discussion, we examine how the SSW definition has changed over time and how sensitive the detection of SSWs is to the definition used. We argue that the general form of the SSW definition should be clarified to ensure that it serves current research and forecasting purposes, and propose possible ways to update the definition.

  3. Evidence for Dynamical Coupling of Stratosphere-MLT during recent minor Stratospheric Warmings in Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Kim, Yongha; Sunkara, Eswaraiah; Hong, Junseok; Ratnam, Venkat; Chandran, Amal; Rao, Svb; Riggin, Dennis

    2015-04-01

    The mesosphere-lower thermosphere (MLT) response to extremely rare minor sudden stratospheric warming (SSW) events was observed for the first time in the southern hemisphere (SH) during 2010 and is investigated using the meteor radar located at King Sejong Station (62.22°S, 58.78°W), Antarctica. Three episodic SSWs were noticed from early August to late October 2010. The mesospheric wind field was found to significantly differ from normal years due to enhanced planetary wave (PW) activity before the SSWs and secondary PWs in the MLT afterwards. The zonal winds in the mesosphere reversed approximately a week before the SSW occurrence in the stratosphere as has been observed 2002 major SSW, suggesting the downward propagation of disturbance during minor SSWs as well. Signatures of mesospheric cooling (MC) in association with SSWs are found in the Microwave Limb Sounder (MLS) measurements. SD-WACCM simulations are able to produce these observed features.

  4. A New Look at Stratospheric Sudden Warmings. Part II: Evaluation of Numerical Model Simulations

    NASA Technical Reports Server (NTRS)

    Charlton, Andrew J.; Polvani, Lorenza M.; Perlwitz, Judith; Sassi, Fabrizio; Manzini, Elisa; Shibata, Kiyotaka; Pawson, Steven; Nielsen, J. Eric; Rind, David

    2007-01-01

    The simulation of major midwinter stratospheric sudden warmings (SSWs) in six stratosphere-resolving general circulation models (GCMs) is examined. The GCMs are compared to a new climatology of SSWs, based on the dynamical characteristics of the events. First, the number, type, and temporal distribution of SSW events are evaluated. Most of the models show a lower frequency of SSW events than the climatology, which has a mean frequency of 6.0 SSWs per decade. Statistical tests show that three of the six models produce significantly fewer SSWs than the climatology, between 1.0 and 2.6 SSWs per decade. Second, four process-based diagnostics are calculated for all of the SSW events in each model. It is found that SSWs in the GCMs compare favorably with dynamical benchmarks for SSW established in the first part of the study. These results indicate that GCMs are capable of quite accurately simulating the dynamics required to produce SSWs, but with lower frequency than the climatology. Further dynamical diagnostics hint that, in at least one case, this is due to a lack of meridional heat flux in the lower stratosphere. Even though the SSWs simulated by most GCMs are dynamically realistic when compared to the NCEP-NCAR reanalysis, the reasons for the relative paucity of SSWs in GCMs remains an important and open question.

  5. The western Pacific pattern bridging stratospheric sudden warming and ENSO

    NASA Astrophysics Data System (ADS)

    Dai, Ying; Tan, Benkui

    2016-04-01

    Previous studies show that the stratospheric sudden warmings (SSWs) are closely linked to the low height anomalies (LHAs) over the North Pacific and the presence of the LHAs is independent of the phases of the El Nino-Southern Oscillation (ENSO). Based on the wintertime daily reanalysis data from 1958 to 2013, this study demonstrates that most of the LHAs which are linked to SSWs are the footprints left by the western Pacific patterns (WPs), few of them by the Pacific-North American patterns (PNAs), or by mixed WP-PNA patterns. This study also demonstrates that the WPs' LHAs, and therefore the SSWs, are strongly modulated by ENSO and the modulation effects changed over 1958-2013: before 1980, the WPs' LHAs have stronger intensity and longer duration in El Nino winters (EN) than La Nina winters (LN) and ENSO neutral winters (ENSON), and the SSWs occur twice as often during EN, compared to LN and ENSON. After 1980, the WPs' LHAs have stronger intensity in EN and larger frequency during LN than ENSON. Consistently, the SSWs occur nearly twice as often during both EN and LN for this period, compared to ENSON.

  6. Circulation Changes in the Mesosphere and the Lower Thermosphere Associated with Sudden Stratospheric Warmings

    NASA Astrophysics Data System (ADS)

    Hirooka, Toshihiko; Iwao, Koki

    2016-07-01

    Influences of sudden stratospheric warmings (SSWs) reach the mesosphere and the thermosphere. Recently, significant global cooling during SSWs in the thermosphere have been reported on the basis of numerical simulations. However, observational studies are insufficient for the region, so that detailed 3-dimendional structure and the dynamical mechanism are still unclear. Hence, we investigate circulation changes in the mesosphere and thermosphere along with in the stratosphere during SSWs by using TIMED/SABER satellite data and radar data. The SABER observes the atmospheric temperature field in high altitudes up to the lower thermosphere (~120km). Time series of the SABER data includes tidal components, because the satellite orbit is not sun-synchronous and the local time of observation gradually decreases at a specific latitude. The perfect separation of the time series data into tidal and daily changes is difficult especially when diurnal components are amplified. Therefore, we additionally analyze the radar data at some selected stations. Resultantly, north polar temperatures during SSWs show lower thermosphere warming and mesospheric cooling along with the anti-correlated temperature changes in the wide region except over the north pole. In the presentation, we discuss further detailed features of circulation changes associated with SSWs.

  7. Composite analysis of a major sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Hocke, K.; Lainer, M.; Schanz, A.

    2015-06-01

    We present the characteristics of a major sudden stratospheric warming (SSW) by using the composite analysis method and ERA Interim reanalysis data from 1979 to 2014. The anomalies of the parameters total ozone column density (TOC), temperature (T), potential vorticity (PV), eastward wind (u), northward wind (v), vertical wind (w), and geopotential height (z) are derived with respect to the ERA Interim climatology (mean seasonal behaviour 1979 to 2014). The composites are calculated by using the time series of the anomalies and the central dates of 20 major SSWs. Increases of up to 90 Dobson units are found for polar TOC after the SSW. Polar TOC remains enhanced until the summer after the major SSW. Precursors of the SSW are a negative TOC anomaly 3 months before the SSW and enhanced temperature at 10 hPa at mid-latitudes about 1 month before the SSW. Eastward wind at 1 hPa is decreased at mid-latitudes about 1 month before the SSW. The 1 hPa geopotential height level is increased by about 500 m during the month before the SSW. These features are significant at the 2σ level for the mean behaviour of the ensemble of the major SSWs. However, knowledge of these precursors may not lead to a reliable prediction of an individual SSW since the variability of the individual SSWs and the polar winter stratosphere is large.

  8. Satellite observations of gravity wave activity and dissipation during sudden stratospheric warmings

    NASA Astrophysics Data System (ADS)

    Ern, Manfred; Preusse, Peter; Riese, Martin

    2015-04-01

    Sudden stratospheric warmings (SSWs) are a circulation anomaly that occurs mainly at high northern latitudes in boreal winter. During major SSWs the eastward directed polar jet reverses, and, for a certain period, the stratosphere is governed by anomalous westward winds. It is known that both planetary waves and gravity waves contribute to the formation and evolution of SSWs. However, the small horizontal scales of gravity waves (tens to a few thousand km) challenge both observations and modeling of gravity waves. Therefore, the role of gravity waves during SSWs is still not fully understood. In particular, gravity waves should play an important role during the recovery of the stratopause and of the eastward directed polar jet after major SSWs. This is indicated by several modeling efforts. However, validation by global observations of gravity waves is still an open issue. Gravity wave momentum fluxes and potential gravity wave drag were derived from HIRDLS and SABER satellite observations, and the role of gravity waves during recent SSWs in the boreal winters 2001/2002-2013/2014 is investigated. We find that gravity waves with slow horizontal phase speeds, likely mountain waves, play an important role during SSWs. Both gravity wave momentum fluxes and gravity wave drag are enhanced before the central date of major SSWs. After the central date, gravity wave momentum fluxes and gravity wave drag in the stratosphere are strongly reduced. Still, gravity wave drag contributes to the wind reversals related to the anomalous westward winds. Another finding is that, after major SSWs, the contribution of gravity wave drag at the bottom of re-established eastward directed polar jets is small. At the top of those jets, however, strong gravity wave drag is found, which indicates that gravity waves contribute to the downward propagation of newly formed polar jets and of elevated stratopauses to their "climatological" altitude. This confirms recent modeling work by, for example

  9. The surface impact of stratospheric sudden warmings in a 1000 year control simulation: sensitivity to event definition and type

    NASA Astrophysics Data System (ADS)

    Maycock, Amanda

    2014-05-01

    Major sudden stratospheric warmings (SSWs) are characterised by large departures of the northern hemisphere winter-time circulation from climatology. Numerous studies have shown that on average these events impact on tropospheric weather patterns leading to a more negative North Atlantic Oscillation index; however, recent studies have suggested that the nature of this downward coupling may be sensitive to the type of SSW (vortex split or displacement). This study explores this issue using a 1000 year pre-industrial control simulation from the IPSL-CM5A-LR model taken from the CMIP5 archive. We identify SSW events using two distinct methods: the widely applied algorithm of Charlton and Polvani (2007) and a 2-D moments-based approach described by Seviour et al (2013). The long simulation offers a unique opportunity to analyse a very large sample of SSW events (~500). We evaluate the relative timing and frequency of SSWs identified by the two methods and examine their impact on the tropospheric state. In contrast to other recent studies, we do not find a significant difference between the impact of split and displacement SSWs on the troposphere in this model. We analyse the evolution of the SSWs that are not consistently identified by the two algorithms, and examine whether they have a significant role in determining the overall impact of SSWs on the troposphere. The large number of warming events enables a comprehensive assessment of the noise that may be associated with analysing stratosphere-troposphere coupling in smaller sample sizes.

  10. Stratospheric predictability and sudden stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Stan, Cristiana; Straus, David M.

    2009-06-01

    A comparative study of the limit of predictability in the stratosphere and troposphere in a coupled general circulation model is carried out using the National Center for Environmental Prediction (NCEP) Climate Forecast System Interactive Ensemble (CFSIE). In "identical twin experiments", we compare the forecast errors of zonal wind and potential temperature in the troposphere and stratosphere for various wave groups. The results show smaller intrinsic error growth in the lower stratosphere compared with troposphere. The limit of predictability of sudden stratospheric warming events, measured by the errors in the divergence of the Eliassen-Palm flux, is dominated by the amplification of small errors in the individual fields due to differences between the phase of the waves.

  11. Ionospheric reaction on sudden stratospheric warming events in Russiás Asia region

    NASA Astrophysics Data System (ADS)

    Polyakova, Anna; Perevalova, Natalya; Chernigovskaya, Marina

    2015-12-01

    The response of the ionosphere to sudden stratospheric warmings (SSWs) in the Asian region of Russia is studied. Two SSW events observed in 2008-2009 and 2012-2013 winter periods of extreme solar minimum and moderate solar maximum are considered. To detect the ionospheric effects caused by SSWs, we carried out a joint analysis of global ionospheric maps (GIM) of the total electron content (TEC), MLS (Microwave Limb Sounder, EOS Aura) measurements of temperature vertical profiles, as well as NCEP/NCAR and UKMO Reanalysis data. For the first time, it was found that during strong SSWs, in the mid-latitude ionosphere the amplitude of diurnal TEC variation decreases nearly half compared to quiet days. At the same time, the intensity of TEC deviations from the background level increases. It was also found that at SSW peak the midday TEC maximum decreases, and night/morning TEC values increase compared to quiet days. It was shown that during SSWs, TEC dynamics was identical for different geophysical conditions.The response of the ionosphere to sudden stratospheric warmings (SSWs) in the Asian region of Russia is studied. Two SSW events observed in 2008-2009 and 2012-2013 winter periods of extreme solar minimum and moderate solar maximum are considered. To detect the ionospheric effects caused by SSWs, we carried out a joint analysis of global ionospheric maps (GIM) of the total electron content (TEC), MLS (Microwave Limb Sounder, EOS Aura) measurements of temperature vertical profiles, as well as NCEP/NCAR and UKMO Reanalysis data. For the first time, it was found that during strong SSWs, in the mid-latitude ionosphere the amplitude of diurnal TEC variation decreases nearly half compared to quiet days. At the same time, the intensity of TEC deviations from the background level increases. It was also found that at SSW peak the midday TEC maximum decreases, and night/morning TEC values increase compared to quiet days. It was shown that during SSWs, TEC dynamics was

  12. Sudden stratospheric warmings and tropospheric blockings in a multi-century simulation of the IPSL-CM5A coupled climate model

    NASA Astrophysics Data System (ADS)

    Vial, Jessica; Osborn, Tim J.; Lott, François

    2013-05-01

    The relation between sudden stratospheric warmings (SSWs) and blocking events is analyzed in a multi-centennial pre-industrial simulation of the Institut Pierre Simon Laplace coupled model (IPSL-CM5A), prepared for the fifth phase of the coupled model intercomparison project. The IPSL model captures a fairly realistic distribution of both SSWs and tropospheric blocking events, albeit with a tendency to overestimate the frequency of blocking in the western Pacific and underestimate it in the Euro-Atlantic sector. The 1000-year long simulation reveals statistically significant differences in blocking frequency and duration over the 40-day periods preceding and following the onset of SSWs. More specifically, there is an enhanced blocking frequency over Eurasia before SSWs, followed by an westward displacement of blocking anomalies over the Atlantic region as SSWs evolve and then decline. The frequency of blocking is reduced over the western Pacific sector during the life-cycle of SSWs, while the model simulates no significant relationship with eastern Pacific blocks. Finally, these changes in blocking frequency tend to be associated with a shift in the distribution of blocking lifetime toward longer-lasting blocking events before the onset of SSWs and shorter-lived blocks after the warmings. This study systematically verifies that the results are consistent with the two pictures that (1) blockings produce planetary scale anomalies that can force vertically propagating Rossby waves and then SSWs when the waves break and (2) SSWs affect blockings in return, for instance via the effect they have on the North Atlantic Oscillation.

  13. Temperature Deviations in the Midlatitude Mesosphere During Stratospheric Warmings as Measured with Rayleigh-Scatter Lidar

    NASA Astrophysics Data System (ADS)

    Sox, Leda; Wickwar, Vincent; Fish, Chad; Herron, Joshua P.

    2016-06-01

    While mesospheric temperature anomalies associated with Sudden Stratospheric Warmings (SSWs) have been observed extensively in the polar regions, observations of these anomalies at midlatitudes are sparse. The original Rayleigh-scatter lidar that operated at the Atmospheric Lidar Observatory (ALO; 41.7°N, 111.8°W) in the Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU) collected an extensive set of temperature data for 11 years in the 45-90 km altitude range. This work focuses on the extensive Rayleigh lidar observations made during six major SSW events that occurred between 1993 and 2004, providing a climatological study of the midlatitude mesospheric temperatures during these SSW events. An overall disturbance pattern was observed in the mesospheric temperatures during these SSWs. It included coolings in the upper mesosphere, comparable to those seen in the polar regions during SSW events, and warmings in the lower mesosphere.

  14. Analysis of data from spacecraft (stratospheric warmings)

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The details of the stratospheric warming processes as to time, area, and intensity were established, and the warmings with other terrestrial and solar phenomena occurring at satellite platform altitudes, or observable from satellite platforms, were correlated. Links were sought between the perturbed upper atmosphere (mesosphere and thermosphere) and the stratosphere that might explain stratospheric warmings.

  15. TEC disturbances during major Sudden Stratospheric Warmings in the mid-latitude ionosphere.

    NASA Astrophysics Data System (ADS)

    Polyakova, Anna; Voeykov, Sergey; Chernigovskaya, Marina; Perevalova, Natalia

    Using total electron content (TEC) global ionospheric maps, dual-frequency GPS receivers TEC data and MLS (Microwave Limb Sounder, EOS Aura) atmospheric temperature data the ionospheric disturbances during the strong sudden stratospheric warmings (SSWs) of 2008/2009 and 2012/2013 winters are investigated in Russia's Asia region. It is established that during the SSW maximum the midday TEC decrease and the night/morning TEC increase compared to quiet days are observed in the mid-latitude ionosphere. As a result it caused the decrease of the diurnal TEC variations amplitude of about two times in comparison with the undisturbed level. The analysis of TEC deviations from the background level during the SSWs has shown that deviations dynamics vary depending on the observation point position. Negative deviations of TEC are registered in the ionosphere above the region of maximum stratosphere heating (the region of the stratospheric circulation change) as well as above the anticyclone. On the contrary, TEC values increase compared to the quiet day's values above the stratosphere cyclone. It is shown that during maximum phase of a warming, and within several days after it the amplification of wave TEC variations intensity with periods of up to 60 min is registered in ionosphere. The indicated effects may be attributed to the vertical transfer of molecular gas from a stratospheric heating region to the thermosphere as well as to the increase in activity of planetary and gravity waves which is usually observed during strong SSWs. The study is supported by the RF President Grant of Public Support for RF Leading Scientific Schools (NSh-2942.2014.5), the RF President Grant No. MK-3771.2012.5 and RFBR Grant No. 12-05-00865_а.

  16. Absorbing and reflecting sudden stratospheric warming events and their relationship with tropospheric circulation

    NASA Astrophysics Data System (ADS)

    Kodera, Kunihiko; Mukougawa, Hitoshi; Maury, Pauline; Ueda, Manabu; Claud, Chantal

    2016-01-01

    Sudden stratospheric warming (SSW) events have received increased attention since their impacts on the troposphere became evident recently. Studies of SSW usually focus on polar stratospheric conditions; however, understanding the global impact of these events requires studying them from a wider perspective. Case studies are used to clarify the characteristics of the stratosphere-troposphere dynamical coupling, and the meridional extent of the phenomena associated with SSW. Results show that differences in the recovery phase can be used to classify SSW events into two types. The first is the absorbing type of SSW, which has a longer timescale as well as a larger meridional extent due to the persistent incoming planetary waves from the troposphere. The absorbing type of SSW is related to the annular mode on the surface through poleward and downward migration of the deceleration region of the polar night jet. The other is the reflecting type. This is characterized by a quick termination of the warming episode due to the reflection of planetary waves in the stratosphere, which leads to an amplification of tropospheric planetary waves inducing strong westerlies over the North Atlantic and blocking over the North Pacific sector. Differences in the tropospheric impact of the absorbing and reflecting SSWs are also confirmed with composite analysis of 22 major SSWs.

  17. Stratospheric sudden warming and lunar tide

    NASA Astrophysics Data System (ADS)

    Yamazaki, Yosuke; Kosch, Michael

    2016-07-01

    A stratospheric sudden warming is a large-scale disturbance in the middle atmosphere. Recent studies have shown that the effect of stratospheric sudden warnings extends well into the upper atmosphere. A stratospheric sudden warming is often accompanied by an amplification of lunar tides in the ionosphere/theremosphere. However, there are occasionally winters when a stratospheric sudden warming occurs without an enhancement of the lunar tide in the upper atmosphere, and other winters when large lunar tides are observed without a strong stratospheric sudden warming. We examine the winters when the correlation breaks down and discuss possible causes.

  18. Gravity waves in the thermosphere during a sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Yigit, E.; Medvedev, A. S.

    2012-12-01

    For the first time, the propagation and dissipation of internal gravity waves (GWs) of lower atmospheric origin to the thermosphere above the turbopause (~105 km) during a sudden stratospheric warming (SSW) are examined. The study is performed with a general circulation model (GCM) coupling the lower atmosphere with the thermosphere and the implemented spectral nonlinear extended GW parameterization of Yigit et al. (2008). The Yigit et al. (2008) extended GW parameterization calculates the propagation and dissipation of small-scale GWs in the whole atmosphere system by physically taking into account ion drag, molecular viscosity and thermal conduction, eddy viscosity, nonlinear diffusion, and radiative damping in form of Newtonian cooling. Model simulations reveal a strong modulation by SSWs of GW activity, momentum deposition rates, and the circulation feedbacks at heights up to F region altitudes (~270 km). Wave-induced root mean square wind fluctuations increase several times during the warming in the thermosphere above the turbopause. This occurs mainly due to a reduction of filtering eastward traveling GWs by the weaker stratospheric jet. These waves propagate higher under the favorable conditions, grow in amplitude, and produce stronger forcing on the mean flow, compared to pre-warming period, when they are dissipated in the thermosphere. The evolution of stratospheric and mesospheric winds during an SSW life-cycle creates a robust and distinctive response in GW activity and mean fields deeply in the thermosphere. Yigit, E., A.~D. Aylward, and A.~S. Medvedev (2008), Parameterization of the effects of vertically propagating gravity waves for thermosphere general circulation models: Sensitivity study, J. Geophys. Res., 113, D19106, doi:10.1029/2008JD010135.

  19. Tropospheric predictability around stratospheric warming events examined with an idealized forecast ensemble

    NASA Astrophysics Data System (ADS)

    Hörnqvist, E.; Körnich, H.

    2012-04-01

    By representing sudden stratospheric warming events (SSWs) in numerical weather prediction models, the predictability length could possibly be improved. It has been suggested that this improvement depends on the initial day of the forecast relative to the central date of the SSW. In this project this hypothesis is tested in the framework of an idealized general circulation model. Furthermore, it will be examined how uncertainties of the initial conditions and model errors in the forecast model affect the predictability around stratospheric warming events. Identical-twin forecast experiments are performed with the Kühlungsborn Mechanistic general Circulation Model KMCM that extends to the stratopause. In a 20-year truth run with perpetual January conditions, 21 SSWs are identified. Ensemble forecasts using random field perturbations in the initial conditions are conducted with initial dates from 20 days before to 20 days after each SSW central date. In four different experiments, we examine how the tropospheric predictability depends on perturbations in troposphere, stratosphere or both, and on model errors in the stratospheric radiative equilibrium temperature. The results show that a forecast initialised before the SSW central date has a greater forecast skill than after. On average useful forecast for the zonal mean zonal wind at 60N and 850 hPa are extended by 10 days, when initialized up to 12 days before the SSW. This extension is robust for the different perturbation experiments and also when a model error was introduced. Thus, the experiments confirm that the largest improvement of predictability is achieved, when the forecast is initialised before the sudden stratospheric warming event.

  20. Satellite observations of middle atmosphere gravity wave absolute momentum flux and of its vertical gradient during recent stratospheric warmings

    NASA Astrophysics Data System (ADS)

    Ern, Manfred; Trinh, Quang Thai; Kaufmann, Martin; Krisch, Isabell; Preusse, Peter; Ungermann, Jörn; Zhu, Yajun; Gille, John C.; Mlynczak, Martin G.; Russell, James M., III; Schwartz, Michael J.; Riese, Martin

    2016-08-01

    Sudden stratospheric warmings (SSWs) are circulation anomalies in the polar region during winter. They mostly occur in the Northern Hemisphere and affect also surface weather and climate. Both planetary waves and gravity waves contribute to the onset and evolution of SSWs. While the role of planetary waves for SSW evolution has been recognized, the effect of gravity waves is still not fully understood, and has not been comprehensively analyzed based on global observations. In particular, information on the gravity wave driving of the background winds during SSWs is still missing.We investigate the boreal winters from 2001/2002 until 2013/2014. Absolute gravity wave momentum fluxes and gravity wave dissipation (potential drag) are estimated from temperature observations of the satellite instruments HIRDLS and SABER. In agreement with previous work, we find that sometimes gravity wave activity is enhanced before or around the central date of major SSWs, particularly during vortex-split events. Often, SSWs are associated with polar-night jet oscillation (PJO) events. For these events, we find that gravity wave activity is strongly suppressed when the wind has reversed from eastward to westward (usually after the central date of a major SSW). In addition, gravity wave potential drag at the bottom of the newly forming eastward-directed jet is remarkably weak, while considerable potential drag at the top of the jet likely contributes to the downward propagation of both the jet and the new elevated stratopause. During PJO events, we also find some indication for poleward propagation of gravity waves. Another striking finding is that obviously localized gravity wave sources, likely mountain waves and jet-generated gravity waves, play an important role during the evolution of SSWs and potentially contribute to the triggering of SSWs by preconditioning the shape of the polar vortex. The distribution of these hot spots is highly variable and strongly depends on the zonal and

  1. Sudden stratospheric warmings as catastrophes

    NASA Technical Reports Server (NTRS)

    Chao, W. C.

    1985-01-01

    The sudden stratospheric warming (SSW) process is qualitatively studied using a conceptual and numerical approach guided by catastrophe theory. A simple example of a catastrophe taken from nonlinear dynamics is given, and results from previous modelling studies of SSW are interpreted in light of catastrophe theory. Properties of this theory such as hysteresis, cusp, and triggering essential to SSW are numerically demonstrated using the truncated quasi-geostrophic beta-plane model of Holton and Mass (1976). A qualitative explanation of the transition from the steady regime to the vacillation regime is given for the Holton and Mass model in terms of the topographically induced barotropic Rossby wave instability. Some implications for the simulation and prediction of SSW are discussed.

  2. Gravity wave activity during stratospheric sudden warmings in the 2007-2008 Northern Hemisphere winter

    NASA Astrophysics Data System (ADS)

    Wang, Ling; Alexander, M. Joan

    2009-09-01

    We use temperature retrievals from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC)/Formosa Satellite Mission 3 (FORMOSAT-3) and Challenging Minisatellite Payload (CHAMP) Global Positioning Satellite (GPS) radio occultation profiles and independent temperature retrievals from the EOS satellite High Resolution Dynamics Limb Sounder (HIRDLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) aboard the TIMED satellite to investigate stratospheric sudden warming (SSW) events and the accompanying gravity wave (GW) temperature amplitudes in the 2007-2008 Northern Hemisphere winter. We identify four SSW events (including a major one) occurring from late January to late February in 2008. We detect enhanced GW amplitudes in the stratosphere and subdued GW amplitudes in the lower mesosphere during the warming events. The timing of GW enhancement/suppression and warming/cooling events was generally close (within a couple days). We also find that stratospheric GW amplitudes were generally larger at the polar vortex edge and smaller in the vortex core and outside of the vortex and that stratospheric GW amplitudes were generally small over the North Pacific. Using a simplified GW dispersion relation and a GW ray-tracing experiment, we demonstrate that the enhanced GW amplitudes in the stratosphere during SSWs could be explained largely by GW propagation considerations. The existence of GW critical levels (the level at which the background wind is the same as the GW phase speed) near the stratopause during SSWs would block propagation of GWs into the mesosphere and thus could lead to the observed subdued GW activity in the lower mesosphere. Since this is the first study to analyze the COSMIC and CHAMP GPS temperature retrievals up to 60 km in altitude, we compare the GPS analysis with those from HIRDLS and SABER measurements. We find that the temporal variability of zonal mean temperatures derived from the GPS data is

  3. Sudden Stratospheric Warming of 2012-2013, its predictability, and its impact on the Northern Hemispheric winter

    NASA Astrophysics Data System (ADS)

    Tripathi, O. P.; Charlton-Perez, A. J.; Baldwin, M. P.; Charron, M.; Sigmond, M.; Eckermann, S. D.; Gerber, E. P.; Kuroda, Y.; Mizuta, R.; Jackson, D.; Lang, A.; Roff, G.; Son, S.; Kim, B.

    2013-12-01

    The stratospheric winter is characterized by strong circumpolar westerly winds and the region of colder polar cap temperatures called the polar vortex. During every other winter or so this polar winter circulation undergoes a Stratospheric Sudden Warming (SSW), a rapid deceleration resulting in easterly winds on the time scale of a few days a large increase in polar cap temperature. The predictability of these extreme stratospheric events are crucial for their impact on the tropospheric forecast on a timescale of one to two weeks. The Stratospheric Network on Assessment of Predictability (SNAP), a network of major operational forecasting centers, aims to understand the stratosphere-troposphere link and quantify how far in advance SSWs can be predicted and add skill to tropospheric forecasts. During the 2012-2013 winter, anomalous upward propagating planetary wave activity was observed during the second and third weak of December. Around 22nd of December there was a large eddy heat flux anomaly at 10 hPa. This was followed by a rapid deceleration of westerly circulation in the stratosphere starting around January 2, and within 3-4 days the circulation reversed on January 7, 2013. Within a couple of days the polar vortex split in two with a large increase in polar cap temperature. This stratospheric dynamical activity was followed by an equatorward shift of the tropospheric jet stream and a high pressure anomaly over North Atlantic, resulting in severe cold conditions in the UK and Northern Europe. Our current skill in predicting SSWs and therefore its consequential impact on tropospheric weather forecast is very limited due to the gap in proper understanding of stratosphere-troposphere coupling. SNAP has organized predictability experiments in different phases conducted by the operational centers. In this presentation we will show first results from SNAP for the Sudden Stratospheric Warming of January 2013. We will show how far in advance different models were able

  4. Observations of planetary waves in the mesosphere-lower thermosphere during stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Stray, N. H.; Orsolini, Y. J.; Espy, P. J.; Limpasuvan, V.; Hibbins, R. E.

    2015-05-01

    This study investigates the effect of stratospheric sudden warmings (SSWs) on planetary wave (PW) activity in the mesosphere-lower thermosphere (MLT). PW activity near 95 km is derived from meteor wind data using a chain of eight SuperDARN radars at high northern latitudes that span longitudes from 150° W to 25° E and latitudes from 51 to 66° N. Zonal wave number 1 and 2 components were extracted from the meridional wind for the years 2000-2008. The observed wintertime PW activity shows common features associated with the stratospheric wind reversals and the accompanying stratospheric warming events. Onset dates for seven SSW events accompanied by an elevated stratopause (ES) were identified during this time period using the Specified Dynamics Whole Atmosphere Community Climate Model (SD-WACCM). For the seven events, a significant enhancement in wave number 1 and 2 PW amplitudes near 95 km was found to occur after the wind reversed at 50 km, with amplitudes maximizing approximately 5 days after the onset of the wind reversal. This PW enhancement in the MLT after the event was confirmed using SD-WACCM. When all cases of polar cap wind reversals at 50 km were considered, a significant, albeit moderate, correlation of 0.4 was found between PW amplitudes near 95 km and westward polar-cap stratospheric winds at 50 km, with the maximum correlation occurring ∼ 3 days after the maximum westward wind. These results indicate that the enhancement of PW amplitudes near 95 km is a common feature of SSWs irrespective of the strength of the wind reversal.

  5. Investigating troposhpere-stratosphere coupling during the southern hemisphere sudden stratospheric warming using an adjoint model.

    NASA Astrophysics Data System (ADS)

    Holdaway, D.; Coy, L.

    2015-12-01

    In September 2002 a major sudden stratospheric warming (SSW) occurred in the southern hemisphere. Although numerous SSWs have been observed in the northern hemisphere, this remains the only recorded major SSW in the southern hemisphere. Much debate has focused on this unique event and the causes, even resulting in a special issue of the Journal of Atmospheric Science. In this work we use the adjoint of NASA's Goddard Earth Observing System version 5 (GEOS-5) to investigate sensitivity to initial conditions during the onset of the 2002 SSW. The adjoint model provides a framework for propagating gradients with respect to the model state backwards in time. As such it is used to reveal aspects of the model initial conditions that have the biggest impact on the temperature in the stratosphere during the warming. The adjoint model reveals a large sensitivity over the southern Atlantic ocean and in the troposphere. This reinforces previous studies that attributed the SSW to a blocking ridge in this region. By converting sensitivity to perturbations it is shown that relatively small localized tropospheric perturbations to winds and temperature can be transported to the stratosphere and have a large impact on the SSW.

  6. Mixing processes following the final stratospheric warming

    NASA Technical Reports Server (NTRS)

    Hess, Peter G.

    1991-01-01

    An investigation is made of the dynamics responsible for the mixing and dissolution of the polar vortex during the final stratospheric warmings. The dynamics and transport during a Northern Hemisphere final stratospheric warming are simulated via a GCM and an associated offline N2O transport model. The results are compared with those obtained from LIMS data for the final warming of 1979, with emphasis on the potential vorticity evolution in the two datasets, the modeled N2O evolution, and the observed O3 evolution. Following each warming, the remnants of the originally intact vortex are found to gradually homogenize with the atmosphere at large. Two processes leading to this homogenization are identified following the final warmings, namely, the potential vorticity field becomes decorrelated from that of the chemical tracer, and the vortex remnants begin to tilt dramatically in a vertical direction.

  7. Analysis of data from spacecraft (stratospheric warmings)

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Investigations involved a search through existing literature and data to obtain case histories for the six or more stratospheric warmings that occurred in April - May 1969, June - July 1969, August 1969, December 1969 - January 1970, December 1970 - January 1971, and January 1973 - February 1973. For each of these warmings the following steps have been taken in preparation for analysis: (1) defining the nature of the problem; (2) literature search of stratwarmings and solar-terrestrial phenomens; and (3) file of data sources, especially stratospheric temperatures (radiances) and geophysical indices.

  8. Simulated sudden stratospheric warming - Synoptic evolution

    NASA Technical Reports Server (NTRS)

    Blackshear, W. T.; Grose, W. L.; Turner, R. E.

    1987-01-01

    An analysis is presented of a sudden stratospheric warming event which occurred spontaneously during a general circulation model simulation of the global atmospheric circulation. Two separate warming pulses exhibit the same dynamical evolution with a 'cycle' of about two weeks. Two distinct phases of the warming cycle are apparent: (1) the generation of an intense localized warm cell in conjunction with significant adiabatic heating associated with cross-isobar flow which has been induced by vertically propagating long wave disturbances; and (2) the northward transport of that warm cell via advection by the essentially geostrophic windfield corresponding to an intense, offset polar cyclone, in conjunction with a strong Aleutian anticyclone. During the first warming pulse in January, a moderate Aleutian anticyclone was in place prior to the warming cycle and was intensified by interaction with an eastward traveling anticyclone induced by the differential advection of the warm cell. The second warming pulse occurred in early February with a strong Aleutian anticyclone already established. In contrast to the January event, the warming in February culminated with reversal of the zonal westerlies to easterlies over a significant depth of the stratosphere.

  9. Coupling in the middle atmosphere related to the 2013 major sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    de Wit, R. J.; Hibbins, R. E.; Espy, P. J.; Hennum, E. A.

    2015-03-01

    The previously reported observation of anomalous eastward gravity wave forcing at mesopause heights around the onset of the January 2013 major sudden stratospheric warming (SSW) over Trondheim, Norway (63° N, 10° E), is placed in a global perspective using Microwave Limb Sounder (MLS) temperature observations from the Aura satellite. It is shown that this anomalous forcing results in a clear cooling over Trondheim about 10 km below mesopause heights. Conversely, near the mesopause itself, where the gravity wave forcing was measured, observations with meteor radar, OH airglow and MLS show no distinct cooling. Polar cap zonal mean temperatures show a similar vertical profile. Longitudinal variability in the high northern-latitude mesosphere and lower thermosphere (MLT) is characterized by a quasi-stationary wave-1 structure, which reverses phase at altitudes below ~ 0.1 hPa. This wave-1 develops prior to the SSW onset, and starts to propagate westward at the SSW onset. The latitudinal pole-to-pole temperature structure associated with the major SSW shows a warming (cooling) in the winter stratosphere (mesosphere) which extends to about 40° N. In the stratosphere, a cooling extending over the equator and far into the summer hemisphere is observed, whereas in the mesosphere an equatorial warming is noted. In the Southern Hemisphere mesosphere, a warm anomaly overlaying a cold anomaly is present, which is shown to propagate downward in time. This observed structure is in accordance with the temperature perturbations predicted by the proposed interhemispheric coupling mechanism for cases of increased winter stratospheric planetary wave activity, of which major SSWs are an extreme case. These results provide observational evidence for the interhemispheric coupling mechanism, and for the wave-mean flow interaction believed to be responsible for the establishment of the anomalies in the summer hemisphere.

  10. The 2010 Antarctic ozone hole: Observed reduction in ozone destruction by minor sudden stratospheric warmings

    PubMed Central

    de Laat, A. T. J.; van Weele, M.

    2011-01-01

    Satellite observations show that the 2010 Antarctic ozone hole is characterized by anomalously small amounts of photochemical ozone destruction (40-60% less than the 2005-2009 average). Observations from the MLS instrument show that this is mainly related to reduced photochemical ozone destruction between 20-25 km altitude. Lower down between 15-20 km the atmospheric chemical composition and photochemical ozone destruction is unaffected. The modified chemical composition and chemistry between 20-25 km altitude in 2010 is related to the occurrence of a mid-winter minor Antarctic Sudden Stratospheric Warming (SSW). The measurements indicate that the changes in chemical composition are related to downward motion of air masses rather than horizontal mixing, and affect stratospheric chemistry for several months. Since 1979, years with similar anomalously small amounts of ozone destruction are all characterized by either minor or major SSWs, illustrating that their presence has been a necessary pre-condition for reduced Antarctic stratospheric ozone destruction. PMID:22355557

  11. The 2010 Antarctic ozone hole: observed reduction in ozone destruction by minor sudden stratospheric warmings.

    PubMed

    de Laat, A T J; van Weele, M

    2011-01-01

    Satellite observations show that the 2010 Antarctic ozone hole is characterized by anomalously small amounts of photochemical ozone destruction (40-60% less than the 2005-2009 average). Observations from the MLS instrument show that this is mainly related to reduced photochemical ozone destruction between 20-25 km altitude. Lower down between 15-20 km the atmospheric chemical composition and photochemical ozone destruction is unaffected. The modified chemical composition and chemistry between 20-25 km altitude in 2010 is related to the occurrence of a mid-winter minor Antarctic Sudden Stratospheric Warming (SSW). The measurements indicate that the changes in chemical composition are related to downward motion of air masses rather than horizontal mixing, and affect stratospheric chemistry for several months. Since 1979, years with similar anomalously small amounts of ozone destruction are all characterized by either minor or major SSWs, illustrating that their presence has been a necessary pre-condition for reduced Antarctic stratospheric ozone destruction. PMID:22355557

  12. Connection between the midlatitude mesosphere and sudden stratospheric warmings as measured by Rayleigh-scatter lidar

    NASA Astrophysics Data System (ADS)

    Sox, Leda; Wickwar, Vincent B.; Fish, Chad S.; Herron, Joshua P.

    2016-05-01

    While the mesospheric temperature anomalies associated with Sudden Stratospheric Warmings (SSWs) have been observed extensively in the polar regions, observations of these anomalies at midlatitudes are much more sparse. The Rayleigh-scatter lidar system, which operated at the Center for Atmospheric and Space Sciences on the campus of Utah State University (41.7°N, 111.8°W), collected a very dense set of observations, from 1993 to 2004, over a 45-90 km altitude range. This paper focuses on Rayleigh lidar temperatures derived during the six major SSW events that occurred during the 11 year period when the lidar was operating and aims to characterize the local response to these midlatitude SSW events. In order to determine the characteristics of these mesospheric temperature anomalies, comparisons were made between the temperatures from individual nights during a SSW event and a climatological temperature profile. An overall disturbance pattern was observed in the mesospheric temperatures associated with SSW events, including coolings in the upper mesosphere and warmings in the upper stratosphere and lower mesosphere, both comparable to those seen at polar latitudes.

  13. Observations of Enhanced Semi Diurnal Lunar Tides in the Mesosphere and Lower Thermosphere at Mid and High Northern Latitudes during Sudden Stratospheric Warming Events

    NASA Astrophysics Data System (ADS)

    Chau, J. L.; Hoffmann, P.; Pedatella, N. M.; Matthias, V.

    2014-12-01

    In recent years, there have been a series of reported ground- and satellite-based observations of lunar tide signatures in the equatorial and low latitude ionosphere around sudden stratospheric warming (SSW) events. More recently, Pedatella et al. [2014], using the Whole Atmosphere Community Climate Model Extended version (WACCM-X) and the thermosphere-ionosphere-mesosphere electrodynamics general circulation model (TIME-GCM) has demonstrated that the semi-diurnal lunar tide (M2) is an important contributor to the ionosphere variability during the 2009 SSW. Although the model results were focused on the low-latitude ionosphere and compare with Jicamarca electric fields, Pedatella et al. [2014] also reported that the M2 was enhanced in the northern mid and high latitudes (between 30 and 70oN) at mesospheric and lower thermospheric altitudes during the 2009 SSW. Motivated by this finding, we have analyzed winds from 80 to 100 kms obtained with meteor radars from Juliusruh (54oN) and Andøya (69oN) stations during five SSWs (2008, 2009, 2010, 2012, and 2013). By fitting the usual solar components (diurnal and semidiurnal and M2, we have been able to identify clearly the enhancement of the M2 as well as the semi diurnal solar tide during all these SSWs. The qualitative agreement with the Pedatella et al. [2014] simulations is very good, i.e., stronger signature at 54oN than at 69oN and enhanced around SSW. The analysis of other SSWs not only show the clear relationship with SSWs, but also the different behaviors in strength, time of occurrence, duration, etc., that appear to be associated to the mean wind dynamics as well as the stratospheric planetary wave characteristics.

  14. Stratospheric warmings during February and March 1993

    NASA Technical Reports Server (NTRS)

    Manney, G. L.; Zurek, R. W.; O'Neill, A.; Swinbank, R.; Kumer, J. B.; Mergenthaler, J. L.; Roche, A. E.

    1994-01-01

    Two stratospheric warmings during February and March 1993 are described using United Kingdom Meteorological Office (UKMO) analyses, calculated potential vorticity (PV) and diabetic heating, and N2O observed by the Cryogenic Limb Array Etalon Spectrometer (CLAES) instrument on the Upper Atmosphere Research Satellite (UARS). The first warming affected temperatures over a larger region, while the second produced a larger region of reversed zonal winds. Tilted baroclinic zones formed in the temperature field, and the polar vortex tilted westward with height. Narrow tongues of high PV and low N2O were drawn off the polar vortex, and irreversibly mixed. Tongues of material were drawn from low latitudes into the region between the polar vortex and the anticyclone; diabatic descent was also strongest in this region. Increased N2O over a broad region near the edge of the polar vortex indicates the importance of horizontal transport. N2O decreased in the vortex, consistent with enhanced diabatic descent during the warmings.

  15. Impact of the semidiurnal lunar tide on the midlatitude thermospheric wind and ionosphere during sudden stratosphere warmings

    NASA Astrophysics Data System (ADS)

    Pedatella, N. M.; Maute, A.

    2015-12-01

    Variability of the midlatitude ionosphere and thermosphere during the 2009 and 2013 sudden stratosphere warmings (SSWs) is investigated in the present study using a combination of Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) observations and thermosphere-ionosphere-mesosphere electrodynamics general circulation model (TIME-GCM) simulations. Both the COSMIC observations and TIME-GCM simulations reveal perturbations in the F region peak height (hmF2) at Southern Hemisphere midlatitudes during SSW time periods. The perturbations are ˜20-30 km, which corresponds to 10-20% variability of the background mean hmF2. The TIME-GCM simulations and COSMIC observations of the hmF2 variability are in overall good agreement, and the simulations can thus be used to understand the physical processes responsible for the hmF2 variability. Through comparison of simulations with and without the migrating semidiurnal lunar tide (M2), we conclude that the midlatitude hmF2 variability is primarily driven by the propagation of the M2 into the thermosphere where it modulates the field-aligned neutral winds, which in turn raise and lower the F region peak height. Though there are subtle differences, the consistency of the behavior between the 2009 and 2013 SSWs suggests that variability in the Southern Hemisphere midlatitude ionosphere and thermosphere is a consistent feature of the SSW impact on the upper atmosphere.

  16. Evidence for stratospheric sudden warming effects on the upper thermosphere derived from satellite orbital decay data during 1967-2013

    NASA Astrophysics Data System (ADS)

    Yamazaki, Yosuke; Kosch, Michael J.; Emmert, John T.

    2015-08-01

    We investigate possible impact of stratospheric sudden warmings (SSWs) on the thermosphere by using long-term data of the global average thermospheric total mass density derived from satellite orbital drag during 1967-2013. Residuals are analyzed between the data and empirical Global Average Mass Density Model (GAMDM) that takes into account density variability due to solar activity, season, geomagnetic activity, and long-term trend. A superposed epoch analysis of 37 SSW events reveals a density reduction of 3-7% at 250-575 km around the time of maximum polar vortex weakening. The relative density perturbation is found to be greater at higher altitudes. The temperature perturbation is estimated to be -7.0 K at 400 km. We show that the density reduction can arise from enhanced wave forcing from the lower atmosphere.

  17. Mesospheric signatures observed during 2010 minor stratospheric warming at King Sejong Station (62°S, 59°W)

    NASA Astrophysics Data System (ADS)

    Eswaraiah, S.; Kim, Yong Ha; Hong, Junseok; Kim, Jeong-Han; Ratnam, M. Venkat; Chandran, A.; Rao, S. V. B.; Riggin, Dennis

    2016-03-01

    A minor stratospheric sudden warming (SSW) event was noticed in the southern hemisphere (SH) during September (day 259) 2010 along with two episodic warmings in early August (day 212) and late October (day 300) 2010. Among the three warming events, the signature of mesosphere response was detected only for the September event in the mesospheric wind dataset from both meteor radar and MF radar located at King Sejong Station (62°S, 59°W) and Rothera (68°S, 68°W), Antarctica, respectively. The zonal winds in the mesosphere reversed approximately a week before the September SSW event, as has been observed in the 2002 major SSW. Signatures of mesospheric cooling (MC) in association with stratospheric warmings are found in temperatures measured by the Microwave Limb Sounder (MLS). Simulations of specified dynamics version of Whole Atmosphere Community Climate Model (SD-WACCM) are able to reproduce these observed features. The mesospheric wind field was found to differ significantly from that of normal years probably due to enhanced planetary wave (PW) activity before the SSW. From the wavelet analysis of wind data of both stations, we find that strong 14-16 day PWs prevailed prior to the SSW and disappeared suddenly after the SSW in the mesosphere. Our study provides evidence that minor SSWs in SH can result in significant effects on the mesospheric dynamics as in the northern hemisphere.

  18. Middle-atmospheric Ozone and HCl anomalies during the polar stratospheric warming 2010 observed by JEM/SMILES

    NASA Astrophysics Data System (ADS)

    Esmaeili Mahani, M.; Kreyling, D.; Sagawa, H.; Murata, I.; Kasaba, Y.; Kasai, Y.

    2012-12-01

    In this study we focused on investigating ozone and HCl variations and anomalies in the middle atmosphere due to the Stratospheric Sudden Warming (SSW) event of Arctic winter 2009-2010 using JEM/SMILES data. HCl anomalies in evolution of a SSW have been studied for the first time. SSWs are dramatic events in the winter stratosphere of the Northern Hemisphere where the deceleration or reversal of the eastward winds is accompanied by an increase of temperature by several tens of degrees. The main cause of this phenomenon is known to be the interaction of zonal mean flow with upward propagating transient planetary waves from the troposphere in mid-winter leading to a vortex displacement or break down. SSWs are dynamical disturbances found to affect both dynamics and chemical compositions of the middle atmosphere still having several different atmospheric features and behaviors to be studied. The Superconducting sub-Millimeter Limb Emission Sounder (SMILES) is a highly sensitive radiometer to observe various atmospheric compositions from upper troposphere to the mesosphere. SMILES was developed by the Japanese Aerospace eXploration Agency (JAXA) and the National Institute of Communications and Technology (NICT) located at the Japanese Experiment Module (JEM) on board the International Space Station (ISS). From October 2009 to April 2010, SMILES has accurately measured the vertical distributions and the diurnal variations of for example ozone and HCl with the accuracy of less than 8% and 5% in the middle atmosphere respectively. By using SMILES data the SSW event of 2010 was confirmed on 25-January categorized as a major, vortex displacement warming. After the SSW, ozone values enhanced up to 15-20% in mid-stratosphere due to the meridional transport from lower latitudes and weakening of the polar vortex. The mesospheric ozone response will also be demonstrated and discussed. For HCl, the total increase of 10% in Upper Stratosphere Lower Mesosphere (USLM) before the

  19. Role of Planetary waves in Winter Stratospheric Warming: Decadal variability

    NASA Astrophysics Data System (ADS)

    Bhagavathiammal, G. J.

    2016-07-01

    Winter Stratospheric dynamics is quiet variable and fascinating in nature, because of the energetic planetary waves, propagates upward from troposphere. Using ECMWF ERA Interim Reanalysis datasets, this paper presents the decadal behaviour of winter stratosphere. Traditional diagnostic tool, Eliassen Palm (E-P) flux provides a realistic understanding of the middle atmospheric processes. Horizontal and vertical component of E-P flux is used to characterize the intensity of upward propagating tropospheric planetary waves. Inter annual variability reveals that the intensification planetary wave energy in the extratropical stratosphere was observed in the month of December; revert the stratospheric circulation, by creating the preconditioning state for the occurrence of stratospheric warming in January (mid-winter). After SSW, No evidence of heat flux energy is observed. This work will provide a better understanding in planetary wave - stratospheric warming mechanism.

  20. Meridional heat transport at the onset of winter stratospheric warming

    NASA Technical Reports Server (NTRS)

    Conte, M.

    1981-01-01

    A continuous vertical flow of energy toward high altitude was verified. This process produced a dynamic instability of the stratospheric polar vortex. A meridional heat transport ws primed toward the north, which generated a warming trend.

  1. Aura Microwave Limb Sounder Observations of Dynamics and Transport During the Record-Breaking 2009 Arctic Stratospheric Major Warming

    NASA Technical Reports Server (NTRS)

    Manney, Gloria L.; Schwartz, Michael J.; Krueger, Kirstin; Santee, Michelle L.; Pawson, Steven; Lee, Jae N.; Daffer, William H.; Fuller, Ryan A.; Livesey, Nathaniel J.

    2009-01-01

    A major stratospheric sudden warming (SSW) in January 2009 was the strongest and most prolonged on record. Aura Microwave Limb Sounder (MLS) observations are used to provide an overview of dynamics and transport during the 2009 SSW, and to compare with the intense, long-lasting SSW in January 2006. The Arctic polar vortex split during the 2009 SSW, whereas the 2006 SSW was a vortex displacement event. Winds reversed to easterly more rapidly and reverted to westerly more slowly in 2009 than in 2006. More mixing of trace gases out of the vortex during the decay of the vortex fragments, and less before the fulfillment of major SSW criteria, was seen in 2009 than in 2006; persistent well-defined fragments of vortex and anticyclone air were more prevalent in 2009. The 2009 SSW had a more profound impact on the lower stratosphere than any previously observed SSW, with no significant recovery of the vortex in that region. The stratopause breakdown and subsequent reformation at very high altitude, accompanied by enhanced descent into a rapidly strengthening upper stratospheric vortex, were similar in 2009 and 2006. Many differences between 2006 and 2009 appear to be related to the different character of the SSWs in the two years.

  2. Global variations of zonal mean ozone during stratospheric warming events

    NASA Technical Reports Server (NTRS)

    Randel, William J.

    1993-01-01

    Eight years of Solar Backscatter Ultraviolet (SBUV) ozone data are examined to study zonal mean variations associated with stratospheric planetary wave (warming) events. These fluctuations are found to be nearly global in extent, with relatively large variations in the tropics, and coherent signatures reaching up to 50 deg in the opposite (summer) hemisphere. These ozone variations are a manifestation of the global circulation cells associated with stratospheric warming events; the ozone responds dynamically in the lower stratosphere to transport, and photochemically in the upper stratosphere to the circulation-induced temperature changes. The observed ozone variations in the tropics are of particular interest because transport is dominated by zonal-mean vertical motions (eddy flux divergences and mean meridional transports are negligible), and hence, substantial simplifications to the governing equations occur. The response of the atmosphere to these impulsive circulation changes provides a situation for robust estimates of the ozone-temperature sensitivity in the upper stratosphere.

  3. Gravity wave activities in the stratosphere and mesosphere during sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Li, Tao; Leblanc, Thierry; McDermid, I. Stuart; Riggin, Dennis; Fritts, Dave C.

    The gravity wave activities in the stratosphere and mesosphere of subtropics during the sudden stratospheric warming were studied using the temperature profiles measured by the Jet Propul-sion Laboratory (JPL) Rayleigh lidar at Mauna Loa Observatory (19.5N, 195.6W), Hawaii, and horizontal wind profiles measured by the MF radar at Kauai (22N, 200.2W), Hawaii. We found that the significant enhancement of gravity wave activities was observed before the sudden stratospheric warming in winter 2005/2006, followed by the decrease of activity during and after the warming. The significant change of GW activities during the warming will be dis-cussed together with the ECMWF wind in the stratosphere and MF radar mean wind in the mesosphere.

  4. Infrasonic signature of the 2009 major sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Evers, L. G.; Siegmund, P.

    2009-12-01

    The study of infrasound is experiencing a renaissance since it was chosen as a verification technique for the Comprehensive Nuclear-Test-Ban Treaty. The success of the verification technique strongly depends on knowledge of upper atmospheric processes. The ability of infrasound to probe the upper atmosphere starts to be exploited, taking the field beyond its monitoring application. Processes in the stratosphere couple to the troposphere and influence our daily weather and climate. Infrasound delivers actual observations on the state of the stratosphere with a high spatial and temporal resolution. Here we show the infrasonic signature, passively obtained, of a drastic change in the stratosphere due to the major sudden stratospheric warming (SSW) of January 2009. With this study, we infer the enormous capacity of infrasound in acoustic remote sensing of stratospheric processes on a global scale with surface based instruments.

  5. Using finite-time Lyapunov exponents to investigate the effect of stratospheric sudden warmings on the polar vortices

    NASA Astrophysics Data System (ADS)

    Smith, M.; McDonald, A. J.

    2012-04-01

    Finite-time Lyapunov exponents are often used to measure mixing in the stratosphere and have been used to investigate the horizontal transport of trace gases near the polar vortices. A better understanding of the dynamics of the polar vortices should provide insight into the circumstances under which odd nitrogen and hydrogen produced by energetic particle precipitation (EPP) in the mesosphere and lower thermosphere (MLT) can be transported to lower levels of the atmosphere. A climatology of finite-time Lyapunov exponents for isentropic surfaces in the stratosphere ranging from 550-2300K for both the northern and southern hemispheres has been created for the observational period of the EOS-MLS instrument.The Lyapunov exponents are derived by using output from a Lagrangian trajectory model forced by data from the MERRA reanalysis. They are calculated at each point on a 2° x 4° global grid by running trajectories for two neighbouring parcels which are initially 1km apart and measuring their separation after a period of time. In order to ensure that the parcel trajectories remain close enough to each other for the exponents to be a good measure of local mixing, the distance between the parcels is periodically reset to 1km. In order to provide a consistency check Lyapunov exponents and trajectories have also been calculated at 550K using NCEP/NCAR reanalysis data. Initial comparisons suggest that the qualitative agreement is quite good between the results using the two different reanalyses. Comparison of the variations in the Lyapunov exponents and trace gas distributions using EOS-MLS data during periods where the stratospheric polar vortices are undisturbed and periods which are disturbed by stratospheric sudden warmings are also discussed. Studying how stratospheric sudden warmings (SSWs) affect the atmospheric dynamics in polar regions is particularly worthwhile since recent studies have shown that they have a significant modulating influence upon the EPP

  6. Simulation of the December 1998 Stratospheric Major Warming

    NASA Technical Reports Server (NTRS)

    Manney, G. L.; Lahoz, W. A.; Swinbank, R.; ONeill, A.; Connew, P. M.; Zurek, R. W.

    1999-01-01

    Prior to 1991, major warmings (defined by increasing zonal mean temperatures and zonal mean easterly winds from 60degN to the pole at 10 hPa) typically occurred approximately once every two Arctic winters; a major warming in mid-Dec. 1998 was the first since Feb. 1991. The Dec. 1998 warming was also the second earliest on record. The earliest, and the only other major warming on record before the end of Dec. was in early Dec 1987; prior to that, the earliest was in late Dec./early Jan. 1984-85. The 1984-85 and 1987 warmings resulted in the warmest and weakest lower stratospheric polar vortices in the 20 years before 1998-99. Fig. 1 compares temperatures and vortex strength in 1998-99 with those in the previous 20 years, using the US National Center for Environmental Prediction (NCEP) record; 1987-88 and 1984-85 are also highlighted. The Dec. 1998 warming had a more pronounced effect on mid-stratospheric temperatures than the Dec. 1987 warming (Fig. 1a), although smaller than that of warmings later in winter (e.g., 1984-85). 10-hPa temperatures fell well below average again in late Jan. 1999 and remained unusually low until an early final warming began in late Feb. 840 K PV gradients (Fig. 1c) set a record minimum in Jan. 1999, but were near average in Feb before the final warming. The effect of the Dec. 1998 warming on lower stratospheric temperatures was comparable to that of other major warmings; there was a brief period of record-high minimum 46-hPa temperatures in early Jan 1999 (Fig. 1b), and temperatures then fell to near average for a short period in mid-Feb. Lower stratospheric PV gradients were the weakest on record during the 1998-99 winter (Fig. 1d). The evolution of the vortex and minimum temperatures during 1998-99 was remarkably similar to that during 1987-88, the only previous year when a major warming was observed before the end of Dec.

  7. Stratospheric warmings: Synoptic, dynamic and general-circulation aspects

    NASA Technical Reports Server (NTRS)

    Mcinturff, R. M. (Editor)

    1978-01-01

    Synoptic descriptions consist largely of case studies, which involve a distinction between major and minor warmings. Results of energetics studies show the importance of tropospheric-stratospheric interaction, and the significance of the pressure-work term near the tropopause. Theoretical studies have suggested the role of wave-zonal flow interaction as well as nonlinear interaction between eddies, chemical and photochemical reactions, boundary forcing, and other factors. Numerical models have been based on such considerations, and these are discussed under various categories. Some indication is given as to why some of the models have been more successful than others in simulating warnings. The question of ozone and its role in warmings is briefly discussed. Finally, a broad view is taken of stratospheric warmings in relation to man's activities.

  8. Upper mesospheric lunar tides over middle and high latitudes during sudden stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Chau, J. L.; Hoffmann, P.; Pedatella, N. M.; Matthias, V.; Stober, G.

    2015-04-01

    In recent years there have been a series of reported ground- and satellite-based observations of lunar tide signatures in the equatorial and low latitude ionosphere/thermosphere around sudden stratospheric warming (SSW) events. This lower atmosphere/ionosphere coupling has been suggested to be via the E region dynamo. In this work we present the results of analyzing 6 years of hourly upper mesospheric winds from specular meteor radars over a midlatitude (54°N) station and a high latitude (69°N) station. Instead of correlating our results with typical definitions of SSWs, we use the definition of polar vortex weaking (PVW) used by Zhang and Forbes. This definition provides a better representation of the strength in middle atmospheric dynamics that should be responsible for the waves propagating to the E region. We have performed a wave decomposition on hourly wind data in 21 day segments, shifted by 1 day. In addition to the radar wind data, the analysis has been applied to simulations from Whole Atmosphere Community Climate Model Extended version and the thermosphere-ionosphere-mesosphere electrodynamics general circulation model. Our results indicate that the semidiurnal lunar tide (M2) enhances in northern hemispheric winter months, over both middle and high latitudes. The time and magnitude of M2 are highly correlated with the time and associated zonal wind of PVW. At middle/high latitudes, M2 in the upper mesosphere occurs after/before the PVW. At both latitudes, the maximum amplitude of M2 is directly proportional to the strength of PVW westward wind. We have found that M2 amplitudes could be comparable to semidiurnal solar tide amplitudes, particularly around PVW and equinoxes. Besides these general results, we have also found peculiarities in some events, particularly at high latitudes. These peculiarities point to the need of considering the longitudinal features of the polar stratosphere and the upper mesosphere and lower thermosphere regions. For

  9. Discrimination of a major stratospheric warming event in February-March 1984 from earlier minor warmings

    NASA Technical Reports Server (NTRS)

    Johnson, K. W.; Quiroz, R. S.; Gelman, M. E.

    1985-01-01

    As part of its responsibility for stratospheric monitoring, the Climate Analysis Center derives time trends of various dynamic parameters from NMC stratospheric analyses. Selected figures from this stratospheric monitoring data base are published in Climate Diagnostics Bulletin in March and October, after each hemispheric winter. During the Northern Hemisphere winter of December 1983-February 1984 several warming events may be seen in the plot of 60 deg. N zonal mean temperatures for 10 mb. Minor warmings may be noted in early December, late December, mid January and early February. A major warming with the 60 deg. N zonal mean temperatures reaching -40C is observed in late February, associated with a circulation reversal. In all of the minor warming episodes, there is a polarward movement of the Aleutian anticyclone; however, at 10 mb the North Pole remains in the cyclonic circulation of the stratospheric vortex which is not displaced far from its usual position. In the case of the later February major warming, the 10 mb circulation pattern over the North Pole is anticyclonic, and the cyclonic circulation has moved to the south and east with a considerable elongation. Cross sections of heat transport and momentum transport are not dramatically different for the minor and major warming episodes.

  10. The infrasonic signature of the 2009 major Sudden Stratospheric Warming

    NASA Astrophysics Data System (ADS)

    Evers, L.; Siegmund, P.

    2009-12-01

    The study of infrasound is experiencing a renaissance since it was chosen as a verification technique for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The success of the verification technique strongly depends on knowledge of upper atmospheric processes. The ability of infrasound to probe the upper atmosphere starts to be exploited, taking the field beyond its monitoring application. Processes in the stratosphere couple to the troposphere and influence our daily weather and climate. Infrasound delivers actual observations on the state of the stratosphere with a high spatial and temporal resolution. Here we show the infrasonic signature, passively obtained, of a drastic change in the stratosphere due to the major Sudden Stratospheric Warming (SSW) of January 2009. A major SSW started around January 15. At the altitude of 30 km, the average temperature to the north of 65N increased in one week by more than 50 deg C, leading to exceptionally high temperatures of about -20 deg C. Simultaneously, the polar vortex reversed direction from eastward to westward. The warming was accompanied by a split-up of the polar vortex and an increased amplitude of the zonal wavenumber number 2 planetary waves. Infrasound recordings on the Northern Hemisphere have been analysed. These arrays are part of the International Monitoring System (IMS) for the CTBT. Interacting oceanic waves are almost continuously emitting infrasound, where the whole atmospheric wind and temperature structure determines the detectability of these so-called microbaroms. Changes in this detectability have been associated to wind and temperatures changes around 50 km altitude due to the major SSW. With this study, we infer the enormous capacity of infrasound in passive acoustic remote sensing of stratospheric processes on a global scale with surface based instruments.

  11. Future Changes in Major Stratospheric Warmings in CCMI Models

    NASA Technical Reports Server (NTRS)

    Ayarzaguena, B.; Langematz, U.; Polvani, L. M; Abalichin, J.; Akiyoshi, H.; Klekociuk, A.; Michou, M.; Morgenstern, O.; Oman, L.

    2015-01-01

    Major stratospheric warmings (MSWs) are one of the most important phenomena of wintertime Arctic stratospheric variability. They consist of a warming of the Arctic stratosphere and a deceleration of the polar night jet, triggered by an anomalously high injection of tropospheric wave activity into the stratosphere. Due to the relevance and the impact of MSWs on the tropospheric circulation, several model studies have investigated their potential responses to climate change. However, a wide range of results has been obtained, extending from a future increase in the frequency of MSWs to a decrease. These discrepancies might be explained by different factors such as a competition of radiative and dynamical contributors with opposite effects on the Arctic polar vortex, biases of models to reproduce the related processes, or the metric chosen for the identification of MSWs. In this study, future changes in wintertime Arctic stratospheric variability are examined in order to obtaina more precise picture of future changes in the occurrence of MSWs. In particular, transient REFC2 simulations of different CCMs involved in the Chemistry Climate Model Initiative (CCMI) are used. These simulations extend from 1960 to 2100 and include forcings by halogens and greenhouse gases following the specifications of the CCMI-REF-C2 scenario. Sea surface temperatures (SSTs) and sea-ice distributions are either prescribed from coupled climate model integrations or calculated internally in the case of fully coupled atmosphere-ocean CCMs. Potential changes in the frequency and main characteristics of MSWs in the future are investigated with special focus on the dependence of the results on the criterion for the identification of MSWs and the tropospheric forcing of these phenomena.

  12. Analysis of the February 2002 stratospheric warming using SABER data

    NASA Astrophysics Data System (ADS)

    Grose, W.; Lingenfelser, G.; Remsberg, E.; Harvey, V.

    2003-04-01

    The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument began acquiring data in January 2002. Version 1.01 Level 2A LTE temperature data have been compared with various correlative data sources (e.g. satellites, lidar, and falling spheres). These results generally show good agreement in the stratosphere. Synoptic temperature distributions are being generated from the SABER data using a sequential estimation technique which was developed for the use with the Nimbus 7 LIMS data. From these temperature distributions, corresponding synoptic fields of geopotential height and geostrophic winds can be obtained. The evolution of the lower stratosphere of the Northern Hemisphere during the warming of February 2002 will be analyzed using these SABER data and compared with a similar analysis using assimilated data.

  13. Large stratospheric sudden warming in Antarctic late winter and shallow ozone hole in 1988

    SciTech Connect

    Kanzawa, Hiroshi; Kawaguchi, Sadao )

    1990-01-01

    There occurred a large stratospheric sudden warming in the southern hemisphere in late winter of 1988 which competes in suddenness and size with major mid-winter warmings in the northern hemisphere. Associated with the dynamical phenomenon of the sudden warming, total ozone increased over the eastern hemispheric part of Antarctica. The sudden warming as well as other warmings which followed it made the 1988 Antarctic ozone hole shallow in depth and small in area.

  14. A review of vertical coupling in the Atmosphere-Ionosphere system: Effects of waves, sudden stratospheric warmings, space weather, and of solar activity

    NASA Astrophysics Data System (ADS)

    Yiğit, Erdal; Koucká Knížová, Petra; Georgieva, Katya; Ward, William

    2016-04-01

    This brief introductory review of some recent developments in atmosphere-ionosphere science is written for the "Vertical Coupling Special Issue" that is motivated by the 5th IAGA/ICMA/SCOSTEP Workshop on Vertical Coupling in the Atmosphere-Ionosphere System. Basic processes of vertical coupling in the atmosphere-ionosphere system are discussed, focusing on the effects of internal waves, such as gravity waves and solar tides, sudden stratospheric warmings (SSWs), and of solar activity on the structure of the atmosphere. Internal waves play a crucial role in the current state and evolution of the upper atmosphere-ionosphere system. SSW effects extend into the upper atmosphere, producing changes in the thermospheric circulation and ionospheric disturbances. Sun, the dominant energy source for the atmosphere, directly impacts the upper atmosphere and modulates wave-induced coupling. The emphasis is laid on the most recent developments in the field, while giving credits to older works where necessary. Various international activities in atmospheric vertical coupling, such as SCOSTEP's ROSMIC project, and a brief contextual discussion of the papers published in the special issue are presented.

  15. Simulations of the February 1979 stratospheric sudden warming: Model comparisons and three-dimensional evolution

    SciTech Connect

    Manney, G.L. ); Farrara, J.D.; Mechoso, C.R. )

    1994-06-01

    The evolution of the stratospheric flow during the major stratospheric sudden warming of February 1979 is studied using two primitive equation models of the stratosphere and mesosphere. The United Kingdom Meteorological Office Stratosphere-Mesosphere Model (SMM) uses log pressure as a vertical coordinate. A spectral, entropy coordinate version of the SMM (entropy coordinate model, or ECM) that has recently been developed is also used. The ECM produces a more realistic recombination and recovery of the polar vortex in the midstratosphere after the warming. Comparison of SMM simulations with forecasts performed using the University of California, Los Angeles general circulation model confirms the previously noted sensitivity of stratospheric forecasts to tropospheric forecast and emphasizes the importance of adequate vertical resolution in modeling the stratosphere. The ECM simulations provide a schematic description of the three-dimensional evolution of the polar vortex and the motion of air through it. During the warming, the two cyclonic vortices tilt westward and equatorward with height. Strong upward velocities develop in the lower stratosphere on the west (cold) side of a baroclinic zone as it forms over Europe and Asia. Strong downward velocities appear in the upper stratosphere on the east (warm) side, strengthening the temperature gradients. After the peak of the warming, vertical velocities decrease, downward velocities move into the lower stratosphere, and upward velocities move into the upper stratosphere. Transport calculations show that air with high ozone mixing ratios is advected toward the pole from low latitudes during the warming, and air with low ozone mixing ratios is transported to the midstratosphere from both higher and lower altitudes along the baroclinic zone in the polar regions. 32 refs., 23 figs., 1 tab.

  16. The role of wave-wave interaction during stratospheric splits

    NASA Astrophysics Data System (ADS)

    Miller, Andreas; Plumb, Alan

    2016-04-01

    Sudden Stratospheric Warmings (SSWs) are the most studied example of troposphere-stratosphere coupling. They are often categorized as either splits (dominated by wavenumber 2) or displacements (wavenumber 1) and many studies (e.g. Charlton and Polvani (2007)) found statistically significant differences between the zonal wind fields and associated momentum fluxes. These differences are observed from the stratosphere to the surface. Our study focuses on how wave-wave interactions within the stratosphere can determine the type of SSW. We derive an energy budget for each wavenumber that allows us to quantify the major stratospheric processes within each wavenumber as well as the energy transfer from one wavenumber into another. Calculating these budgets, using MERRA reanalysis data, we find that for many split events the energy flux into the stratosphere is predominantly in wavenumber one. Thus, wave-wave interactions within the stratosphere, which can flux energy between wavenumbers, play a key role in splitting the polar stratospheric vortex. However, the signal is weak when we calculate composites over all splits as the timing of wave-wave interactions is unrelated to classic definitions (e.g. central date) highlighting the need for a dynamically more meaningful definition of SSWs. In order to better understand the role of wave-wave interactions, we employ GFDL's FMS shallow water model to simulate the stratospheric vortex under idealized forcings (similar to Polavani et al. (1994)). Contrary to many other idealized experiments, we are able to simulate both types of warmings with pure wavenumber one or two forcings. We further explore the strength of the necessary forcing to cause stratospheric splits in relation to the state of of the polar vortex. These results are compared to the work of Matthewman and Esler (2011) on splits being a result of resonance. We finally use the energy budget described above to determine the importance of wave-wave interaction in this

  17. Thermospheric meridional circulation during sudden stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Laskar, F. I.; Duggirala, P. R.

    2014-12-01

    Oxygen dayglow emission intensities, at OI 557.7, OI 630.0, and OI 777.4 nm, over a low-latitude location showed systematic enhancements in intensities throughout the daytime hours during the four sudden stratospheric warming (SSW) events that occurred in the years 2010 - 2013. The arctic latitude lower thermospheric temperatures at around 120 km altitudes obtained from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument are found to be enhanced during SSW events and show a latitudinal gradient (temperature decreasing towards low-latitudes). Commensurately, the Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) Doppler Interferometer (TIDI) measurements showed equatorward winds in the mesosphere lower thermosphere (MLT) altitudes over high latitudes during these events. Both, the high-latitude lower thermospheric temperature enhancements and the MLT region equatorward winds occur simultaneously with the observed enhancements in the OI dayglow emission intensities at all the wavelengths. From these observations and other supporting observational and modeling results it is proposed that a new cell of meridional circulation in the MLT winds is set up during SSW events, which enables transport of atomic oxygen from high-to-low latitudes. Such an additional contribution of oxygen density over low-latitudes interacts with daytime lower thermospheric dynamics and is attributed to be the cause for the observed enhancement in the oxygen daytime optical emission intensities over low-latitudes. These results will presented in the light of experimental evidence to such circulation alluded to by earlier simulation studies.

  18. Ionospheric signatures of non-migrating tides and stratospheric warming

    NASA Astrophysics Data System (ADS)

    Lühr, Hermann; Stolle, Claudia; Häusler, Kathrin

    2010-05-01

    Observational data bases from recent years provided more and more evidence that climate and weather phenomena influence the dynamics of the high atmosphere. In the first part of this presentation we will address the dynamical interaction caused by non-migrating tides. Several of these tidal modes are generated in the lower atmosphere and are believed to propagate all the way up to the exosphere. Quantities that reflect the characteristics of the tides very well, are thermospheric temperature and wind. The dynamics of the neutrals is partly transferred to charged particles in the ionospheric E-layer. For that reason tidal signals are also present in the ionospheric E and F region. We show, as examples, the effect on the equatorial electrojet (EEJ), vertical plasma drift and F region electron density. Since the coupling conditions and strength between neutral and charged particles vary over the course of a day (a year, a solar cycle), the recovery of the complete ionospheric tidal signals is complex. We will present the amplitude and annual variation for the most prominent tidal components. A very recent topic of vertical coupling is the influence of sudden stratospheric warming (SSW) on the ionospheric electrodynamics. SSW has been shown to modify among others the diurnal variation of the vertical plasma drift and the electric field at equatorial latitudes. We will present global observations of the EEJ and its response to SSW events in 2002/2003. A typical feature is an enhancement of the EEJ intensity in the pre-noon hours and a reduction in the afternoon. Possible mechanisms causing these modifications will be discussed.

  19. A New Connection Between Greenhouse Warming and Stratospheric Ozone Depletion

    NASA Technical Reports Server (NTRS)

    Salawitch, R.

    1998-01-01

    The direct radiative effects of the build-up of carbon dioxide and other greenhouse gases have led to a gradual cooling of the stratosphere with largest changes in temperature occurring in the upper stratosphere, well above the region of peak ozone concentration.

  20. The interaction of radiative and dynamical processes during a simulated sudden stratospheric warming

    NASA Technical Reports Server (NTRS)

    Pierce, R. B.; Blackshear, W. T.; Fairlie, T. D.; Grose, W. L.; Turner, R. E.

    1993-01-01

    An analysis of a spontaneous sudden stratospheric warming that occurred during a 2-year integration of the Langley Research Center (LaRC) Atmospheric Simulation Model is presented. The simulated warming resembles observed 'wave 1' warmings in the Northern Hemisphere stratosphere and provides an opportunity to investigate the radiative and dynamical processes occurring during the warming event. Isentropic analysis of potential vorticity sources and sinks indicates that dynamically induced departures from radiative equilibrium play an important role in the warming event. Enhanced radiative cooling associated with a series of upper stratospheric warm pools leads to radiative dampening within the polar vortex. Within the 'surf zone' large-scale radiative cooling leads to diabatic advection of high potential vorticity air from aloft. Lagrangian area diagnostics of the simulated warming agree well with Limb Infrared Monitor of the Stratosphere (LIMS) analyses. Dynamical mixing is shown to account for the majority of the decrease in the size of the polar vortex during the simulated warming. An investigation of the nonlinear deformation of material lines that are initially coincident with diagnosed potential vorticity isopleths is conducted to clarify the relationship between the Lagrangian area diagnostics and potential vorticity advection during wave breaking events.

  1. Chemistry and transport in a three-dimensional stratospheric model - Chlorine species during a simulated stratospheric warming

    NASA Technical Reports Server (NTRS)

    Kaye, Jack A.; Rood, Richard B.

    1989-01-01

    The distributions in the stratosphere of a variety of chemical species were calculated for a 6-day period during the February 1979 stratospheric major warming, using winds derived from a spectral forecast model which included O(x), NO(x), HO(x), and ClO(x) chemistries as well as longitudinally varying reaction rate coefficients and photolysis rates for these molecules. The results obtained indicate a particular importance of chemistry and transport for the Cl-containing species ClO, ClONO2, HCl, and HOCl. Dynamical effects dominate the variability of HCl, while diurnal effects dominate that of ClONO2 and ClO. The effects of strong planetary wave activity may be seen in terms of large longitudinal variability of the total HCl and ClONO columns in the stratosphere; in the middle and high northern latitudes, it is sufficiently large to exceed the diurnal variability of the column.

  2. Signature of a sudden stratospheric warming in the near-ground 7Be flux

    NASA Astrophysics Data System (ADS)

    Pacini, A. A.; Usoskin, I. G.; Mursula, K.; Echer, E.; Evangelista, H.

    2015-07-01

    We present here an evidence that cosmogenic 7Be isotopes produced in the lower stratosphere were measured in near-ground air at Rio de Janeiro, Brazil, after the southern hemispheric Sudden Stratospheric Warming (SSW) of 2002. The analysis presented here is based on a comparison of 7Be data measured around Angra Nuclear Power Station (23°S 44°W) during the last three decades and a model estimate of the near-ground air 7Be concentration using the CRAC:7Be model of cosmogenic production together with a simplified model for atmospheric 7Be deposition that assimilates the regional precipitation data. Our results indicate that an anomalous stratosphere-troposphere coupling associated to the unique SSW of 2002 allowed stratospheric aerosols carrying 7Be to reach the ground level very quickly. This methodology points to an important use of 7Be as a quantitative tracer for stratospheric influence on near-ground air patterns.

  3. Response of the Antarctic Stratosphere to Warm Pool EI Nino Events in the GEOS CCM

    NASA Technical Reports Server (NTRS)

    Hurwitz, Margaret M.; Song, In-Sun; Oman, Luke D.; Newman, Paul A.; Molod, Andrea M.; Frith, Stacey M.; Nielsen, J. Eric

    2011-01-01

    A new type of EI Nino event has been identified in the last decade. During "warm pool" EI Nino (WPEN) events, sea surface temperatures (SSTs) in the central equatorial Pacific are warmer than average. The EI Nino signal propagates poleward and upward as large-scale atmospheric waves, causing unusual weather patterns and warming the polar stratosphere. In austral summer, observations show that the Antarctic lower stratosphere is several degrees (K) warmer during WPEN events than during the neutral phase of EI Nino/Southern Oscillation (ENSO). Furthermore, the stratospheric response to WPEN events depends of the direction of tropical stratospheric winds: the Antarctic warming is largest when WPEN events are coincident with westward winds in the tropical lower and middle stratosphere i.e., the westward phase of the quasi-biennial oscillation (QBO). Westward winds are associated with enhanced convection in the subtropics, and with increased poleward wave activity. In this paper, a new formulation of the Goddard Earth Observing System Chemistry-Climate Model, Version 2 (GEOS V2 CCM) is used to substantiate the observed stratospheric response to WPEN events. One simulation is driven by SSTs typical of a WPEN event, while another simulation is driven by ENSO neutral SSTs; both represent a present-day climate. Differences between the two simulations can be directly attributed to the anomalous WPEN SSTs. During WPEN events, relative to ENSO neutral, the model simulates the observed increase in poleward planetary wave activity in the South Pacific during austral spring, as well as the relative warming of the Antarctic lower stratosphere in austral summer. However, the modeled response to WPEN does not depend on the phase of the QBO. The modeled tropical wind oscillation does not extend far enough into the lower stratosphere and upper troposphere, likely explaining the model's insensitivity to the phase of the QBO during WPEN events.

  4. Chemistry and transport in a three-dimensional stratospheric model: Chlorine species during a simulated stratospheric warming

    SciTech Connect

    Kaye, J.A.; Rood, R.B. )

    1989-01-20

    Calculations of coupled chemistry and transport for the stratosphere are carried out for a 6-day period during the February 1979 stratospheric major warming, using winds derived from a spectral forecast model. All major families of stratospheric chemistry (odd oxygen, odd nitrogen, odd hydrogen, and odd chlorine), as well as longitudinally varying reaction rate coefficients and photolysis rates, are included in the model. Eight constituents and/or families are transported in the model; additional ones are held fixed or inferred by photochemical equilibrium approximations. Results presented include zonal mean fields, latitude-longitude distributions (and their changes with time), vertical profiles, and time series of the mixing ratios of transported constituents and families as well as of their total stratospheric column amounts. The results obtained show the relative importance of chemistry and transport for the chlorine-containing species ClO, ClONO{sub 2}, HCl, and HOCl. Dynamical effects dominate the variability of HCl, while diurnal ones dominate that of ClONO{sub 2} and ClO. Diurnal chemistry and dynamical variability are of similar magnitude for HOCl. The effects of strong planetary wave activity may be seen as large longitudinal variability of the total HCl and ClONO{sub 2} columns in the stratosphere; in middle and high northern latitudes it is sufficiently large that it exceeds the diurnal variability of the column.

  5. Contributions of stratospheric water vapor to decadal changes in the rate of global warming.

    PubMed

    Solomon, Susan; Rosenlof, Karen H; Portmann, Robert W; Daniel, John S; Davis, Sean M; Sanford, Todd J; Plattner, Gian-Kasper

    2010-03-01

    Stratospheric water vapor concentrations decreased by about 10% after the year 2000. Here we show that this acted to slow the rate of increase in global surface temperature over 2000-2009 by about 25% compared to that which would have occurred due only to carbon dioxide and other greenhouse gases. More limited data suggest that stratospheric water vapor probably increased between 1980 and 2000, which would have enhanced the decadal rate of surface warming during the 1990s by about 30% as compared to estimates neglecting this change. These findings show that stratospheric water vapor is an important driver of decadal global surface climate change. PMID:20110466

  6. Wintertime Polar Ozone Evolution during Stratospheric Vortex Break-Down

    NASA Astrophysics Data System (ADS)

    Tweedy, O.; Limpasuvan, V.; Smith, A. K.; Richter, J. H.; Orsolini, Y.; Stordal, F.; Kvissel, O.

    2011-12-01

    Stratospheric Sudden Warming (SSW) is characterized by the rapid warming of the winter polar stratosphere and the weakening of the circumpolar flow. During the onset of a major SSW (when the circumpolar flow reverses direction), the warm stratopause layer (SL) descends from its climatological position to the mid-stratosphere level. As the vortex recovers from SSW, a "new" SL forms in the mid-mesosphere region before returning to its typical level. This SL discontinuity appears in conjunction with enhanced downward intrusion of chemical species from the lower thermosphere/upper mesosphere to the stratosphere. The descended species can potentially impact polar ozone. In this study, the NCAR's Whole Atmosphere Community Climate Model (WACCM) is used to investigate the behavior of polar ozone related to major SSWs. Specifically, dynamical evolution and chemistry of NOx, CO, and O3 are examined during three realistic major SSWs and compared with a non-SSW winter season. The simulated (zonal-mean) polar ozone distribution exhibits a "primary" maximum near 40 km, a "secondary" maximum between 90-105 km, and a "tertiary" maximum near 70 km. The concentration of the secondary maximum reduces by ~1.5 parts per million by volume (ppmv) as the vortex recovers and the upper mesospheric polar easterlies return. Enhanced downwelling above the newly formed SL extends up to just above this secondary maximum (~110 km). With an averaged concentration of 2 ppmv, the tertiary ozone maximum layer displaces upward with enhanced upwelling during SSW in conjunction with the lower mesospheric cooling. The downward propagation of the stratospheric wind reversal is accompanied by CO intrusion toward the lowermost stratosphere and anomalous behavior in the primary ozone maximum. Overall, the major SSW, SL, and polar ozone evolution mimic recently reported satellite observations.

  7. Transport of polar winter lower-thermospheric Nitric Oxide to the Stratosphere

    NASA Astrophysics Data System (ADS)

    Bailey, S. M.; Thurairajah, B.; Randall, C. E.; Siskind, D. E.; Hervig, M. E.; Russell, J. M.

    2013-12-01

    Nitric oxide (NO) is a key minor constituent of the lower thermosphere. It is produced there via processes that are initiated with the ionization of N2. This ionization occurs by solar soft X-ray irradiance globally and by precipitating energetic particles in the polar regions. In the mesosphere and stratosphere NO participates in an important catalytic reaction which results in the destruction of ozone. Evidence of NO transported in the Northern Hemisphere (NH) winter from the lower thermosphere to the stratosphere has been growing in recent years. In particular, Stratospheric Sudden Warmings (SSWs) have been identified as triggers of enhanced NO descent. In this talk, we discuss observations of NO from the Solar Occultation for Ice Experiment (SOFIE) instrument on-board the Aeronomy of Ice in the Mesosphere (AIM) satellite. Six years of polar NO observations from 40 to 140 km are now available, including the NH winters of 2007-2008 through 2012-2013. SOFIE shows dramatic transport of NO in the NH winters of both 2008-2009 and 2012-2013. Both of these episodes occur after major SSWs. A weaker but very large enhancement of NO was observed in 2012 after a minor SSW. In each case, SOFIE observations of water also show evidence of transport and SOFIE observations of temperature show an elevated stratopause. These results are consistent with previous observations and the inferred role of SSWs. We will show the SOFIE observations and explore how the strength and timing of SSWs control the magnitude of the NO transport.

  8. Variance in trace constituents following the final stratospheric warming

    NASA Technical Reports Server (NTRS)

    Hess, Peter

    1990-01-01

    Concentration variations with time in trace stratospheric constituents N2O, CF2Cl2, CFCl3, and CH4 were investigated using samples collected aboard balloons flown over southern France during the summer months of 1977-1979. Data are analyzed using a tracer transport model, and the mechanisms behind the modeled tracer variance are examined. An analysis of the N2O profiles for the month of June showed that a large fraction of the variance reported by Ehhalt et al. (1983) is on an interannual time scale.

  9. On the composite response of the MLT to major sudden stratospheric warming events with elevated stratopause

    NASA Astrophysics Data System (ADS)

    Limpasuvan, Varavut; Orsolini, Yvan J.; Chandran, Amal; Garcia, Rolando R.; Smith, Anne K.

    2016-05-01

    Based on a climate-chemistry model (constrained by reanalyses below ~50 km), the zonal-mean composite response of the mesosphere and lower thermosphere (MLT) to major sudden stratospheric warming events with elevated stratopauses demonstrates the role of planetary waves (PWs) in driving the mean circulation in the presence of gravity waves (GWs), helping the polar vortex recover and communicating the sudden stratospheric warming (SSW) impact across the equator. With the SSW onset, strong westward PW drag appears above 80 km primarily from the dissipation of wave number 1 perturbations with westward period of 5-12 days, generated from below by the unstable westward polar stratospheric jet that develops as a result of the SSW. The filtering effect of this jet also allows eastward propagating GWs to saturate in the winter MLT, providing eastward drag that promotes winter polar mesospheric cooling. The dominant PW forcing translates to a net westward drag above the eastward mesospheric jet, which initiates downwelling over the winter pole. As the eastward polar stratospheric jet returns, this westward PW drag persists above 80 km and acts synergistically with the return of westward GW drag to drive a stronger polar downwelling that warms the pole adiabatically and helps reform the stratopause at an elevated altitude. With the polar wind reversal during the SSW onset, the westward drag by the quasi-stationary PW in the winter stratosphere drives an anomalous equatorial upwelling and cooling that enhance tropical stratospheric ozone. Along with equatorial wind anomalies, this ozone enhancement subsequently amplifies the migrating semidiurnal tide amplitude in the winter midlatitudes.

  10. Improved predictability of stratospheric sudden warming events in an atmospheric general circulation model with enhanced stratospheric resolution

    NASA Astrophysics Data System (ADS)

    Marshall, Andrew G.; Scaife, Adam A.

    2010-08-01

    The impact of stratospheric resolution on the predictability of stratospheric sudden warming (SSW) events and their effect on European climate is cleanly assessed in two versions of the Hadley Center's atmospheric climate model, Hadley Center global environmental model. The standard 38-level version of the model extends to an altitude of 39 km (˜3 mbar) while the extended 60-level version has enhanced stratospheric resolution and reaches 84 km altitude (˜0.004 mbar). We show that the L60 model captures SSW events earlier than the L38 model (12 days before an event compared with 8 days) and influences the simulation of European surface winter cold spells at seasonal time scales, highlighting the benefit of high vertical resolution and daily initialization for seasonal forecasting. This is likely due to earlier initialization of the downward-propagating SSW signal in the higher-top L60 model. We suggest however that the increased lead time for predicting SSW events is unlikely to be improved much further by raising the model lid above the L60 model domain.

  11. The Remarkable 2003--2004 Winter and Other Recent Warm Winters in the Arctic Stratosphere Since the Late 1990s

    NASA Technical Reports Server (NTRS)

    Manney, Gloria L.; Kruger, Kirstin; Sabutis, Joseph L.; Sena, Sara Amina; Pawson, Steven

    2005-01-01

    The 2003-2004 Arctic winter was remarkable in the approximately 50-year record of meteorological analyses. A major warming beginning in early January 2004 led to nearly 2 months of vortex disruption with high-latitude easterlies in the middle to lower stratosphere. The upper stratospheric vortex broke up in late December, but began to recover by early January, and in February and March was the strongest since regular observations began in 1979. The lower stratospheric vortex broke up in late January. Comparison with 2 previous years, 1984-1985 and 1986-1987, with prolonged midwinter warming periods shows unique characteristics of the 2003-2004 warming period: The length of the vortex disruption, the strong and rapid recovery in the upper stratosphere, and the slow progression of the warming from upper to lower stratosphere. January 2004 zonal mean winds in the middle and lower stratosphere were over 2 standard deviations below average. Examination of past variability shows that the recent frequency of major stratospheric warmings (7 in the past 6 years) is unprecedented. Lower stratospheric temperatures were unusually high during 6 of the past 7 years, with 5 having much lower than usual potential for polar stratospheric cloud (PSC) formation and ozone loss (nearly none in 1998-1999, 2001-2002, and 2003-2004, and very little in 1997-1998 and 2000-2001). Middle and upper stratospheric temperatures, however, were unusually low during and after February. The pattern of 5 of the last 7 years with very low PSC potential would be expected to occur randomly once every 850 years. This cluster of warm winters, immediately following a period of unusually cold winters, may have important implications for possible changes in interannual variability and for determination and attribution of trends in stratospheric temperatures and ozone.

  12. The Remarkable 2003-2004 Winter and Other Recent Warm Winters in the Arctic Stratosphere Since the Late 1990s

    NASA Technical Reports Server (NTRS)

    Manney, Gloria L.; Krueger, Kirstin; Sabutis, Joseph L.; Sena, Sara Amina; Pawson, Steven

    2004-01-01

    The 2003-2004 Arctic winter was remarkable in the 40-year record of meteorological analyses. A major warming beginning in early January 2004 led to nearly two months of vortex disruption with high-latitude easterlies in the middle to lower stratosphere. The upper stratospheric vortex broke up in late December, but began to recover by early January, and in February and March was the strongest since regular observations began in 1979. The lower stratospheric vortex broke up in late January. Comparison with two previous years, 1984-1985 and 1986-1987, with prolonged mid-winter warming periods shows unique characteristics of the 2003-2004 warming period: The length of the vortex disruption, the strong and rapid recovery in the upper stratosphere, and the slow progression of the warming from upper to lower stratosphere. January 2004 zonal mean winds in the middle and lower stratosphere were over two standard deviations below average. Examination of past variability shows that the recent frequency of major stratospheric warmings (seven in the past six years) is unprecedented. Lower stratospheric temperatures were unusually high during six of the past seven years, with five having much lower than usual potential for PSC formation and ozone loss (nearly none in 1998-1999, 2001-2002 and 2003-2004, and very little in 1997-1998 and 2000-2001). Middle and upper stratospheric temperatures, however, were unusually low during and after February. The pattern of five of the last seven years with very low PSC potential would be expected to occur randomly once every approximately 850 years. This cluster of warm winters, immediately following a period of unusually cold winters, may have important implications for possible changes in interannual variability and for determination and attribution of trends in stratospheric temperatures and ozone.

  13. Troposphere-Stratosphere Coupled Chemistry-Climate Interactions: From Global Warming Projections to Air Quality

    NASA Astrophysics Data System (ADS)

    Nowack, P. J.; Abraham, N. L.; Maycock, A. C.; Braesicke, P.; Pyle, J. A.

    2015-12-01

    Changes in stratospheric composition can affect tropospheric composition and vice versa. Of particular interest are trace gas concentrations at the interface between these two atmospheric layers in the tropical upper troposphere and lower stratosphere (UTLS). This is due to the crucial importance of composition changes in the UTLS for the global energy budget. In a recent study (Nowack et al., 2015), we provided further evidence that composition changes in the tropical UTLS can significantly affect global warming projections. Using a state-of-the-art atmosphere-ocean chemistry-climate model, we found a ~20% smaller global warming in response to an abrupt 4xCO2 forcing if composition feedbacks were included in the calculations as compared to simulations in which composition feedbacks were not considered. We attributed this large difference in surface warming mainly to circulation-driven decreases in tropical UTLS ozone and related changes in stratospheric water vapor, partly counteracted by simultaneous changes in ice clouds. Here, we explain why this result is expected to differ between models and how, inter alia, tropospheric chemical mechanisms can contribute to this uncertainty. We highlight that improving our understanding of processes in the tropical UTLS and their representation in Earth system models remains a key challenge in climate research.Finally, taking geoengineering as a new example, we show that changes in the stratosphere can have an impact on air quality in the troposphere. In particular, we explain for a simple solar radiation management scenario how changes in surface ozone can be linked to changes in meteorology and composition in the troposphere and stratosphere. In conclusion, we highlight the importance of considering air quality impacts when evaluating a variety of geoengineering scenarios. Reference: Nowack, P.J., Abraham, N.L., Maycock, A.C., Braesicke, P., Gregory, J.M., Joshi, M.M., Osprey, A., and Pyle, J.A. Nature Climate Change 5, 41

  14. Behavior of the sodium and hydroxyl nighttime emissions during a stratospheric warming

    NASA Technical Reports Server (NTRS)

    Walker, J. D.; Reed, E. I.

    1975-01-01

    The behavior of the sodium and hydroxyl nighttime emissions during a stratospheric warming has been studied principally by use of data from the airglow photometers on the OGO-4 satellite. It was found that during the late stages of a major warming, both emissions increase appreciably, with the sodium emission returning to normal levels prior to the decrease in hydroxyl emission. The emission behaviors are attributed to temperature and density variations from 70 to 94 km, and a one-dimensional hydrostatic model for that altitude range is used to calculate the effects on the emissions and on the mesospheric ozone densities.

  15. Rapid increases of CO and H2O in the tropical lower stratosphere during January 2010 stratospheric sudden warming event

    NASA Astrophysics Data System (ADS)

    Eguchi, Nawo; Kodera, Kunihiko; Ueyama, Rei; Li, Qian

    2014-05-01

    A potential transport mechanism of various tracers from the tropical troposphere to the lower stratosphere (LS) across the tropical tropopause layer (TTL) is the overshooting convective clouds which inject air with tropospheric characteristics (high CO, high H2O, low O3) into the LS over a period of a few days. Evidence of such convective intrusions extending up to the 90 hPa level are observed over the southern African continent at the end of January 2010 in MLS and CALIOP satellite measurements. Rapid increases of CO and water vapor concentrations over Africa are associated with increased convective activity over the region a few days prior to the onset of stratospheric sudden warming (SSW) event and contribute to enhancements in their zonal tropical mean concentrations during January and February 2010. The modulation of tropical upwelling by SSW appears to force stronger and deeper tropical convection, particularly in the Southern Hemisphere tropics. The January 2010 SSW event induced the lowest recorded LS temperature in MLS history (2004-13), allowing an unprecedented clear detection of stratosphere-troposphere exchange process by way of CO, H2O and O3 intrusions. The present study suggests that short duration, overshooting clouds can have a large impact on the zonally averaged fields of LS composition (zonally-averaged tracer fields in the tropical LS). In this presentation, we present the simulated CO, water vapor and ozone mixing ratios during Jan 2010 SSW using GEOS-Chem model. We further investigate the transport pathways based on trajectory analysis of air parcels in convective regions of the tropics.

  16. Sudden Stratospheric Warming (SSW) and its immediate and broader influence on tropical dynamics using COSMIC Observations

    NASA Astrophysics Data System (ADS)

    Dhaka, Surendra

    2016-07-01

    We have analyzed temperature changes in troposphere and stratosphere from polar to tropical region during major sudden stratospheric warming (SSW) using data derived from COSMIC over a period of 2007-2014. During peak period of SSW, a large variability noted in temperature structure, rise in temperature occurred down to the tropopause height (~8 km height) in polar region. At around 40 km altitudes (as data is available to this height), temperature increased by several tens of degrees within few days of SSW. After SSW termination, temperature decreased up to ~ 80°C in strong SSW cases. After about a week of SSW event, descending cold anomalies emerged at polar region. These features are emerging normally known as polar night jet oscillations (PJO). The cooling phase was much longer along with large spatial coverage than the warm phase. Due to SSW, polar T-CPT and H-CPT alter significantly. As a consequence of SSW, bottom of stratospheric region expands and hence the tropospheric region shrunk by the same height. A rapid atmospheric response is identified between polar and tropical region possibly through set up of strong meridional circulation. During occurrence of SSW, at 40 km altitude in polar region, large increase in temperature noted, while in the tropics temperature dropped at similar heights. After termination of SSW, descending warm anomalies observed over the tropical region for a longer duration, while the long cold phase persisted at the polar region. These warm anomalies at tropical region are much longer and deeper in comparison to those of the cold anomalies. It is concluded that SSW event at polar region connects to the entire tropical tropopause region across the equator in SH up to 40° S. Hence these processes need to be understood thoroughly to contribute to the temperature change.

  17. Wave Signatures in the Polar Mesopause Region during the January, 2009 Sudden Stratospheric Warming

    NASA Astrophysics Data System (ADS)

    Ward, W. E.; Kristoffersen, S.; Vail, C.

    2012-12-01

    Observations on a two minute cadence at the Polar Environment Atmospheric Research Laboratory (PEARL, Eureka, Nunavut, 80N) with an all sky imager and a Doppler Imaging Interferometer were taken during the January, 2009 major stratospheric warming. These observations complement temperature and irradiance measurments previously reported from the same location. Oscillations with periods of 4 days, 2.5 days, 24 hours, 16 hours 12 hours and 8 hours are observed during this warming period. In addition shorter period oscillations in the airglow observations and wind observations are observed. This paper summarizes these observations and delineates the evolution of these features and the large scale winds during this warming event.Meridional winds from Doppler shifts in the oxygen green line airglow observed with the ERWIN II instrument from January 16-31, 2009. Individual points are observations every 2 minutes with an error of 2 m/s.

  18. Mesosphere-to-stratosphere descent of odd nitrogen in February-March 2009 after sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Salmi, S.-M.; Verronen, P. T.; Thölix, L.; Kyrölä, E.; Backman, L.; Karpechko, A. Yu.; Seppälä, A.

    2011-01-01

    We use the 3-D FinROSE chemistry transport model (CTM) and ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) observations to study the connection between atmospheric dynamics and NOx descent during early 2009 in the northern polar region. We force the model NOx at 80 km poleward of 60° N with ACE-FTS observations and then compare the model results with observations at lower altitudes. Low geomagnetic indices indicate absence of local NOx production in early 2009, which gives a good opportunity to study the effects of atmospheric transport on polar NOx. No in-situ production of NOx by energetic particle precipitation is therefore included. This is the first model study using ECMWF (The European Centre for Medium-Range Weather Forecasts) data up to 80 km and simulating the exceptional winter of 2009 with one of the strongest major sudden stratospheric warmings (SSW). The model results show a strong NOx descent in February-March 2009 from the upper mesosphere to the stratosphere after the major SSW. Both observations and model results suggest an increase of NOx to 150-200 ppb (i.e. by factor of 50) at 65 km due to the descent following the SSW. The model, however, underestimates the amount of NOx around 55 km by 40-60 ppb. The results also show that the chemical loss of NOx was insignificant i.e. NOx was mainly controlled by the dynamics. Both ACE-FTS observations and FinROSE show a decrease of ozone of 20-30% at 30-50 km after mid-February to mid-March. However, these changes are not related to the NOx descent, but are due to activation of the halogen chemistry.

  19. Role of Stratospheric Water Vapor in Global Warming from GCM Simulations Constrained by MLS Observation

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Stek, P. C.; Su, H.; Jiang, J. H.; Livesey, N. J.; Santee, M. L.

    2014-12-01

    Over the past century, global average surface temperature has warmed by about 0.16°C/decade, largely due to anthropogenic increases in well-mixed greenhouse gases. However, the trend in global surface temperatures has been nearly flat since 2000, raising a question regarding the exploration of the drivers of climate change. Water vapor is a strong greenhouse gas in the atmosphere. Previous studies suggested that the sudden decrease of stratospheric water vapor (SWV) around 2000 may have contributed to the stall of global warming. Since 2004, the SWV observed by Microwave Limb Sounder (MLS) on Aura satellite has shown a slow recovery. The role of recent SWV variations in global warming has not been quantified. We employ a coupled atmosphere-ocean climate model, the NCAR CESM, to address this issue. It is found that the CESM underestimates the stratospheric water vapor by about 1 ppmv due to limited representations of the stratospheric dynamic and chemical processes important for water vapor variabilities. By nudging the modeled SWV to the MLS observation, we find that increasing SWV by 1 ppmv produces a robust surface warming about 0.2°C in global-mean when the model reaches equilibrium. Conversely, the sudden drop of SWV from 2000 to 2004 would cause a surface cooling about -0.08°C in global-mean. On the other hand, imposing the observed linear trend of SWV based on the 10-year observation of MLS in the CESM yields a rather slow surface warming, about 0.04°C/decade. Our model experiments suggest that SWV contributes positively to the global surface temperature variation, although it may not be the dominant factor that drives the recent global warming hiatus. Additional sensitivity experiments show that the impact of SWV on surface climate is mostly governed by the SWV amount at 100 hPa in the tropics. Furthermore, the atmospheric model simulations driven by observed sea surface temperature (SST) show that the inter-annual variation of SWV follows that of SST

  20. Signature of a Sudden Stratospheric Warming in the near-ground 7Be flux.

    NASA Astrophysics Data System (ADS)

    Pacini, A. A.

    2015-12-01

    We present here a study of the impact of one Sudden Stratospheric Warming (SSW) upon the atmospheric vertical dynamics based on 7Be measurements in near ground air, using both numerical and conceptual. In late September 2002, an unprecedented SSW event occurred in the southern hemisphere (SH), causing changes in the tropospheric circulation, ozone depletion and weakening of the polar jet in the mesosphere. There is an observational evidence suggesting that anomalies in the stratosphere play an important role in driving tropospheric weather producing tropospheric changes that can persists for up to 60 days in NH and up to about 90 days in the SH, as observed after the 2002 SSW (Thompson et al., 2005). Radioactive environmental techniques for tracing large-scale air-mass transport have been applied in studies of atmospheric dynamics for decades and they are becoming more and more precise due to the improvement of the instrumental sensitivity and associated modeling. Temporal variations of the cosmogenic 7Be concentration in the near-surface atmosphere can provide information on the air mass dynamics, precipitation patterns, stratosphere-troposphere coupling and cosmic ray variations. The present study is based on an analysis of 7Be concentration measured in near-ground air in the city of Angra dos Reis, Rio de Janeiro state, Brazil between 1987 and 2009. Using a simplified tropospheric 7Be model deposition based on a two-layer transport model, Pacini (2011) reported that the occurrence of strong downward air flux leave an imprint of the 3D motion of air masses to the near-ground air 7Be data in the studied region. In this work, we have further developed the two-layer model by adding one more layer: the lower stratosphere (LS). In normal conditions, the contribution of the LS 7Be to the near-ground isotopic variability would be very small. On the other hand, stratospheric source can be crucial for the SSW event, indicating that a strong stratospheric air intrusion

  1. A comparison of SAGE I data during the stratospheric warming of February-March, 1979

    NASA Technical Reports Server (NTRS)

    Nagatani, R. M.; Mccormick, M. P.; Mcmaster, L. R.

    1985-01-01

    The fine scale vertical structure of SAGE I ozone and aerosol data during a stratospheric warming is investigated using meteorological and SBUV ozone data. By stratifying the ozone and aerosol data for a limited time period, a comparison of the structure of profiles becomes possible under different meteorological conditions. For example, the cold air region shows more laminated structures than the other regions. In addition, vertical motions calculated at the same locations as the SAGE profiles show that they are consistent with variances found in the ozone and aerosol data.

  2. A Lagrangian analysis of a sudden stratospheric warming - Comparison of a model simulation and LIMS observations

    NASA Technical Reports Server (NTRS)

    Pierce, R. B.; Remsberg, Ellis E.; Fairlie, T. D.; Blackshear, W. T.; Grose, William L.; Turner, Richard E.

    1992-01-01

    Lagrangian area diagnostics and trajectory techniques are used to investigate the radiative and dynamical characteristics of a spontaneous sudden warming which occurred during a 2-yr Langley Research Center model simulation. The ability of the Langley Research Center GCM to simulate the major features of the stratospheric circulation during such highly disturbed periods is illustrated by comparison of the simulated warming to the observed circulation during the LIMS observation period. The apparent sink of vortex area associated with Rossby wave-breaking accounts for the majority of the reduction of the size of the vortex and also acts to offset the radiatively driven increase in the area occupied by the 'surf zone'. Trajectory analysis of selected material lines substantiates the conclusions from the area diagnostics.

  3. First forecast of a sudden stratospheric warming with a coupled whole-atmosphere/ionosphere model IDEA

    NASA Astrophysics Data System (ADS)

    Wang, H.; Akmaev, R. A.; Fang, T.-W.; Fuller-Rowell, T. J.; Wu, F.; Maruyama, N.; Iredell, M. D.

    2014-03-01

    We present the first "weather forecast" with a coupled whole-atmosphere/ionosphere model of Integrated Dynamics in Earth's Atmosphere (IDEA) for the January 2009 Sudden Stratospheric Warming (SSW). IDEA consists of the Whole Atmosphere Model and Global Ionosphere-Plasmasphere model. A 30 day forecast is performed using the IDEA model initialized at 0000 UT on 13 January 2009, 10 days prior to the peak of the SSW. IDEA successfully predicts both the time and amplitude of the peak warming in the polar cap. This is about 2 days earlier than the National Centers for Environmental Prediction operational Global Forecast System terrestrial weather model forecast. The forecast of the semidiurnal, westward propagating, zonal wave number 2 (SW2) tide in zonal wind also shows an increase in the amplitude and a phase shift to earlier hours in the equatorial dynamo region during and after the peak warming, before recovering to their prior values about 15 days later. The SW2 amplitude and phase changes are shown to be likely due to the stratospheric ozone and/or circulation changes. The daytime upward plasma drift and total electron content in the equatorial American sector show a clear shift to earlier hours and enhancement during and after the peak warming, before returning to their prior conditions. These ionospheric responses compare well with other observational studies. Therefore, the predicted ionospheric response to the January 2009 SSW can be largely explained in simple terms of the amplitude and phase changes of the SW2 zonal wind in the equatorial E region.

  4. Estimating efficiency of the controlled sulphur emissions in the stratosphere to mitigate global warming

    NASA Astrophysics Data System (ADS)

    Eliseev, A. V.; Mokhov, I. I.; Chernokulsky, A. V.; Karpenko, A. A.

    2008-12-01

    An attempt is made to estimate an efficiency of sulphur loading in the stratosphere to mitigate global warming employing a large ensemble of numerical experiments with the climate model of intermediate complexity developed at the A.M.Obukhov Institute of Atmospheric Physics RAS (IAP RAS CM). In this ensemble, the model is forced by the historical+SRES A1B anthropogenical greenhouse gases+tropospheric sulphates scenario for 1860--2100 with an additional sulphur emissions in the stratosphere started in 2012. Different ensemble members were constructed by varying emission intensity, residence time and optical properites of stratospheric sulphur. Given global loading of the sulphates in the stratosphere, at the global basis the most efficient latitudinal distribution of geoengineering aerosols is that peaked between 50° N and 70° N. At regional scale other latitudinal distributions may be superior. In particular, the distributions peaked in the tropics are the most efficient to reduce warming in the subtropics and the distrbutions peaked at 50° N is the superior to mitigate annual warming in Siberia. However, an approach of geoengineering has inherent flaws. First, it results in a widespread dryness. The second, and perhaps more dangerous, issue is due to the fast removal of geoengineering climatic effect if the corresponding emissions are stopped. After this stop, climate trajectory returns to the non--mitigated one within few decades. This results in a necessity to continue a geoengineering mitigation very long in future. Third, estimated sulphur emissions amount 5-10 TgS/yr in 2050 and 10-14 TgS/yr in 2100 which is not a small part of the current emissions of tropospheric sulphates. The latter may lead to marked enhancement of the tropospheric sulphates pollution. The results obtained with the IAP RAS CM are further interpreted by making use of an energy--balance climate model. As a whole, the results obtained with this simpler model support conclusions made on

  5. Mesosphere-to-stratosphere descent of odd nitrogen in February-March 2009 after sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Salmi, S.-M.; Verronen, P. T.; Thölix, L.; Kyrölä, E.; Backman, L.; Karpechko, A. Yu.; Seppälä, A.

    2011-05-01

    We use the 3-D FinROSE chemistry transport model (CTM) and Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) observations to study connections between atmospheric dynamics and middle atmospheric NOx (NOx = NO + NO2) distribution. Two cases are considered in the northern polar regions: (1) descent of mesospheric NOx in February-March 2009 after a major sudden stratospheric warming (SSW) and, for comparison, (2) early 2007 when no NOx descent occurred. The model uses the European Centre for Medium-Range Weather Forecasts (ECMWF) operational data for winds and temperature, and we force NOx at the model upper altitude boundary (80 km) with ACE-FTS observations. We then compare the model results with ACE-FTS observations at lower altitudes. For the periods studied, geomagnetic indices are low, which indicates absence of local NOx production by particle precipitation. This gives us a good opportunity to study effects of atmospheric transport on polar NOx. The model results show no NOx descent in 2007, in agreement with ACE-FTS. In contrast, a large amount of NOx descends in February-March 2009 from the upper to lower mesosphere at latitudes larger than 60° N, i.e. inside the polar vortex. Both observations and model results suggest NOx increases of 150-200 ppb (i.e. by factor of 50) at 65 km due to the descent. However, the model underestimates the amount of NOx around 55 km by 40-60 ppb. According to the model results, chemical loss of NOx is insignificant during the descent period, i.e. polar NOx is mainly controlled by dynamics. The descent is terminated and the polar NOx amounts return to pre-descent levels in mid-March, when the polar vortex breaks. The break-up prevents the descending NOx from reaching the upper stratosphere, where it could participate in catalytic ozone destruction. Both ACE-FTS observations and FinROSE show a decrease of ozone of 20-30 % at 30-50 km from mid-February to mid-March. In the model, these ozone changes are not

  6. Towards a physical understanding of stratospheric cooling under global warming through a process-based decomposition method

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Ren, R.-C.; Cai, Ming

    2016-02-01

    The stratosphere has been cooling under global warming, the causes of which are not yet well understood. This study applied a process-based decomposition method (CFRAM; Coupled Surface-Atmosphere Climate Feedback Response Analysis Method) to the simulation results of a Coupled Model Intercomparison Project, phase 5 (CMIP5) model (CCSM4; Community Climate System Model, version 4), to demonstrate the responsible radiative and non-radiative processes involved in the stratospheric cooling. By focusing on the long-term stratospheric temperature changes between the "historical run" and the 8.5 W m-2 Representative Concentration Pathway (RCP8.5) scenario, this study demonstrates that the changes of radiative radiation due to CO2, ozone and water vapor are the main divers of stratospheric cooling in both winter and summer. They contribute to the cooling changes by reducing the net radiative energy (mainly downward radiation) received by the stratospheric layer. In terms of the global average, their contributions are around -5, -1.5, and -1 K, respectively. However, the observed stratospheric cooling is much weaker than the cooling by radiative processes. It is because changes in atmospheric dynamic processes act to strongly mitigate the radiative cooling by yielding a roughly 4 K warming on the global average base. In particular, the much stronger/weaker dynamic warming in the northern/southern winter extratropics is associated with an increase of the planetary-wave activity in the northern winter, but a slight decrease in the southern winter hemisphere, under global warming. More importantly, although radiative processes dominate the stratospheric cooling, the spatial patterns are largely determined by the non-radiative effects of dynamic processes.

  7. Stratospheric Impacts on Arctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Reichler, Thomas

    2016-04-01

    Long-term circulation change in the stratosphere can have substantial effects on the oceans and their circulation. In this study we investigate whether and how sea ice at the ocean surface responds to intraseasonal stratospheric variability. Our main question is whether the surface impact of stratospheric sudden warmings (SSWs) is strong and long enough to affect sea ice. A related question is whether the increased frequency of SSWs during the 2000s contributed to the rapid decrease in Arctic sea ice during this time. To this end we analyze observations of sea ice, NCEP/NCAR reanalysis, and a long control integration with a stratospherically-enhanced version of the GFDL CM2.1 climate model. From both observations and the model we find that stratospheric extreme events have a demonstrable impact on the distribution of Arctic sea ice. The areas most affected are near the edge of the climatological ice line over the North Atlantic, North Pacific, and the Arctic Ocean. The absolute changes in sea ice coverage amount to +/-10 %. Areas and magnitudes of increase and decrease are about the same. It is thus unlikely that the increased SSW frequency during the 2000s contributed to the decline of sea ice during that period. The sea ice changes are consistent with the impacts of a negative NAO at the surface and can be understood in terms of (1) dynamical change due to altered surface wind stress and (2) thermodynamical change due to altered temperature advection. Both dynamical and thermodynamical change positively reinforce each other in producing sea change. A simple advection model is used to demonstrate that most of the sea ice change can be explained from the sea ice drift due to the anomalous surface wind stress. Changes in the production or melt of sea ice by thermodynamical effects are less important. Overall, this study adds to an increasing body of evidence that the stratosphere not only impacts weather and climate of the atmosphere but also the surface and

  8. Upper atmosphere response to stratosphere sudden warming: Local time and height dependence simulated by GAIA model

    NASA Astrophysics Data System (ADS)

    Liu, Huixin; Jin, Hidekatsu; Miyoshi, Yasunobu; Fujiwara, Hitoshi; Shinagawa, Hiroyuki

    2013-02-01

    Abstract The whole atmosphere model GAIA is employed to shed light on atmospheric response to the 2009 major <span class="hlt">stratosphere</span> sudden <span class="hlt">warming</span> (SSW) from the ground to exobase. Distinct features are revealed about SSW impacts on thermospheric temperature and density above 100 km altitude. (1) The effect is primarily quasi-semidiurnal in tropical regions, with <span class="hlt">warming</span> in the noon and pre-midnight sectors and cooling in the dawn and dusk sectors. (2) This pattern exists at all altitudes above 100 km, with its phase being almost constant above 200 km, but propagates downward in the lower thermosphere between 100 and 200 km. (3) The northern polar region experiences <span class="hlt">warming</span> in a narrow layer between 100 and 130 km, while the southern polar region experiences cooling throughout 100-400 km altitudes. (4) The global net thermal effect on the atmosphere above 100 km is a cooling of approximately -12 K. These characteristics provide us with an urgently needed global context to better connect and understand the increasing upper atmosphere observations during SSW events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.A33K0344C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.A33K0344C&link_type=ABSTRACT"><span id="translatedtitle">The Plunger Hypothesis: an overview of a new theory of <span class="hlt">stratosphere</span>-troposphere dynamic coupling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clark, S.; Baldwin, M. P.; Stephenson, D.</p> <p>2015-12-01</p> <p>I will demonstrate the advantages of a new method of quantifying polar <span class="hlt">stratosphere</span>-troposphere coupling by considering large-scale movements of mass into and out of the polar <span class="hlt">stratosphere</span>. This project aims to use these mass movements to explain pressure and temperature anomalies throughout the polar troposphere and lower <span class="hlt">stratosphere</span> in the aftermath of extreme <span class="hlt">stratospheric</span> events. We hypothesise that these mass movements are induced by deposition of momentum by breaking waves in the <span class="hlt">stratosphere</span>, slowing the wintertime polar vortex, and so are associated with sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> (<span class="hlt">SSWs</span>). Such a mass movement in the upper <span class="hlt">stratosphere</span> acts to compress the polar atmosphere below it in the manner of a plunger. In this way the pressure anomaly in the upper polar <span class="hlt">stratosphere</span> 'controls' the pressure and temperature anomalies below by adiabatic compression of the polar atmospheric column. Better understanding this method of control will allow us to use <span class="hlt">stratospheric</span> data to improve medium-range forecasting ability in the troposphere. One of the key innovations featured in this project is considering pressure and temperature fields at fixed geopotential surfaces, allowing for the easy observation of mass movement into and out of a polar cap region (which we have defined as north of 65N) as a function of altitude. Reanalysis data considered in this manner demonstrates a relationship between tropospheric pressure anomalies and <span class="hlt">stratospheric</span> anomalies in the polar cap, and so a way to predict tropospheric variability given <span class="hlt">stratospheric</span> information. This work forms part of a three and a half year PhD project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSA41B2340M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSA41B2340M"><span id="translatedtitle">Lunar tidal effects during the 2013 <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> as simulated by the TIME-GCM</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maute, A. I.; Forbes, J. M.; Zhang, X.; Fejer, B. G.; Yudin, V. A.; Pedatella, N. M.</p> <p>2015-12-01</p> <p><span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warmings</span> (SSW) are associated with strong planetary wave activity in the winterpolar <span class="hlt">stratosphere</span> which result in a very disturbed middle atmosphere. The changes in the middle atmospherealter the propagation conditions and the nonlinear interactions of waves and tides, and result in SSW signals in the upper atmosphere in e.g., neutral winds, electric fields, ionospheric currents and plasma distribution. The upper atmosphere changes can be significant at low-latitudes even during medium solar flux conditions. Observationsalso reveal a strong lunar signal during SSW periods in the low latitude vertical drifts and in ionospheric quantities. Forbes and Zhang [2012] demonstrated that during the 2009 SSW period the Pekeris resonance peak of the atmosphere was altered such that the M2 and N2 lunar tidal componentsgot amplified. This study focuses on the effect of the lunar tidal forcing on the thermosphere-ionosphere system during theJanuary 2013 SSW period. We employthe NCAR Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM)with a nudging scheme using the Whole-Atmosphere-Community-Climate-Model-Extended (WACCM-X)/Goddard Earth Observing System Model, Version 5 (GEOS5) results to simulate the effects of meteorological forcing on the upper atmosphere. Additionally lunar tidal forcingis included at the lower boundary of the model. To delineate the lunar tidal effects a base simulation without lunar forcingis employed. Interestingly, Jicamarca observations of that period reveal a suppression of the daytime vertical drift before and after the drift enhancement due the SSW. The simulation suggests that the modulation of the vertical driftmay be caused by the interplay of the migrating solar and lunar semidiurnal tide, and therefore can only be reproduced by the inclusion of both lunar and solar tidal forcings in the model. In this presentation the changes due to the lunar tidal forcing will be quantified, and compared</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38..982P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38..982P"><span id="translatedtitle">The polar Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> (SSW) and it's possible manifestations in the equatorial Mesosphere-Thermosphere-Ionosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pant, Tarun</p> <p></p> <p>In this study, the variations in daytime mesopause temperature and the Equatorial Electrojet over equator during Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> (SSW) events over high latitudes have been investigated. To reflect upon the <span class="hlt">stratospheric</span> conditions NCEP-NCAR reanalysis data have also been used. This study indicates a possible dynamical coupling between the two regions through the planetary wave activity. The amplified wave signatures of quasi-16 day period are seen in the equatorial mesopause temperature and zonal mean polar <span class="hlt">stratospheric</span> temperature (at 10 hPa) during the course of SSW. The possibility that the planetary waves over the polar <span class="hlt">stratosphere</span>, which play an important role in the generation of SSW, could also have contribu-tion from the tropics has been indicated through numerical simulations in the past [Dunkerton, 1981], but due to the paucity of global measurements it could not be established unequivocally. These simulations also indicated the presence of a zero-wind line whose real counterparts were not observed in the atmosphere. The NCEP-NCAR reanalysis of <span class="hlt">stratospheric</span> wind and tem-peratures clearly shows that (i) a dynamical feature similar to the zero-wind line appears over the tropics 60 days prior to the major <span class="hlt">warming</span> and progresses poleward and, (ii) enhanced PW activity is seen almost simultaneously. This study shows that the recent SSW events had tropical associations. Further, favored occurrences of Equatorial Counter Electrojets (CEJs) with a quasi 16-day periodicity over Trivandrum (8.5oN, 76.5oE, 0.5oN diplat.) in association with the polar <span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warming</span> (SSW) events are presented. It is seen that, the <span class="hlt">stratospheric</span> temperature at 30 km over Trivandrum showed a sudden cooling prior to the SSW and the first bunch of CEJs occurred around this time. <span class="hlt">Stratospheric</span> zonal mean zonal wind at 30 km exhibited a distinctly different pattern during the SSW period. These circula-tion changes are proposed to be conducive for the upward</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.2343P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.2343P"><span id="translatedtitle">The polar Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> (SSW) and it's possible manifestations in the equatorial Mesosphere-Thermosphere-Ionosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pant, Tarun; Vineeth, C.; Sridharan, R.</p> <p></p> <p>In this study, the variations in daytime mesopause temperature and the Equatorial Electrojet over equator during Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> (SSW) events over high latitudes have been investigated. To reflect upon the <span class="hlt">stratospheric</span> conditions NCEP-NCAR reanalysis data have also been used. This study indicates a possible dynamical coupling between the two regions through the planetary wave activity. The amplified wave signatures of quasi-16 day period are seen in the equatorial mesopause temperature and zonal mean polar <span class="hlt">stratospheric</span> temperature (at 10 hPa) during the course of SSW. The possibility that the planetary waves over the polar <span class="hlt">stratosphere</span>, which play an important role in the generation of SSW, could also have contribution from the tropics has been indicated through numerical simulations in the past [Dunkerton, 1981], but due to the paucity of global measurements it could not be established unequivocally. These simulations also indicated the presence of a zero-wind line whose real counterparts were not observed in the atmosphere. The NCEP-NCAR reanalysis of <span class="hlt">stratospheric</span> wind and temperatures clearly shows that (i) a dynamical feature similar to the zero-wind line appears over the tropics 60 days prior to the major <span class="hlt">warming</span> and progresses poleward and, (ii) enhanced PW activity is seen almost simultaneously. This study shows that the recent SSW events had tropical associations. Further, favored occurrences of Equatorial Counter Electrojets (CEJs) with a quasi 16-day periodicity over Trivandrum (8.5oN, 76.5oE, 0.5oN diplat.) in association with the polar <span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warming</span> (SSW) events are presented. It is seen that, the <span class="hlt">stratospheric</span> temperature at 30 km over Trivandrum showed a sudden cooling prior to the SSW and the first bunch of CEJs occurred around this time. <span class="hlt">Stratospheric</span> zonal mean zonal wind at 30 km exhibited a distinctly different pattern during the SSW period. These circulation changes are proposed to be conducive for the upward</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1710094S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1710094S"><span id="translatedtitle">Subtropical influence on January 2009 major sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> event: diagnostic analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schneidereit, Andrea; Peters, Dieter; Grams, Christian; Wolf, Gabriel; Riemer, Michael; Gierth, Franziska; Quinting, Julian; Keller, Julia; Martius, Olivia</p> <p>2015-04-01</p> <p>In January 2009 a major sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (MSSW) event occurred with the strongest NAM anomaly ever observed at 10 hPa. Also <span class="hlt">stratospheric</span> Eliassen-Palm flux convergence and zonal mean eddy heat fluxes of ultra-long waves at 100 hPa layer were unusually strong in the mid-latitudes just before and after the onset of the MSSW. Beside internal interactions between the background flow and planetary waves and between planetary waves among themselves the subtropical tropospheric forcing of these enhanced heat fluxes is still an open question. This study investigates in more detail the dynamical reasons for the pronounced heat fluxes based on ERA-Interim re-analysis data. Investigating the regional contributions of the eddy heat flux to the northern hemispheric zonal mean revealed a distinct spatial pattern with maxima in the Eastern Pacific/North America and the Eastern North Atlantic/ Europe in that period. The first region is related with an almost persistent tropospheric blocking high (BH) over the Gulf of Alaska dominating the upper-level flow and the second region with a weaker BH over Northern Europe. The evolution of the BH over the Gulf of Alaska can be explained by a chain of tropospheric weather events linked to and maintained by subtropical and tropical influences: MJO (phase 7-8) and the developing cold phase of ENSO (La Niña), which are in coherence over the Eastern Pacific favor enhanced subtropical baroclinicity. In turn extratropical cyclone activity increases and shifts more poleward associated with an increase of the frequency of <span class="hlt">warm</span> conveyor belts (WCB). These WCBs support enhanced poleward directed eddy heat fluxes in Eastern Pacific/North-American region. The Eastern North Atlantic/European positive heat flux anomaly is associated with a blocking high over Scandinavia. This BH is maintained by an eastward propagating Rossby wave train, emanating from the block over the Gulf of Alaska. Eddy feedback processes support this high pressure</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ACP....16.4885G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ACP....16.4885G"><span id="translatedtitle">Influence of the sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> on quasi-2-day waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gu, Sheng-Yang; Liu, Han-Li; Dou, Xiankang; Li, Tao</p> <p>2016-04-01</p> <p>The influence of the sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) on a quasi-2-day wave (QTDW) with westward zonal wave number 3 (W3) is investigated using the Thermosphere-Ionosphere-Mesosphere Electrodynamics General Circulation Model (TIME-GCM). The summer easterly jet below 90 km is strengthened during an SSW, which results in a larger refractive index and thus more favorable conditions for the propagation of W3. In the winter hemisphere, the Eliassen-Palm (EP) flux diagnostics indicate that the strong instabilities at middle and high latitudes in the mesopause region are important for the amplification of W3, which is weakened during SSW periods due to the deceleration or even reversal of the winter westerly winds. Nonlinear interactions between the W3 and the wave number 1 stationary planetary wave produce QTDW with westward zonal wave number 2 (W2). The meridional wind perturbations of the W2 peak in the equatorial region, while the zonal wind and temperature components maximize at middle latitudes. The EP flux diagnostics indicate that the W2 is capable of propagating upward in both winter and summer hemispheres, whereas the propagation of W3 is mostly confined to the summer hemisphere. This characteristic is likely due to the fact that the phase speed of W2 is larger, and therefore its waveguide has a broader latitudinal extension. The larger phase speed also makes W2 less vulnerable to dissipation and critical layer filtering by the background wind when propagating upward.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1410911K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1410911K"><span id="translatedtitle">Simultaneous microwave measurements of middle atmospheric ozone and temperature during sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kulikov, M. Y.; Krasil'nikov, A. A.; Shvetsov, A. A.; Mukhin, D. N.; Fedoseev, L. I.; Ryskin, V. G.; Belikovich, M. V.; Karashtin, D. A.; Kukin, L. M.; Feigin, A. M.</p> <p>2012-04-01</p> <p>At the present time we carry out the experimental campaign aimed to study the response of middle atmosphere on current sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> above Nizhny Novgorod, Russia (56N, 44E). The equipment consists of two room-temperature radiometers which specially have been designed to detect emission ozone line at 110.8 GHz and atmospheric radiation in the frequency range 52.5 - 54.5 GHz accordingly. Two digital fast Fourier transform spectroanalyzers developed by "Acqiris" are employed for signal analysis in the intermediate frequency range 0.05-1 GHz with the effective resolution 61 KHz. For retrieval vertical profiles of ozone and temperature from radiometric data we apply novel method based on Bayesian approach to inverse problems which assumes a construction of probability distribution of the characteristics of retrieved profiles with taking into account measurement noise and available a priori information about possible distributions of ozone and temperature in the middle atmosphere. Here we are going to introduce the fist results of the campaign in comparison with Aura MLS data and temperature maps from High Resolution Transport Model MIMOSA. The work was done under support of the RFBR (projects 11-05-97050 and 12-05-00999).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSA41B2341G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSA41B2341G"><span id="translatedtitle">Deep Ionospheric Hole Created by Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> in the Nighttime Ionosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goncharenko, L. P.</p> <p>2015-12-01</p> <p>Multiple observational studies have demonstrated large ionospheric variations associated with sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) events during the daytime, but only limited evidence of ionospheric disturbances during the night-time was reported up to now. We focus on the American longitudinal sector with its extensive observational network and utilize observations by GPS receivers, three digisondes located at low and middle latitudes, and Arecibo and Millstone Hill incoherent scatter radars. The study focuses on a major SSW event of January 2013 to investigate large-scale disturbances in the nighttime ionosphere. We report a deep decrease in TEC that reaches a factor of 2-6 as compared to the background level and is observed between the local midnight and local sunrise (6-12UT). This decrease is observed for several consecutive days in the range of latitudes from ~55oS to ~45oN. It is accompanied by a strong downward plasma motion and a significant decrease in ion temperature, as observed by both Arecibo and Millstone Hill radars. We discuss variations in electric field and F-region dynamics as possible drivers of this behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18..982G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18..982G"><span id="translatedtitle">Worldwide impacts of sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> on the ionosphere and thermosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goncharenko, Larisa; Coster, Anthea; Zhang, Shun-Rong; Erickson, Phillip; Aponte, Nestor; Harvey, V. Lynn; Pedatella, Nicholas; Maute, Astrid</p> <p>2016-04-01</p> <p>Recent studies have demonstrated large variations in the low-latitude ionosphere during strong, persistent meteorological disturbances known as sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span>. Several possible lower/upper atmosphere coupling mechanisms were identified, including changes in the dynamics of the background neutral atmosphere, modification of solar and lunar tides, and subsequent variations in electric field. We extend these studies using observations by GNSS TEC receivers, by several ionosondes located at low, middle, and high latitudes, and by Jicamarca, Arecibo and Millstone Hill incoherent scatter radars to investigate large-scale ionospheric disturbances for several SSW events. To separate ionospheric anomalies associated with SSW from regular ionospheric behavior, we develop an empirical model of ionospheric parameters (TEC, NmF2) using available long-term data records (10-40 years of data depending on the instrument). The models describe variations in parameters for each longitude/latitude bin (or ionosonde location) as a function of solar activity, geomagnetic activity, day of year, and local time. Ionospheric anomalies are obtained as the difference between the observations and the empirical model. Ionospheric anomalies are observed for both major and minor SSW events, reaching 50-100% variation from expected seasonal behavior for major SSW events and 30-60% variation for minor SSW events. The largest variations in the daytime TEC and NmF2 are observed both in the crests of equatorial ionization anomaly and at 40-60S (geodetic). Recent expansion of GNSS TEC receiver network to high latitudes in the southern hemisphere indicates that SSW anomalies are communicated across the globe and associated with ionospheric disturbances even over Antarctica. Observational studies focused on SSW events present an important opportunity to better understand processes governing the behavior of the Earth's ionosphere and thermosphere. We use examples of observations from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E1115L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E1115L&link_type=ABSTRACT"><span id="translatedtitle">Vertical and Horizontal Coupling of Atmospheres During Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> Events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laskar, Fazlul; Pallamraju, Duggirala; Chau, Jorge L.</p> <p>2016-07-01</p> <p>The dynamics of neutral behavior over low- mid- and high-latitudes and electrodynamic behavior over low-latitude middle and upper atmosphere during sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) events have been investigated in this study. Over a decade long datasets of equatorial electrojet (EEJ) and total electron content (TEC) from Indian longitudes at low-latitudes have been used for studying the electrodynamical behavior. From the amplitudes of quasi-16 day waves in these two datasets it has been observed that the vertical coupling is stronger during strong major SSW events and weaker but significant for the minor SSW events. The neutral dynamical behavior has been investigated using both optical and radio measurements. The oxygen dayglow emission intensities from low-latitudes showed enhancements in and around the duration of SSW occurrences. Evidences of equatorward winds at mesosphere lower thermosphere altitude from TIMED-TIDI and lower-thermospheric temperature enhancements from TIMED-SABER are observed in the duration of enhancement in dayglow emission intensities. The results from these three independent datasets and discrete results from earlier modeling and observational studies suggest that an equatorward circulation in the winds is set up in the MLT-region during SSW. The low-latitude oxygen intensity enhancements during SSW are attributed to be due to the transport of oxygen from high- to low-latitudes. Enhanced semi-diurnal tides are also observed during the SSW events in the low-latitude dayglow emission intensities and specular meteor radar-based mid- and high-latitude horizontal winds. These results will be presented in the context of neutral and wave dynamics of the mesosphere-thermosphere region during SSW events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014cosp...40E2462P&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014cosp...40E2462P&link_type=ABSTRACT"><span id="translatedtitle">Ionospheric variability over Indian low latitude linked with the 2009 sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Patra, Amit; Alex, Sobhana; Samireddipalle, Sripathi; Peddapati, PavanChaitanya</p> <p></p> <p>In this paper, we analyze radar observations of ExB drift and plasma irregularities, ionosonde observations of E- and F-layer parameters including spread F, and magnetic field observations made from Indian low latitudes linked with the 2009 sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) event. ExB drift variations presented here are the first of their kind from the Indian sector as far as the effect of SSW is concerned. Difference of magnetic fields observed from the equator and low latitude (∆H) and ExB drift show linear relation and both show remarkably large positive values in the morning and negative values in the afternoon exhibiting semidiurnal behavior. Remarkable changing patterns in the critical frequency of F2 layer (foF2) and F3 layer (foF3) were observed after the occurrence of SSW. Large variations with quasi-16-day periodicity were observed in ∆H, foF2 and foF3. Both semidiurnal and quasi-16-day wave modulation observed after the 2009 SSW event are consistent with those reported earlier. We also noted quasi-6 day variations in ∆H and foF2 soon after the SSW commencement, not much reported before. During the counter-electrojet events linked with the SSW event, while equatorial Es (Esq) disappeared as expected, there were no blanketing Es (Esb), a finding not reported and discussed earlier. Esb was also not formed at the off-equatorial location, indicating the absence of required vertical wind shear, but E region plasma irregularities were observed by the ionosonde and radar with a close relationship between the two. Weak F region irregularities were observed in the post-midnight hours and case studies suggest the possible role of SSW related background electric field in the manifestation of post-midnight F region irregularities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014JGRA..119.4044P&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014JGRA..119.4044P&link_type=ABSTRACT"><span id="translatedtitle">Ionospheric variability over Indian low latitude linked with the 2009 sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Patra, A. K.; Pavan Chaitanya, P.; Sripathi, S.; Alex, S.</p> <p>2014-05-01</p> <p>In this paper, we analyze radar observations of E × B drift and plasma irregularities, ionosonde observations of E and F layer parameters including spread F, and magnetic field observations made from Indian low latitudes linked with the 2009 sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) event. E × B drift variations presented here are the first of their kind from the Indian sector as far as the effect of SSW is concerned. Difference of magnetic fields observed from the equator and low-latitude (∆H) and E × B drift show linear relation, and both show remarkably large positive values in the morning and negative values in the afternoon exhibiting semidiurnal behavior. Remarkable changing patterns in the critical frequency of F2 layer (foF2) and F3 layer (foF3) were observed after the occurrence of SSW. Large variations with quasi 16 day periodicity were observed in ∆H, foF2, and foF3. Both semidiurnal and quasi 16 day wave modulation observed after the 2009 SSW event are consistent with those reported earlier. We also noted quasi 6 day variations in ∆H and foF2 soon after the SSW commencement, not much reported before. During the counterelectrojet events linked with the SSW event, while equatorial Es (Esq) disappeared as expected, there were no blanketing Es (Esb), a finding not reported and discussed earlier. Esb was also not formed at the off-equatorial location, indicating the absence of required vertical wind shear, but E region plasma irregularities were observed by the ionosonde and radar with a close relationship between the two. Weak F region irregularities were observed in the postmidnight hours, and case studies suggest the possible role of SSW-related background electric field in the manifestation of postmidnight F region irregularities.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E1342J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E1342J"><span id="translatedtitle">Atmospheric and Ionospheric Response to <span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warming</span> of January 2013.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jonah, Olusegun Folarin; De Paula, Eurico; Kherani, Esfhan alam; Severino, Dutra</p> <p></p> <p>In this work, we examine the atmospheric and ionospheric responses to the January 2013 <span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warming</span> (SSW) event. To examine the atmospheric and ionospheric behavior during this event, three main parameters are used: (1) Total Electron Content (TEC) collected from the International Global Positioning System (IGS) and from the Brazilian Network of Continuous Monitoring (RBMC) stations, (2) Daytime ExB vertical drift derived from the magnetometers located at the equatorial station Alta Floresta (9.9ºS, 55.9ºW, dip lat: 1.96º) and an off equatorial station Cuiaba (15.3ºS, 56.0ºW, dip lat: 7.10º), both in the Brazilian sector, (3) The Mesosphere and lower thermosphere (MLT) meridional and zonal wind components measured by the Meteor Radar located at the southern mid-latitude Santa Maria (29.4ºS, 53.3ºW, dip lat: 17.8º). We identify the anomalous variation in ExB drift based on later local time migration of peak value with SSW days, as reported recently by Goncharenko et al [2013]. A novel feature of the present study is the identification of the similar migration pattern in the TEC anomaly, in spite that the simultaneous solar-flux increase during the SSW event also acts as another dominant forcing. Other novel features are the amplification of the 13-16 day periods in the TEC anomaly during the SSW days, and simultaneous amplification of these periods in the meridional and zonal wind components in the MLT region. These aspects reveal the presence of coupled atmosphere-ionosphere dynamics during the SSW event and the amplification of the lunar and/or solar tidal component, a characteristic which is recently reported from the electrojet current measurements [Park et al, 2012].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRA..119.4973J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRA..119.4973J"><span id="translatedtitle">Atmospheric and ionospheric response to sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> of January 2013</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jonah, O. F.; Paula, E. R.; Kherani, E. A.; Dutra, S. L. G.; Paes, R. R.</p> <p>2014-06-01</p> <p>In this work, we examine the atmospheric and ionospheric responses to the January 2013 sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) event. To examine the atmospheric and ionospheric behavior during this event, three main parameters are used (1) Total Electron Content (TEC) collected from the International Global Positioning System and from the Brazilian Network of Continuous Monitoring stations, (2) daytime E × B vertical drift derived from the magnetometers located at the equatorial station Alta Floresta (9.9°S, 55.9°W, dip latitude 1.96°) and an off-equatorial station Cuiaba (15.3°S, 56.0°W, dip latitude 7.10°), both in the Brazilian sector, (3) the mesosphere and lower thermosphere (MLT) meridional and zonal wind components measured by the Meteor Radar located at the southern midlatitude Santa Maria (29.4°S, 53.3°W, dip latitude 17.8°). We identify the anomalous variation in E × B drift based on later local-time migration of peak value with SSW days. A novel feature of the present study is the identification of the similar migration pattern in the TEC anomaly, in spite that the simultaneous solar flux increases during the SSW event. Other novel features are the amplification of the 13-16 day period in the TEC anomaly during the SSW days and simultaneous amplification of this period in the meridional and zonal wind components in the MLT region, as far as 30°S. These aspects reveal the presence of coupled atmosphere-ionosphere dynamics during the SSW event and the amplification of the lunar and/or solar tidal component, a characteristic which is recently reported from the electrojet current measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140012679','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140012679"><span id="translatedtitle">The Major <span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warming</span> of January 2013: Analyses and Forecasts in the GEOS-5 Data Assimilation System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coy, Lawrence; Pawson, Steven</p> <p>2014-01-01</p> <p>We examine the major <span class="hlt">stratosphere</span> sudden <span class="hlt">warming</span> (SSW) that occurred on 6 January 2013, using output from the NASA Global Modeling and Assimilation Office (GMAO) GEOS-5 (Goddard Earth Observing System) near-real-time data assimilation system (DAS). Results show that the major SSW of January 2013 falls into the vortex splitting type of SSW, with the initial planetary wave breaking occurring near 10 hPa. The vertical flux of wave activity at the tropopause responsible for the SSW occurred mainly in the Pacific Hemisphere, including the a pulse associated with the preconditioning of the polar vortex by wave 1 identified on 23 December 2012. While most of the vertical wave activity flux was in the Pacific Hemisphere, a rapidly developing tropospheric weather system over the North Atlantic on 28 December is shown to have produced a strong transient upward wave activity flux into the lower <span class="hlt">stratosphere</span> coinciding with the peak of the SSW event. In addition, the GEOS-5 5-day forecasts accurately predicted the major SSW of January 2013 as well as the upper tropospheric disturbances responsible for the <span class="hlt">warming</span>. The overall success of the 5-day forecasts provides motivation to produce regular 10-day forecasts with GEOS-5, to better support studies of <span class="hlt">stratosphere</span>-troposphere interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014cosp...40E2255N&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014cosp...40E2255N&link_type=ABSTRACT"><span id="translatedtitle">The Tropospheric cooling and the <span class="hlt">Stratospheric</span> <span class="hlt">warming</span> at Tirunelveli during the Annular Solar Eclipse of 15 January, 2010</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nelli, Narendra Reddy; Choudhary, Raj Kumar; Rao, Kusuma</p> <p></p> <p>The UTLS region, a transition region between the troposphere and the <span class="hlt">stratosphere</span> is of concern to climate scientists as its temperature variations are crucial in determining the water vapour and the other trace gases transport between the two regions, which inturn determine the radiative <span class="hlt">warming</span> and cooling of the troposphere and the <span class="hlt">stratosphere</span>. To examine, the temperature variations from surface to lower <span class="hlt">stratosphere</span>,a major experiment facility was set up for upper air and surface measurements during the Annular Solar Eclipse (ASE) of January 15, 2010 at Tirunelveli (8.72 N, 77.81 E) located in 94% eclipse path in the southern peninsular India. The instruments,namely, 1. high resolution GPS radiosonde system, 2. an instrumented 15 m high Mini Boundary Layer Mast, 3. an instrumented 1 m high Near Surface Mast (NSM), radiation and other ground sensors were operated during the period 14-19 Jan, 2010. The ASE of January 15, 2010 was unique being the longest in duration (9 min, 15.3 sec) among the similar ones that occurred in the past. The major inference from an analysis of surface and upper air measurements is the occurrence of troposphere cooling during the eclipse with the peak cooling of 5 K at 15 km height with respect to no-eclispe conditions. Also, intense <span class="hlt">warming</span> in the <span class="hlt">stratosphere</span> is observed with the peak <span class="hlt">warming</span> of 7 K at 19 km height.Cooling of the Troposphere as the eclipse advanced and the revival to its normal temperature is clearly captured in upper air measurements. The downward vertical velocities observed at 100 hPa in NCEP Re-analyses, consistent with the tropospheric cooling during the ASE window, may be causing the <span class="hlt">stratospheric</span> <span class="hlt">warming</span>. Partly, these vertical velocities could be induced by the mesoscale circulation associated with the mesoscale convective system that prevailed parallel to the eclipse path as described in METEOSAT imageries of brightness temperatures from IR channel. Further analysis is being carried out to quantify the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E2113Y&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E2113Y&link_type=ABSTRACT"><span id="translatedtitle">Gravity wave effects in the thermosphere during sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> and vertical coupling between the lower and upper atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yiǧit, Erdal; Medvedev, Alexander S.</p> <p>2016-07-01</p> <p>Gravity waves are primarily generated in the lower atmosphere, propagate upward, and have profound effects not only in the middle atmosphere but also at much higher altitudes. However, their effects in the upper atmosphere beyond the turbopause ( 105 km) have not been sufficiently studied. Using a general circulating model extending from the lower atmosphere to upper thermosphere and incorporating a whole atmosphere nonlinear parameterization of small-scale GWs developed by Yiǧit et al. (2008)}, we demonstrate that not only GWs penetrate into the thermosphere above the turbopause but also produce substantial dynamical and thermal effects that are comparable to ion drag and Joule heating. During sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span>, GW propagation in the thermosphere is enhanced by more than a factor of three (Yiǧit and Medvedev, 2012)}, producing appreciable body forcing of up to 600 m s^{-1} day^{-1} around 250-300 km. The resultant impact on the variability of the thermospheric circulation can exceed ± 50% depending on the phase of the sudden <span class="hlt">warming</span> (Yiǧit et al., 2014)}. References: Yiǧit, E., and A. S. Medvedev (2012), Gravity waves in the thermosphere during a sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span>, Geophys. Res. Lett., 39, L21101, doi:10.1029/2012GL053812. Yiǧit, E., A. D. Aylward, and A. S. Medvedev (2008), Parameterization of the effects of vertically propagating gravity waves for thermosphere general circulation models: Sensitivity study, J. Geophys. Res., 113, D19106, doi:10.1029/2008JD010135. Yiǧit, E., A. S. Medvedev, S. L. England, and T. J. Immel (2014), Simulated vari- ability of the high-latitude thermosphere induced by small-scale gravity waves during a sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span>, J. Geophys. Res. Space Physics, 119, doi:10.1002/2013JA019283.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7215K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7215K"><span id="translatedtitle">Definition of <span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warming</span> Events for Multi-Model Analysis and Its Application to the CMIP5</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Junsu; Son, Seok-Woo; Park, Hyo-Seok</p> <p>2015-04-01</p> <p>The onset of major <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> (SSW) events has been often defined as the date when the westerly at 10 hPa and 60°N turns to easterly during winter, corresponding to warmer polar <span class="hlt">stratosphere</span> than mid latitudes. This simple definition effectively detects the observed characteristics of SSW, but its application to climate models, which have different background flow and temporal variability, is often challenging. For example, the model whose <span class="hlt">stratospheric</span> mean wind is too weak tends to overestimate the frequency of zonal-wind reversal and SSW events. In this study we propose a simple definition of major SSW events that is applicable to multi-model analysis. Specifically, SSW events are defined when the tendency of zonal-mean zonal wind at 10 hPa at 60°N crosses -1 m/s/day within 30 to 40 days while growing in magnitude. This tendency-based definition, which is independent of mean wind, is applied to both ERA40 reanalysis and CMIP5 models. The models are further grouped into the high-top models with a well-resolved <span class="hlt">stratosphere</span> and low-top models with a relatively simple <span class="hlt">stratosphere</span>. A new definition successfully reproduces the mean frequency of SSW events that is identified by wind reversal approach, i.e., about 6 events per decade in ERA40. High-top models well capture this frequency. Although low-top models underestimate the frequency, in contrast to previous studies, the difference to high-top models is not statistically significant. Likewise, no significant difference is found in the downward coupling in the high-top and low-top models. These results indicate that model vertical resolution itself may not be a key factor in simulating SSW events and the associated downward coupling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSA23A2038L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSA23A2038L"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warming</span> Effects on the Ionospheric Migrating Tides during 2008-2010 observed by FORMOSAT-3/COSMIC</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, J.; Lin, C.; Chang, L. C.; Liu, H.; Chen, W.; Chen, C.; Liu, J. G.</p> <p>2013-12-01</p> <p>In this paper, ionospheric electron densities obtained from radio occultation soundings of FORMOSAT-3/COSMIC are decomposed into their various constituent tidal components for studying the <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> (SSW) effects on the ionosphere during 2008-2010. The tidal analysis indicates that the amplitudes of the zonal mean and major migrating tidal components (DW1, SW2 and TW3) decrease around the time of the SSW, with phase/time shifts in the daily time of maximum around EIA and middle latitudes. Meanwhile consistent enhancements of the SW2 and nonmigrating SW1 tides are seen after the <span class="hlt">stratospheric</span> temperature increase. In addition to the amplitude changes of the tidal components, well matched phase shifts of the ionospheric migrating tides and the <span class="hlt">stratospheric</span> temperatures are found for the three SSW events, suggesting a good indicator of the ionospheric response. Although the conditions of the planetary waves and the mean winds in the middle atmosphere region during the 2008-2010 SSW events may be different, similar variations of the ionospheric tidal components and their associated phase shifts are found. Futher, these ionospheric responses will be compared with realistic simulations of Thermosphere-Ionosphere-Mesophere-Electrodynamics General Circulation Model (TIME-GCM) by nudging Modern-Era Retrospective analysis for Research and Applications (MERRA) data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27051997','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27051997"><span id="translatedtitle">Dynamics of 2013 Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> event and its impact on cold weather over Eurasia: Role of planetary wave reflection.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nath, Debashis; Chen, Wen; Zelin, Cai; Pogoreltsev, Alexander Ivanovich; Wei, Ke</p> <p>2016-01-01</p> <p>In the present study, we investigate the impact of <span class="hlt">stratospheric</span> planetary wave reflection on tropospheric weather over Central Eurasia during the 2013 Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> (SSW) event. We analyze EP fluxes and Plumb wave activity fluxes to study the two and three dimensional aspects of wave propagation, respectively. The 2013 SSW event is excited by the combined influence of wavenumber 1 (WN1) and wavenumber 2 (WN2) planetary waves, which makes the event an unusual one and seems to have significant impact on tropospheric weather regime. We observe an extraordinary development of a ridge over the Siberian Tundra and the North Pacific during first development stage (last week of December 2012) and later from the North Atlantic in the second development stage (first week of January 2013), and these waves appear to be responsible for the excitation of the WN2 pattern during the SSW. The wave packets propagated upward and were then reflected back down to central Eurasia due to strong negative wind shear in the upper <span class="hlt">stratospheric</span> polar jet, caused by the SSW event. Waves that propagated downward led to the formation of a deep trough over Eurasia and brought extreme cold weather over Kazakhstan, the Southern part of Russia and the Northwestern part of China during mid-January 2013. PMID:27051997</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1412921S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1412921S"><span id="translatedtitle">HALO aircraft measurements of East Asian anthropogenic SO2 import into the lower <span class="hlt">stratosphere</span> by a <span class="hlt">warm</span> conveyor belt uplift</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schlager, H.; Arnold, F.; Aufmhoff, H.; Baumann, R.; Pirjola, L.; Roiger, A.; Sailer, T.; Wirth, M.; Schumann, U.</p> <p>2012-04-01</p> <p>We report on a case study of anthropogenic SO2 pollution transport into the lower <span class="hlt">stratosphere</span> from East Asian source regions. The pollution layer was observed over Central Europe by measurements from the new German research aircraft HALO. The layer contained enhanced SO2, HNO3 and water vapor and caused increased Lidar backscatter radiation. Meteorological analysis and air mass transport and dispersion model simulations reveal that the detected pollutants were released from ground-based sources in East-China, South-Korea, and Japan. The pollution plume was uplifted by a <span class="hlt">warm</span> conveyor belt associated with a West-Pacific cyclone and finally injected into the lower <span class="hlt">stratosphere</span>. Our HALO measurements were performed 5 days after the air mass uplift event, when significant parts of the Northern Hemisphere were already covered by the pollution plume. Accompanying trajectory chemistry and aerosol box model simulations indicate that H2SO4/H2O aerosol droplets were generated in the SO2-rich plume and grew to sizes large enough to explain the observed increased Lidar backscatter signal. Implications of the SO2 transport pathway into the lower <span class="hlt">stratosphere</span> presented in this study will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4823715','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4823715"><span id="translatedtitle">Dynamics of 2013 Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> event and its impact on cold weather over Eurasia: Role of planetary wave reflection</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nath, Debashis; Chen, Wen; Zelin, Cai; Pogoreltsev, Alexander Ivanovich; Wei, Ke</p> <p>2016-01-01</p> <p>In the present study, we investigate the impact of <span class="hlt">stratospheric</span> planetary wave reflection on tropospheric weather over Central Eurasia during the 2013 Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> (SSW) event. We analyze EP fluxes and Plumb wave activity fluxes to study the two and three dimensional aspects of wave propagation, respectively. The 2013 SSW event is excited by the combined influence of wavenumber 1 (WN1) and wavenumber 2 (WN2) planetary waves, which makes the event an unusual one and seems to have significant impact on tropospheric weather regime. We observe an extraordinary development of a ridge over the Siberian Tundra and the North Pacific during first development stage (last week of December 2012) and later from the North Atlantic in the second development stage (first week of January 2013), and these waves appear to be responsible for the excitation of the WN2 pattern during the SSW. The wave packets propagated upward and were then reflected back down to central Eurasia due to strong negative wind shear in the upper <span class="hlt">stratospheric</span> polar jet, caused by the SSW event. Waves that propagated downward led to the formation of a deep trough over Eurasia and brought extreme cold weather over Kazakhstan, the Southern part of Russia and the Northwestern part of China during mid-January 2013. PMID:27051997</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E2004V&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E2004V&link_type=ABSTRACT"><span id="translatedtitle">Total Electron Content (TEC) disturbances over Brazilian region during the minor sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW 2012) event of January 2012</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vieira, Francisco; Fagundes, Paulo Roberto; Kavutarapu, Venkatesh; Gil Pillat, Valdir</p> <p>2016-07-01</p> <p>The effects of Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> on ionosphere have been investigated by several scientists, using different observational techniques and model simulations. However, the 2011-2012 minor event is one of those that are less studied. Since, the zonal westward wind is slowed without reversing to eastward, this SSW was consider as a minor event. The <span class="hlt">stratospheric</span> temperature started increasing on December 26, 2011, reached its peak on January 18, 2012, and afterwards started decreasing slowly. In addition, there was moderate geomagnetic storm on January 22-25, 2012, after the SSW temperature peak. In the present study, the GPS-TEC measurements from a network of 72 receivers over the Brazilian region are considered. This network of 72 GPS-TEC locations lies between 5 N and 30 S (35 degrees) latitudes and 35 W and 65 W (30 degrees) longitudes. Further, two chains of GPS receivers are used to study the response of Equatorial Ionization Anomaly (EIA) changes in the Brazilian East and West sectors, as well as its day-to-day variability before and during the SSW2012. It was noted that the TEC is depleted to the order of 30% all over the Brazilian region, from equator to beyond the EIA regions and from East to West sectors. It is also noticed that the EIA strengths at East and West sectors were suppressed after the <span class="hlt">stratospheric</span> temperature peak. However, the Brazilian West sector was found to be more disturbed compared to the East sector during this SSW event.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110005602','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110005602"><span id="translatedtitle">Can the GEOS CCM Simulate the Temperature Response to <span class="hlt">Warm</span> Pool El Nino Events in the Antarctic <span class="hlt">Stratosphere</span>?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hurwitz, M. M.; Song, I.-S.; Oman, L. D.; Newman, P. A.; Molod, A. M.; Frith, S. M.; Nielsen, J. E.</p> <p>2010-01-01</p> <p>"<span class="hlt">Warm</span> pool" (WP) El Nino events are characterized by positive sea surface temperature (SST) anomalies in the central equatorial Pacific. During austral spring. WP El Nino events are associated with an enhancement of convective activity in the South Pacific Convergence Zone, provoking a tropospheric planetary wave response and thus increasing planetary wave driving of the Southern Hemisphere <span class="hlt">stratosphere</span>. These conditions lead to higher polar <span class="hlt">stratospheric</span> temperatures and to a weaker polar jet during austral summer, as compared with neutral ENSO years. Furthermore, this response is sensitive to the phase of the quasi-biennial oscillation (QBO): a stronger <span class="hlt">warming</span> is seen in WP El Nino events coincident with the easterly phase of the quasi-biennial oscillation (QBO) as compared with WP El Nino events coincident with a westerly or neutral QBO. The Goddard Earth Observing System (GEOS) chemistry-climate model (CCM) is used to further explore the atmospheric response to ENSO. Time-slice simulations are forced by composited SSTs from observed WP El Nino and neutral ENSO events. The modeled eddy heat flux, temperature and wind responses to WP El Nino events are compared with observations. A new gravity wave drag scheme has been implemented in the GEOS CCM, enabling the model to produce a realistic, internally generated QBO. By repeating the above time-slice simulations with this new model version, the sensitivity of the WP El Nino response to the phase of the quasi-biennial oscillation QBO is estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110005628','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110005628"><span id="translatedtitle">Can the GEOS CCM Simulate the Temperature Response to <span class="hlt">Warm</span> Pool El Nino Events in the Antarctic <span class="hlt">Stratosphere</span>?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hurwitz, M. M.; Song, I.-S.; Oman, L. D.; Newman, P. A.; Molod, A. M.; Frith, S. M.; Nielsen, J. E.</p> <p>2011-01-01</p> <p>"<span class="hlt">Warm</span> pool" (WP) El Nino events are characterized by positive sea surface temperature (SST) anomalies in the central equatorial Pacific. During austral spring, WP El Nino events are associated with an enhancement of convective activity in the South Pacific Convergence Zone, provoking a tropospheric planetary wave response and thus increasing planetary wave driving of the Southern Hemisphere <span class="hlt">stratosphere</span>. These conditions lead to higher polar <span class="hlt">stratospheric</span> temperatures and to a weaker polar jet during austral summer, as compared with neutral ENSO years. Furthermore, this response is sensitive to the phase of the quasi-biennial oscillation (QBO): a stronger <span class="hlt">warming</span> is seen in WP El Nino events coincident with the easterly phase of the quasi-biennial oscillation (QBO) as compared with WP El Nino events coincident with a westerly or neutral QBO. The Goddard Earth Observing System (GEOS) chemistry-climate model (CCM) is used to further explore the atmospheric response to ENSO. Time-slice simulations are forced by composited SSTs from observed NP El Nino and neutral ENSO events. The modeled eddy heat flux, temperature and wind responses to WP El Nino events are compared with observations. A new gravity wave drag scheme has been implemented in the GEOS CCM, enabling the model to produce e realistic, internally generated QBO. By repeating the above time-slice simulations with this new model version, the sensitivity of the WP El Nino response to the phase of the quasi-biennial oscillation QBO is estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ACP.....9.4775M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ACP.....9.4775M"><span id="translatedtitle">Satellite observations and modeling of transport in the upper troposphere through the lower mesosphere during the 2006 major <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Manney, G. L.; Harwood, R. S.; MacKenzie, I. A.; Minschwaner, K.; Allen, D. R.; Santee, M. L.; Walker, K. A.; Hegglin, M. I.; Lambert, A.; Pumphrey, H. C.; Bernath, P. F.; Boone, C. D.; Schwartz, M. J.; Livesey, N. J.; Daffer, W. H.; Fuller, R. A.</p> <p>2009-07-01</p> <p>An unusually strong and prolonged <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> (SSW) in January 2006 was the first major SSW for which globally distributed long-lived trace gas data are available covering the upper troposphere through the lower mesosphere. We use Aura Microwave Limb Sounder (MLS), Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) data, the SLIMCAT Chemistry Transport Model (CTM), and assimilated meteorological analyses to provide a comprehensive picture of transport during this event. The upper tropospheric ridge that triggered the SSW was associated with an elevated tropopause and layering in trace gas profiles in conjunction with <span class="hlt">stratospheric</span> and tropospheric intrusions. Anomalous poleward transport (with corresponding quasi-isentropic troposphere-to-<span class="hlt">stratosphere</span> exchange at the lowest levels studied) in the region over the ridge extended well into the lower <span class="hlt">stratosphere</span>. In the middle and upper <span class="hlt">stratosphere</span>, the breakdown of the polar vortex transport barrier was seen in a signature of rapid, widespread mixing in trace gases, including CO, H2O, CH4 and N2O. The vortex broke down slightly later and more slowly in the lower than in the middle <span class="hlt">stratosphere</span>. In the middle and lower <span class="hlt">stratosphere</span>, small remnants with trace gas values characteristic of the pre-SSW vortex lingered through the weak and slow recovery of the vortex. The upper <span class="hlt">stratospheric</span> vortex quickly reformed, and, as enhanced diabatic descent set in, CO descended into this strong vortex, echoing the fall vortex development. Trace gas evolution in the SLIMCAT CTM agrees well with that in the satellite trace gas data from the upper troposphere through the middle <span class="hlt">stratosphere</span>. In the upper <span class="hlt">stratosphere</span> and lower mesosphere, the SLIMCAT simulation does not capture the strong descent of mesospheric CO and H2O values into the reformed vortex; this poor CTM performance in the upper <span class="hlt">stratosphere</span> and lower mesosphere results primarily from biases in the diabatic descent in assimilated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20120002032&hterms=Richter+scale&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2528Richter%2Bscale%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20120002032&hterms=Richter+scale&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2528Richter%2Bscale%2529"><span id="translatedtitle">Mesoscale Simulations of Gravity Waves During the 2008-2009 Major <span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warming</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Limpasuvan, Varavut; Alexander, M. Joan; Orsolini, Yvan J.; Wu, Dong L.; Xue, Ming; Richter, Jadwiga H.; Yamashita, Chihoko</p> <p>2011-01-01</p> <p>A series of 24 h mesoscale simulations (of 10 km horizontal and 400 m vertical resolution) are performed to examine the characteristics and forcing of gravity waves (GWs) relative to planetary waves (PWs) during the 2008-2009 major <span class="hlt">stratospheric</span> sudden wam1ing (SSW). Just prior to SSW occurrence, widespread westward propagating GWs are found along the vortex's edge and associated predominantly with major topographical features and strong near-surface winds. Momentum forcing due to GWs surpasses PW forcing in the upper <span class="hlt">stratosphere</span> and tends to decelerate the polar westerly jet in excess of 30 m/s/d. With SSW onset, PWs dominate the momentum forcing, providing decelerative effects in excess of 50 m/s/d throughout the upper polar <span class="hlt">stratosphere</span>. GWs related to topography become less widespread largely due to incipient wind reversal as the vortex starts to elongate. During the SSW maturation and early recovery, the polar vortex eventually splits and both wave signatures and forcing greatly subside. Nonetheless, during SSW, westward and eastward propagating GWs are found in the polar region and may be generated in situ by flow adjustment processes in the <span class="hlt">stratosphere</span> or by secondary GW breaking. The simulated large-scale features agree well with those resolved in satellite observations and analysis products.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRA..11612321W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRA..11612321W"><span id="translatedtitle">First simulations with a whole atmosphere data assimilation and forecast system: The January 2009 major sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, H.; Fuller-Rowell, T. J.; Akmaev, R. A.; Hu, M.; Kleist, D. T.; Iredell, M. D.</p> <p>2011-12-01</p> <p>A Whole atmosphere Data Assimilation System (WDAS) is used to simulate the January 2009 sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW). WDAS consists of the Whole Atmosphere Model (WAM) and the 3-dimensional variational (3DVar) analysis system GSI (Grid point Statistical Interpolation), modified to be compatible with the WAM model. An incremental analysis update (IAU) scheme was implemented in the data assimilation cycle to overcome the problem of excessive damping by digital filter in WAM of the important tidal waves in the upper atmosphere. IAU updates analysis incrementally into the model, thus avoids the initialization procedure (i.e., digital filter) during the WAM forecast stage. The WDAS simulation of the January 2009 SSW shows a significant increase in TW3 (terdiurnal, westward propagating, zonal wave number 3) and a decrease in SW2 (semidiurnal, westward propagating, zonal wave number 2) wave amplitudes in the E region during the <span class="hlt">warming</span>, which can be attributed likely to the nonlinear wave-wave interactions between SW2, TW3 and DW1 (diurnal, westward propagating, zonal wave number 1). There is a delayed increase in SW2 in the E region after the <span class="hlt">warming</span>, indicating a modulation by the changing large-scale planetary waves in the loweratmosphere during the SSW. These tidal wave responses during SSW appeared to be global in scale. An extended WAM forecast initialized from WDAS analysis shows remarkably consistent tidal wave responses to SSW, indicating a potential forecasting capability of several days in advance of the effects of the large-scale tropospheric and <span class="hlt">stratospheric</span> dynamics on the thermospheric and ionospheric variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ACP....15..297E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ACP....15..297E"><span id="translatedtitle">A global non-hydrostatic model study of a downward coupling through the tropical tropopause layer during a <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eguchi, N.; Kodera, K.; Nasuno, T.</p> <p>2015-01-01</p> <p>The dynamical coupling process between the <span class="hlt">stratosphere</span> and troposphere in the tropical tropopause layer (TTL) during a~<span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> (SSW) in boreal winter was investigated using simulation data from a global non-hydrostatic model (NICAM) that does not use cumulus parameterization. The model reproduced well the observed tropical tropospheric changes during the SSW, including the enhancement of convective activity following the amplification of planetary waves. Deep convective activity was enhanced in the latitude zone 20-10° S, in particular over the southwest Pacific and southwest Indian Ocean. Although the upwelling in the TTL was correlated with that in the <span class="hlt">stratosphere</span>, the temperature tendency in the TTL changed little due to a compensation by diabatic heating originating from cloud formation. This result suggests that the <span class="hlt">stratospheric</span> meridional circulation affects cloud formation in the TTL.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ACPD...14.6803E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ACPD...14.6803E"><span id="translatedtitle">A global non-hydrostatic model study of a downward coupling through the tropical tropopause layer during a <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eguchi, N.; Kodera, K.; Nasuno, T.</p> <p>2014-03-01</p> <p>The dynamical coupling process between the <span class="hlt">stratosphere</span> and troposphere in the tropical tropopause layer (TTL) during a <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> (SSW) in boreal winter was investigated using simulation data from a global non-hydrostatic model (NICAM) that does not use cumulus parameterization. The model reproduced well the observed tropical tropospheric changes during the SSW including the enhancement of convective activity following the amplification of planetary waves. Deep convective activity was enhanced in the latitude zone 20-10° S, in particular over the southwest Pacific and southwest Indian Ocean. Although the upwelling in the TTL was correlated with that in the <span class="hlt">stratosphere</span>, the temperature tendency in the TTL was mainly controlled by diabatic heating originating from cloud formation. This result suggests that the <span class="hlt">stratospheric</span> meridional circulation affects cloud formation in the TTL.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.1318K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.1318K"><span id="translatedtitle">Impacts of a <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> on thermal structures in the high-latitude mesosphere, lower thermosphere, and ionosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kurihara, Junichi; Oyama, Shin-Ichiro; Nozawa, Satonori; Fujii, Ryoichi; Tsutsumi, Masaki; Ogawa, Yasunobu; Tomikawa, Yoshihiro; Hall, Chris</p> <p></p> <p>We analyzed neutral winds, diffusion coefficients, and neutral temperatures observed by the Nippon/Norway Tromsø Meteor Radar (NTMR) and ion temperatures observed by the Eu-ropean Incoherent Scatter (EISCAT) UHF radar at Tromsø (69.6o N, 19.2 E), during a major <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> (SSW) occurred in January 2009. The neutral zonal winds at 80-100 km height reversed about 10 days earlier than the zonal wind reversal in the <span class="hlt">stratosphere</span> and the neutral temperature at 90 km decreased simultaneously with the zonal wind reversal at the same altitude. We found an anticorrelation between geomagnetically quiet nighttime ion temperatures at 100 km and 120-142 km. Our results from the ground-based observations agree well with the satellite observations shown in an accompanying paper. However, significant differences from the previous studies on other SSW events indicate that impacts of a SSW on the upper atmosphere and ionosphere are highly variable with lower atmospheric conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E1520K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E1520K"><span id="translatedtitle">Finding of the key formation mechanisms of the ionospheric response to sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> using GSM TIP model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klimenko, Vladimir; Klimenko, Maxim; Bessarab, Fedor; Korenkov, Yurij; Karpov, Ivan</p> <p></p> <p>The Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> (SSW) is a large-scale phenomenon, which response is detected in the mesosphere, thermosphere and ionosphere. SSW ionospheric effects are studied using multi-instrumental satellites and by ground-based measurements. We report a brief overview of the observational and theoretical results of the global ionospheric response and its formation mechanisms during Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span>. We also present the results of our investigation of thermosphere-ionosphere response to the SSW obtained within the Global Self-consistent Model of the Thermosphere, Ionosphere, Protonosphere (GSM TIP). The SSW effects were modeled by specifying various boundary conditions at the height of 80 km in the GSM TIP model: (1) by setting the stationary perturbations s = 1 of the temperature and density at high latitudes; (2) by setting the global distribution of the neutral atmosphere parameters, calculated in the TIME-GCM and CCM SOCOL models for the conditions of the SSW 2009 event. It has been shown that the selected low boundary conditions do not allow to fully reproduce the observed variation in the ionospheric parameters during SSW 2009 event. Based on observations of the velocity of vertical plasma drift obtained by the incoherent scatter radar at Jicamarca, we introduced additional electric potential in the GSM TIP model, which allowed us to reproduce the zonal electric field (ÉB vertical plasma drift) and the observed SSW effects in the low-latitude ionosphere. Furthermore, we tried to reproduce the SSW ionospheric effects by including internal gravity waves in the high-latitude mesosphere. We discuss the model calculation results and possible reasons for model/data disagreements and give the proposals for further investigations. This work was supported by RFBR Grants №12-05-31217 and №14-05-00578.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920020073&hterms=dao&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddao','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920020073&hterms=dao&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddao"><span id="translatedtitle">Rayleigh/raman Greenland Lidar Observations of Atmospheric Temperature During a Major Arctic <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> Event</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Meriwether, John W.; Farley, Robert; Mcnutt, R.; Dao, Phan D.; Moskowitz, Warren P.</p> <p>1992-01-01</p> <p>Between Jan. 22 1991 to Feb. 5 1991, we made numerous observations of atmospheric temperature profiles between 10 and 70 km by using the combination of Rayleigh and Raman lidar systems contained in the PL Mobile Lidar Facility located at the National Science Foundation Incoherent Radar Facility of Sondrestrom in Greenland. The purpose of these measurements was to observe the dynamics of the winter Arctic <span class="hlt">stratosphere</span> and mesosphere regions during a winter period from the succession of temperature profiles obtained in our campaign observations. Various aspects of this investigation are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRA..119.1287M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRA..119.1287M"><span id="translatedtitle">TIME-GCM study of the ionospheric equatorial vertical drift changes during the 2006 <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maute, A.; Hagan, M. E.; Richmond, A. D.; Roble, R. G.</p> <p>2014-02-01</p> <p>This modeling study quantifies the daytime low-latitude vertical E×B drift changes in the longitudinal wave number 1 (wn1) to wn4 during the major extended January 2006 <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> (SSW) period as simulated by the National Center for Atmospheric Research thermosphere-ionosphere-mesosphere electrodynamics general circulation model (TIME-GCM), and attributes the drift changes to specific tides and planetary waves (PWs). The largest drift amplitude change (approximately 5 m/s) is seen in wn1 with a strong temporal correlation to the SSW. The wn1 drift is primarily caused by the semidiurnal westward propagating tide with zonal wave number 1 (SW1), and secondarily by a stationary planetary wave with zonal wave number 1 (PW1). SW1 is generated by the nonlinear interaction of PW1 and the migrating semidiurnal tide (SW2) at high latitude around 90-100 km. The simulations suggest that the E region PW1 around 100-130 km at the different latitudes has different origins: at high latitudes, the PW1 is related to the original <span class="hlt">stratospheric</span> PW1; at midlatitudes, the model indicates PW1 is due to the nonlinear interaction of SW1 and SW2 around 95-105 km; and at low latitudes, the PW1 might be caused by the nonlinear interaction between DE2 and DE3. The time evolution of the simulated wn4 in the vertical E×B drift amplitude shows no temporal correlation with the SSW. The wn4 in the low-latitude vertical drift is attributed to the diurnal eastward propagating tide with zonal wave number 3 (DE3), and the contributions from SE2, TE1, and PW4 are negligible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ACPD...1220033A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ACPD...1220033A"><span id="translatedtitle">The spring 2011 final <span class="hlt">stratospheric</span> <span class="hlt">warming</span> above Eureka: anomalous dynamics and chemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adams, C.; Strong, K.; Zhao, X.; Bourassa, A. E.; Daffer, W. H.; Degenstein, D.; Drummond, J. R.; Farahani, E. E.; Fraser, A.; Lloyd, N. D.; Manney, G. L.; McLinden, C. A.; Rex, M.; Roth, C.; Strahan, S. E.; Walker, K. A.; Wohltmann, I.</p> <p>2012-08-01</p> <p>In spring 2011, the Arctic polar vortex was stronger than in any other year on record. As the polar vortex started to break up in April, ozone and NO2 columns were measured with UV-visible spectrometers above the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Canada (80.05° N, 86.42° W) using the differential optical absorption spectroscopy (DOAS) technique. These ground-based column measurements were complemented by Ozone Monitoring Instrument (OMI) and Optical Spectrograph and Infra-Red Imager System (OSIRIS) satellite measurements, Global Modeling Initiative (GMI) simulations, and dynamical parameters. On 8 April 2011, NO2 columns above PEARL from the DOAS, OMI, and GMI datasets were approximately twice as large as in previous years. On this day, temperatures and ozone volume mixing ratios above Eureka were high, suggesting enhanced chemical production of NO2 from NO. Additionally, GMI NOx and N2O fields suggest that downward transport along the vortex edge and horizontal transport from lower latitudes also contributed to the enhanced NO2. The anticyclone that transported lower-latitude NOx above PEARL became frozen-in and persisted in dynamical and GMI N2O fields until the end of the measurement period on 31 May 2011. Ozone isolated within this frozen-in anticyclone (FrIAC) in the middle <span class="hlt">stratosphere</span> was depleted due to reactions with the enhanced NOx. Ozone loss was calculated using the passive tracer technique, with passive ozone profiles from the Lagrangian Chemistry and Transport Model, ATLAS. At 600 K, ozone losses between 1 December 2010 and 20 May 2011 reached 4.2 parts per million by volume (ppmv) (58%) and 4.4 ppmv (61%), when calculated using GMI and OSIRIS ozone profiles, respectively. This middle-<span class="hlt">stratosphere</span> gas-phase ozone loss led to a more rapid decrease in ozone column amounts in April/May 2011 compared with previous years. Ground-based, OMI, and GMI ozone total columns within the FrIAC all decreased by more than 100 DU</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.1658M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.1658M"><span id="translatedtitle">Equatorial vertical drift modulation by the lunar and solar semidiurnal tides during the 2013 sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maute, A.; Fejer, B. G.; Forbes, J. M.; Zhang, X.; Yudin, V.</p> <p>2016-02-01</p> <p>During the 2013 <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> (SSW) period the Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere (JULIA) radar at Jicarmarca, Peru, observed low-latitude vertical drift modulation with lows of 0-12 m/s daytime maximum drifts between 6-13 and 22-25 January and enhanced drifts up to 43 m/s between 15 snd 19 January. The NCAR thermosphere-ionosphere-mesosphere-electrodynamics general circulation model reproduces the prevailing vertical drift feature and is used to examine possible causes. The simulations indicate that the modulation of the vertical drift is generated by the beating of the semidiurnal solar SW2 and lunar M2 tides. During the SSW period the beating is observable since the magnitudes of lunar and solar semidiurnal tidal amplitudes are comparable. The theoretical beating frequency between SW2 and M2 is 1/(15.13 day) which may be modified due to phase changes. This study highlights the importance of the lunar tide during SSW periods and indicates that the equatorial vertical drift modulation should be observable at other longitudes as well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10182802','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10182802"><span id="translatedtitle">Indirect global <span class="hlt">warming</span> effects of ozone and <span class="hlt">stratospheric</span> water vapor induced by surface methane emission</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wuebbles, D.J.; Grossman, A.S.; Tamaresis, J.S.; Patten, K.O. Jr.; Jain, A.; Grant, K.A.</p> <p>1994-07-01</p> <p>Methane has indirect effects on climate due to chemical interactions as well as direct radiative forcing effects as a greenhouse gas. We have calculated the indirect, time-varying tropospheric radiative forcing and GWP of O{sub 3} and <span class="hlt">stratospheric</span> H{sub 2}O due to an impulse of CH{sub 4}. This impulse, applied to the lowest layer of the atmosphere, is the increase of the atmospheric mass of CH{sub 4} resulting from a 25 percent steady state increase in the current emissions as a function of latitude. The direct CH{sub 4} radiative forcing and GWP are also calculated. The LLNL 2-D radiative-chemistry-transport model is used to evaluate the resulting changes in the O{sub 3}, H{sub 2}O and CH{sub 4} atmospheric profiles as a function of time. A correlated k-distribution radiative transfer model is used to calculate the radiative forcing at the tropopause of the globally-averaged atmosphere profiles. The O{sub 3} indirect GWPs vary from {approximately}27 after a 20 yr integration to {approximately}4 after 500 years, agreeing with the previous estimates to within about 10 percent. The H{sub 2}O indirect GWPs vary from {approximately}2 after a 20 yr integration to {approximately}0.3 after 500 years, and are in close agreement with other estimates. The CH{sub 4} GWPs vary from {approximately}53 at 20 yrs to {approximately}7 at 500 yrs. The 20 year CH{sub 4} GWP is {approximately}20% larger than previous estimates of the direct CH{sub 4} GWP due to a CH{sub 4} response time ({approximately}17 yrs) that is much longer than the overall lifetime (10 yrs). The increased CH{sub 4} response time results from changes in the OH abundances caused by the CH{sub 4} impulse. The CH{sub 4} radiative forcing results are consistent with IPCC values. Estimates are made of latitude effects in the radiative forcing calculations, and UV effects on the O{sub 3} radiative forcing calculations (10%).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ACP....13..611A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ACP....13..611A"><span id="translatedtitle">The spring 2011 final <span class="hlt">stratospheric</span> <span class="hlt">warming</span> above Eureka: anomalous dynamics and chemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adams, C.; Strong, K.; Zhao, X.; Bourassa, A. E.; Daffer, W. H.; Degenstein, D.; Drummond, J. R.; Farahani, E. E.; Fraser, A.; Lloyd, N. D.; Manney, G. L.; McLinden, C. A.; Rex, M.; Roth, C.; Strahan, S. E.; Walker, K. A.; Wohltmann, I.</p> <p>2013-01-01</p> <p>In spring 2011, the Arctic polar vortex was stronger than in any other year on record. As the polar vortex started to break up in April, ozone and NO2 columns were measured with UV-visible spectrometers above the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Canada (80.05° N, 86.42° W) using the differential optical absorption spectroscopy (DOAS) technique. These ground-based column measurements were complemented by Ozone Monitoring Instrument (OMI) and Optical Spectrograph and Infra-Red Imager System (OSIRIS) satellite measurements, Global Modeling Initiative (GMI) simulations, and meteorological quantities. On 8 April 2011, NO2 columns above PEARL from the DOAS, OMI, and GMI datasets were approximately twice as large as in previous years. On this day, temperatures and ozone volume mixing ratios above Eureka were high, suggesting enhanced chemical production of NO2 from NO. Additionally, GMI NOx (NO + NO2) and N2O fields suggest that downward transport along the vortex edge and horizontal transport from lower latitudes also contributed to the enhanced NO2. The anticyclone that transported lower-latitude NOx above PEARL became frozen-in and persisted in dynamical and GMI N2O fields until the end of the measurement period on 31 May 2011. Ozone isolated within this frozen-in anticyclone (FrIAC) in the middle <span class="hlt">stratosphere</span> was lost due to reactions with the enhanced NOx. Below the FrIAC (from the tropopause to 700 K), NOx driven ozone loss above Eureka was larger than in previous years, according to GMI monthly average ozone loss rates. Using the passive tracer technique, with passive ozone profiles from the Lagrangian Chemistry and Transport Model, ATLAS, ozone losses since 1 December 2010 were calculated at 600 K. In the air mass that was above Eureka on 20 May 2011, ozone losses reached 4.2 parts per million by volume (ppmv) (58%) and 4.4 ppmv (61%), when calculated using GMI and OSIRIS ozone profiles, respectively. This gas-phase ozone loss</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSA21C..04M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSA21C..04M"><span id="translatedtitle">What can we learn from simulating <span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warming</span> periods with the Thermosphere-Ionosphere-Mesosphere-Electrodynamics GCM?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maute, A. I.; Hagan, M. E.; Roble, R. G.; Richmond, A. D.; Yudin, V. A.; Liu, H.; Goncharenko, L. P.; Burns, A. G.; Maruyama, N.</p> <p>2013-12-01</p> <p>The ionosphere-thermosphere system is not only influenced from geospace but also by meteorological variability. Ionospheric observations of GPS TEC during the current solar cycle have shown that the meteorological variability is important during solar minimum, but also can have significant ionospheric effects during solar medium to maximum conditions. Numerical models can be used to help understand the mechanisms that couple the lower and upper atmosphere over the solar cycle. Numerical modelers invoke different methods to simulate realistic, specified events of meteorological variability, e.g. specify the lower boundary forcing, nudge the middle atmosphere, data assimilation. To study the vertical coupling, we first need to assess the numerical models and the various methods used to simulate realistic events with respect to the dynamics of the mesosphere-lower thermosphere (MLT) region, the electrodynamics, and the ionosphere. This study focuses on <span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warming</span> (SSW) periods since these are associated with a strongly disturbed middle atmosphere which can have effects up to the ionosphere. We will use the NCAR Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation model (TIME-GCM) to examine several recent SSW periods, e.g. 2009, 2012, and 2013. The SSW period in TIME-GCM will be specified in three different ways: 1. using reanalysis data to specify the lower boundary; 2. nudging the neutral atmosphere (temperature and winds) with the Whole Atmosphere Community Climate Model (WACCM)/Goddard Earth Observing System Model, Version 5 (GEOS-5) results; 3. nudging the background atmosphere (temperature and winds) with WACCM/GEOS5 results. The different forcing methods will be evaluated for the SSW periods with respect to the dynamics of the MLT region, the low latitude vertical drift changes, and the ionospheric effects for the different SSW periods. With the help of ionospheric data at different longitudinal sectors it will be possible to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..120.5226L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..120.5226L"><span id="translatedtitle">Thermal and dynamical perturbations in the winter polar mesosphere-lower thermosphere region associated with sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> under conditions of low solar activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lukianova, Renata; Kozlovsky, Alexander; Shalimov, Sergey; Ulich, Thomas; Lester, Mark</p> <p>2015-06-01</p> <p>The upper mesospheric neutral winds and temperatures have been derived from continuous meteor radar (MR) measurements over Sodankyla, Finland, in 2008-2014. Under conditions of low solar activity pronounced sudden mesospheric coolings linked to the major <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) in 2009 and a medium SSW in 2010 are observed while there is no observed thermal signature of the major SSW in 2013 occurred during the solar maximum. Mesosphere-ionosphere anomalies observed simultaneously by the MR, the Aura satellite, and the rapid-run ionosonde during a period of major SSW include the following features. The mesospheric temperature minimum occurs 1 day ahead of the <span class="hlt">stratospheric</span> maximum, and the mesospheric cooling is almost of the same value as the <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (~50 K), the former decay faster than the latter. In the course of SSW, a strong mesospheric wind shear of ~70 m/s/km occurs. The wind turns clockwise (anticlockwise) from north-eastward (south-eastward) to south-westward (north-westward) above (below) 90 km. As the mesospheric temperature reaches its minimum, the gravity waves (GW) in the ionosphere with periods of 10-60 min decay abruptly while the GWs with longer periods are not affected. The effect is explained by selective filtering and/or increased turbulence near the mesopause.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1813970M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1813970M&link_type=ABSTRACT"><span id="translatedtitle">The influence of regional Arctic sea-ice decline on <span class="hlt">stratospheric</span> and tropospheric circulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McKenna, Christine; Bracegirdle, Thomas; Shuckburgh, Emily; Haynes, Peter</p> <p>2016-04-01</p> <p>Arctic sea-ice extent has rapidly declined over the past few decades, and most climate models project a continuation of this trend during the 21st century in response to greenhouse gas forcing. A number of recent studies have shown that this sea-ice loss induces vertically propagating Rossby waves, which weaken the <span class="hlt">stratospheric</span> polar vortex and increase the frequency of sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> (<span class="hlt">SSWs</span>). <span class="hlt">SSWs</span> have been shown to increase the probability of a negative NAO in the following weeks, thereby driving anomalous weather conditions over Europe and other mid-latitude regions. In contrast, other studies have shown that Arctic sea-ice loss strengthens the polar vortex, increasing the probability of a positive NAO. Sun et al. (2015) suggest these conflicting results may be due to the region of sea-ice loss considered. They find that if only regions within the Arctic Circle are considered in sea-ice projections, the polar vortex weakens; if only regions outwith the Arctic Circle are considered, the polar vortex strengthens. This is because the anomalous Rossby waves forced in the former/latter scenario constructively/destructively interfere with climatological Rossby waves, thus enhancing/suppressing upward wave propagation. In this study, we investigate whether Sun et al.'s results are robust to a different model. We also divide the regions of sea-ice loss they considered into further sub-regions, in order to examine the regional differences in more detail. We do this by using the intermediate complexity climate model, IGCM4, which has a well resolved <span class="hlt">stratosphere</span> and does a good job of representing <span class="hlt">stratospheric</span> processes. Several simulations are run in atmosphere only mode, where one is a control experiment and the others are perturbation experiments. In the control run annually repeating historical mean surface conditions are imposed at the lower boundary, whereas in each perturbation run the model is forced by SST perturbations imposed in a specific</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSA41C4071F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSA41C4071F"><span id="translatedtitle">Ionospheric Response to the 2009 Sudden <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> over the Equatorial, Low- and Mid-Latitudes in American Sector.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fagundes, P. R.; Goncharenko, L. P.; de Abreu, A. J.; Gende, M.; de Jesus, R.; Pezzopane, M.; Kavutarapu, V.; Coster, A. J.; Pillat, V. G.</p> <p>2014-12-01</p> <p>The equatorial and low-latitude ionosphere/thermosphere system is predominantly disturbed by waves (MSTIDs, tides, and planetary waves), which are generated in the lower atmosphere or in-situ, as well as electric fields and TIDs produced by geomagnetic storm and UV, EUV, and X-ray solar radiation. For many years, it was thought that, during geomagnetic quiet conditions, the equatorial and low-latitude F-layer was mainly perturbed by waves that were generated not far away from the observed location or electric fields generated by the Equatorial Electroject (EEJ). On the contrary, during geomagnetic storms when the energy sources are in high latitudes the waves (TIDs) travel a very long distance from high latitude to equatorial region and electric fields can be mapped via magnetic field lines. However, in the recent times an unexpected coupling between high latitude, mid- latitude, and equatorial/low latitudes was discovered during sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) events. All aspects involved in this process must be explored in order to improve our knowledge about the Earth´s atmosphere. The present study investigates the consequences of vertical coupling from lower to the upper atmosphere in the equatorial and low-latitude ionosphere in Southern Hemisphere during a major SSW event, which took place during January-February 2009 in the Northern Hemisphere. Using seventeen ground-based dual-frequency GPS stations and two ionosonde stations spanning from latitude 2.8oN to 53.8oS and from longitude 36.7oW to 67.8oW over the South American sector, it has been observed that the ionosphere was significantly disturbed by the SSW event from Equator to the mid-latitudes. Using one GPS station located in mid-latitude (South America sector) it is reported for the first time that the mid-latitude in southern hemisphere (American Sector) was disturbed by the SSW event in the Northern hemisphere. The VTEC at all 17 GPS and two ionosonde stations show significant deviations</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JASTP.146..205B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JASTP.146..205B&link_type=ABSTRACT"><span id="translatedtitle">Comparison of the dynamical response of low latitude middle atmosphere to the major <span class="hlt">stratospheric</span> <span class="hlt">warming</span> events in the Northern and Southern Hemispheres</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bhagavathiammal, G. J.; Sathishkumar, S.; Sridharan, S.; Gurubaran, S.</p> <p>2016-08-01</p> <p>This study presents comparison of low-latitude dynamical responses to boreal 2008/09 and austral 2002 winter Major <span class="hlt">Stratospheric</span> <span class="hlt">Warming</span> (MSW) events, as both events are of vortex split type. During these winters, planetary wave (PW) variability and changes in low-latitude circulation are examined using European Center for Medium Range Weather Forecasting (ECMWF) reanalysis (ERA)-interim data sets and mesospheric wind data acquired by the MF radars at Tirunelveli (8.7°N) and Rarotonga (22°S). Eliassen-Palm diagnostic is used to provide an evidence for the lateral PW energy propagation from high to low-latitudes during both the MSW events. The PW flux reaches much lower latitudes during the boreal event than during the austral event. The low-latitude westward winds at <span class="hlt">stratospheric</span> heights are stronger (weaker) during the boreal (austral) MSW. Weak (strong) PW wave activity at low latitude mesospheric heights during boreal (austral) MSW indicates the influence of low-latitude <span class="hlt">stratospheric</span> westward winds on the vertical propagation of PW to low-latitude mesosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JASTP..94...54N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JASTP..94...54N"><span id="translatedtitle">Lower <span class="hlt">stratospheric</span> gravity wave activity over Gadanki (13.5°N, 79.2°E) during the <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> of 2009: Link with potential vorticity intrusion near Indian sector</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nath, D.; Sridharan, S.; Sathishkumar, S.; Gurubaran, S.; Chen, W.</p> <p>2013-03-01</p> <p>The relation between intrusions of <span class="hlt">stratospheric</span> air into the upper troposphere and deep convection at equator during the <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> (SSW) event of 2009 is examined using the ERA-interim reanalysis and NOAA outgoing longwave radiation (OLR) data sets. There is an intrusion of potential vorticity (PV) equatorward and westward, when the amplitude of planetary wave of zonal wavenumber 2 at 10 hPa decreases drastically and polar <span class="hlt">stratospheric</span> temperature increases simultaneously at 60°N. As a special case, the PV intrudes as narrow tongue at longitudes near 60°E (Indian ocean sector) even to latitudes less than 20°N during the SSW, whereas PV normally intrudes near 210°E (eastern Pacific) to equatorial latitudes. Decrease in OLR is observed east of these PV intrusions. Vertical velocity is largely upward at all pressure levels. As the PV intrusion can have profound influence on tropospheric convection and the latent heat release due to equatorial convection is an important source mechanism for the generation of gravity waves, we examined gravity wave activity in the daily radiosonde observations of winds and temperature at Gadanki (13.5°N, 79.2°E). It is observed that the potential energy per unit mass, estimated from the gravity wave temperature perturbations has considerably enhanced in relation with the deep convection. The predominant direction of propagation of the gravity waves is westward prior to the SSW, as a response to the active convection over Indonesia, turns to eastward during and after the SSW, as a response to the PV intrusion induced convection over west of India.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JGRD..121.1361A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JGRD..121.1361A&link_type=ABSTRACT"><span id="translatedtitle">A nudged chemistry-climate model simulation of chemical constituent distribution at northern high-latitude <span class="hlt">stratosphere</span> observed by SMILES and MLS during the 2009/2010 <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Akiyoshi, H.; Nakamura, T.; Miyasaka, T.; Shiotani, M.; Suzuki, M.</p> <p>2016-02-01</p> <p><span class="hlt">Stratospheric</span> sudden <span class="hlt">warming</span> (SSW) is a dramatic phenomenon of the winter <span class="hlt">stratosphere</span> in which the distribution of chemical constituents, associated chemical tendency, and transport of chemical constituents differ significantly inside and outside of the polar vortex. In this study, the chemical constituent distributions in the major SSW of 2009/2010 were simulated by the Model for Interdisciplinary Research on Climate 3.2-Chemistry-Climate Model (CCM) nudged toward the European Center for Medium-Range Weather Forecasts-Interim Re-Analysis data. The results were compared with Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) and Microwave Limb Sounder (MLS) observations. In addition, ozone tendency due to ozone transport and chemical ozone loss in the high-latitude lower <span class="hlt">stratosphere</span> before and after the SSW was analyzed for the period from 1 January 2010 to 11 February 2010. The evolution and distribution of ozone and HCl inside/outside the polar vortex associated with the vortex shift to the midlatitudes in January are quite similar between SMILES and MLS. Those of ClO are also similar, considering the difference in the local time for the measurement. Analyses of the nudged CCM run indicate that inside the polar vortex at 50 hPa, the ozone concentration increased moderately owing to partial cancelation between the large negative ozone tendency due to chemical ozone destruction and large positive ozone tendency due to horizontal ozone influx from outside of the vortex as well as downward advection. In the region of a high ozone concentration with the same area as that of the polar vortex at 50 hPa, the large increase in ozone was primarily due to a downward advection of ozone. SMILES and MLS observations, nudged CCM simulations, and ozone tendency analyses revealed a highly longitudinal dependent ozone tendency at high latitudes during the SSW.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E1778S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E1778S&link_type=ABSTRACT"><span id="translatedtitle">Analysis of <span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warming</span> (SSW) over Tropical and Sub-tropical Regions of India using Rayleigh Lidar and Satellite measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharma, Som Kumar; Chandra, Harish; Jayaraman, Achuthan; Gadhavi, Harish; Vaishnav, Rajesh</p> <p>2016-07-01</p> <p>The <span class="hlt">Stratospheric</span> Sudden <span class="hlt">Warming</span> (SSW) is one of the most spectacular phenomena in the atmosphere and has impacts on the Earth's lower, middle and upper atmospheres. Lidar is one of the best instrument to study Earth's middle atmospheric thermal structure with very temporal and vertical resolution. A Nd: YAG laser based Rayleigh Lidar is operational over Mt. Abu India (24.5 oN, 72.7 oE) since 1997.In this study, two major SSW episodes associated with vortex displacement and vortex splitting occurred in year 1998 and 1999 respectively are investigated first time over Mt. Abu using lidar observations. Analyses show that CIRA-86 and MSISE-90 model fail to capture these SSW episode, whereas ground based lidar and satellite observations from Halogen occultation experiment (HALOE) onboard upper atmospheric research satellite (UARS)are able to capture effect of SSW events. Lidar measurements are able to capture SSW <span class="hlt">warming</span> and its decay very accurately. Impact of SSW is further investigated in ECMWF Interim reanalyzed potential vorticity. Moreover, a detail study has been presented to understand the latitudinal variation of SSW <span class="hlt">warming</span> and associated mesospheric cooling over Indian region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714787S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714787S"><span id="translatedtitle">Chemistry and dynamics of the secondary ozone layer during the sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> in the southern hemisphere in 2002, using WACCM-SD</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith-Johnsen, Christine; Limpasuvan, Varavut; Yvan, Orsolini; Frode, Stordal</p> <p>2015-04-01</p> <p>A sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) will affect the chemistry and dynamics of the middle atmosphere, and up to the thermosphere. The major <span class="hlt">warmings</span> occur roughly every other year in the northern hemispheric winter, but has only been observed once in the southern hemisphere, during the antarctic winter of 2002. In this paper we will investigate the effects of the 2002 southern hemispheric <span class="hlt">warming</span> on the upper atmosphere, by using the National Centre for Atmospheric Research's Whole Atmosphere Community Climate Model with specified dynamics (WACCM-SD). The secondary ozone layer at around 90km altitude will be the focus, and chemical compounds such as hydrogen, oxygen, carbon monoxide and nitric oxide will be studied as well as the temperature and zonal, meridional and vertical winds, all outputs from WACCM-SD. Three reductions of the zonal mean zonal wind occurs before the final reversal from westerlies to easterlies winds defines the onset of the SSW. At about the same time, at 90 km altitude, an increase of O3 can be seen, and a decrease of NOX, O, CO, H and temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23858990','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23858990"><span id="translatedtitle"><span class="hlt">Stratospheric</span> ozone, global <span class="hlt">warming</span>, and the principle of unintended consequences--an ongoing science and policy success story.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Andersen, Stephen O; Halberstadt, Marcel L; Borgford-Parnell, Nathan</p> <p>2013-06-01</p> <p>In 1974, Mario Molina and F. Sherwood Rowland warned that chlorofluorocarbons (CFCs) could destroy the <span class="hlt">stratospheric</span> ozone layer that protects Earth from harmful ultraviolet radiation. In the decade after scientists documented the buildup and long lifetime of CFCs in the atmosphere; found the proof that CFCs chemically decomposed in the <span class="hlt">stratosphere</span> and catalyzed the depletion of ozone; quantified the adverse effects; and motivated the public and policymakers to take action. In 1987, 24 nations plus the European Community signed the Montreal Protocol. Today, 25 years after the Montreal Protocol was agreed, every United Nations state is a party (universal ratification of 196 governments); all parties are in compliance with the stringent controls; 98% of almost 100 ozone-depleting chemicals have been phased out worldwide; and the <span class="hlt">stratospheric</span> ozone layer is on its way to recovery by 2065. A growing coalition of nations supports using the Montreal Protocol to phase down hydrofluorocarbons, which are ozone safe but potent greenhouse gases. Without rigorous science and international consensus, emissions of CFCs and related ozone-depleting substances (ODSs) could have destroyed up to two-thirds of the ozone layer by 2065, increasing the risk of causing millions of cancer cases and the potential loss of half of global agricultural production. Furthermore, because most, ODSs are also greenhouse gases, CFCs and related ODSs could have had the effect of the equivalent of 24-76 gigatons per year of carbon dioxide. This critical review describes the history of the science of <span class="hlt">stratospheric</span> ozone depletion, summarizes the evolution of control measures and compliance under the Montreal Protocol and national legislation, presents a review of six separate transformations over the last 100 years in refrigeration and air conditioning (A/C) technology, and illustrates government-industry cooperation in continually improving the environmental performance of motor vehicle A/C. PMID</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18..955K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18..955K"><span id="translatedtitle">Simulating influence of QBO phase on planetary waves during a <span class="hlt">stratospheric</span> <span class="hlt">warming</span> in a general circulation model of the middle atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koval, Andrey; Gavrilov, Nikolai; Pogoreltsev, Alexander; Savenkova, Elena</p> <p>2016-04-01</p> <p>One of the important factors of dynamical interactions between the lower and upper atmosphere is energy and momentum transfer by atmospheric internal gravity waves. For numerical modeling of the general circulation and thermal regime of the middle and upper atmosphere, it is important to take into account accelerations of the mean flow and heating rates produced by dissipating internal waves. The quasi-biennial oscillations (QBOs) of the zonal mean flow at lower latitudes at <span class="hlt">stratospheric</span> heights can affect the propagation conditions of planetary waves. We perform numerical simulation of global atmospheric circulation for the initial conditions corresponding to the years with westerly and easterly QBO phases. We focus on the changes in amplitudes of stationary planetary waves (SPWs) and traveling normal atmospheric modes (NAMs) in the atmosphere during SSW events for the different QBO phases. For these experiments, we use the global circulation of the middle and upper atmosphere model (MUAM). There is theory of PW waveguide describing atmospheric regions where the background wind and temperature allow the wave propagation. There were introduced the refractive index for PWs and found that strongest planetary wave propagation is in areas of large positive values of this index. Another important PW characteristic is the Eliassen-Palm flux (EP-flux). These characteristics are considered as useful tools for visualizing the PW propagation conditions. Sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) event has significant influence on the formation of the weather anomalous and climate changes in the troposphere. Also, SSW event may affect the dynamical and energy processes in the upper atmosphere. The major SSW events imply significant temperature rises (up to 30 - 40 K) at altitudes 30 - 50 km accompanying with corresponding decreases, or reversals, of climatological eastward zonal winds in the <span class="hlt">stratosphere</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010GeoRL..3713806K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010GeoRL..3713806K"><span id="translatedtitle">Links between a <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> and thermal structures and dynamics in the high-latitude mesosphere, lower thermosphere, and ionosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kurihara, J.; Ogawa, Y.; Oyama, S.; Nozawa, S.; Tsutsumi, M.; Hall, C. M.; Tomikawa, Y.; Fujii, R.</p> <p>2010-07-01</p> <p>We analyzed neutral winds, ambipolar diffusion coefficients, and neutral temperatures observed by the Nippon/Norway Tromsø Meteor Radar (NTMR) and ion temperatures observed by the European Incoherent Scatter (EISCAT) UHF radar at Tromsø (69.6°N, 19.2°E), during a major <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> (SSW) that occurred in January 2009. The zonal winds at 80-100 km height reversed approximately 10 days earlier than the zonal wind reversal in the <span class="hlt">stratosphere</span> and the neutral temperature at 90 km decreased simultaneously with the zonal wind reversal at the same altitude. We found different variations between geomagnetically quiet nighttime ion temperatures at 101-110 km and 120-142 km for about 10 days around the SSW. Our results from the ground-based observations agree well with the satellite observations shown in an accompanying paper. Thus, this study indicates that a SSW is strongly linked to thermal structure and dynamics in the high-latitude mesosphere, lower thermosphere, and ionosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E1832L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E1832L"><span id="translatedtitle">Study of thermospheric and ionospheric tidal responses to the 2009 <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> by an assimilative atmosphere-ionosphere coupled TIME-GCM with FORMOSAT-3/COSMIC observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, Jia-Ting; Liu, Hanli; Liu, Jann-Yenq; Lin, Charles C. H.; Chen, Chia-Hung; Chang, Loren; Chen, Wei-Han</p> <p></p> <p>In this study, ionospheric peak densities obtained from radio occultation soundings of FORMOSAT-3/COSMIC are decomposed into their various constituent tidal components for studying the <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> (SSW) effects on the tidal responses during the 2008/2009. The observations are further compared with the results from an atmosphere-ionosphere coupled model, TIME-GCM. The model assimilates MERRA 3D meteorological data between the lower-boundary (~30km) and 0.1h Pa (~62km) by a nudging method. The comparison shows general agreement in the major features of decrease of migrating tidal signatures (DW1, SW2 and TW3) in ionosphere around the growth phase of SSW, with phase/time shifts in the daily time of maximum around EIA and middle latitudes. Both the observation and simulation indicate a pronounced enhancement of the ionospheric SW2 signatures after the <span class="hlt">stratospheric</span> temperature increase. The model suggest that the typical morning enhancement/afternoon reduction of electron density variation is mainly caused by modification of the ionospheric migrating tidal signatures. The model shows that the thermospheric SW2 tide variation is similar to ionosphere as well as the phase shift. These phases shift of migrating tides are highly related to the present of induced secondary planetary wave 1 in the E region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..120.7873K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..120.7873K"><span id="translatedtitle">Study of the thermospheric and ionospheric response to the 2009 sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> using TIME-GCM and GSM TIP models: First results</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klimenko, M. V.; Klimenko, V. V.; Bessarab, F. S.; Korenkov, Yu N.; Liu, Hanli; Goncharenko, L. P.; Tolstikov, M. V.</p> <p>2015-09-01</p> <p>This paper presents a study of mesosphere and low thermosphere influence on ionospheric disturbances during 2009 major sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) event. This period was characterized by extremely low solar and geomagnetic activity. The study was performed using two first principal models: thermosphere-ionosphere-mesosphere electrodynamics general circulation model (TIME-GCM) and global self-consistent model of thermosphere, ionosphere, and protonosphere (GSM TIP). The <span class="hlt">stratospheric</span> anomalies during SSW event were modeled by specifying the temperature and density perturbations at the lower boundary of the TIME-GCM (30 km altitude) according to data from European Centre for Medium-Range Weather Forecasts. Then TIME-GCM output at 80 km was used as lower boundary conditions for driving GSM TIP model runs. We compare models' results with ground-based ionospheric data at low latitudes obtained by GPS receivers in the American longitudinal sector. GSM TIP simulation predicts the occurrence of the quasi-wave vertical structure in neutral temperature disturbances at 80-200 km altitude, and the positive and negative disturbances in total electron content at low latitude during the 2009 SSW event. According to our model results the formation mechanisms of the low-latitude ionospheric response are the disturbances in the n(O)/n(N2) ratio and thermospheric wind. The change in zonal electric field is key mechanism driving the ionospheric response at low latitudes, but our model results do not completely reproduce the variability in zonal electric fields (vertical plasma drift) at low latitudes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRD..11716101T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRD..11716101T"><span id="translatedtitle">Growth of planetary waves and the formation of an elevated stratopause after a major <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> in a T213L256 GCM</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tomikawa, Yoshihiro; Sato, Kaoru; Watanabe, Shingo; Kawatani, Yoshio; Miyazaki, Kazuyuki; Takahashi, Masaaki</p> <p>2012-08-01</p> <p>Recovery processes after a major <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> (SSW) with the formation of an elevated stratopause and a strong polar-night jet are investigated using a gravity-wave-resolving GCM. The major SSW that occurred in the GCM bears a strong resemblance to observations in January 2006 and January 2009. The recovery phase of the SSW in the GCM is divided into two stages. In the first stage during about five days just after the SSW, a large positive Eliassen-Palm (E-P) flux divergence associated with the growth of planetary waves contributes to the quick recovery of eastward wind above 2 hPa (about 42 km), which is likely due to baroclinic and/or barotropic instabilities. In the second stage over the next three weeks, a prolonged westward wind in the lower <span class="hlt">stratosphere</span> blocked upward propagation of gravity waves with westward intrinsic phase velocities. It reduces the deceleration of eastward wind in the upper mesosphere and raises the breaking height of gravity waves. Since the height of westward gravity wave forcing also rises, the polar stratopause created by the gravity-wave-driven meridional circulation is formed at an elevated height (about 75 km) compared to that before the SSW (55-65 km). In addition, the weaker westward gravity-wave forcing in the upper mesosphere drives weaker downwelling around 1 hPa and forms a cold layer. Consequently, the strong polar-night jet forms at a higher altitude than before the SSW as a result of adjustment toward the thermal wind balance. This indicates that these two stages provide eastward acceleration in different ways.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.5571G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.5571G"><span id="translatedtitle">An incoherent scatter radar study of the midnight temperature maximum that occurred at Arecibo during a sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> event in January 2010</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gong, Yun; Zhou, Qihou; Zhang, Shaodong; Aponte, Nestor; Sulzer, Michael</p> <p>2016-06-01</p> <p>We present an analysis of the thermospheric midnight temperature maximum, a large increment of temperature around midnight. The analysis is based on data collected from the Arecibo incoherent scatter radar during 14-21 January 2010. The experiment overlaps with a major sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) event which commenced on 18 January 2010. Throughout the observation, the ion temperature exhibited moderate increase around postmidnight during 14-17 January, while it showed more intense increment during 18-21 January. In particular, on 20 January, the amplitude of the midnight temperature maximum (MTM) is 310 K, which is seldom seen at Arecibo. During the SSW, the meridional wind reverses toward the pole just before the commencement of the MTM. Then, the poleward wind and the ion temperature maximize almost at the same time. The variation of meridional wind and the MTM are consistent with the Whole Atmosphere Model (WAM) studies, which suggested that the variation is due to effects from an upward propagating terdiurnal tide. On the nights of 18-19 January, the MTM showed clear phase variation at the heights of 265, 303, and 342 km. A strong terdiurnal tide has been observed during the SSW and it is likely generated from low atmosphere and propagating upward. Our results provide direct observational evidence that the propagating upward terdiurnal tide plays an important role in causing the MTM, which supports the WAM simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRD..120.8299H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRD..120.8299H"><span id="translatedtitle">Impacts of <span class="hlt">stratospheric</span> ozone depletion and recovery on wave propagation in the boreal winter <span class="hlt">stratosphere</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Dingzhu; Tian, Wenshou; Xie, Fei; Wang, Chunxiao; Zhang, Jiankai</p> <p>2015-08-01</p> <p>This paper uses a state-of-the-art general circulation model to study the impacts of the <span class="hlt">stratospheric</span> ozone depletion from 1980 to 2000 and the expected partial ozone recovery from 2000 to 2020 on the propagation of planetary waves in December, January, and February. In the Southern Hemisphere (SH), the <span class="hlt">stratospheric</span> ozone depletion leads to a cooler and stronger Antarctic <span class="hlt">stratosphere</span>, while the <span class="hlt">stratospheric</span> ozone recovery has the opposite effects. In the Northern Hemisphere (NH), the impacts of the <span class="hlt">stratospheric</span> ozone depletion on polar <span class="hlt">stratospheric</span> temperature are not opposite to that of the <span class="hlt">stratospheric</span> ozone recovery; i.e., the <span class="hlt">stratospheric</span> ozone depletion causes a weak cooling and the <span class="hlt">stratospheric</span> ozone recovery causes a statistically significant cooling. The <span class="hlt">stratospheric</span> ozone depletion leads to a weakening of the Arctic polar vortex, while the <span class="hlt">stratospheric</span> ozone recovery leads to a strengthening of the Arctic polar vortex. The cooling of the Arctic polar vortex is found to be dynamically induced via modulating the planetary wave activity by <span class="hlt">stratospheric</span> ozone increases. Particularly interesting is that <span class="hlt">stratospheric</span> ozone changes have opposite effects on the stationary and transient wave fluxes in the NH <span class="hlt">stratosphere</span>. The analysis of the wave refractive index and Eliassen-Palm flux in the NH indicates (1) that the wave refraction in the <span class="hlt">stratosphere</span> cannot fully explain wave flux changes in the Arctic <span class="hlt">stratosphere</span> and (2) that <span class="hlt">stratospheric</span> ozone changes can cause changes in wave propagation in the northern midlatitude troposphere which in turn affect wave fluxes in the NH <span class="hlt">stratosphere</span>. In the SH, the radiative cooling (<span class="hlt">warming</span>) caused by <span class="hlt">stratospheric</span> ozone depletion (recovery) produces a larger (smaller) meridional temperature gradient in the midlatitude upper troposphere, accompanied by larger (smaller) zonal wind vertical shear and larger (smaller) vertical gradients of buoyancy frequency. Hence, there are more (fewer) transient waves</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5147105','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5147105"><span id="translatedtitle"><span class="hlt">Stratospheric</span> chemistry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Brune, W.H. )</p> <p>1991-01-01</p> <p>Advances in <span class="hlt">stratospheric</span> chemistry made by investigators in the United States from 1987 to 1990 are reviewed. Subject areas under consideration include photochemistry of the polar <span class="hlt">stratosphere</span>, photochemistry of the global <span class="hlt">stratosphere</span>, and assessments of inadvertent modification of the <span class="hlt">stratosphere</span> by anthropogenic activity. Particular attention is given to early observations and theories, gas phase chemistry, Antarctic observations, Arctic observations, odd-oxygen, odd-hydrogen, odd-nitrogen, halogens, aerosols, modeling of <span class="hlt">stratospheric</span> ozone, and reactive nitrogen effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGC43D1086K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGC43D1086K"><span id="translatedtitle">How Much Winter <span class="hlt">Stratospheric</span> Polar-cap <span class="hlt">Warming</span> Is Explained By Upward-propagating Planetary Waves In CMIP5 Models?: Part 1. An Indirect Approach Using A Wave Interference Index</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, J.; Kim, B.</p> <p>2013-12-01</p> <p>The breaking of upward-propagating planetary (typically characterized by the combination of zonal wave number 1 and 2) waves in the <span class="hlt">stratosphere</span> is regarded as one of the factors that provoke the sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) and the accompanying collapse of <span class="hlt">stratospheric</span> polar vortex during winter. It is also known that if the anomalous stationary wave pattern is in phase with that of the climatology during a certain period, this period is dynamically favorable for the upward propagation and amplification of planetary waves. This kind of phenomenon that amplitude of resultant wave increases by combining two or more waves in phase is called the constructive interference. Our research evaluates whether and to what degree the Coupled Model Intercomparison Project Phase 5 (CMIP5) models simulate such a relation between tropospheric wave interference and Northern polar <span class="hlt">stratosphere</span> temperature anomaly during winter. Here the 500-hPa wave interference index (WII500) is defined as the coefficient that is obtained by projecting the anomaly of wave number 1 and 2 components of 500-hPa geopotential height onto its climatology. Using monthly outputs of the CMIP5 historical runs currently available to us, we examine the lagged relationship (R-square) between the WII500 during November-December-January (NDJ) and the polar-cap temperature anomaly at 50 hPa (PCT50) during December-January-February (DJF) on an interannual timescale. By sampling uncertainty in R-squares of 33-yr samples (chosen fit with the modern reanalysis period, 1980-2012) with bootstrap resampling, we obtain the sampled medians for all models. The observed relations are then calculated using six reanalyses (ERA-40, ERA-Interim, JRA-25, MERRA, NCEP-R1, and NCEP-R2), and the 5-95% confidence interval of their observed R-square is obtained again with bootstrap resampling of all six reanalyses blended. Then we evaluate which CMIP5 model simulates the WII500-PCT50 relation within the probable range of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22391276','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22391276"><span id="translatedtitle"><span class="hlt">Stratospheric</span> aerosol geoengineering</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Robock, Alan</p> <p>2015-03-30</p> <p>The Geoengineering Model Intercomparison Project, conducting climate model experiments with standard <span class="hlt">stratospheric</span> aerosol injection scenarios, has found that insolation reduction could keep the global average temperature constant, but global average precipitation would reduce, particularly in summer monsoon regions around the world. Temperature changes would also not be uniform; the tropics would cool, but high latitudes would <span class="hlt">warm</span>, with continuing, but reduced sea ice and ice sheet melting. Temperature extremes would still increase, but not as much as without geoengineering. If geoengineering were halted all at once, there would be rapid temperature and precipitation increases at 5–10 times the rates from gradual global <span class="hlt">warming</span>. The prospect of geoengineering working may reduce the current drive toward reducing greenhouse gas emissions, and there are concerns about commercial or military control. Because geoengineering cannot safely address climate change, global efforts to reduce greenhouse gas emissions and to adapt are crucial to address anthropogenic global <span class="hlt">warming</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1609402','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1609402"><span id="translatedtitle"><span class="hlt">Stratospheric</span> ozone depletion</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rowland, F. Sherwood</p> <p>2006-01-01</p> <p>Solar ultraviolet radiation creates an ozone layer in the atmosphere which in turn completely absorbs the most energetic fraction of this radiation. This process both <span class="hlt">warms</span> the air, creating the <span class="hlt">stratosphere</span> between 15 and 50 km altitude, and protects the biological activities at the Earth's surface from this damaging radiation. In the last half-century, the chemical mechanisms operating within the ozone layer have been shown to include very efficient catalytic chain reactions involving the chemical species HO, HO2, NO, NO2, Cl and ClO. The NOX and ClOX chains involve the emission at Earth's surface of stable molecules in very low concentration (N2O, CCl2F2, CCl3F, etc.) which wander in the atmosphere for as long as a century before absorbing ultraviolet radiation and decomposing to create NO and Cl in the middle of the <span class="hlt">stratospheric</span> ozone layer. The growing emissions of synthetic chlorofluorocarbon molecules cause a significant diminution in the ozone content of the <span class="hlt">stratosphere</span>, with the result that more solar ultraviolet-B radiation (290–320 nm wavelength) reaches the surface. This ozone loss occurs in the temperate zone latitudes in all seasons, and especially drastically since the early 1980s in the south polar springtime—the ‘Antarctic ozone hole’. The chemical reactions causing this ozone depletion are primarily based on atomic Cl and ClO, the product of its reaction with ozone. The further manufacture of chlorofluorocarbons has been banned by the 1992 revisions of the 1987 Montreal Protocol of the United Nations. Atmospheric measurements have confirmed that the Protocol has been very successful in reducing further emissions of these molecules. Recovery of the <span class="hlt">stratosphere</span> to the ozone conditions of the 1950s will occur slowly over the rest of the twenty-first century because of the long lifetime of the precursor molecules. PMID:16627294</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16627294','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16627294"><span id="translatedtitle"><span class="hlt">Stratospheric</span> ozone depletion.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rowland, F Sherwood</p> <p>2006-05-29</p> <p>Solar ultraviolet radiation creates an ozone layer in the atmosphere which in turn completely absorbs the most energetic fraction of this radiation. This process both <span class="hlt">warms</span> the air, creating the <span class="hlt">stratosphere</span> between 15 and 50 km altitude, and protects the biological activities at the Earth's surface from this damaging radiation. In the last half-century, the chemical mechanisms operating within the ozone layer have been shown to include very efficient catalytic chain reactions involving the chemical species HO, HO2, NO, NO2, Cl and ClO. The NOX and ClOX chains involve the emission at Earth's surface of stable molecules in very low concentration (N2O, CCl2F2, CCl3F, etc.) which wander in the atmosphere for as long as a century before absorbing ultraviolet radiation and decomposing to create NO and Cl in the middle of the <span class="hlt">stratospheric</span> ozone layer. The growing emissions of synthetic chlorofluorocarbon molecules cause a significant diminution in the ozone content of the <span class="hlt">stratosphere</span>, with the result that more solar ultraviolet-B radiation (290-320 nm wavelength) reaches the surface. This ozone loss occurs in the temperate zone latitudes in all seasons, and especially drastically since the early 1980s in the south polar springtime-the 'Antarctic ozone hole'. The chemical reactions causing this ozone depletion are primarily based on atomic Cl and ClO, the product of its reaction with ozone. The further manufacture of chlorofluorocarbons has been banned by the 1992 revisions of the 1987 Montreal Protocol of the United Nations. Atmospheric measurements have confirmed that the Protocol has been very successful in reducing further emissions of these molecules. Recovery of the <span class="hlt">stratosphere</span> to the ozone conditions of the 1950s will occur slowly over the rest of the twenty-first century because of the long lifetime of the precursor molecules. PMID:16627294</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFMSA43C..04N&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFMSA43C..04N&link_type=ABSTRACT"><span id="translatedtitle">The Future of the <span class="hlt">Stratosphere</span> and the Ozone Layer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Newman, P. A.; Oman, L.; Pawson, S.; Fleming, E. L.; Li, F.; Jackman, C. H.</p> <p>2014-12-01</p> <p><span class="hlt">Stratospheric</span> ozone has been slightly depleted (2-4 % globally) by emissions of ozone depleting substances (ODSs). The landmark 1987 Montreal Protocol led to the end of most these ODS emissions, and total levels of ODSs have been declining since the late 1990s. The interim replacements for these ODSs were hydroclorofluorocarbons (HCFCs), but these HCFCs have also now been regulated. The period in which <span class="hlt">stratospheric</span> change has been dominated by CFC-induced ozone loss (the "CFC era") is now coming to an end, as a period begins when the impacts of <span class="hlt">stratospheric</span> circulation and chemistry changes induced by Greenhouse Gas increases (the "GHG era"). The <span class="hlt">stratosphere</span> GHG-era will be characterized by continued decreases of ODSs and increases of CO2, N2O, and CH4. In this talk, we will describe how these factors will modify <span class="hlt">stratospheric</span> ozone levels and the basic <span class="hlt">stratospheric</span> climatology: CO2 and CH4 increases will increase <span class="hlt">stratospheric</span> ozone, while N2O increases will decrease <span class="hlt">stratospheric</span> ozone. In particular, GHG increases and the associated <span class="hlt">warming</span> of the troposphere will modify <span class="hlt">stratospheric</span> transport and cool the upper <span class="hlt">stratosphere</span>. We will quantitatively show the contributions by various GHGs to these changes and the specifics of the chemical, dynamical, and radiative changes. Further, we will show how the <span class="hlt">stratosphere</span> evolves under future GHG projections from the various Representative Concentration Pathways, illustrating the different changes in <span class="hlt">stratospheric</span> ozone caused by the concurrent radiative, chemical and dynamical impacts of GHG changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10162460','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10162460"><span id="translatedtitle"><span class="hlt">Stratospheric</span> aircraft: Impact on the <span class="hlt">stratosphere</span>?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Johnston, H.</p> <p>1992-02-01</p> <p>The steady-state distribution of natural <span class="hlt">stratospheric</span> ozone is primarily maintained through production by ultraviolet photolysis of molecular oxygen, destruction by a catalytic cycle involving nitrogen oxides (NO{sub x}), and relocation by air motions within the <span class="hlt">stratosphere</span>. Nitrogen oxides from the exhausts of a commercially viable fleet of supersonic transports would exceed the natural source of <span class="hlt">stratospheric</span> nitrogen oxides if the t should be equipped with 1990 technology jet engines. This model-free comparison between a vital natural global ingredient and a proposed new industrial product shows that building a large fleet of passenger <span class="hlt">stratospheric</span> aircraft poses a significant global problem. NASA and aircraft industries have recognized this problem and are studying the redesign of jet aircraft engines in order to reduce the nitrogen oxides emissions. In 1989 atmospheric models identified two other paths by which the ozone destroying effects of <span class="hlt">stratospheric</span> aircraft might be reduced or eliminated: (1) Use relatively low supersonic Mach numbers and flight altitudes. For a given rate of nitrogen oxides injection into the <span class="hlt">stratosphere</span>, the calculated reduction of total ozone is a strong function of altitude, and flight altitudes well below 20 kilometers give relatively low calculated ozone reductions. (2) Include heterogeneous chemistry in the two-dimensional model calculations. Necessary conditions for answering the question on the title above are to improve the quality of our understanding of the lower <span class="hlt">stratosphere</span> and to broaden our knowledge of hetergeneous <span class="hlt">stratospheric</span> chemistry. This article reviews recently proposed new mechanisms for heterogeneous reactions on the global <span class="hlt">stratospheric</span> sulfate aerosols.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/7279879','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/7279879"><span id="translatedtitle"><span class="hlt">Stratospheric</span> aircraft: Impact on the <span class="hlt">stratosphere</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Johnston, H.</p> <p>1992-02-01</p> <p>The steady-state distribution of natural <span class="hlt">stratospheric</span> ozone is primarily maintained through production by ultraviolet photolysis of molecular oxygen, destruction by a catalytic cycle involving nitrogen oxides (NO{sub x}), and relocation by air motions within the <span class="hlt">stratosphere</span>. Nitrogen oxides from the exhausts of a commercially viable fleet of supersonic transports would exceed the natural source of <span class="hlt">stratospheric</span> nitrogen oxides if the t should be equipped with 1990 technology jet engines. This model-free comparison between a vital natural global ingredient and a proposed new industrial product shows that building a large fleet of passenger <span class="hlt">stratospheric</span> aircraft poses a significant global problem. NASA and aircraft industries have recognized this problem and are studying the redesign of jet aircraft engines in order to reduce the nitrogen oxides emissions. In 1989 atmospheric models identified two other paths by which the ozone destroying effects of <span class="hlt">stratospheric</span> aircraft might be reduced or eliminated: (1) Use relatively low supersonic Mach numbers and flight altitudes. For a given rate of nitrogen oxides injection into the <span class="hlt">stratosphere</span>, the calculated reduction of total ozone is a strong function of altitude, and flight altitudes well below 20 kilometers give relatively low calculated ozone reductions. (2) Include heterogeneous chemistry in the two-dimensional model calculations. Necessary conditions for answering the question on the title above are to improve the quality of our understanding of the lower <span class="hlt">stratosphere</span> and to broaden our knowledge of hetergeneous <span class="hlt">stratospheric</span> chemistry. This article reviews recently proposed new mechanisms for heterogeneous reactions on the global <span class="hlt">stratospheric</span> sulfate aerosols.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Ozone+AND+depletion&id=EJ912888','ERIC'); return false;" href="http://eric.ed.gov/?q=Ozone+AND+depletion&id=EJ912888"><span id="translatedtitle">Global <span class="hlt">Warming</span>: Lessons from Ozone Depletion</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Hobson, Art</p> <p>2010-01-01</p> <p>My teaching and textbook have always covered many physics-related social issues, including <span class="hlt">stratospheric</span> ozone depletion and global <span class="hlt">warming</span>. The ozone saga is an inspiring good-news story that's instructive for solving the similar but bigger problem of global <span class="hlt">warming</span>. Thus, as soon as students in my physics literacy course at the University of…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JASTP.136..187P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JASTP.136..187P"><span id="translatedtitle">Interannual and intraseasonal variability of <span class="hlt">stratospheric</span> dynamics and <span class="hlt">stratosphere</span>-troposphere coupling during northern winter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pogoreltsev, A. I.; Savenkova, E. N.; Aniskina, O. G.; Ermakova, T. S.; Chen, W.; Wei, K.</p> <p>2015-12-01</p> <p>The UK Met Office reanalysis data have been used to investigate the interannual and intraseasonal variability of the <span class="hlt">stratospheric</span> dynamics and thermal structure. The results obtained show that the maximum of interannual variability of the mean zonal flow associated with the quasi-biennial oscillation (QBO) is observed at the altitude of about 30 km. It is shown that there is a statistically significant influence of the QBO phase on the extratropical <span class="hlt">stratosphere</span>, the so-called, Holton-Tan effect. The results of data analysis show that the conditions under the easterly QBO phase are more favorable for the development of the sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> (SSW). The statistical analysis of 15 major SSW observed during two last decades has been performed. The obtained results demonstrate that in recent years internal processes associated with nonlinear interactions of stationary planetary waves (SPW) with the mean flow played a dominant role. It is shown that the first enhancement of the SPW1 in the upper <span class="hlt">stratosphere</span> takes place because of an amplification of nonlinear interactions between this wave and the mean flow. This enhancement is accompanied by a subsequent increase in the wave activity flux from the <span class="hlt">stratosphere</span> into the troposphere with further redistribution of wave activity in the horizontal plane. Then, an increase of the upward flux from the troposphere into the <span class="hlt">stratosphere</span> in another region occurs. The secondary enhancement of the planetary wave activity in the <span class="hlt">stratosphere</span> is accompanied by the heating of the polar region and the weakening, or even reversal of the <span class="hlt">stratospheric</span> jet. Additionally to the well-known result that meridional refraction of SPW to the polar region in <span class="hlt">stratosphere</span> is one of the preconditions of development SSW, the nonlinear wave-wave and wave-mean flow interactions can play an important role before and during SSW. It is shown that the upper <span class="hlt">stratosphere</span> can be considered as the region where SPW2 is generated during SSW.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9242G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9242G"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Response to Intraseasonal Changes in Incoming Solar Radiation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garfinkel, Chaim; silverman, vered; harnik, nili; Erlich, caryn</p> <p>2016-04-01</p> <p>Superposed epoch analysis of meteorological reanalysis data is used to demonstrate a significant connection between intraseasonal solar variability and temperatures in the <span class="hlt">stratosphere</span>. Decreasing solar flux leads to a cooling of the tropical upper <span class="hlt">stratosphere</span> above 7hPa, while increasing solar flux leads to a <span class="hlt">warming</span> of the tropical upper <span class="hlt">stratosphere</span> above 7hPa, after a lag of approximately six to ten days. Late winter (February-March) Arctic <span class="hlt">stratospheric</span> temperatures also change in response to changing incoming solar flux in a manner consistent with that seen on the 11 year timescale: ten to thirty days after the start of decreasing solar flux, the polar cap <span class="hlt">warms</span> during the easterly phase of the Quasi-Biennal Oscillation. In contrast, cooling is present after decreasing solar flux during the westerly phase of the Quasi-Biennal Oscillation (though it is less robust than the <span class="hlt">warming</span> during the easterly phase). The estimated composite mean changes in Northern Hemisphere upper <span class="hlt">stratospheric</span> (~ 5hPa) polar temperatures exceed 8K, and are potentially a source of intraseasonal predictability for the surface. These changes in polar temperature are consistent with the changes in wave driving entering the <span class="hlt">stratosphere</span>. Garfinkel, C.I., V. Silverman, N. Harnik, C. Erlich, Y. Riz (2015), <span class="hlt">Stratospheric</span> Response to Intraseasonal Changes in Incoming Solar Radiation, J. Geophys. Res. Atmos., 120, 7648-7660. doi: 10.1002/2015JD023244.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23698448','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23698448"><span id="translatedtitle">Weakened <span class="hlt">stratospheric</span> quasibiennial oscillation driven by increased tropical mean upwelling.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kawatani, Yoshio; Hamilton, Kevin</p> <p>2013-05-23</p> <p>The zonal wind in the tropical <span class="hlt">stratosphere</span> switches between prevailing easterlies and westerlies with a period of about 28 months. In the lowermost <span class="hlt">stratosphere</span>, the vertical structure of this quasibiennial oscillation (QBO) is linked to the mean upwelling, which itself is a key factor in determining <span class="hlt">stratospheric</span> composition. Evidence for changes in the QBO have until now been equivocal, raising questions as to the extent of <span class="hlt">stratospheric</span> circulation changes in a global <span class="hlt">warming</span> context. Here we report an analysis of near-equatorial radiosonde observations for 1953-2012, and reveal a long-term trend of weakening amplitude in the zonal wind QBO in the tropical lower <span class="hlt">stratosphere</span>. The trend is particularly notable at the 70-hectopascal pressure level (an altitude of about 19 kilometres), where the QBO amplitudes dropped by roughly one-third over the period. This trend is also apparent in the global <span class="hlt">warming</span> simulations of the four models in the Coupled Model Intercomparison Project Phase 5 (CMIP5) that realistically simulate the QBO. The weakening is most reasonably explained as resulting from a trend of increased mean tropical upwelling in the lower <span class="hlt">stratosphere</span>. Almost all comprehensive climate models have projected an intensifying tropical upwelling in global <span class="hlt">warming</span> scenarios, but attempts to estimate changes in the upwelling by using observational data have yielded ambiguous, inconclusive or contradictory results. Our discovery of a weakening trend in the lower-<span class="hlt">stratosphere</span> QBO amplitude provides strong support for the existence of a long-term trend of enhanced upwelling near the tropical tropopause. PMID:23698448</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..43.2323D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.2323D"><span id="translatedtitle">Transport of ice into the <span class="hlt">stratosphere</span> and the humidification of the <span class="hlt">stratosphere</span> over the 21st century</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dessler, A. E.; Ye, H.; Wang, T.; Schoeberl, M. R.; Oman, L. D.; Douglass, A. R.; Butler, A. H.; Rosenlof, K. H.; Davis, S. M.; Portmann, R. W.</p> <p>2016-03-01</p> <p>Climate models predict that tropical lower <span class="hlt">stratospheric</span> humidity will increase as the climate <span class="hlt">warms</span>. We examine this trend in two state-of-the-art chemistry-climate models. Under high greenhouse gas emissions scenarios, the <span class="hlt">stratospheric</span> entry value of water vapor increases by ~1 ppmv over the 21st century in both models. We show with trajectory runs driven by model meteorological fields that the <span class="hlt">warming</span> tropical tropopause layer (TTL) explains 50-80% of this increase. The remainder is a consequence of trends in evaporation of ice convectively lofted into the TTL and lower <span class="hlt">stratosphere</span>. Our results further show that within the models we examined, ice lofting is primarily important on long time scales; on interannual time scales, TTL temperature variations explain most of the variations in lower <span class="hlt">stratospheric</span> humidity. Assessing the ability of models to realistically represent ice lofting processes should be a high priority in the modeling community.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26158244','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26158244"><span id="translatedtitle">Significant radiative impact of volcanic aerosol in the lowermost <span class="hlt">stratosphere</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Andersson, Sandra M; Martinsson, Bengt G; Vernier, Jean-Paul; Friberg, Johan; Brenninkmeijer, Carl A M; Hermann, Markus; van Velthoven, Peter F J; Zahn, Andreas</p> <p>2015-01-01</p> <p>Despite their potential to slow global <span class="hlt">warming</span>, until recently, the radiative forcing associated with volcanic aerosols in the lowermost <span class="hlt">stratosphere</span> (LMS) had not been considered. Here we study volcanic aerosol changes in the <span class="hlt">stratosphere</span> using lidar measurements from the NASA CALIPSO satellite and aircraft measurements from the IAGOS-CARIBIC observatory. Between 2008 and 2012 volcanism frequently affected the Northern Hemisphere <span class="hlt">stratosphere</span> aerosol loadings, whereas the Southern Hemisphere generally had loadings close to background conditions. We show that half of the global <span class="hlt">stratospheric</span> aerosol optical depth following the Kasatochi, Sarychev and Nabro eruptions is attributable to LMS aerosol. On average, 30% of the global <span class="hlt">stratospheric</span> aerosol optical depth originated in the LMS during the period 2008-2011. On the basis of the two independent, high-resolution measurement methods, we show that the LMS makes an important contribution to the overall volcanic forcing. PMID:26158244</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4510655','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4510655"><span id="translatedtitle">Significant radiative impact of volcanic aerosol in the lowermost <span class="hlt">stratosphere</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Andersson, Sandra M.; Martinsson, Bengt G.; Vernier, Jean-Paul; Friberg, Johan; Brenninkmeijer, Carl A. M.; Hermann, Markus; van Velthoven, Peter F. J.; Zahn, Andreas</p> <p>2015-01-01</p> <p>Despite their potential to slow global <span class="hlt">warming</span>, until recently, the radiative forcing associated with volcanic aerosols in the lowermost <span class="hlt">stratosphere</span> (LMS) had not been considered. Here we study volcanic aerosol changes in the <span class="hlt">stratosphere</span> using lidar measurements from the NASA CALIPSO satellite and aircraft measurements from the IAGOS-CARIBIC observatory. Between 2008 and 2012 volcanism frequently affected the Northern Hemisphere <span class="hlt">stratosphere</span> aerosol loadings, whereas the Southern Hemisphere generally had loadings close to background conditions. We show that half of the global <span class="hlt">stratospheric</span> aerosol optical depth following the Kasatochi, Sarychev and Nabro eruptions is attributable to LMS aerosol. On average, 30% of the global <span class="hlt">stratospheric</span> aerosol optical depth originated in the LMS during the period 2008–2011. On the basis of the two independent, high-resolution measurement methods, we show that the LMS makes an important contribution to the overall volcanic forcing. PMID:26158244</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..APRM14006Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..APRM14006Z"><span id="translatedtitle">Studying <span class="hlt">Stratospheric</span> Temperature Variation with Cosmic Ray Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Xiaohang; He, Xiaochun</p> <p>2015-04-01</p> <p>The long term <span class="hlt">stratospheric</span> cooling in recent decades is believed to be equally important as surface <span class="hlt">warming</span> as evidence of influences of human activities on the climate system. Un- fortunatly, there are some discrepancies among different measurements of <span class="hlt">stratospheric</span> tem- peratures, which could be partially caused by the limitations of the measurement techniques. It has been known for decades that cosmic ray muon flux is sensitive to <span class="hlt">stratospheric</span> temperature change. Dorman proposed that this effect could be used to probe the tempera- ture variations in the stratophere. In this talk, a method for reconstructing <span class="hlt">stratospheric</span> temperature will be discussed. We verify this method by comparing the <span class="hlt">stratospheric</span> tem- perature measured by radiosonde with the ones derived from cosmic ray measurement at multiple locations around the globe.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850061224&hterms=variance&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dvariance','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850061224&hterms=variance&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dvariance"><span id="translatedtitle">The origin of temporal variance in long-lived trace constituents in the summer <span class="hlt">stratosphere</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hess, P. G.; Holton, J. R.</p> <p>1985-01-01</p> <p>Temporal variances in the concentrations of N2O, CF2Cl2, CFCl3 and CH4 in the summer <span class="hlt">stratosphere</span> at a midlatitude location have been measured by Ehhalt and others. A simple dynamical model is used to argue that these variances are created by irreversible mixing associated with the springtime final <span class="hlt">stratospheric</span> <span class="hlt">warming</span>. Tracer perturbations generated during the <span class="hlt">warming</span> are advected passively in the zonal mean easterlies so that the tracer variance is effectively frozen into the summertime <span class="hlt">stratosphere</span>. Temperature perturbations, on the other hand, are subject to radiative dissipation; the temperature variance created during the final <span class="hlt">warming</span> relaxes quickly to an ambient value.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20060026077&hterms=stratosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dstratosphere','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20060026077&hterms=stratosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dstratosphere"><span id="translatedtitle">Weather from the <span class="hlt">Stratosphere</span>?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baldwin, Mark P.; Thompson, David W. J.; Shuckburgh, Emily F.; Norton, Warwick A.; Gillett, Nathan P.</p> <p>2006-01-01</p> <p>Is the <span class="hlt">stratosphere</span>, the atmospheric layer between about 10 and 50 km, important for predicting changes in weather and climate? The traditional view is that the <span class="hlt">stratosphere</span> is a passive recipient of energy and waves from weather systems in the underlying troposphere, but recent evidence suggests otherwise. At a workshop in Whistler, British Columbia (1), scientists met to discuss how the <span class="hlt">stratosphere</span> responds to forcing from below, initiating feedback processes that in turn alter weather patterns in the troposphere. The lowest layer of the atmosphere, the troposphere, is highly dynamic and rich in water vapor, clouds, and weather. The <span class="hlt">stratosphere</span> above it is less dense and less turbulent (see the figure). Variability in the <span class="hlt">stratosphere</span> is dominated by hemispheric-scale changes in airflow on time scales of a week to several months. Occasionally, however, <span class="hlt">stratospheric</span> air flow changes dramatically within just a day or two, with large-scale jumps in temperature of 20 K or more. The troposphere influences the <span class="hlt">stratosphere</span> mainly through atmospheric waves that propagate upward. Recent evidence shows that the <span class="hlt">stratosphere</span> organizes this chaotic wave forcing from below to create long-lived changes in the <span class="hlt">stratospheric</span> circulation. These <span class="hlt">stratospheric</span> changes can feed back to affect weather and climate in the troposphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010050736','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010050736"><span id="translatedtitle">Climate and Ozone Response to Increased <span class="hlt">Stratospheric</span> Water Vapor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shindell, Drew T.</p> <p>2001-01-01</p> <p><span class="hlt">Stratospheric</span> water vapor abundance affects ozone, surface climate, and <span class="hlt">stratospheric</span> temperatures. From 30-50 km altitude, temperatures show global decreases of 3-6 K over recent decades. These may be a proxy for water vapor increases, as the Goddard Institute for Space Studies (GISS) climate model reproduces these trends only when <span class="hlt">stratospheric</span> water vapor is allowed to increase. Observations suggest that <span class="hlt">stratospheric</span> water vapor is indeed increasing, however, measurements are extremely limited in either spatial coverage or duration. The model results suggest that the observed changes may be part of a global, long-term trend. Furthermore, the required water vapor change is too large to be accounted for by increased production within the <span class="hlt">stratosphere</span>, suggesting that ongoing climate change may be altering tropospheric input. The calculated <span class="hlt">stratospheric</span> water vapor increase contributes an additional approximately equals 24% (approximately equals 0.2 W/m(exp 2)) to the global <span class="hlt">warming</span> from well-mixed greenhouse gases over the past two decades. Observed ozone depletion is also better reproduced when destruction due to increased water vapor is included. If the trend continues, it could increase future global <span class="hlt">warming</span> and impede <span class="hlt">stratospheric</span> ozone recovery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoRL..43.4609M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoRL..43.4609M&link_type=ABSTRACT"><span id="translatedtitle">The contribution of ozone to future <span class="hlt">stratospheric</span> temperature trends</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maycock, A. C.</p> <p>2016-05-01</p> <p>The projected recovery of ozone from the effects of ozone depleting substances this century will modulate the <span class="hlt">stratospheric</span> cooling due to CO2, thereby affecting the detection and attribution of <span class="hlt">stratospheric</span> temperature trends. Here the impact of future ozone changes on <span class="hlt">stratospheric</span> temperatures is quantified for three representative concentration pathways (RCPs) using simulations from the Fifth Coupled Model Intercomparison Project (CMIP5). For models with interactive chemistry, ozone trends offset ~50% of the global annual mean upper <span class="hlt">stratospheric</span> cooling due to CO2 for RCP4.5 and 20% for RCP8.5 between 2006-2015 and 2090-2099. For RCP2.6, ozone trends cause a net <span class="hlt">warming</span> of the upper and lower <span class="hlt">stratosphere</span>. The misspecification of ozone trends for RCP2.6/RCP4.5 in models that used the International Global Atmospheric Chemistry (IGAC)/<span class="hlt">Stratosphere</span>-troposphere Processes and their Role in Climate (SPARC) Ozone Database causes anomalous <span class="hlt">warming</span> (cooling) of the upper (lower) <span class="hlt">stratosphere</span> compared to chemistry-climate models. The dependence of ozone chemistry on greenhouse gas concentrations should therefore be better represented in CMIP6.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140013024','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140013024"><span id="translatedtitle">Contrasting Effects of Central Pacific and Eastern Pacific El Nino on <span class="hlt">Stratospheric</span> Water Vapor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Garfinkel, Chaim I.; Hurwitz, Margaret M.; Oman, Luke D.; Waugh, Darryn W.</p> <p>2013-01-01</p> <p>Targeted experiments with a comprehensive chemistry-climate model are used to demonstrate that seasonality and the location of the peak <span class="hlt">warming</span> of sea surface temperatures dictate the response of <span class="hlt">stratospheric</span> water vapor to El Nino. In spring, El Nino events in which sea surface temperature anomalies peak in the eastern Pacific lead to a <span class="hlt">warming</span> at the tropopause above the <span class="hlt">warm</span> pool region, and subsequently to more <span class="hlt">stratospheric</span> water vapor (consistent with previous work). However, in fall and in early winter, and also during El Nino events in which the sea surface temperature anomaly is found mainly in the central Pacific, the response is qualitatively different: temperature changes in the <span class="hlt">warm</span> pool region are nonuniform and less water vapor enters the <span class="hlt">stratosphere</span>. The difference in water vapor in the lower <span class="hlt">stratosphere</span> between the two variants of El Nino approaches 0.3 ppmv, while the difference between the winter and spring responses exceeds 0.5 ppmv.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.2963S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.2963S"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Airships: New Opportunities</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, Ira; Perry, William; West, Mark</p> <p></p> <p>Southwest Research Institute (SwRI) and Aerostar International, Inc. have been involved in developing a lightweight, expendable <span class="hlt">stratospheric</span> airship since 1997. The concept of a <span class="hlt">stratospheric</span> airship has been around almost as long as <span class="hlt">stratospheric</span> free balloons. Airships are defined as lighter-than-air vehicles with propulsion and steering systems. The basic technology that makes <span class="hlt">stratospheric</span> airships possible is rooted in the free floating <span class="hlt">stratospheric</span> super pressure balloon technology developed for NASA and the U.S. Air Force over the last 40 years. The current efforts are the next step in a spiral development program for a family of portable launch, long-endurance autonomous solar-electric, <span class="hlt">stratospheric</span> airships. These low-cost systems will be capable of lifting small to medium payloads (20-200 pounds) to near-space pressure altitudes of 50 mbs for a duration of 30 days or greater. Designed for launch from remote sites like a free balloon, these airships will not require large hangars or special facilities. The paper will include a brief history of <span class="hlt">stratospheric</span> airship development, a discussion of the flight environment, key technologies and performance trade study results for <span class="hlt">stratospheric</span> airships. An overview of the application of this technology to Earth and Space Sciences will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920006240','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920006240"><span id="translatedtitle">Trends in <span class="hlt">stratospheric</span> temperature</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schoeberl, M. R.; Newman, P. A.; Rosenfield, J. E.; Angell, J.; Barnett, J.; Boville, B. A.; Chandra, S.; Fels, S.; Fleming, E.; Gelman, M.</p> <p>1989-01-01</p> <p><span class="hlt">Stratospheric</span> temperatures for long-term and recent trends and the determination of whether observed changes in upper <span class="hlt">stratospheric</span> temperatures are consistent with observed ozone changes are discussed. The long-term temperature trends were determined up to 30mb from radiosonde analysis (since 1970) and rocketsondes (since 1969 and 1973) up to the lower mesosphere, principally in the Northern Hemisphere. The more recent trends (since 1979) incorporate satellite observations. The mechanisms that can produce recent temperature trends in the <span class="hlt">stratosphere</span> are discussed. The following general effects are discussed: changes in ozone, changes in other radiatively active trace gases, changes in aerosols, changes in solar flux, and dynamical changes. Computations were made to estimate the temperature changes associated with the upper <span class="hlt">stratospheric</span> ozone changes reported by the Solar Backscatter Ultraviolet (SBUV) instrument aboard Nimbus-7 and the <span class="hlt">Stratospheric</span> Aerosol and Gas Experiment (SAGE) instruments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGC11C0996J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGC11C0996J"><span id="translatedtitle">The impacts of Unilateral <span class="hlt">Stratospheric</span> Geoengineering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jones, A.; Haywood, J. M.; Bellouin, N.; Stephenson, D.</p> <p>2013-12-01</p> <p><span class="hlt">Stratospheric</span> geoengineering proposals have been suggested on the premise that the cooling impacts of volcanic eruptions could be deliberately mimicked to offset the impacts of increased greenhouse gas concentrations in the future by counterbalance global <span class="hlt">warming</span>. Here, we examine both the impacts of hemispherically asymmetric volcanoes in the observational record and the impact of prolonged deliberate injection of <span class="hlt">stratospheric</span> aerosol into either the northern or southern hemisphere <span class="hlt">stratosphere</span> or into both hemispheres equally to assess the impacts on Sahelian rainfall and agriculture (Haywood et al., 2013). While the frequency of volcanic eruptions during the past 100 years is too sparse for definitive attribution, there is a suggestion that volcanic eruptions that preferentially load the northern hemisphere are the harbinger of Sahelian drought. Simulations are then performed with the HadGEM2 couple atmospheric-ocean model to assess the impacts of these volcanic eruptions and deliberate unilateral <span class="hlt">stratospheric</span> geoengineering. Figure 1 shows the impacts of the geoengineering simulations which show that <span class="hlt">stratospheric</span> injection into the northern hemisphere induces a severe and prolonged Sahelian drought with undoubted detrimental consequences for the local population. Conversely injection into the southern hemisphere causes a significant greening of the Sahel with vegetation productivity enhanced by over 100%. On the face of it, this suggests potential advocacy of injection into the southern hemisphere: we will investigate potential other side-effects from such a strategy...... Haywood, J.M., A. Jones, N. Bellouin, and D.B. Stephenson, Asymmetric forcing from <span class="hlt">stratospheric</span> aerosols impacts Sahelian drought, Nature Climate Change, Vol 3, No 7, 660-665, doi: 10.1038/NCLIMATE1857, 2013.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920005321','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920005321"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Data Analysis System (STRATAN)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rood, Richard B.; Fox-Rabinovitz, Michael; Lamich, David J.; Newman, Paul A.; Pfaendtner, James W.</p> <p>1990-01-01</p> <p>A state of the art <span class="hlt">stratospheric</span> analyses using a coupled <span class="hlt">stratosphere</span>/troposphere data assimilation system is produced. These analyses can be applied to <span class="hlt">stratospheric</span> studies of all types. Of importance to this effort is the application of the <span class="hlt">Stratospheric</span> Data Analysis System (STRATAN) to constituent transport and chemistry problems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19890062622&hterms=Carl+Sagan&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DCarl%2BSagan','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19890062622&hterms=Carl+Sagan&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DCarl%2BSagan"><span id="translatedtitle">Triton - <span class="hlt">Stratospheric</span> molecules and organic sediments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thompson, W. Reid; Singh, Sushil K.; Khare, B. N.; Sagan, Carl</p> <p>1989-01-01</p> <p>Continuous-flow plasma discharge techniques show production rates of hydrocarbons and nitriles in N2 + CH4 atmospheres appropriate to the <span class="hlt">stratosphere</span> of Titan, and indicate that a simple eddy diffusion model together with the observed electron flux quantitatively matches the Voyager IRIS observations for all the hydrocarbons, except for the simplest ones. Charged particle chemistry is very important in Triton's <span class="hlt">stratosphere</span>. In the more CH4-rich case of Titan, many hydrocarbons and nitriles are produced in high yield. If N2 is present, the CH4 fraction is low, but hydrocarbons and nitriles are produced in fair yield, abundances of HCN and C2H2 in Triton's <span class="hlt">stratosphere</span> exceed 10 to the 19th molecules/sq cm per sec, and NCCN, C3H4, and other species are predicted to be present. These molecules may be detected by IRIS if the <span class="hlt">stratosphere</span> is as <span class="hlt">warm</span> as expected. Both organic haze and condensed gases will provide a substantial UV and visible opacity in Triton's atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040161514&hterms=NaSH&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DNaSH','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040161514&hterms=NaSH&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DNaSH"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Impact of Varying Sea Surface Temperatures</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Newman, Paul A.; Nash, Eric R.; Nielsen, Jon E.; Waugh, Darryn; Pawson, Steven</p> <p>2004-01-01</p> <p>The Finite-Volume General Circulation Model (FVGCM) has been run in 50 year simulations with the: 1) 1949-1999 Hadley Centre sea surface temperatures (SST), and 2) a fixed annual cycle of SSTs. In this presentation we first show that the 1949-1999 FVGCM simulation produces a very credible <span class="hlt">stratosphere</span> in comparison to an NCEP/NCAR reanalysis climatology. In particular, the northern hemisphere has numerous major and minor <span class="hlt">stratospheric</span> <span class="hlt">warming</span>, while the southern hemisphere has only a few over the 50-year simulation. During the northern hemisphere winter, temperatures are both warmer in the lower <span class="hlt">stratosphere</span> and the polar vortex is weaker than is found in the mid-winter southern hemisphere. Mean temperature differences in the lower <span class="hlt">stratosphere</span> are shown to be small (less than 2 K), and planetary wave forcing is found to be very consistent with the climatology. We then will show the differences between our varying SST simulation and the fixed SST simulation in both the dynamics and in two parameterized trace gases (ozone and methane). In general, differences are found to be small, with subtle changes in planetary wave forcing that lead to reduced temperatures in the SH and increased temperatures in the NH.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850012148','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850012148"><span id="translatedtitle">Abnormal Circulation Changes in the Winter <span class="hlt">Stratosphere</span>, Detected Through Variations of D Region Ionospheric Absorption</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Delamorena, B. A.</p> <p>1984-01-01</p> <p>A method to detect <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> using ionospheric absorption records obtained by an Absorption Meter (method A3) is introduced. The activity of the <span class="hlt">stratospheric</span> circulation and the D region ionospheric absorption as well as other atmospheric parameters during the winter anomaly experience an abnormal variation. A simultaneity was found in the beginning of abnormal variation in the mentioned parameters, using the absorption records for detecting the initiation of the <span class="hlt">stratospheric</span> <span class="hlt">warming</span>. Results of this scientific experience of forecasting in the El Arenosillo Range, are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=47358&keyword=WARMING+AND+EARTH&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=75968783&CFTOKEN=90720403','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=47358&keyword=WARMING+AND+EARTH&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=75968783&CFTOKEN=90720403"><span id="translatedtitle">LINKAGE BETWEEN CLIMATE CHANGE AND <span class="hlt">STRATOSPHERIC</span> OZONE DEPLETION</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Two primary areas link the issue of <span class="hlt">stratospheric</span> ozone depletion to global climate change: atmospheric processes and ecological processes. tmospheric processes establish a linkage through the dual roles of certain trace gases in promoting global <span class="hlt">warming</span> and in depleting the ozon...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PhDT.......187A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhDT.......187A"><span id="translatedtitle">Pathways for Communicating the Effects of <span class="hlt">Stratospheric</span> Ozone to Northern Hemisphere <span class="hlt">Stratospheric</span> Climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Albers, John Robert</p> <p></p> <p> the upper <span class="hlt">stratosphere</span>, where damping due to photochemically accelerated cooling dominates, causing a large reduction in planetary wave drag and thus a colder polar vortex. Task two examines the role of ozone in communicating secular and episodic changes in lower <span class="hlt">stratospheric</span> ozone to affect the upper <span class="hlt">stratosphere</span> and lower mesosphere. It is found that while the radiative effects of the ozone loss are confined to the ozone loss region (below ˜30 km in height), the ozone-dynamical feedbacks amplify the response throughout the <span class="hlt">stratosphere</span> and lower mesosphere. In particular, ozone-dynamical feedbacks cause decreased zonal-mean winds and increased residual downwelling in the upper <span class="hlt">stratosphere</span>. The final task utilizes an atmospheric general circulation model. It is found that ZAO profoundly changes the morphology of the NH planetary waveguide (PWG). ZAO causes the PWG to contract meridionally and expand vertically, with a significant increase in vertical wave propagation. Consequently, there is a significant increase in the upward flux of wave activity from the troposphere and lower <span class="hlt">stratosphere</span> into the interior of the <span class="hlt">stratosphere</span> and lower mesosphere. The ZAO-induced changes in the PWG increase the Eliassen-Palm flux divergence, causing a warmer and weaker <span class="hlt">stratospheric</span> polar vortex. The implications for accurately modeling wave-driven phenomena in the middle atmosphere, including sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span>, 11-year solar cycle-modulated wave activity, and the Brewer-Dobson circulation is examined in light of the ability of ZAO to alter the flux of planetary wave activity into the polar vortex.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3831493','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3831493"><span id="translatedtitle"><span class="hlt">Stratospheric</span> water vapor feedback</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dessler, A. E.; Schoeberl, M. R.; Wang, T.; Davis, S. M.; Rosenlof, K. H.</p> <p>2013-01-01</p> <p>We show here that <span class="hlt">stratospheric</span> water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that <span class="hlt">stratospheric</span> water vapor increases with tropospheric temperature, implying the existence of a <span class="hlt">stratospheric</span> water vapor feedback. We estimate the strength of this feedback in a chemistry–climate model to be +0.3 W/(m2⋅K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the <span class="hlt">stratosphere</span> through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause. PMID:24082126</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24082126','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24082126"><span id="translatedtitle"><span class="hlt">Stratospheric</span> water vapor feedback.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dessler, A E; Schoeberl, M R; Wang, T; Davis, S M; Rosenlof, K H</p> <p>2013-11-01</p> <p>We show here that <span class="hlt">stratospheric</span> water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that <span class="hlt">stratospheric</span> water vapor increases with tropospheric temperature, implying the existence of a <span class="hlt">stratospheric</span> water vapor feedback. We estimate the strength of this feedback in a chemistry-climate model to be +0.3 W/(m(2)⋅K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the <span class="hlt">stratosphere</span> through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause. PMID:24082126</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994AdSpR..14...41T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994AdSpR..14...41T"><span id="translatedtitle"><span class="hlt">Stratospheric</span> and mesospheric observations with ISAMS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taylor, F. W.; Ballard, J.; Dudhia, A.; Goss-Custard, M.; Kerridge, B. J.; Lambert, A.; López-Valverde, M.; Rodgers, C. D.; Remedios, J. J.</p> <p>1994-09-01</p> <p>The scientific objectives of the Improved <span class="hlt">Stratospheric</span> and Mesospheric Sounder (ISAMS) experiment involve the measurement of global temperature and composition profiles from an instrument on the Upper Atmosphere Research Satellite (UARS). This paper discusses these objectives in the light of the data acquired during the first ten months of the mission. Interesting interim results include detailed observations of a <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> and a nitrogen dioxide (NO2) ``Noxon cliff'', enhanced thermospheric nitric oxide (NO) production during a solar flare, strongly increased concentrations of carbon monoxide (CO) over the winter poles, non-LTE behaviour of mesospheric water vapour (H2O), and unexpected transport properties of volcanic aerosol, and the long-lived tracers methane (CH4) and nitrous oxide (N2O).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.1112B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.1112B"><span id="translatedtitle">Influence of <span class="hlt">Stratospheric</span> Ozone Distribution on Tropospheric Circulation Patterns</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barodka, Siarhei; Krasouski, Aliaksandr; Mitskevich, Yaroslav; Shalamyansky, Arkady</p> <p>2015-04-01</p> <p>In the present study we investigate the cause-and-effect relationship between the <span class="hlt">stratospheric</span> ozone distribution and tropospheric circulation, focusing our attention mainly on the possible "top-down" side of this interaction: the impact of the <span class="hlt">stratosphere</span> on tropospheric circulation patterns and the associated weather and climate conditions. Proceeding from analysis of several decades of observational data performed at the A.I. Voeikov Main Geophysical Observatory, which suggests a clear relation between the <span class="hlt">stratospheric</span> ozone distribution, temperature field of the lower <span class="hlt">stratosphere</span> and air-masses boundaries in the upper troposphere, we combine atmospheric reanalyzes and ground-based observations with numerical simulations to identify features of the general circulation that can be traced back to anomalies in the <span class="hlt">stratospheric</span> ozone field. Specifically, we analyze the time evolution of instantaneous position of the stationary upper-level atmospheric fronts, defining the boundaries of global tropospheric air masses associated with basic cells of general circulation. We assume that <span class="hlt">stratospheric</span> heating in ozone-related processes can exert its influence on the location of stationary fronts and characteristics of general circulation cells by displacing the tropopause, which itself is defined by a dynamical equilibrium between tropospheric vertical convection and <span class="hlt">stratospheric</span> radiative heating. As an example, we consider the Spring season of 2013. Unusually high total ozone column (TOC) values observed in Northern Hemisphere (NH) at the beginning of 2013 induced low tropopause level in the Atlantic region and southward displacement of the polar front, leading to an anomalously cold Spring in Europe. Furthermore, we study manifestations of this mechanism in the aftermath of sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) events. In particular, the November 2013 SSW over Eastern Siberia, which is characterized by abrupt <span class="hlt">stratospheric</span> temperatures change in the course of one day</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AtmRe.164..358I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AtmRe.164..358I"><span id="translatedtitle">Characteristics of cirrus clouds in the tropical lower <span class="hlt">stratosphere</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Iwasaki, Suginori; Luo, Zhengzhao Johnny; Kubota, Hisayuki; Shibata, Takashi; Okamoto, Hajime; Ishimoto, Hiroshi</p> <p>2015-10-01</p> <p>A unique type of cloud in the tropical lower <span class="hlt">stratosphere</span>, which we call "<span class="hlt">stratospheric</span> cirrus", is described in this study. <span class="hlt">Stratospheric</span> cirrus clouds are generally detached from overshooting deep convection and are much smaller than subvisual cirrus often observed near the tropical tropopause. We analyzed two cases of <span class="hlt">stratospheric</span> cirrus in the tropical and subtropical lower <span class="hlt">stratosphere</span> captured by the space-borne lidar, Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Both cases occurred 2-3 hours after the most active phase of the nearby convective cloud clusters. Case 1 has a double-layer structure above the cold point height (CPH); the CPH and two cloud top heights are, respectively, 17.8, 18.9, and 19.9 km. Case 2 has a single cloud layer where CPH and the cloud top height are, respectively, 16.5 and 18.7 km. The mode radius and ice water content of the <span class="hlt">stratospheric</span> cirrus clouds are estimated to be 4-10 μm and 0.2-0.8 mg/m3 based on the radar-lidar method and consideration of the cloud particle terminal velocity. Comparisons with previous numerical model simulation studies suggest that the double-layer <span class="hlt">stratospheric</span> cirrus clouds are likely from an overshooting plume, pushed up into the <span class="hlt">stratosphere</span> in an overshoot when <span class="hlt">warm</span> <span class="hlt">stratospheric</span> air is inhomogeneously mixed with cold overshooting air. The single-layer <span class="hlt">stratospheric</span> cirrus cloud is associated with some non-negligible wind shear, so it could be a jumping cirrus cloud, although we cannot rule out the possibility that it came from an overshooting plume because of the similarity in cloud characteristics and morphology between the two cases. Guided by the case studies, an automatic algorithm was developed to select <span class="hlt">stratospheric</span> cirrus clouds for global survey and statistical analysis. A total of four years of CALIPSO and space-borne cloud radar (CloudSat) data were analyzed. Statistical analysis suggests that <span class="hlt">stratospheric</span> cirrus clouds occur on the order of 3.0 × 103 times a year</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.5779H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.5779H"><span id="translatedtitle"><span class="hlt">Stratospheric</span> changes caused by geoengineering aerosols</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heckendorn, P.; Peter, T.; Weisenstein, D.; Luo, B. P.; Rozanov, E.; Fueglistaler, S.; Thomason, L. W.</p> <p>2010-05-01</p> <p>Anthropogenic greenhouse gas emissions are <span class="hlt">warming</span> the global climate at an unprecedented rate. Significant emission reductions will be required soon to avoid a rapid temperature rise. One of the most prominent geoengineering ideas to counteract global <span class="hlt">warming</span> is the increase of Earth's albedo by artificially enhancing <span class="hlt">stratospheric</span> sulphate aerosols. This idea is based on the observed increase of atmospheric optical thickness after volcanic eruptions. The most straightforward method, from a technical point of view, is to inject sulphur in the tropical <span class="hlt">stratosphere</span>. We use a 3D chemistry climate model, fed by aerosol size distributions from a zonal mean aerosol model, to simulate continuous injection of 1-10 Mt/a sulphur in form of SO2 into the lower tropical <span class="hlt">stratosphere</span>. The volcanic and geoengineering forcings differ in terms of their radiative, chemical and dynamical impact on climate, mainly because the geoengineering forcing has to be continuously applied over a long period of time, whereas volcanic eruptions are single events, leading to a non-linear relationship between annual sulphur input and <span class="hlt">stratospheric</span> sulphur burden. The reason is the continuous supply of sulphuric acid and hence freshly formed small aerosol particles, which enhance the formation of large aerosol particles by coagulation and, to a lesser extent, also by condensation. This shows the importance of investigating carefully the microphysics of the sulphate aerosols. The growth of the particles is sensitive to the injection region and the sulphur loading per injection time. The consequences of the formation of large particles lead to notable disadvantages. Larger particles are less efficient in cooling than small particles with the same mass. Furthermore, a large fraction of the emitted sulphur is lost rapidly by gravitational settling and subsequent tropospheric washout. Hence, larger sulphur amounts are needed to achieve a targeted cooling. Some particles are trapped in the tropopause</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011PhDT.......202K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011PhDT.......202K&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Stratospheric</span> geoengineering with black carbon aerosols</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kravitz, Benjamin S.</p> <p></p> <p>I use a general circulation model of Earth's climate to simulate <span class="hlt">stratospheric</span> geoengineering with black carbon aerosols, varying the altitude of injection, initial particle size, and whether the deposited black carbon modifies ground albedo. 1 Tg of black carbon aerosols injected into the <span class="hlt">stratosphere</span> each year will cause significant enough surface cooling to negate anthropogenic <span class="hlt">warming</span> if the aerosols are small (r=0.03 mum) or if the aerosols are injected into the middle <span class="hlt">stratosphere</span>, although using small aerosols causes large regional cooling effects that would be catastrophic to agriculture. The aerosols cause significant <span class="hlt">stratospheric</span> heating, resulting in <span class="hlt">stratospheric</span> ozone destruction and circulation changes, most notably an increase in the Northern Hemisphere polar jet, which forms an Arctic ozone hole and forces a positive mode of the Arctic Oscillation. The hydrologic cycle is perturbed, specifically the summer monsoon system of India, Africa, and East Asia, resulting in monsoon precipitation collapse. Global primary productivity is decreased by 35.5% for the small particle case. Surface cooling causes some sea ice regrowth, but not at statistically significant levels. All of these climate impacts are exacerbated for small particle geoengineering, with high altitude geoengineering with the default particle size (r=0.08 mum) causing a reasonable amount of cooling, and large particle (r=0.15 mum) geoengineering or particle injection into the lower <span class="hlt">stratosphere</span> causing few of these effects. The modification of ground albedo by the soot particles slightly perturbs the radiative budget but does not cause any distinguishable climate effects. The cheapest means we investigated for placing 1 Tg of black carbon aerosols into the <span class="hlt">stratosphere</span> by diesel fuel combustion would cost 1.4 trillion initially and 541 billion annual, or 2.0% and 0.8% of GDP, respectively. The additional carbon dioxide released from combusting diesel to produce these aerosols is about 1</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150011025','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150011025"><span id="translatedtitle">Disentangling the Roles of Various Forcing Mechanisms on <span class="hlt">Stratospheric</span> Temperature Changes Since 1979 with the NASA GEOSCCM</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Aquila, Valentina; Swartz, W.; Colarco, P.; Pawson, S.; Polvani, L.; Stolarski, R.; Waugh, D.</p> <p>2015-01-01</p> <p>Observations show that the cooling of global <span class="hlt">stratospheric</span> temperatures from 1979 to 2015 took place in two major steps coincident with the 1982 El Chichon and 1991 Mount Pinatubo eruptions. In order to attribute the features of the global <span class="hlt">stratospheric</span> temperature time series to the main forcing agents, we performed a set of simulations with the NASA Goddard Earth Observing System Chemistry Climate Model. Our results show that the characteristic step-like behavior is to be attributed to the effects of the solar cycle, except for the post-1995 flattening of the lower <span class="hlt">stratospheric</span> temperatures, where the decrease in ozone depleting substances due to the Montreal Protocol slowed ozone depletion and therefore also the cooling of the <span class="hlt">stratosphere</span>. Volcanic eruptions also caused a significant <span class="hlt">warming</span> of the <span class="hlt">stratosphere</span> after 1995. The observed general cooling is mainly caused by increasing ozone depleting substances in the lower <span class="hlt">stratosphere</span>, and greenhouse gases in the middle and upper <span class="hlt">stratosphere</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19810028856&hterms=variance&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dvariance','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810028856&hterms=variance&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dvariance"><span id="translatedtitle">Seasonal variation of radiance variances from satellite observations Implication of seasonal variation of available potential energy in the <span class="hlt">stratosphere</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chen, T.-C.; Stanford, J. L.</p> <p>1980-01-01</p> <p>Nimbus 5 satellite radiances for the period 1973-74 are used to examine the seasonal variation of available potential energy in the <span class="hlt">stratosphere</span> in order to provide a further observational basis for a long-term numerical simulation of <span class="hlt">stratospheric</span> circulation. The maximum value of <span class="hlt">stratospheric</span> zonal available potential energy, A(Z), in the upper and middle <span class="hlt">stratosphere</span> shows pronounced variations between winter and summer, while little variation occurs in the lower <span class="hlt">stratospheric</span> A(Z). The aperiodic occurrence of sudden <span class="hlt">warmings</span> complicates the seasonal variation of A(Z) and A(E) (eddy available potential energy) in the <span class="hlt">stratosphere</span>, making the energetics irregular. Time-Fourier analysis reveals that the primary variation of A(Z) and A(E) in the <span class="hlt">stratosphere</span> is annual and semiannual, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007ACPD....7.6557K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007ACPD....7.6557K"><span id="translatedtitle">Observation of Polar <span class="hlt">Stratospheric</span> Clouds down to the Mediterranean coast</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keckhut, P.; David, Ch.; Marchand, M.; Bekki, S.; Jumelet, J.; Hauchecorne, A.</p> <p>2007-05-01</p> <p>A Polar <span class="hlt">Stratospheric</span> Cloud (PSC) was detected for the first time in January 2006 over Southern Europe after 25 years of systematic lidar observations. This cloud was observed while the polar vortex was highly distorted during the initial phase of a major <span class="hlt">stratospheric</span> <span class="hlt">warming</span>. Very cold <span class="hlt">stratospheric</span> temperatures (<190 K) centred over the Northern-Western Europe were reported, extending down to the South of France where lidar observations were performed. CTM (Chemical Transport Model) investigations show that this event led to a significant direct ozone destruction (35 ppb/day), within and outside the vortex as chlorine activated air masses were moved to sunlight regions allowing ozone destruction. If such exceptional events of mid-latitudes PSCs were to become frequent in the future, they should not compromise the ozone recovery because their effect appears to be limited temporally and spatially. More importantly, these events might tend to be associated with the initial phase of a <span class="hlt">stratospheric</span> <span class="hlt">warming</span> that results into a weakening and <span class="hlt">warming</span> of the polar vortex and hence into a reduced probability occurrence of PSC temperatures during the rest of the winter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007ACP.....7.5275K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007ACP.....7.5275K"><span id="translatedtitle">Observation of Polar <span class="hlt">Stratospheric</span> Clouds down to the Mediterranean coast</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keckhut, P.; David, Ch.; Marchand, M.; Bekki, S.; Jumelet, J.; Hauchecorne, A.; Höpfner, M.</p> <p>2007-10-01</p> <p>A Polar <span class="hlt">Stratospheric</span> Cloud (PSC) was detected for the first time in January 2006 over Southern Europe after 25 years of systematic lidar observations. This cloud was observed while the polar vortex was highly distorted during the initial phase of a major <span class="hlt">stratospheric</span> <span class="hlt">warming</span>. Very cold <span class="hlt">stratospheric</span> temperatures (<190 K) centred over the Northern-Western Europe were reported, extending down to the South of France where lidar observations were performed. CTM (Chemical Transport Model) investigations show that this event led to a significant direct ozone destruction (35 ppb/day), within and outside the vortex as chlorine activated air masses were moved to sunlight regions allowing ozone destruction. If such exceptional events of mid-latitudes PSCs were to become frequent in the future, they should not compromise the ozone recovery because their effect appears to be limited temporally and spatially. More importantly, these events might tend to be associated with the initial phase of a <span class="hlt">stratospheric</span> <span class="hlt">warming</span> that results into a weakening and <span class="hlt">warming</span> of the polar vortex and hence into a reduced probability occurrence of PSC temperatures during the rest of the winter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20080030230&hterms=stratosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dstratosphere','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20080030230&hterms=stratosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dstratosphere"><span id="translatedtitle">Analysis of the Interactions of Planetary Waves with the Mean Flow of the <span class="hlt">Stratosphere</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Newman, Paul A.</p> <p>2007-01-01</p> <p>During the winter period, large scale waves (planetary waves) are observed to propagate from the troposphere into the <span class="hlt">stratosphere</span>. Such wave events have been recognized since the 1 950s. The very largest wave events result in major <span class="hlt">stratospheric</span> <span class="hlt">warmings</span>. These large scale wave events have typical durations of a few days to 2 weeks. The wave events deposit easterly momentum in the <span class="hlt">stratosphere</span>, decelerating the polar night jet and <span class="hlt">warming</span> the polar region. In this presentation we show the typical characteristics of these events via a compositing analysis. We will show the typical periods and scales of motion and the associated decelerations and <span class="hlt">warmings</span>. We will illustrate some of the differences between major and minor <span class="hlt">warming</span> wave events. We will further illustrate the feedback by the mean flow on subsequent wave events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012cosp...39.1850S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012cosp...39.1850S&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Airship Design Sensitivity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, Ira Steve; Fortenberry, Michael; Noll, . James; Perry, William</p> <p>2012-07-01</p> <p>The concept of a <span class="hlt">stratospheric</span> or high altitude powered platform has been around almost as long as <span class="hlt">stratospheric</span> free balloons. Airships are defined as Lighter-Than-Air (LTA) vehicles with propulsion and steering systems. Over the past five (5) years there has been an increased interest by the U. S. Department of Defense as well as commercial enterprises in airships at all altitudes. One of these interests is in the area of <span class="hlt">stratospheric</span> airships. Whereas DoD is primarily interested in things that look down, such platforms offer a platform for science applications, both downward and outward looking. Designing airships to operate in the <span class="hlt">stratosphere</span> is very challenging due to the extreme high altitude environment. It is significantly different than low altitude airship designs such as observed in the familiar advertising or tourism airships or blimps. The <span class="hlt">stratospheric</span> airship design is very dependent on the specific application and the particular requirements levied on the vehicle with mass and power limits. The design is a complex iterative process and is sensitive to many factors. In an effort to identify the key factors that have the greatest impacts on the design, a parametric analysis of a simplified airship design has been performed. The results of these studies will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020009749','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020009749"><span id="translatedtitle">Human Health Effects of Ozone Depletion From <span class="hlt">Stratospheric</span> Aircraft</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wey, Chowen (Technical Monitor)</p> <p>2001-01-01</p> <p>This report presents EPA's initial response to NASA's request to advise on potential environmental policy issues associated with the future development of supersonic flight technologies. Consistent with the scope of the study to which NASA and EPA agreed, EPA has evaluated only the environmental concerns related to the <span class="hlt">stratospheric</span> ozone impacts of a hypothetical HSCT fleet, although recent research indicates that a fleet of HSCT is predicted to contribute to climate <span class="hlt">warming</span> as well. This report also briefly describes the international and domestic institutional frameworks established to address <span class="hlt">stratospheric</span> ozone depletion, as well as those established to control pollution from aircraft engine exhaust emissions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880029795&hterms=Ozone+layer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2528Ozone%2Blayer%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880029795&hterms=Ozone+layer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2528Ozone%2Blayer%2529"><span id="translatedtitle">Ozone and the <span class="hlt">stratosphere</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shimazaki, Tatsuo</p> <p>1987-01-01</p> <p>It is shown that the <span class="hlt">stratospheric</span> ozone is effective in absorbing almost all radiation below 300 nm at heights below 300 km. The distribution of global ozone in the troposphere and the lower <span class="hlt">stratosphere</span>, and the latitudinal variations of the total ozone column over four seasons are considered. The theory of the ozone layer production is discussed together with catalytic reactions for ozone loss and the mechanisms of ozone transport. Special attention is given to the anthropogenic perturbations, such as SST exhaust gases and freon gas from aerosol cans and refrigerators, that may cause an extensive destruction of the <span class="hlt">stratospheric</span> ozone layer and thus have a profound impact on the world climate and on life.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1113073K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1113073K"><span id="translatedtitle"><span class="hlt">Stratospheric</span> changes caused by geoengineering applications: potential repercussions and uncertainties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kenzelmann, P.; Weisenstein, D.; Peter, T.; Luo, B. P.; Rozanov, E.; Fueglistaler, S.; Thomason, L. W.</p> <p>2009-04-01</p> <p>Anthropogenic greenhouse gas emissions tend to <span class="hlt">warm</span> the global climate, calling for significant rapid emission reductions. As potential support measures various ideas for geoengineering are currently being discussed. The assessment of the possible manifold and as yet substantially unexplored repercussions of implementing geoengineering ideas to ameliorate climate change poses enormous challenges not least in the realm of aerosol-cloud-climate interactions. Sulphur aerosols cool the Earth's surface by reflecting short wave radiation. By increasing the amount of sulphur aerosols in the <span class="hlt">stratosphere</span>, for example by sulphur dioxide injections, part of the anthropogenic climate <span class="hlt">warming</span> might be compensated due to enhanced albedo. However, we are only at the beginning of understanding possible side effects. One such effect that such aerosol might have is the <span class="hlt">warming</span> of the tropical tropopause and consequently the increase of the amount of <span class="hlt">stratospheric</span> water vapour. Using the 2D AER Aerosol Model we calculated the aerosol distributions for yearly injections of 1, 2, 5 and 10 Mt sulphur into the lower tropical <span class="hlt">stratosphere</span>. The results serve as input for the 3D chemistry-climate model SOCOL, which allows calculating the aerosol effect on <span class="hlt">stratospheric</span> temperatures and chemistry. In the injection region the continuously formed sulphuric acid condensates rapidly on sulphate aerosol, which eventually grow to such extent that they sediment down to the tropical tropopause region. The growth of the aerosol particles depends on non-linear processes: the more sulphur is emitted the faster the particles grow. As a consequence for the scenario with continuous sulphur injection of totally 10 Mt per year, only 6 Mt sulphur are in the <span class="hlt">stratosphere</span> if equilibrium is reached. According to our model calculations this amount of sulphate aerosols leads to a net surface forcing of -3.4 W/m2, which is less then expected radiative forcing by doubling of carbon dioxide concentration. Hence</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19840055075&hterms=Bromine&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DBromine','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19840055075&hterms=Bromine&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DBromine"><span id="translatedtitle">Measurements of <span class="hlt">stratospheric</span> bromine</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sedlacek, W. A.; Lazrus, A. L.; Gandrud, B. W.</p> <p>1984-01-01</p> <p>From 1974 to 1977, molecules containing acidic bromine were sampled in the <span class="hlt">stratosphere</span> by using tetrabutyl ammonium hydroxide impregnated filters. Sampling was accomplished by WB-57F aircraft and high-altitude balloons, spanning latitudes from the equator to 75 deg N and altitudes up to 36.6 km. Analytical results are reported for 4 years of measurements and for laboratory simulations that determined the filter collection efficiencies for a number of brominated species. Mass mixing ratios for the collected bromine species in air average about 27 pptm in the <span class="hlt">stratosphere</span>. Seasonal variability seems to be small.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010PhTea..48..525H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010PhTea..48..525H&link_type=ABSTRACT"><span id="translatedtitle">Global <span class="hlt">Warming</span>: Lessons from Ozone Depletion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hobson, Art</p> <p>2010-11-01</p> <p>My teaching and textbook have always covered many physics-related social issues, including <span class="hlt">stratospheric</span> ozone depletion and global <span class="hlt">warming</span>. The ozone saga is an inspiring good-news story that's instructive for solving the similar but bigger problem of global <span class="hlt">warming</span>. Thus, as soon as students in my physics literacy course at the University of Arkansas have developed a conceptual understanding of energy and of electromagnetism, including the electromagnetic spectrum, I devote a lecture (and a textbook section) to ozone depletion and another lecture (and section) to global <span class="hlt">warming</span>. Humankind came together in 1986 and quickly solved, to the extent that humans can solve it, ozone depletion. We could do the same with global <span class="hlt">warming</span>, but we haven't and as yet there's no sign that we will. The parallel between the ozone and global <span class="hlt">warming</span> cases, and the difference in outcomes, are striking and instructive.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770024750','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770024750"><span id="translatedtitle">Chlorofluoromethanes and the <span class="hlt">Stratosphere</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hudson, R. D. (Editor)</p> <p>1977-01-01</p> <p>The conclusions of a workshop held by the National Aeronautics and Space Administration to assess the current knowledge of the impact of chlorofluoromethane release in the troposphere on <span class="hlt">stratospheric</span> ozone concentrations. The following topics are discussed; (1) Laboratory measurements; (2) Ozone measurements and trends; (3) Minor species and aerosol measurements; (4) One dimensional modeling; and (5) Multidimensional modeling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140017638','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140017638"><span id="translatedtitle">Northern Winter Climate Change: Assessment of Uncertainty in CMIP5 Projections Related to <span class="hlt">Stratosphere</span>-Troposphere Coupling</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Manzini, E.; Karpechko, A.Yu.; Anstey, J.; Shindell, Drew Todd; Baldwin, M.P.; Black, R.X.; Cagnazzo, C.; Calvo, N.; Charlton-Perez, A.; Christiansen, B.; Davini, Paolo; Gerber, E.; Giorgetta, M.; Gray, L.; Hardiman, S.C.; Lee, Y.-Y.; Marsh, D.R.; McDaniel, B.A.; Purich, A.; Scaife, A.A.; Shindell, Drew; Son, S.-W; Watanabe, S.; Zappa, G.</p> <p>2014-01-01</p> <p>Future changes in the <span class="hlt">stratospheric</span> circulation could have an important impact on northern winter tropospheric climate change, given that sea level pressure (SLP) responds not only to tropospheric circulation variations but also to vertically coherent variations in troposphere-<span class="hlt">stratosphere</span> circulation. Here we assess northern winter <span class="hlt">stratospheric</span> change and its potential to influence surface climate change in the Coupled Model Intercomparison Project-Phase 5 (CMIP5) multimodel ensemble. In the <span class="hlt">stratosphere</span> at high latitudes, an easterly change in zonally averaged zonal wind is found for the majority of the CMIP5 models, under the Representative Concentration Pathway 8.5 scenario. Comparable results are also found in the 1% CO2 increase per year projections, indicating that the <span class="hlt">stratospheric</span> easterly change is common feature in future climate projections. This <span class="hlt">stratospheric</span> wind change, however, shows a significant spread among the models. By using linear regression, we quantify the impact of tropical upper troposphere <span class="hlt">warming</span>, polar amplification, and the <span class="hlt">stratospheric</span> wind change on SLP. We find that the intermodel spread in <span class="hlt">stratospheric</span> wind change contributes substantially to the intermodel spread in Arctic SLP change. The role of the <span class="hlt">stratosphere</span> in determining part of the spread in SLP change is supported by the fact that the SLP change lags the <span class="hlt">stratospheric</span> zonally averaged wind change. Taken together, these findings provide further support for the importance of simulating the coupling between the <span class="hlt">stratosphere</span> and the troposphere, to narrow the uncertainty in the future projection of tropospheric circulation changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5702593','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5702593"><span id="translatedtitle">Scientific assessment of <span class="hlt">stratospheric</span> ozone: 1989, volume 1</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1989-01-01</p> <p>A review is presented of the current understanding of <span class="hlt">stratospheric</span> ozone (SO). The focus is on four major current aspects of SO: (1) polar ozone; (2) global trends; (3) theoretical predictions; and (4) halocarbon ozone depleting materials and global <span class="hlt">warming</span> potentials. Other ozone related topics are also discussed: (1) the trends of <span class="hlt">stratospheric</span> temperature, <span class="hlt">stratospheric</span> aerosols, source gases, and surface ultraviolet radiation; and (2) the oxidizing capacity of the troposphere as it pertains to the lifetimes of ozone related chemicals. There have been highly significant advances in the understanding of the impact of human activities on the Earth's protective ozone layer. There are four major findings that each heighten the concern that chlorine and bromine containing chemicals can lead to a significant depletion of SO: (1) Antarctic Ozone Hole; (2) Perturbed Arctic Chemistry; (3) Long-term Ozone Decreases; and (4) Model Limitations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ACPD...1328869R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ACPD...1328869R"><span id="translatedtitle">A Tropical West Pacific OH minimum and implications for <span class="hlt">stratospheric</span> composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rex, M.; Wohltmann, I.; Ridder, T.; Lehmann, R.; Rosenlof, K.; Wennberg, P.; Weisenstein, D.; Notholt, J.; Krüger, K.; Mohr, V.; Tegtmeier, S.</p> <p>2013-11-01</p> <p>Hundreds of biogenic and anthropogenic chemical species are emitted into the atmosphere. Most break down efficiently by reaction with OH and do not reach the <span class="hlt">stratosphere</span>. Here we show the existence of pronounced minima in the tropospheric columns of ozone and OH over the West Pacific, the main source region for <span class="hlt">stratospheric</span> air. We show that this amplifies the impact of surface emissions on the <span class="hlt">stratospheric</span> composition. Specifically, emissions of biogenic halogenated species from natural sources and from kelp and seaweed farming can have a larger effect on <span class="hlt">stratospheric</span> ozone depletion. Increasing anthropogenic emissions of SO2 in South East Asia or from minor volcanic eruptions can play a larger role for the <span class="hlt">stratospheric</span> aerosol budget, a key element for explaining the recently observed decrease in global <span class="hlt">warming</span> rates (Solomon et al., 2011).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1812060N&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1812060N&link_type=ABSTRACT"><span id="translatedtitle">Validation of <span class="hlt">stratospheric</span> temperature profiles from a ground-based microwave radiometer with other techniques</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Navas, Francisco; Kämpfer, Niklaus; Haefele, Alexander; Keckhut, Philippe; Hauchecorne, Alain</p> <p>2016-04-01</p> <p>Vertical profiles of atmospheric temperature trends has become recognized as an important indicator of climate change, because different climate forcing mechanisms exhibit distinct vertical <span class="hlt">warming</span> and cooling patterns. For example, the cooling of the <span class="hlt">stratosphere</span> is an indicator for climate change as it provides evidence of natural and anthropogenic climate forcing just like surface <span class="hlt">warming</span>. Despite its importance, our understanding of the observed <span class="hlt">stratospheric</span> temperature trend and our ability to test simulations of the <span class="hlt">stratospheric</span> response to emissions of greenhouse gases and ozone depleting substances remains limited. One of the main reason is because <span class="hlt">stratospheric</span> long-term datasets are sparse and obtained trends differ from one another. Different techniques allow to measure <span class="hlt">stratospheric</span> temperature profiles as radiosonde, lidar or satellite. The main advantage of microwave radiometers against these other instruments is a high temporal resolution with a reasonable good spatial resolution. Moreover, the measurement at a fixed location allows to observe local atmospheric dynamics over a long time period, which is crucial for climate research. This study presents an evaluation of the <span class="hlt">stratospheric</span> temperature profiles from a newly ground-based microwave temperature radiometer (TEMPERA) which has been built and designed at the University of Bern. The measurements from TEMPERA are compared with the ones from other different techniques such as in-situ (radiosondes), active remote sensing (lidar) and passive remote sensing on board of Aura satellite (MLS) measurements. In addition a statistical analysis of the <span class="hlt">stratospheric</span> temperature obtained from TEMPERA measurements during four years of data has been performed. This analysis evidenced the capability of TEMPERA radiometer to monitor the temperature in the <span class="hlt">stratosphere</span> for a long-term. The detection of some singular sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) during the analyzed period shows the necessity of these</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040085351','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040085351"><span id="translatedtitle">Mesosphere-<span class="hlt">Stratosphere</span> Coupling: Implications for Climate Variability and Trends</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baldwin, Mark P.</p> <p>2004-01-01</p> <p>A key aspect of this project is the establishment of a causal link from circulation anomalies in the lower mesosphere and stratopause region downward through the <span class="hlt">stratosphere</span> to the troposphere. The observational link for <span class="hlt">stratospheric</span> sudden <span class="hlt">warmings</span> and surface climate is fairly clear. However, our understanding of the dynamics is incomplete. We have been making significant progress in the area of dynamical mechanisms by which circulation anomalies in the <span class="hlt">stratosphere</span> affect the troposphere. We are trying to understand the details and sequence of events that occur when a middle atmosphere (wind) anomaly propagates downward to near the tropopause. The wind anomaly could be caused by a <span class="hlt">warming</span> or solar variations in the low-latitude stratopause region, or could have other causes. The observations show a picture that is consistent with a circulation anomaly that descends to the tropopause region, and can be detected as low as the mid-troposphere. Processes near the stratopause in the tropics appear to be important precursors to the wintertime development of the northern polar vortex. This may affect significantly our understanding of the process by which low-latitude wind anomalies in the low mesosphere and upper <span class="hlt">stratosphere</span> evolve through the winter and affect the polar vortex.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20050232880&hterms=stratosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dstratosphere','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20050232880&hterms=stratosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dstratosphere"><span id="translatedtitle">In-situ Observations of Mid-latitude Forest Fire Plumes Deep in the <span class="hlt">Stratosphere</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jost, Hans-Juerg; Drdla, Katja; Stohl, Andreas; Pfister, Leonhard; Loewenstein, Max; Lopez, Jimena P.; Hudson, Paula K.; Murphy, Daniel M.; Cziczo, Daniel J.; Fromm, Michael</p> <p>2004-01-01</p> <p>We observed a plume of air highly enriched in carbon monoxide and particles in the <span class="hlt">stratosphere</span> at altitudes up to 15.8 km. It can be unambiguously attributed to North American forest fires. This plume demonstrates an extratropical direct transport path from the planetary boundary layer several kilometers deep into the <span class="hlt">stratosphere</span>, which is not fully captured by large-scale atmospheric transport models. This process indicates that the <span class="hlt">stratospheric</span> ozone layer could be sensitive to changes in forest burning associated with climatic <span class="hlt">warming</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140001055','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140001055"><span id="translatedtitle">Sensitivity of <span class="hlt">Stratospheric</span> Geoengineering with Black Carbon to Aerosol Size and Altitude of Injection</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kravitz, Ben; Robock, Alan; Shindell, Drew T.; Miller, Mark A.</p> <p>2012-01-01</p> <p>Simulations of <span class="hlt">stratospheric</span> geoengineering with black carbon (BC) aerosols using a general circulation model with fixed sea surface temperatures show that the climate effects strongly depend on aerosol size and altitude of injection. 1 Tg BC/a injected into the lower <span class="hlt">stratosphere</span> would cause little surface cooling for large radii but a large amount of surface cooling for small radii and <span class="hlt">stratospheric</span> <span class="hlt">warming</span> of over 60 C. With the exception of small particles, increasing the altitude of injection increases surface cooling and <span class="hlt">stratospheric</span> <span class="hlt">warming</span>. <span class="hlt">Stratospheric</span> <span class="hlt">warming</span> causes global ozone loss by up to 50% in the small radius case. The Antarctic shows less ozone loss due to reduction of polar <span class="hlt">stratospheric</span> clouds, but strong circumpolar winds would enhance the Arctic ozone hole. Using diesel fuel to produce the aerosols is likely prohibitively expensive and infeasible. Although studying an absorbing aerosol is a useful counterpart to previous studies involving sulfate aerosols, black carbon geoengineering likely carries too many risks to make it a viable option for deployment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17569652','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17569652"><span id="translatedtitle">Ensemble climate simulations using a fully coupled ocean-troposphere-<span class="hlt">stratosphere</span> general circulation model.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huebener, H; Cubasch, U; Langematz, U; Spangehl, T; Niehörster, F; Fast, I; Kunze, M</p> <p>2007-08-15</p> <p>Long-term transient simulations are carried out in an initial condition ensemble mode using a global coupled climate model which includes comprehensive ocean and <span class="hlt">stratosphere</span> components. This model, which is run for the years 1860-2100, allows the investigation of the troposphere-<span class="hlt">stratosphere</span> interactions and the importance of representing the middle atmosphere in climate-change simulations. The model simulates the present-day climate (1961-2000) realistically in the troposphere, <span class="hlt">stratosphere</span> and ocean. The enhanced <span class="hlt">stratospheric</span> resolution leads to the simulation of sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span>; however, their frequency is underestimated by a factor of 2 with respect to observations.In projections of the future climate using the Intergovernmental Panel on Climate Change special report on emissions scenarios A2, an increased tropospheric wave forcing counteracts the radiative cooling in the middle atmosphere caused by the enhanced greenhouse gas concentration. This leads to a more dynamically active, warmer <span class="hlt">stratosphere</span> compared with present-day simulations, and to the doubling of the number of <span class="hlt">stratospheric</span> <span class="hlt">warmings</span>. The associated changes in the mean zonal wind patterns lead to a southward displacement of the Northern Hemisphere storm track in the climate-change signal. PMID:17569652</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRD..118..563A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRD..118..563A"><span id="translatedtitle"><span class="hlt">Stratospheric</span> ozone and the morphology of the northern hemisphere planetary waveguide</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Albers, John R.; McCormack, John P.; Nathan, Terrence R.</p> <p>2013-01-01</p> <p>A middle atmosphere general circulation model is used to examine the effects of zonally asymmetric ozone (ZAO) on the Northern Hemisphere planetary waveguide (PWG) during winter (December-February). The morphology of the PWG is measured by a refractive index, Eliassen-Palm flux vectors, the latitude of the subtropical zero wind line, and the latitude of the subtropical jet. ZAO causes the PWG to contract meridionally in the upper <span class="hlt">stratosphere</span>, expand meridionally in the lower <span class="hlt">stratosphere</span>, and expand vertically in the upper <span class="hlt">stratosphere</span> and lower mesosphere. The ZAO-induced changes in the PWG are the result of increased upward and poleward flux of planetary wave activity into the extratropical <span class="hlt">stratosphere</span> and lower mesosphere. These changes cause an increase in the Eliassen-Palm flux convergence at high latitudes, which produces a warmer and weaker <span class="hlt">stratospheric</span> polar vortex and an increase in the frequency of <span class="hlt">stratospheric</span> sudden <span class="hlt">warmings</span>. The ability of ZAO to alter the flux of planetary wave activity into the polar vortex has important implications for accurately modeling wave-modulated and wave-driven phenomena in the middle atmosphere, including the 11-year solar cycle, <span class="hlt">stratospheric</span> sudden <span class="hlt">warmings</span>, and the phase of the Northern Hemisphere annular mode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JASTP.136..201S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JASTP.136..201S&link_type=ABSTRACT"><span id="translatedtitle">Generation of waves by jet-stream instabilities in winter polar <span class="hlt">stratosphere</span>/mesosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shpynev, B. G.; Churilov, S. M.; Chernigovskaya, M. A.</p> <p>2015-12-01</p> <p>In the paper we investigate the manifestation of large-scale and middle-scale atmospheric irregularities observed on <span class="hlt">stratosphere</span>/mesosphere heights. We consider typical patterns of circulation in <span class="hlt">stratosphere</span> and lower mesosphere which are formed due to a difference of air potential energy between equatorial and polar latitudes, especially in polar night conditions. On the base of ECMWF Era Interim reanalysis data we consider the dynamics of midlatitude winter jet-streams which transfer heat from low latitudes to polar region and which develop due to equator/pole baroclinic instabilities. We consider typical patterns of general circulation in <span class="hlt">stratosphere</span>/lower mesosphere and reasons for creation of flaky structure of polar <span class="hlt">stratosphere</span>. Also we analyze conditions that are favorable for splitting of winter circumpolar vortex during sudden <span class="hlt">stratosphere</span> <span class="hlt">warming</span> events and role of phase difference tides in this process. The analysis of vertical structure of the <span class="hlt">stratosphere</span> wind shows the presence of regions with significant shear of horizontal velocity which favors for inducing of shear-layer instability that appears as gravity wave on boundary surface. During powerful sudden <span class="hlt">stratosphere</span> <span class="hlt">warming</span> events the main jet-stream can amplify these gravity waves to very high amplitudes that causes wave overturning and releasing of wave energy into the heat due to the cascade breakdown and turbulence. For the dynamics observed in reanalysis data we consider physical mechanisms responsible for observed phenomena.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040031806&hterms=space+travelling&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dspace%2Btravelling','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040031806&hterms=space+travelling&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dspace%2Btravelling"><span id="translatedtitle">On the Eastward Travelling Wavenumber Two in the Northern <span class="hlt">Stratosphere</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pawson, Steven; Krueger, Kirstin</p> <p>2003-01-01</p> <p>Disturbances in the middle atmosphere are often interpreted in the framework of waves superimposed on a zonal-mean flow. This paper presents an analysis of travelling waves in the northern hemisphere <span class="hlt">stratosphere</span>, concentrating on planetary wavenumber two (W2). Space-time spectral analysis reveals the existence of a substantial eastward-travelling planetary W2 at high latitudes in winter. While a similar feature is well documented in the southern hemisphere <span class="hlt">stratosphere</span>, where it is observed in most winters, this northern hemisphere counterpart is less common and has not been examined in detail. A climatology of occurrence of the wave is given for the northern <span class="hlt">stratospheric</span> winter. It is denoted as the quasi-16-day eastward travelling W2, because of its dominant periodicity, which ranges from about one to three weeks. Although the wave has some similarities with the southern hemispheric wave, there is much larger interannual and intraseasonal variability in the northern hemisphere. will emphasize the variations in the spatial and temporal structure of this wave, as isolated in meteorological analyses of radiosonde and satellite data. The possible role of these travelling waves in preconditioning the <span class="hlt">stratosphere</span> as a precursor to sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> in both hemispheres will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1008259','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1008259"><span id="translatedtitle">Impact of geoengineered aerosols on the troposphere and <span class="hlt">stratosphere</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tilmes, S.; Garcia, Rolando R.; Kinnison, Douglas E.; Gettelman, A.; Rasch, Philip J.</p> <p>2009-06-27</p> <p>A coupled chemistry climate model, the Whole Atmosphere Community Climate Model was used to perform a transient climate simulation to quantify the impact of geoengineered aerosols on atmospheric processes. In contrast to previous model studies, the impact on <span class="hlt">stratospheric</span> chemistry, including heterogeneous chemistry in the polar regions, is considered in this simulation. In the geoengineering simulation, a constant <span class="hlt">stratospheric</span> distribution of volcanic-sized, liquid sulfate aerosols is imposed in the period 2020–2050, corresponding to an injection of 2 Tg S/a. The aerosol cools the troposphere compared to a baseline simulation. Assuming an Intergovernmental Panel on Climate Change A1B emission scenario, global <span class="hlt">warming</span> is delayed by about 40 years in the troposphere with respect to the baseline scenario. Large local changes of precipitation and temperatures may occur as a result of geoengineering. Comparison with simulations carried out with the Community Atmosphere Model indicates the importance of <span class="hlt">stratospheric</span> processes for estimating the impact of <span class="hlt">stratospheric</span> aerosols on the Earth’s climate. Changes in <span class="hlt">stratospheric</span> dynamics and chemistry, especially faster heterogeneous reactions, reduce the recovery of the ozone layer in middle and high latitudes for the Southern Hemisphere. In the geoengineering case, the recovery of the Antarctic ozone hole is delayed by about 30 years on the basis of this model simulation. For the Northern Hemisphere, a onefold to twofold increase of the chemical ozone depletion occurs owing to a simulated stronger polar vortex and colder temperatures compared to the baseline simulation, in agreement with observational estimates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7129539','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7129539"><span id="translatedtitle">Antarctic <span class="hlt">stratospheric</span> ice crystals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Goodman, J. ); Toon, O.B.; Pueschel, R.F.; Snetsinger, K.G. ) Verma, S. )</p> <p>1989-11-30</p> <p>Ice crystals were replicated over the Palmer Peninsula at approximately 72{degree}S on six occasions during the 1987 Airborne Antarctic Ozone Experiment. The sampling altitude was between 12.5 and 18.5 km (45-65 thousand ft pressure altitude) with the temperature between 190 and 201 K. The atmosphere was subsaturated with respect to ice in all cases. The collected crystals were predominantly solid and hollow columns. The largest crystals were sampled at lower altitudes where the potential temperature was below 400 K. While the crystals were larger than anticipated, their low concentration results in a total surface area that is less than one tenth of the total aerosol surface area. The large ice crystals may play an important role in the observed <span class="hlt">stratospheric</span> dehydration processes through sedimentation. Evidence of scavenging of submicron particles further suggests that the ice crystals may be effective in the removal of <span class="hlt">stratospheric</span> chemicals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013grcc.book...21K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013grcc.book...21K"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Aerosols for Solar Radiation Management</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kravitz, Ben</p> <p></p> <p>SRM in the context of this entry involves placing a large amount of aerosols in the <span class="hlt">stratosphere</span> to reduce the amount of solar radiation reaching the surface, thereby cooling the surface and counteracting some of the <span class="hlt">warming</span> from anthropogenic greenhouse gases. The way this is accomplished depends on the specific aerosol used, but the basic mechanism involves backscattering and absorbing certain amounts of solar radiation aloft. Since <span class="hlt">warming</span> from greenhouse gases is due to longwave (thermal) emission, compensating for this <span class="hlt">warming</span> by reduction of shortwave (solar) energy is inherently imperfect, meaning SRM will have climate effects that are different from the effects of climate change. This will likely manifest in the form of regional inequalities, in that, similarly to climate change, some regions will benefit from SRM, while some will be adversely affected, viewed both in the context of present climate and a climate with high CO2 concentrations. These effects are highly dependent upon the means of SRM, including the type of aerosol to be used, the particle size and other microphysical concerns, and the methods by which the aerosol is placed in the <span class="hlt">stratosphere</span>. SRM has never been performed, nor has deployment been tested, so the research up to this point has serious gaps. The amount of aerosols required is large enough that SRM would require a major engineering endeavor, although SRM is potentially cheap enough that it could be conducted unilaterally. Methods of governance must be in place before deployment is attempted, should deployment even be desired. Research in public policy, ethics, and economics, as well as many other disciplines, will be essential to the decision-making process. SRM is only a palliative treatment for climate change, and it is best viewed as part of a portfolio of responses, including mitigation, adaptation, and possibly CDR. At most, SRM is insurance against dangerous consequences that are directly due to increased surface air</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.A12A..02D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.A12A..02D"><span id="translatedtitle">A <span class="hlt">stratospheric</span> water vapor feedback</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dessler, A. E.; Schoeberl, M. R.; Wang, T.; Davis, S. M.; Rosenlof, K. H.</p> <p>2013-12-01</p> <p>Variations in <span class="hlt">stratospheric</span> water vapor play a role in the evolution of our climate. We show here that variations in water vapor since 2004 can be traced to tropical tropopause layer (TTL) temperature perturbations from at least three processes: the quasi-biennial oscillation, the strength of the Brewer-Dobson circulation, and the temperature of the troposphere. The connection between <span class="hlt">stratospheric</span> water vapor and the temperature of the troposphere implies the existence of a <span class="hlt">stratospheric</span> water vapor feedback. We estimate the feedback in a chemistry-climate model to have a magnitude of +0.3 W/m2/K, which could be a significant contributor to the overall climate sensitivity. About two-thirds of the feedback comes from the extratropical <span class="hlt">stratosphere</span> below ~16 km (the lowermost <span class="hlt">stratosphere</span>), with the rest coming from the <span class="hlt">stratosphere</span> above ~16 km (the overworld).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980006745','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980006745"><span id="translatedtitle">Science in the <span class="hlt">Stratosphere</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lester, Dan</p> <p>1997-01-01</p> <p>The Science in the <span class="hlt">Stratosphere</span> program, first established in 1992, was conceived to introduce K-6 teachers to airborne infrared astronomy through the Kuiper Airborne Observatory (KAO), and to use this venue as a basis for seeing scientists at work in a mission-intensive program. The teachers selected for this program would bring their new perspectives back to their schools and students. Unlike the related FOSTER program, the emphasis of this program was on more intensive exposure of the KAO mission to a small number of teachers. The teachers in the Science in the <span class="hlt">Stratosphere</span> program essentially lived with the project scientists and staff for almost a week. One related goal was to imbed the KAO project with perspectives of working teachers, thereby sensitizing the project staff and scientists to educational outreach efforts in general, which is an important goal of the NASA airborne astronomy program. A second related goal was to explore the ways in which K-5 educators could participate in airborne astronomy missions. Also unlike FOSTER, the Science in the <span class="hlt">Stratosphere</span> program was intentionally relatively unstructured, in that the teacher participants were wholly embraced by the science team, and were encouraged to 'sniff out' the flavor of the whole facility by talking with people.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970004797','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970004797"><span id="translatedtitle">Freezing Behavior of <span class="hlt">Stratospheric</span> Sulfate Aerosols Inferred from Trajectory Studies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tabazadeh, A.; Toon, O. B.; Hamill, Patrick</p> <p>1995-01-01</p> <p>Based on the trajectory analysis presented in this paper, a new mechanism is described for the freezing of the <span class="hlt">stratospheric</span> sulfate aerosols. Temperature histories based on 10-day back trajectories for six ER-2 flights during AASE-I (1989) and AAOE (1987) are presented. The mechanism requires, as an initial step, the cooling of a H2SO4/H2O aerosol to low temperatures. If a cooling cycle is then followed up by a <span class="hlt">warming</span> to approximately 196-198 K, the aerosols may freeze due to the growth of the crystallizing embryos formed at the colder temperature. The HNO3 absorbed at colder temperatures may increase the nucleation rate of the crystalling embryos and therefore influence the crystallization of the supercooled aerosols upon <span class="hlt">warming</span>. Of all the ER-2 flights described, only the polar <span class="hlt">stratospheric</span> clouds (PSC), observed on the flights of January 24, and 25, 1989 are consistent with the thermodynamics of liquid ternary solutions of H2SO4/HNO3/H2O (type Ib PSCs). For those two days, back trajectories indicate that the air mass was exposed to sulfuric acid tetrahydrate (SAT) melting temperatures about 24 hours prior to being sampled by the ER-2. Temperature histories, recent laboratory measurements, and the properties of glassy solids suggest that <span class="hlt">stratospheric</span> H2SO4 aerosols may undergo a phase transition to SAT upon <span class="hlt">warming</span> at approximately 198 K after going through a cooling cycle to about 194 K or lower.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930040390&hterms=eruptions+volcanic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Deruptions%2Bvolcanic','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930040390&hterms=eruptions+volcanic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Deruptions%2Bvolcanic"><span id="translatedtitle">Winter <span class="hlt">warming</span> from large volcanic eruptions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Robock, Alan; Mao, Jianping</p> <p>1992-01-01</p> <p>An examination of the Northern Hemisphere winter surface temperature patterns after the 12 largest volcanic eruptions from 1883-1992 shows <span class="hlt">warming</span> over Eurasia and North America and cooling over the Middle East which are significant at the 95-percent level. This pattern is found in the first winter after tropical eruptions, in the first or second winter after midlatitude eruptions, and in the second winter after high latitude eruptions. The effects are independent of the hemisphere of the volcanoes. An enhanced zonal wind driven by heating of the tropical <span class="hlt">stratosphere</span> by the volcanic aerosols is responsible for the regions of <span class="hlt">warming</span>, while the cooling is caused by blocking of incoming sunlight.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6459161','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6459161"><span id="translatedtitle">Winter <span class="hlt">warming</span> from large volcanic eruptions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Robock, A.; Mao, J.</p> <p>1992-01-01</p> <p>An examination of the Northern Hemisphere winter surface temperature patterns after the 12 largest volcanic eruptions from 1883-1992 shows <span class="hlt">warming</span> over Eurasia and North America and cooling over the Middle East which are significant at the 95 percent level. This pattern is found in the first winter after tropical eruptions, in the first or second winter after midlatitude eruptions, and in the second winter after high latitude eruptions. The effects are independent of the hemisphere of the volcanoes. An enhanced zonal wind driven by heating of the tropical <span class="hlt">stratosphere</span> by the volcanic aerosols is responsible for the regions of <span class="hlt">warming</span>, while the cooling is caused by blocking of incoming sunlight.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=evidence+AND+global+AND+warming&pg=2&id=EJ484206','ERIC'); return false;" href="http://eric.ed.gov/?q=evidence+AND+global+AND+warming&pg=2&id=EJ484206"><span id="translatedtitle">Global <span class="hlt">Warming</span>?</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Eichman, Julia Christensen; Brown, Jeff A.</p> <p>1994-01-01</p> <p>Presents information and data on an experiment designed to test whether different atmosphere compositions are affected by light and temperature during both cooling and heating. Although flawed, the experiment should help students appreciate the difficulties that researchers face when trying to find evidence of global <span class="hlt">warming</span>. (PR)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ACP....11.7687H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ACP....11.7687H"><span id="translatedtitle">Tropospheric temperature response to <span class="hlt">stratospheric</span> ozone recovery in the 21st century</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Y.; Xia, Y.; Fu, Q.</p> <p>2011-08-01</p> <p>Recent simulations predicted that the <span class="hlt">stratospheric</span> ozone layer will likely return to pre-1980 levels in the middle of the 21st century, as a result of the decline of ozone depleting substances under the Montreal Protocol. Since the ozone layer is an important component in determining <span class="hlt">stratospheric</span> and tropospheric-surface energy balance, the recovery of <span class="hlt">stratospheric</span> ozone may have significant impact on tropospheric-surface climate. Here, using multi-model results from both the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC-AR4) models and coupled chemistry-climate models, we show that as ozone recovery is considered, the troposphere is <span class="hlt">warmed</span> more than that without considering ozone recovery, suggesting an enhancement of tropospheric <span class="hlt">warming</span> due to ozone recovery. It is found that the enhanced tropospheric <span class="hlt">warming</span> is mostly significant in the upper troposphere, with a global and annual mean magnitude of ~0.41 K for 2001-2050. We also find that relatively large enhanced <span class="hlt">warming</span> occurs in the extratropics and polar regions in summer and autumn in both hemispheres, while the enhanced <span class="hlt">warming</span> is stronger in the Northern Hemisphere than in the Southern Hemisphere. Enhanced <span class="hlt">warming</span> is also found at the surface. The global and annual mean enhancement of surface <span class="hlt">warming</span> is about 0.16 K for 2001-2050, with maximum enhancement in the winter Arctic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ClDy..tmp..364R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ClDy..tmp..364R"><span id="translatedtitle">A decomposition of ENSO's impacts on the northern winter <span class="hlt">stratosphere</span>: competing effect of SST forcing in the tropical Indian Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rao, Jian; Ren, Rongcai</p> <p>2015-09-01</p> <p>This study applies WACCM, a <span class="hlt">stratosphere</span>-resolving model to dissect the <span class="hlt">stratospheric</span> responses in the northern winter extratropics to the imposed ENSO-related SST anomalies in the tropics. It is found that the anomalously warmer and weaker <span class="hlt">stratospheric</span> polar vortex during <span class="hlt">warm</span> ENSO is basically a balance of the opposite effects between the SST anomalies in the tropical Pacific (TPO) and that over the tropical Indian Ocean basin (TIO). Specifically, the ENSO-related SST anomalies over the TIO are to induce an anomalously colder and stronger <span class="hlt">stratospheric</span> polar vortex during <span class="hlt">warm</span> ENSO, which acts to partially cancel out the much stronger warmer and weaker polar vortex response to the SST anomalies over the TPO. Further analysis indicates that, while the SST forcing from the TPO contributes to the anomalously positive Pacific North America (PNA) pattern in the troposphere and the enhancement of the stationary wavenumber (WN)-1 in the <span class="hlt">stratosphere</span> during <span class="hlt">warm</span> ENSO, the TIO SST forcing is to induce an anomalously negative PNA and a reduction of both WN-1 and WN-2 in the <span class="hlt">stratosphere</span>. Diagnosis of E-P flux confirms that, the anomalously upward propagation of stationary waves in the extratropics mainly lies over the western coast of North America during <span class="hlt">warm</span> ENSO, which is mainly associated with the TPO-induced positive PNA response and is partially suppressed by the effect of the accompanying TIO SST forcing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ClDy...46.3689R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ClDy...46.3689R"><span id="translatedtitle">A decomposition of ENSO's impacts on the northern winter <span class="hlt">stratosphere</span>: competing effect of SST forcing in the tropical Indian Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rao, Jian; Ren, Rongcai</p> <p>2016-06-01</p> <p>This study applies WACCM, a <span class="hlt">stratosphere</span>-resolving model to dissect the <span class="hlt">stratospheric</span> responses in the northern winter extratropics to the imposed ENSO-related SST anomalies in the tropics. It is found that the anomalously warmer and weaker <span class="hlt">stratospheric</span> polar vortex during <span class="hlt">warm</span> ENSO is basically a balance of the opposite effects between the SST anomalies in the tropical Pacific (TPO) and that over the tropical Indian Ocean basin (TIO). Specifically, the ENSO-related SST anomalies over the TIO are to induce an anomalously colder and stronger <span class="hlt">stratospheric</span> polar vortex during <span class="hlt">warm</span> ENSO, which acts to partially cancel out the much stronger warmer and weaker polar vortex response to the SST anomalies over the TPO. Further analysis indicates that, while the SST forcing from the TPO contributes to the anomalously positive Pacific North America (PNA) pattern in the troposphere and the enhancement of the stationary wavenumber (WN)-1 in the <span class="hlt">stratosphere</span> during <span class="hlt">warm</span> ENSO, the TIO SST forcing is to induce an anomalously negative PNA and a reduction of both WN-1 and WN-2 in the <span class="hlt">stratosphere</span>. Diagnosis of E-P flux confirms that, the anomalously upward propagation of stationary waves in the extratropics mainly lies over the western coast of North America during <span class="hlt">warm</span> ENSO, which is mainly associated with the TPO-induced positive PNA response and is partially suppressed by the effect of the accompanying TIO SST forcing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800006383','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800006383"><span id="translatedtitle">The <span class="hlt">stratosphere</span>: Present and future</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hudson, R. D. (Editor); Reed, E. I. (Editor)</p> <p>1979-01-01</p> <p>The present status of <span class="hlt">stratospheric</span> science is discussed. The three basic elements of <span class="hlt">stratospheric</span> science-laboratory measurements, atmospheric observations, and theoretical studies are presented along with an attempt to predict, with reasonable confidence, the effect on ozone of particular anthropogenic sources of pollution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/963441','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/963441"><span id="translatedtitle">Sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> seen in MINOS deep underground muon data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Osprey, S.; Barnett, J.; Smith, J.; Adamson, P.; Andreopoulos, C.; Arms, K.E.; Armstrong, R.; Auty, D.J.; Ayres, D.S.; Baller, B.; Barnes, P.D., Jr.; /LLNL, Livermore /Oxford U.</p> <p>2009-01-01</p> <p>The rate of high energy cosmic ray muons as measured underground is shown to be strongly correlated with upper-air temperatures during short-term atmospheric (10-day) events. The effects are seen by correlating data from the MINOS underground detector and temperatures from the European Centre for Medium Range Weather Forecasts during the winter periods from 2003-2007. This effect provides an independent technique for the measurement of meteorological conditions and presents a unique opportunity to measure both short and long-term changes in this important part of the atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.U41E..05T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.U41E..05T"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Aerosol Injection for Geoengineering Purposes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Turco, R. P.; Yu, F.</p> <p>2008-12-01</p> <p>A number of studies have focused on the large-scale aspects of massive <span class="hlt">stratospheric</span> aerosol injections for the purpose of modifying global climate to counterbalance current and future greenhouse <span class="hlt">warming</span> effects. However, no descriptions of actual injection schemes have been presented at any level of detail; it is generally assumed that the procedure would be straightforward. Approaches mentioned include direct injection of dispersed microparticles of sulfates or other mineral particles, or the emission of precursor vapors, such as sulfur dioxide or hydrogen sulfide, that lead to particle formation. Using earlier aircraft plume research as a guide, we investigate the fate of injected aerosols/precursors from a <span class="hlt">stratospheric</span> platform in terms of the chemical and microphysical evolution occurring in a mixing plume. We utilize an advanced microphysics model that treats nucleation, coagulation, condensation and other processes relevant to the injection of particulates at high altitudes, as well as the influence of plume dilution. The requirements of particle size and concentration for producing the desired engineered radiative forcing place significant constraints on the injection system. Here, we focus on the effects of early microphysical processing on the formation of a suitable aerosol layer, and consider strategies to overcome potential hurdles. Among the problems explicitly addressed are: the propensity for emitted particles to coagulate to sizes that are optically inefficient at solar wavelengths, accelerated scavenging by an enhanced background aerosol layer, the evolution of size dispersion leading to significant infrared effects, and total mass injection rates implied by <span class="hlt">stratospheric</span> residence times. We also investigate variability in aerosol properties owing to uncertain nucleation rates in evolving plumes. In the context of the microphysical simulations, we discuss infrastructure requirements in terms of the scale of the intervention and, hence, the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005RPPh...68.1343H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005RPPh...68.1343H"><span id="translatedtitle">Global <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Houghton, John</p> <p>2005-06-01</p> <p>'Global <span class="hlt">warming</span>' is a phrase that refers to the effect on the climate of human activities, in particular the burning of fossil fuels (coal, oil and gas) and large-scale deforestation, which cause emissions to the atmosphere of large amounts of 'greenhouse gases', of which the most important is carbon dioxide. Such gases absorb infrared radiation emitted by the Earth's surface and act as blankets over the surface keeping it warmer than it would otherwise be. Associated with this <span class="hlt">warming</span> are changes of climate. The basic science of the 'greenhouse effect' that leads to the <span class="hlt">warming</span> is well understood. More detailed understanding relies on numerical models of the climate that integrate the basic dynamical and physical equations describing the complete climate system. Many of the likely characteristics of the resulting changes in climate (such as more frequent heat waves, increases in rainfall, increase in frequency and intensity of many extreme climate events) can be identified. Substantial uncertainties remain in knowledge of some of the feedbacks within the climate system (that affect the overall magnitude of change) and in much of the detail of likely regional change. Because of its negative impacts on human communities (including for instance substantial sea-level rise) and on ecosystems, global <span class="hlt">warming</span> is the most important environmental problem the world faces. Adaptation to the inevitable impacts and mitigation to reduce their magnitude are both necessary. International action is being taken by the world's scientific and political communities. Because of the need for urgent action, the greatest challenge is to move rapidly to much increased energy efficiency and to non-fossil-fuel energy sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012cosp...39.1147M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012cosp...39.1147M"><span id="translatedtitle">Studies on the Effect of Cloud Coverage and Galactic Cosmic Ray on <span class="hlt">Stratospheric</span> Moistening</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maitra, Animesh; Saha, Upal; Das, Saurabh</p> <p>2012-07-01</p> <p>Increased <span class="hlt">stratospheric</span> water vapor is one of the significant causes of global <span class="hlt">warming</span> as increased <span class="hlt">stratospheric</span> water vapor acts to cool the <span class="hlt">stratosphere</span> but it <span class="hlt">warms</span> the underlying troposphere. The sun can influence the clouds by mediating through Galactic cosmic rays (GCR) which controls the nucleation of water droplets in the atmosphere. The role of primary GCR in generating low-level cloud condensation nuclei reflects solar energy back into space affecting the temperature on earth. In the present study, variations of different types of cloud coverage (low, mid and high) are correlated with the intensity of GCR flux and their effects on the <span class="hlt">stratospheric</span> moistening in the equatorial, mid- latitude and polar region have been investigated for the years 2004 and 2005 using the Aura's Microwave Limb Sounder (MLS) water vapor data, ISCCP cloud data and GCR from neutron monitor observations at Calgary (51.080 N, 245.870 E). The relation between GCR and <span class="hlt">stratospheric</span> moistening is also investigated in this paper. Additionally, the latitudinal variation of different types of cloud coverage is also studied for the same period. The southern mid-latitudinal region has the highest coverage of low-level cloud, followed by the equatorial region. Both the Polar Regions are highly covered with mid-level cloud. The mid-latitudinal region shows highest coverage of high-cloud, followed by the equatorial region. Lower level clouds exert a large net cooling effect on the climate indicating an inter-relationship between cosmic ray and cloud coverage. However, the mid and high cloud coverage have no significant correlation with GCR flux. The <span class="hlt">stratospheric</span> moistening is controlled by transport of water vapour from troposphere to <span class="hlt">stratosphere</span> through the tropopause region and the oxidation of methane within the <span class="hlt">stratosphere</span>. Water vapour plays a major role in the chemistry and radiative budget of the <span class="hlt">stratosphere</span>. One possible water vapor source in the <span class="hlt">stratosphere</span> is the advection of</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19760087420&hterms=summer+camp&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsummer%2Bcamp','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19760087420&hterms=summer+camp&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsummer%2Bcamp"><span id="translatedtitle"><span class="hlt">Stratospheric</span> aerosols and climatic change</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baldwin, B.; Pollack, J. B.; Summers, A.; Toon, O. B.; Sagan, C.; Van Camp, W.</p> <p>1976-01-01</p> <p>Generated primarily by volcanic explosions, a layer of submicron silicate particles and particles made of concentrated sulfuric acids solution is present in the <span class="hlt">stratosphere</span>. Flights through the <span class="hlt">stratosphere</span> may be a future source of <span class="hlt">stratospheric</span> aerosols, since the effluent from supersonic transports contains sulfurous gases (which will be converted to H2SO4) while the exhaust from Space Shuttles contains tiny aluminum oxide particles. Global heat balance calculations have shown that the <span class="hlt">stratospheric</span> aerosols have made important contributions to some climatic changes. In the present paper, accurate radiative transfer calculations of the globally-averaged surface temperature (T) are carried out to estimate the sensitivity of the climate to changes in the number of <span class="hlt">stratospheric</span> aerosols. The results obtained for a specified model atmosphere, including a vertical profile of the aerosols, indicate that the climate is unlikely to be affected by supersonic transports and Space Shuttles, during the next decades.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950036038&hterms=Motion+pictures&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DMotion%2Bpictures','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950036038&hterms=Motion+pictures&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DMotion%2Bpictures"><span id="translatedtitle">On the motion of air through the <span class="hlt">stratospheric</span> polar vortex</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Manney, G. L.; Zurek, R. W.; O'Neill, A.; Swinbank, R.</p> <p>1994-01-01</p> <p>Trajectory calculations using horizontal winds from the U.K. Meteorological Office data assimilation system and vertical velocities from a radiation calculation are used to simulate the three-dimensional motion of air through the <span class="hlt">stratospheric</span> polar vortex for Northern Hemisphere (NH) and Southern Hemisphere (SH) winters since the launch of the Upper Atmosphere Research Satellite (UARS). Throughout the winter, air from the upper <span class="hlt">stratosphere</span> moves poleward and descends into the middle <span class="hlt">stratosphere</span>. In the SH lower to middle <span class="hlt">stratosphere</span>, strongest descent occurs near the edge of the polar vortex, with that edge defined by mixing characteristics. The NH shows a similar pattern in late winter, but in early winter strongest descent is near the center of the vortex, except when wave activity is particularly strong. Strong barriers to latitudinal mixing exist above about 420 K throughout the winter. Below this, the polar night jet is weak in early winter, so air descending below that level mixes between polar and middle latitudes. In late winter, parcels descend less and the polar night jet moves downward, so there is less latitudinal mixing. The degree of mixing in the lower <span class="hlt">stratosphere</span> thus depends strongly on the position and evolution of the polar night jet and on the amount of descent experienced by the air parcels; these characteristics show considerable interannual variability in both hemispheres. The computed trajectories provide a three-dimensional picture of air motion during the final <span class="hlt">warming</span>. Large tongues of air are drawn off the vortex and stretched into increasingly long and narrow tongues extending into low latitudes. This vortex erosion process proceeds more rapidly in the NH than in he SH. In the lower <span class="hlt">stratosphere</span>, the majority of air parcels remain confined within a lingering region of strong potential vorticity gradients into December in the SH and April in the NH, well after the vortex breaks up in the midstratosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20070034992&hterms=global+warming+climate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dglobal%2Bwarming%2Bclimate','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20070034992&hterms=global+warming+climate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dglobal%2Bwarming%2Bclimate"><span id="translatedtitle">AO/NAO Response to Climate Change. 1; Respective Influences of <span class="hlt">Stratospheric</span> and Tropospheric Climate Changes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rind, D.; Perlwitz, J.; Lonergan, P.</p> <p>2005-01-01</p> <p>We utilize the GISS Global Climate Middle Atmosphere Model and 8 different climate change experiments, many of them focused on <span class="hlt">stratospheric</span> climate forcings, to assess the relative influence of tropospheric and <span class="hlt">stratospheric</span> climate change on the extratropical circulation indices (Arctic Oscillation, AO; North Atlantic Oscillation, NAO). The experiments are run in two different ways: with variable sea surface temperatures (SSTs) to allow for a full tropospheric climate response, and with specified SSTs to minimize the tropospheric change. The results show that tropospheric <span class="hlt">warming</span> (cooling) experiments and <span class="hlt">stratospheric</span> cooling (<span class="hlt">warming</span>) experiments produce more positive (negative) AO/NAO indices. For the typical magnitudes of tropospheric and <span class="hlt">stratospheric</span> climate changes, the tropospheric response dominates; results are strongest when the tropospheric and <span class="hlt">stratospheric</span> influences are producing similar phase changes. Both regions produce their effect primarily by altering wave propagation and angular momentum transports, but planetary wave energy changes accompanying tropospheric climate change are also important. <span class="hlt">Stratospheric</span> forcing has a larger impact on the NAO than on the AO, and the angular momentum transport changes associated with it peak in the upper troposphere, affecting all wavenumbers. Tropospheric climate changes influence both the A0 and NAO with effects that extend throughout the troposphere. For both forcings there is often vertical consistency in the sign of the momentum transport changes, obscuring the difference between direct and indirect mechanisms for influencing the surface circulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ClDy...46.1397O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ClDy...46.1397O"><span id="translatedtitle">Troposphere-<span class="hlt">stratosphere</span> response to large-scale North Atlantic Ocean variability in an atmosphere/ocean coupled model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Omrani, N.-E.; Bader, Jürgen; Keenlyside, N. S.; Manzini, Elisa</p> <p>2016-03-01</p> <p>The instrumental records indicate that the basin-wide wintertime North Atlantic <span class="hlt">warm</span> conditions are accompanied by a pattern resembling negative North Atlantic oscillation (NAO), and cold conditions with pattern resembling the positive NAO. This relation is well reproduced in a control simulation by the <span class="hlt">stratosphere</span> resolving atmosphere-ocean coupled Max-Planck-Institute Earth System Model (MPI-ESM). Further analyses of the MPI-ESM model simulation shows that the large-scale <span class="hlt">warm</span> North Atlantic conditions are associated with a <span class="hlt">stratospheric</span> precursory signal that propagates down into the troposphere, preceding the wintertime negative NAO. Additional experiments using only the atmospheric component of MPI-ESM (ECHAM6) indicate that these <span class="hlt">stratospheric</span> and tropospheric changes are forced by the <span class="hlt">warm</span> North Atlantic conditions. The basin-wide <span class="hlt">warming</span> excites a wave-induced <span class="hlt">stratospheric</span> vortex weakening, <span class="hlt">stratosphere</span>/troposphere coupling and a high-latitude tropospheric <span class="hlt">warming</span>. The induced high-latitude tropospheric <span class="hlt">warming</span> is associated with reduction of the growth rate of low-level baroclinic waves over the North Atlantic region, contributing to the negative NAO pattern. For the cold North Atlantic conditions, the strengthening of the westerlies in the coupled model is confined to the troposphere and lower <span class="hlt">stratosphere</span>. Comparing the coupled and uncoupled model shows that in the cold phase the tropospheric changes seen in the coupled model are not well reproduced by the standalone atmospheric configuration. Our experiments provide further evidence that North Atlantic Ocean variability (NAV) impacts the coupled <span class="hlt">stratosphere</span>/troposphere system. As NAV has been shown to be predictable on seasonal-to-decadal timescales, these results have important implications for the predictability of the extra-tropical atmospheric circulation on these time-scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981Natur.294..733F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981Natur.294..733F"><span id="translatedtitle">Halocarbons in the <span class="hlt">stratosphere</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fabian, P.; Borchers, R.</p> <p>1981-12-01</p> <p>The possible impact of chlorine compounds on the Earth's ozone layer has caused concern. Profiles of the anthropogenic halocarbons F-11 (CFC13) and F-12 (CF2Cl2) have already been measured in the <span class="hlt">stratosphere</span>1-4. Measurements of the vertical distribution of methyl chloride (CH3Cl), the most important natural chlorine-bearing species confirm that chlorine of anthropogenic origin now predominates the <span class="hlt">stratosphere</span>5,6. More halogen radicals are added through decomposition of various other halocarbons, most of them released by man. We report here the first measurements of vertical profiles of F-13 (CF3Cl), F-14 (CF4), F-113 (C2F3Cl3), F-114 (C2F4Cl2), F-115 (C2F5Cl), F-116 (C2F6), and F-13 B(CF3Br) resulting from gas chromatography-mass spectrometer (GC-MS) analysis of air samples collected cryogenically between 10 and 33 km, at 44° N. Some data for F-22 (CHF2C1), methyl bromide (CH3Br) and methyl chloroform (CH3CC13) also presented are subject to confirmation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E1481O&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E1481O&link_type=ABSTRACT"><span id="translatedtitle">ORISON, a <span class="hlt">stratospheric</span> project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ortiz Moreno, Jose Luis; Mueller, Thomas; Duffard, Rene; Juan Lopez-Moreno, Jose; Wolf, Jürgen; Schindler, Karsten; Graf, Friederike</p> <p>2016-07-01</p> <p>Astronomical research based on satellites is extremely expensive, complex, requires years of development, and the overall difficulties are immense. The ORISON project addresses the feasibility study and the design of a global solution based on platforms on-board <span class="hlt">stratospheric</span> balloons, which allows overcoming the limitations of the Earth's atmosphere, but at a much lower cost and with fewer complications than on satellite platforms. The overall idea is the use of small low-cost <span class="hlt">stratospheric</span> balloons, either individually or as a fleet, equipped with light-weight medium-sized telescopes and other instruments to perform specific tasks on short-duration missions. They could carry different payloads for specific "experiments" too, and should be configurable to some degree to accommodate variable instrumentation. These balloon-based telescopes should be designed to be launched from many sites on Earth, not necessarily from remote sites such as Antarctica or near the North Pole, and at low cost. This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 690013.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150007705','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150007705"><span id="translatedtitle">Effect of Recent Sea Surface Temperature Trends on the Arctic <span class="hlt">Stratospheric</span> Vortex</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Garfinkel, Chaim I.; Oman, Luke; Hurwitz, Margaret</p> <p>2015-01-01</p> <p>The springtime Arctic polar vortex has cooled significantly over the satellite era, with consequences for ozone concentrations in the springtime transition season. The causes of this cooling trend are deduced by using comprehensive chemistry-climate model experiments. Approximately half of the satellite era early springtime cooling trend in the Arctic lower <span class="hlt">stratosphere</span> was caused by changing sea surface temperatures (SSTs). An ensemble of experiments forced only by changing SSTs is compared to an ensemble of experiments in which both the observed SSTs and chemically- and radiatively-active trace species are changing. By comparing the two ensembles, it is shown that <span class="hlt">warming</span> of Indian Ocean, North Pacific, and North Atlantic SSTs, and cooling of the tropical Pacific, have strongly contributed to recent polar <span class="hlt">stratospheric</span> cooling in late winter and early spring, and to a weak polar <span class="hlt">stratospheric</span> <span class="hlt">warming</span> in early winter. When concentrations of ozone-depleting substances and greenhouse gases are fixed, polar ozone concentrations show a small but robust decline due to changing SSTs. Ozone changes are magnified in the presence of changing gas concentrations. The <span class="hlt">stratospheric</span> changes can be understood by examining the tropospheric height and heat flux anomalies generated by the anomalous SSTs. Finally, recent SST changes have contributed to a decrease in the frequency of late winter <span class="hlt">stratospheric</span> sudden <span class="hlt">warmings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100031214','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100031214"><span id="translatedtitle">Response of the Antarctic <span class="hlt">Stratosphere</span> to Two Types of El Nino Events</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hurwitz, M. M.; Newman, P. A.; Oman, L. D.; Molod, A. M.</p> <p>2010-01-01</p> <p>This study is the first to identify a robust El Nino/Southern Oscillation (ENSO) signal in the Antarctic <span class="hlt">stratosphere</span>. El Nino events are classified as either conventional "cold tongue" events (positive SST anomalies in the Nino 3 region) or "<span class="hlt">warm</span> pool" events (positive SST anomalies in the Nino 4 region). The ERA-40, NCEP and MERRA meteorological reanalyses are used to show that the Southern Hemisphere <span class="hlt">stratosphere</span> responds differently to these two types of El Nino events. Consistent with previous studies, "cold tongue" events do not impact temperatures in the Antarctic <span class="hlt">stratosphere</span>. During "<span class="hlt">warm</span> pool" El Nino events, the poleward extension and increased strength of the South Pacific Convergence Zone (SPCZ) favor an enhancement of planetary wave activity during the SON season. On average, these conditions lead to higher polar <span class="hlt">stratospheric</span> temperatures and a weakening of the Antarctic polar jet in November and December, as compared with neutral ENSO years. The phase of the quasi-biennial oscillation (QBO) modulates the <span class="hlt">stratospheric</span> response to "<span class="hlt">warm</span> pool" El Nino events: the strongest planetary wave driving events are coincident with the easterly phase of the QBO.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AGUFMGC22A..09X&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AGUFMGC22A..09X&link_type=ABSTRACT"><span id="translatedtitle">Effects of <span class="hlt">Stratospheric</span> Sulfate Geoengineering on Food Supply in China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xia, L.; Robock, A.</p> <p>2010-12-01</p> <p>Possible food supply change is one of the most important concerns in the discussion of <span class="hlt">stratospheric</span> geoengineering. In regions with high population density, climate changes such as precipitation reduction spurred by <span class="hlt">stratospheric</span> sulfate injection may cause drought, reduce crop yield, and affect the food supply for hundreds of millions of people. Therefore, as part of the research into the benefits and risks of <span class="hlt">stratospheric</span> geoengineering, it is necessary to fully investigate its effects on the regional climate system and crop yields, which is the goal of this study. In particular, we focus on China, not only because of its high risk to experience severe regional climate change after <span class="hlt">stratospheric</span> geoengineering, but also because of its high vulnerability due to a large share of its population living on agriculture. To examine the effects of climate changes induced by geoengineering on Chinese agriculture, we use the DSSAT and CLICROP agricultural simulation models. We first evaluate these models by forcing them with daily weather data and management practices for the period 1978-2008 for all the provinces in China, and compare the results to observations of the yields of major crops in China (early season paddy, double crop paddy, spring wheat, winter wheat, corn, sorghum and soybean). Overall, there is a strong upward trend in both yield and fertilizer use, but interannual variations can be associated with temperature and precipitation variations. Using climate model simulations with the NASA GISS general circulation model forced by both a standard global <span class="hlt">warming</span> scenario (A1B) and A1B combined with <span class="hlt">stratospheric</span> geoengineering, we then apply scenarios of changes of precipitation and temperature from these runs to examine their effects on Chinese agricultural production. Compared to global <span class="hlt">warming</span> only, the geoengineering runs produced summer precipitation reductions in northeastern China but precipitation increases in the Yangtze River region. Without changes</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015A%26A...580A..89G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015A%26A...580A..89G"><span id="translatedtitle"><span class="hlt">Stratospheric</span> benzene and hydrocarbon aerosols detected in Saturn's auroral regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guerlet, S.; Fouchet, T.; Vinatier, S.; Simon, A. A.; Dartois, E.; Spiga, A.</p> <p>2015-08-01</p> <p>Context. Saturn's polar upper atmosphere exhibits significant auroral activity; however, its impact on <span class="hlt">stratospheric</span> chemistry (i.e. the production of benzene and heavier hydrocarbons) and thermal structure remains poorly documented. Aims: We aim to bring new constraints on the benzene distribution in Saturn's <span class="hlt">stratosphere</span>, to characterize polar aerosols (their vertical distribution, composition, thermal infrared optical properties), and to quantify the aerosols' radiative impact on the thermal structure. Methods: Infrared spectra acquired by the Composite Infrared Spectrometer (CIRS) on board Cassini in limb viewing geometry are analysed to derive benzene column abundances and aerosol opacity profiles over the 3 to 0.1 mbar pressure range. The spectral dependency of the haze opacity is assessed in the ranges 680-900 and 1360-1440 cm-1. Then, a radiative climate model is used to compute equilibrium temperature profiles, with and without haze, given the haze properties derived from CIRS measurements. Results: On Saturn's auroral region (80°S), benzene is found to be slightly enhanced compared to its equatorial and mid-latitude values. This contrasts with the Moses & Greathouse (2005, J. Geophys. Res., 110, 9007) photochemical model, which predicts a benzene abundance 50 times lower at 80°S than at the equator. This advocates for the inclusion of ion-related reactions in Saturn's chemical models. The polar <span class="hlt">stratosphere</span> is also enriched in aerosols, with spectral signatures consistent with vibration modes assigned to aromatic and aliphatic hydrocarbons, and presenting similarities with the signatures observed in Titan's <span class="hlt">stratosphere</span>. The aerosol mass loading at 80°S is estimated to be 1-4 × 10-5 g cm-2, an order of magnitude less than on Jupiter, which is consistent with the order of magnitude weaker auroral power at Saturn. We estimate that this polar haze <span class="hlt">warms</span> the middle <span class="hlt">stratosphere</span> by 6 K in summer and cools the upper <span class="hlt">stratosphere</span> by 5 K in winter. Hence</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140011364','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140011364"><span id="translatedtitle">On the Lack of <span class="hlt">Stratospheric</span> Dynamical Variability in Low-top Versions of the CMIP5 Models</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Charlton-Perez, Andrew J.; Baldwin, Mark P.; Birner, Thomas; Black, Robert X.; Butler, Amy H.; Calvo, Natalia; Davis, Nicholas A.; Gerber, Edwin P.; Gillett, Nathan; Hardiman, Steven; Kim, Junsu; Kruger, Kirstin; Lee, Yun-Young; Manzini, Elisa; McDaniel, Brent A.; Polvani, Lorenzo; Reichler, Thomas; Shaw, Tiffany A.; Sigmond, Michael; Son, Seok-Woo; Toohey, Matthew; Wilcox, Laura; Yoden, Shigeo; Christiansen, Bo; Lott, Francois; Shindell, Drew; Yukimoto, Seiji; Watanabe, Shingo</p> <p>2013-01-01</p> <p>We describe the main differences in simulations of <span class="hlt">stratospheric</span> climate and variability by models within the fifth Coupled Model Intercomparison Project (CMIP5) that have a model top above the stratopause and relatively fine <span class="hlt">stratospheric</span> vertical resolution (high-top), and those that have a model top below the stratopause (low-top). Although the simulation of mean <span class="hlt">stratospheric</span> climate by the two model ensembles is similar, the low-top model ensemble has very weak <span class="hlt">stratospheric</span> variability on daily and interannual time scales. The frequency of major sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> events is strongly underestimated by the low-top models with less than half the frequency of events observed in the reanalysis data and high-top models. The lack of <span class="hlt">stratospheric</span> variability in the low-top models affects their <span class="hlt">stratosphere</span>-troposphere coupling, resulting in short-lived anomalies in the Northern Annular Mode, which do not produce long-lasting tropospheric impacts, as seen in observations. The lack of <span class="hlt">stratospheric</span> variability, however, does not appear to have any impact on the ability of the low-top models to reproduce past <span class="hlt">stratospheric</span> temperature trends. We find little improvement in the simulation of decadal variability for the high-top models compared to the low-top, which is likely related to the fact that neither ensemble produces a realistic dynamical response to volcanic eruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140010937','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140010937"><span id="translatedtitle">Modifications of the Quasi-biennial Oscillation by a Geoengineering Perturbation of the <span class="hlt">Stratospheric</span> Aerosol Layer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Aquila, V.; Garfinkel, C. I.; Newman, P. A.; Oman, L. D.; Waugh, D. W.</p> <p>2014-01-01</p> <p>This paper examines the impact of geoengineering via <span class="hlt">stratospheric</span> sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System (GEOS-5) Chemistry Climate Model. We performed four 30-year simulations with a continuous injection of sulfur dioxide on the equator at 0 degree longitude. The four simulations differ by the amount of sulfur dioxide injected (5Tg per year and 2.5 Tg per year) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. In the case of maximum perturbation, i.e. highest <span class="hlt">stratospheric</span> aerosol burden, the lower tropical <span class="hlt">stratosphere</span> is locked into a permanent westerly QBO phase. This locked QBO westerly phase is caused by the increased aerosol heating and associated <span class="hlt">warming</span> in the tropical lower <span class="hlt">stratosphere</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20100004813&hterms=Ozone+layer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2528Ozone%2Blayer%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20100004813&hterms=Ozone+layer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2528Ozone%2Blayer%2529"><span id="translatedtitle">The Impact of Geoengineering Aerosols on <span class="hlt">Stratospheric</span> Temperature and Ozone</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Heckendorn, P.; Weisenstein, D.; Fueglistaler, S.; Luo, B. P.; Rozanov, E.; Schraner, M.; Peter, T.; Thomason, L. W.</p> <p>2009-01-01</p> <p>Anthropogenic greenhouse gas emissions are <span class="hlt">warming</span> the global climate at an unprecedented rate. Significant emission reductions will be required soon to avoid a rapid temperature rise. As a potential interim measure to avoid extreme temperature increase, it has been suggested that Earth's albedo be increased by artificially enhancing <span class="hlt">stratospheric</span> sulfate aerosols. We use a 3D chemistry climate model, fed by aerosol size distributions from a zonal mean aerosol model, to simulate continuous injection of 1-10 Mt/a into the lower tropical <span class="hlt">stratosphere</span>. In contrast to the case for all previous work, the particles are predicted to grow to larger sizes than are observed after volcanic eruptions. The reason is the continuous supply of sulfuric acid and hence freshly formed small aerosol particles, which enhance the formation of large aerosol particles by coagulation and, to a lesser extent, by condensation. Owing to their large size, these particles have a reduced albedo. Furthermore, their sedimentation results in a non-linear relationship between <span class="hlt">stratospheric</span> aerosol burden and annual injection, leading to a reduction of the targeted cooling. More importantly, the sedimenting particles heat the tropical cold point tropopause and, hence, the <span class="hlt">stratospheric</span> entry mixing ratio of H2O increases. Therefore, geoengineering by means of sulfate aerosols is predicted to accelerate the hydroxyl catalyzed ozone destruction cycles and cause a significant depletion of the ozone layer even though future halogen concentrations will be significantly reduced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20110014198&hterms=Ozone+layer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2528Ozone%2Blayer%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20110014198&hterms=Ozone+layer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2528Ozone%2Blayer%2529"><span id="translatedtitle">The Impact of Geoengineering Aerosols on <span class="hlt">Stratospheric</span> Temperature and Ozone</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Heckendorn, P.; Weisenstein, D.; Fueglistaler, S.; Luo, B. P.; Rozanov, E.; Schraner, M.; Thomason, L. W.; Peter, T.</p> <p>2011-01-01</p> <p>Anthropogenic greenhouse gas emissions are <span class="hlt">warming</span> the global climate at an unprecedented rate. Significant emission reductions will be required soon to avoid a rapid temperature rise. As a potential interim measure to avoid extreme temperature increase, it has been suggested that Earth's albedo be increased by artificially enhancing <span class="hlt">stratospheric</span> sulfate aerosols. We use a 3D chemistry climate model, fed by aerosol size distributions from a zonal mean aerosol model. to simulate continuous injection of 1-10 Mt/a into the lower tropical <span class="hlt">stratosphere</span>. In contrast to the case for all previous work, the particles are predicted to grow to larger sizes than are observed after volcanic eruptions. The reason is the continuous supply of sulfuric acid and hence freshly formed small aerosol particles, which enhance the formation of large aerosol particles by coagulation and, to a lesser extent, by condensation. Owing to their large size, these particles have a reduced albedo. Furthermore, their sedimentation results in a non-linear relationship between <span class="hlt">stratospheric</span> aerosol burden and annual injection, leading to a reduction of the targeted cooling. More importantly, the sedimenting particles heat the tropical cold point tropopause and, hence, the <span class="hlt">stratospheric</span> entry mixing ratio of H2O increases. Therefore, geoengineering by means of sulfate aerosols is predicted to accelerate the hydroxyl catalyzed ozone destruction cycles and cause a significant depletion of the ozone layer even though future halogen concentrations will he significantly reduced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMGC31A0860M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMGC31A0860M"><span id="translatedtitle">Arctic climate response to geoengineering with <span class="hlt">stratospheric</span> sulfate aerosols</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McCusker, K. E.; Battisti, D. S.; Bitz, C. M.</p> <p>2010-12-01</p> <p>Recent <span class="hlt">warming</span> and record summer sea-ice area minimums have spurred expressions of concern for arctic ecosystems, permafrost, and polar bear populations, among other things. Geoengineering by <span class="hlt">stratospheric</span> sulfate aerosol injections to deliberately cancel the anthropogenic temperature rise has been put forth as a possible solution to restoring Arctic (and global) climate to modern conditions. However, climate is particularly sensitive in the northern high latitudes, responding easily to radiative forcing changes. To that end, we explore the extent to which tropical injections of <span class="hlt">stratospheric</span> sulfate aerosol can accomplish regional cancellation in the Arctic. We use the Community Climate System Model version 3 global climate model to execute simulations with combinations of doubled CO2 and imposed <span class="hlt">stratospheric</span> sulfate burdens to investigate the effects on high latitude climate. We further explore the sensitivity of the polar climate to ocean dynamics by running a suite of simulations with and without ocean dynamics, transiently and to equilibrium respectively. We find that, although annual, global mean temperature cancellation is accomplished, there is over-cooling on land in Arctic summer, but residual <span class="hlt">warming</span> in Arctic winter, which is largely due to atmospheric circulation changes. Furthermore, the spatial extent of these features and their concurrent impacts on sea-ice properties are modified by the inclusion of ocean dynamical feedbacks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JAtS...61..161H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JAtS...61..161H"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Tracer Spectra.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haynes, P. H.; Vanneste, J.</p> <p>2004-01-01</p> <p>The combined effects of advection and diffusion on the equilibrium spatial structure of a tracer whose spatial variation is maintained by a large-scale forcing are considered. Motivated by the lower <span class="hlt">stratosphere</span>, the flow is taken to be large-scale, time-dependent, and purely horizontal but varying in the vertical, with the vertical shear much larger than horizontal velocity gradients. As a result, the ratio α between horizontal and vertical tracer scales is large. (For the lower <span class="hlt">stratospheric</span> surf zone α has been shown to be about 250.) The diffusion parameterizes the mixing effects of small-scale processes.The three space dimensions and the large range between the forcing scale and the diffusive scale mean that direct numerical simulation would be prohibitively expensive for this problem. Instead, an ensemble approach is used that takes advantage of the separation between the large scale of the flow and the small scale of the tracer distribution. This approach, which has previously been used in theoretical investigations of two-dimensional flows, provides an efficient technique to derive statistical properties of the tracer distributions such as horizontal-wavenumber spectrum.First, the authors consider random-strain models in which the velocity gradient experienced by a fluid parcel is modeled by a random process. The results show the expected k-1 Batchelor spectrum at large scales, with a deviation from this form at a scale that is larger by a factor α than the diffusive scale found in the absence of vertical shear. This effect may be crudely captured by replacing the diffusivity κ by an “=uivalent diffusivity” α2κ, but the diffusive dissipation is then substantially overestimated, and the spectrum at large k is too steep. This may be attributed to the failure of the equivalent diffusivity to capture the variability of the vertical shear.The technique is then applied to lower-<span class="hlt">stratospheric</span> velocity fields. For realistic values of the diffusivity κ</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1817925O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1817925O"><span id="translatedtitle">Dynamics of the future anthropogenic climate change in the Northern Hemisphere coupled <span class="hlt">stratosphere</span>/troposphere system.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Omrani, Nour-Eddine</p> <p>2016-04-01</p> <p>There is increasing evidence that the response to future anthropogenic climate changes in Northern hemisphere is characterized by weakening of high-latitude westerlies in the coupled <span class="hlt">stratosphere</span>/troposphere-system and strengthening of mid-latitude tropospheric eddy-driven jet with strong impact on large-scale precipitation. Here we show using different model experiments and wave geometry diagnostics that the overall dynamics of this response can be understood in the framework of two competing atmospheric bridges. One bridge is located in the <span class="hlt">stratosphere</span> and connect the tropical Sea Surface Temperature (SST) with the coupled high-latitude <span class="hlt">stratosphere</span>/troposphere system through changes in the upper flank of subtropical jet and downward <span class="hlt">stratosphere</span>/troposphere dynamical coupling. This bridge is responsible for the weakening of the westerlies in high latitude <span class="hlt">stratosphere</span>/troposphere system. The second bridge is in the troposphere and connects the tropical ocean <span class="hlt">warming</span> with the extra-tropics trough changes in the static stability. This bridge is responsible for the wave-induced strengthening of the tropospheric eddy-driven jet. It is shown that the large-scale precipitation response in mid-to-high latitudes results mainly from the dynamical adjustment to wave-driven changes in the tropospheric meridional overturning circulation. The competing interaction between the <span class="hlt">stratospheric</span> and tropospheric pathway constitutes another aspect of <span class="hlt">stratosphere</span>/troposphere dynamical coupling. Her we will show how that such coupling can help understanding model discrepancies in the Northern Hemisphere future climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880042145&hterms=Nitrous+oxide+chemistry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DNitrous%2Boxide%2Bchemistry','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880042145&hterms=Nitrous+oxide+chemistry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DNitrous%2Boxide%2Bchemistry"><span id="translatedtitle">Chemistry of the Antarctic <span class="hlt">stratosphere</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcelroy, Michael B.; Salawitch, Ross J.; Wofsy, Steven C.</p> <p>1988-01-01</p> <p>Interferometric measurements of HCl, ClNO3, HNO3, NO2, and NO obtained over the Antarctic in 1986 are used to model the chemistry of the atmosphere in the region of the Ozone Hole. The low abundance noted in <span class="hlt">stratospheric</span> HCl is attributed to incorporation of HCl in polar <span class="hlt">stratospheric</span> clouds and subsequent reaction of HCl with ClNO3. The results point to a net loss of HNO3 from the <span class="hlt">stratosphere</span> and to the suppression of the abundance of odd nitrogen at high altitudes in the vortex. O3 loss is suggested to be due to the catalytic influence of halogen radicals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950054948&hterms=love&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dlove','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950054948&hterms=love&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dlove"><span id="translatedtitle">Densities of <span class="hlt">stratospheric</span> micrometeorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Love, Stanley G.; Joswiak, David J.; Brownlee, Donald E.</p> <p>1994-01-01</p> <p>We have measured the densities of roughly 150 5- to 15-microns interplanetary dust particles (IDPs) harvested in the <span class="hlt">stratosphere</span>. Care was taken to minimize selection bias in the sample population. Masses were determined using an absolute X-ray analysis technique with a transmission electron microscope, and volumes were found using scanning electron microscope imagery. Unmelted chondritic particles have densities ranging between 0.3 and 6.2 g/cu cm, averaging 2.0 g/cu cm. The low medium densities indicates appreciable porosity, suggesting primitive, uncompacted parent bodies for these particles. Porosities greater than 70% are rare. IDPs with densities above 3.5 g/cu cm usually contain large sulfide grains. We find no evidence of bimodality in the unmelted particle density distribution. Chondritic spherules (melted particles) have densities near 3.4 g/cu cm, consistent with previous results for stony spheurles culled from deep-sea sediments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810024205','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810024205"><span id="translatedtitle"><span class="hlt">Stratospheric</span> CCN sampling program</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rogers, C. F.</p> <p>1981-01-01</p> <p>When Mt. St. Helens produced several major eruptions in the late spring of 1980, there was a strong interest in the characterization of the cloud condensation nuclei (CCN) activity of the material that was injected into the troposphere and <span class="hlt">stratosphere</span>. The scientific value of CCN measurements is two fold: CCN counts may be directly applied to calculations of the interaction of the aerosol (enlargement) at atmospherically-realistic relative humidities or supersaturations; and if the chemical constituency of the aerosol can be assumed, the number-versus-critical supersaturation spectrum may be converted into a dry aerosol size spectrum covering a size region not readily measured by other methods. The sampling method is described along with the instrumentation used in the experiments.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A23A0174S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A23A0174S"><span id="translatedtitle">Numerical simulation of the gravitational separation in the <span class="hlt">stratosphere</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sugawara, S.; Ishidoya, S.; Morimoto, S.; Aoki, S.; Nakazawa, T.; Honda, H.; Murayama, S.</p> <p>2012-12-01</p> <p>It has been shown that the gravitational separation effect in the <span class="hlt">stratosphere</span> can be observable from the measurements of N2, O2 and Ar isotopic ratios and Ar/N2 ratio. The gravitational separation has a possibility to be a new tracer of <span class="hlt">stratospheric</span> circulation. In this study, theoretical simulations were performed to validate an existence of the gravitational separation in the <span class="hlt">stratosphere</span>, as well as to evaluate the magnitude of the isotopic discrimination of the atmospheric major components driven by molecular diffusion process. The 2-dimensional model of the middle atmosphere (SOCRATES) developed by NCAR was used to evaluate the gravitational separation in the <span class="hlt">stratosphere</span>. This model originally includes mass transport processes caused by molecular diffusion to take into account only above the mesosphere, since the molecular diffusion effect has been thought to be negligibly small in the <span class="hlt">stratosphere</span>, compared with the eddy diffusion effect. In this study, we simply lowered its vertical domain to the tropopause for the calculation of molecular diffusion. We assumed the thermal diffusion factor to be zero, since the thermal diffusion effect would be of no importance in the <span class="hlt">stratosphere</span>. We simulated the height-latitude distributions of 44CO2 and 45CO2 concentrations, and then calculated the isotopic ratio as a δ value (in per meg). As a result, it is concluded that the magnitude of the gravitational separation in the <span class="hlt">stratosphere</span> will be significant enough to be detected by recent isotopic measurements. To examine how the CO2 age and the δ value are influenced by changes in the <span class="hlt">stratospheric</span> circulation, we made numerical simulations under the condition that the meridional mass transport is arbitrarily accelerated on the supposition that the Brewer-Dobson circulation (BDC) is enhanced due to global <span class="hlt">warming</span>. The relationships between the two variables under the enhanced-BDC condition are clearly different from those under the normal condition, indicating that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ESASP.730..641L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ESASP.730..641L"><span id="translatedtitle">Project Together into the <span class="hlt">Stratosphere</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lenza, L.; Kapus, J.; Zavodsky, O.; Erdziak, J.; Zitka, J.; Kizek, R.; Peciva, T.</p> <p>2015-09-01</p> <p><span class="hlt">Stratosphere</span> is easily accessible near-space environment with potential to be extensively used for experiments and interdisciplinary research requiring harsh conditions difficult to simulate on Earth. But it turns out that it has other properties as well. It can also connect people. In this case young people, students and scientists from both sides of former Czechosloyak border, which led to project called "Together into <span class="hlt">stratosphere</span>". It is a cross-border collaboration project between Valasské Mezirici Observatory in Czech Republic and Slovak Organization for Space Activities in Slovakia, which started in 2013. By sending probes on meteorological balloons to <span class="hlt">stratosphere</span>, members of this project already executed multiple experiments, which involved biological experiments, measurements of cosmic radiation, technology experiments like tests of photovoltaic panels, JR radiation measurements, R-wave measurements, tests of picosatellite, communication between ground station and <span class="hlt">stratospheric</span> platform and tests of GPS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015PrAeS..75...26W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015PrAeS..75...26W&link_type=ABSTRACT"><span id="translatedtitle">Thermal modeling of <span class="hlt">stratospheric</span> airships</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Jiangtao; Fang, Xiande; Wang, Zhenguo; Hou, Zhongxi; Ma, Zhenyu; Zhang, Helei; Dai, Qiumin; Xu, Yu</p> <p>2015-05-01</p> <p>The interest in <span class="hlt">stratospheric</span> airships has increased and great progress has been achieved since the late 1990s due to the advancement of modern techniques and the wide range of application demands in military, commercial, and scientific fields. Thermal issues are challenging for <span class="hlt">stratospheric</span> airships, while there is no systematic review on this aspect found yet. This paper presents a comprehensive literature review on thermal issues of <span class="hlt">stratospheric</span> airships. The main challenges of thermal issues on <span class="hlt">stratospheric</span> airships are analyzed. The research activities and results on the main thermal issues are surveyed, including solar radiation models, environmental longwave radiation models, external convective heat transfer, and internal convective heat transfer. Based on the systematic review, guides for thermal model selections are provided, and topics worthy of attention for future research are suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960016947','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960016947"><span id="translatedtitle">NDSC and JPL <span class="hlt">stratospheric</span> lidars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McDermid, I. Stuart</p> <p>1995-01-01</p> <p>The Network for the Detection of <span class="hlt">Stratospheric</span> Change is an international cooperation providing a set of high-quality, remote-sensing instruments at observing stations around the globe. A brief description of the NDSC and its goals is presented. Lidar has been selected as the NDSC instrument for measurements of <span class="hlt">stratospheric</span> profiles of ozone, temperature, and aerosol. The Jet Propulsion Laboratory has developed and implemented two <span class="hlt">stratospheric</span> lidar systems for NDSC. These are located at Table Mountain, California, and at Mauna Loa, Hawaii. These systems, which utilize differential absorption lidar, Rayleigh lidar, raman lidar, and backscatter lidar, to measure ozone, temperature, and aerosol profiles in the <span class="hlt">stratosphere</span> are briefly described. Examples of results obtained for both long-term and individual profiles are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6702538','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6702538"><span id="translatedtitle">Greenhouse gases in the <span class="hlt">stratosphere</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wenyi Zhong; Haigh, J.D. ); Pyle, J.A. )</p> <p>1993-02-20</p> <p>The potential radiative forcing in the <span class="hlt">stratosphere</span> of changing concentrations of ozone, methane, nitrous oxide and chlorofluorocarbons 11 and 12 is assessed. Significant changes in heating rate in the lower <span class="hlt">stratosphere</span> are found. The response of a fully interactive radiative-photochemical-dynamical two-dimensional model to such changes in gaseous concentrations is investigated. The inclusion of CH[sub 4], N[sub 2]O and the CFC in the radiation scheme causes a small (1 K) decrease in temperature throughout the <span class="hlt">stratosphere</span> after 50 model years with a resulting increase in ozone column up to 1% in summer high latitudes. An experiment in which lower <span class="hlt">stratospheric</span> ozone concentrations were forcibly reduced in line with recent satellite observations results in significant (several degrees) temperature decrease in this region. Such decreases may be very significant in maintaining polar ozone loss. 20 refs., 12 figs., 2 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRD..12011438Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRD..12011438Y"><span id="translatedtitle">Signal of central Pacific El Niño in the Southern Hemispheric <span class="hlt">stratosphere</span> during austral spring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Chengyun; Li, Tao; Dou, Xiankang; Xue, Xianghui</p> <p>2015-11-01</p> <p>Using ERA-Interim and Modern-Era Retrospective Analysis for Research and Applications reanalysis data sets, we investigated the effects of the central Pacific (CP) El Niño on the Southern Hemispheric (SH) <span class="hlt">stratosphere</span> particularly during the austral spring. SH <span class="hlt">stratosphere</span> <span class="hlt">warming</span> is at a maximum in September rather than in November and December, as suggested by previous studies. SH <span class="hlt">stratospheric</span> temperature anomalies become significant beginning in July and reach a peak of approximately 4 K in September, reflecting a weakened SH vortex and a strengthened SH <span class="hlt">stratospheric</span> Brewer-Dobson circulation. The anomalous Eliassen-Palm flux and its divergence in the SH midlatitudes are most significantly enhanced in August, leading to the SH maximum <span class="hlt">stratospheric</span> temperature anomalies approximately 1 month later. In the middle latitudes of the SH, the poleward and upward propagation of enhanced planetary waves (PWs) during the austral winter (July-September) causes anomalous SH polar <span class="hlt">warming</span> and tropical cooling in the <span class="hlt">stratosphere</span>. The wave number 1 (WN1) pattern is responsible for PW anomalies in August, whereas the WN2 pattern is responsible for those in September. Eddy heat flux during CP El Niño is also anomalously enhanced in extratropical SH <span class="hlt">stratosphere</span> in both August and September and subsequently weaken during the following months.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E3411T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E3411T"><span id="translatedtitle">Universal <span class="hlt">stratospheric</span> balloon gradiometer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsvetkov, Yury; Filippov, Sergey; Brekhov, Oleg; Nikolaev, Nikolay</p> <p></p> <p>The study of the interior structure of the Earth and laws of its evolution is one of the most difficult problems of natural science. Among the geophysical fields the anomaly magnetic field is one of the most informational in questions of the Earth’s crust structure. Many important parameters of an environment are expedient for measuring at lower altitudes, than satellite ones. So, one of the alternatives is <span class="hlt">stratospheric</span> balloon survey. The balloon flight altitudes cover the range from 20 to 50 km. At such altitudes there are steady zone air flows due to which the balloon flight trajectories can be of any direction, including round-the-world (round-the-pole). For investigation of Earth's magnetic field one of the examples of such sounding system have been designed, developed and maintained at IZMIRAN and MAI during already about 25 years. This system consists of three instrumental containers uniformly placed along a vertical 6 km line. Up today this set has been used only for geomagnetic purposes. So we describe this system on example of the measuring of the geomagnetic field gradient. System allows measuring a module and vertical gradient of the geomagnetic field along the whole flight trajectory and so one’s name is - <span class="hlt">stratospheric</span> balloon magnetic gradiometer (SMBG). The GPS-receivers, located in each instrumental container, fix the flight coordinates to within several tens meters. Process of SBMG deployment, feature of the exit of rope from the magazine at the moment of balloon launching has been studied. Used magazine is cellular type. The hodograph of the measuring base of SBMG and the technique of correction of the deviations of the measuring base from the vertical line (introduction of the amendments for the deviation) during the flight have been investigated. It is shown that estimation of the normal level of values of the vertical gradient of the geomagnetic field is determined by the accuracy of determining the length of the measuring base SBMG</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009APS..APR.Q7002R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009APS..APR.Q7002R"><span id="translatedtitle">The Many Problems with Geoengineering Using <span class="hlt">Stratospheric</span> Aerosols</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robock, Alan</p> <p>2009-05-01</p> <p>In response to the global <span class="hlt">warming</span> problem, there has been a recent renewed call for geoengineering ``solutions'' involving injecting particles into the <span class="hlt">stratosphere</span> or blocking sunlight with satellites between the Sun and Earth. While volcanic eruptions have been suggested as innocuous examples of <span class="hlt">stratospheric</span> aerosols cooling the planet, the volcano analog actually argues against geoengineering because of ozone depletion and regional hydrologic and temperature responses. In this talk, I consider the suggestion to create an artificial <span class="hlt">stratospheric</span> aerosol layer. No systems to conduct geoengineering now exist, but a comparison of different proposed <span class="hlt">stratospheric</span> injection schemes, airplanes, balloons, artillery, and a space elevator, shows that using airplanes would not be that expensive. We simulated the climate response to both tropical and Arctic <span class="hlt">stratospheric</span> injection of sulfate aerosol precursors using a comprehensive atmosphere-ocean general circulation model, the National Aeronautics and Space Administration Goddard Institute for Space Studies ModelE. We simulated the injection of SO2 and the model converts it to sulfate aerosols, transports them and removes them through dry and wet deposition, and calculates the climate response to the radiative forcing from the aerosols. We conducted simulations of future climate with the Intergovernmental Panel on Climate Change A1B business-as-usual scenario both with and without geoengineering, and compare the results. We found that if there were a way to continuously inject SO2 into the lower <span class="hlt">stratosphere</span>, it would produce global cooling. Acid deposition from the sulfate would not be enough to disturb most ecosystems. Tropical SO2 injection would produce sustained cooling over most of the world, with more cooling over continents. Arctic SO2 injection would not just cool the Arctic. But both tropical and Arctic SO2 injection would disrupt the Asian and African summer monsoons, reducing precipitation to the food supply</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1213034G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1213034G"><span id="translatedtitle">The relationship between the polar vortex and ozone in the boreal <span class="hlt">stratosphere</span> from ERA-40 reanalysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>González-Merino, Beatriz; Serrano, Encarna</p> <p>2010-05-01</p> <p>The relation between the ozone and the polar vortex in the <span class="hlt">stratosphere</span> has an outstanding role in climate studios, and also a large repercussion in the improvement of the climate models. This importance is due to the combination of two reasons: the key role of the <span class="hlt">stratospheric</span> ozone in the Earth climate due to its radiative properties, and that the most important dynamic activity in the high-latitude <span class="hlt">stratosphere</span> is associated with the polar vortex (present during the whole winter and part of the spring). This work focuses on the spring months, a transitional period in the <span class="hlt">stratospheric</span> circulation between the winter westerlies (the <span class="hlt">stratospheric</span> polar vortex, SPV, is completely developed) and summer easterlies (SPV has already disappeared). This breakdown of the SPV is known as the <span class="hlt">Stratospheric</span> Final <span class="hlt">Warming</span>, SFW. Using ERA-40 data, currently the longest-period reanalysis (1979-2002) with a sufficiently realistic representation of the <span class="hlt">stratosphere</span> circulation, we analyze different aspects about the relation between the ozone concentration and the intensity of polar vortex in the boreal <span class="hlt">stratosphere</span> during the springtime. Among other results, we see that the 24-yr mean evolution of the <span class="hlt">stratospheric</span> ozone, averaged over the polar region (60°N-80°N), exhibits a slow increase along March followed by a progressive decrease during April and May. The interannual variability of the monthly mean of zonal wind and ozone mixing ratio at 50 hPa in the analyzed polar region decreases gradually along the season as well. When analyzing the springtime <span class="hlt">stratospheric</span> preconditioning, we found that almost all the <span class="hlt">warm</span> Februaries are not associated with low ozone content and strong SPV at the beginning of March; and that none cold February was followed by a weak SPV in the first third of March. Also, the <span class="hlt">stratospheric</span> conditions around the SFW occurrence have been studied. It is seen that the 50-hPa ozone over the polar region is nearly constant prior to the SFW, while it gets</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000074253&hterms=Datasets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DDatasets','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000074253&hterms=Datasets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DDatasets"><span id="translatedtitle">Troposphere-<span class="hlt">Stratosphere</span> Connections in Recent Northern Winters in NASA GEOS Assimilated Datasets</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pawson, Steven</p> <p>2000-01-01</p> <p>The northern winter <span class="hlt">stratosphere</span> displays a wide range of interannual variability, much of which is believed to result from the response to the damping of upward-propagating waves. However, there is considerable (growing) evidence that the <span class="hlt">stratospheric</span> state can also impact the tropospheric circulation. This issue will be examined using datasets generated in the Data Assimilation Office (DAO) at NASA's Goddard Space Flight Center. Just as the tropospheric circulation in each of these years was dominated by differing synoptic-scale structures, the <span class="hlt">stratospheric</span> polar vortex also displayed different evolutions. The two extremes are the winter 1998/1999, when the <span class="hlt">stratosphere</span> underwent a series of <span class="hlt">warming</span> events (including two major <span class="hlt">warmings</span>), and the winter 1999/2000, which was dominated by a persistent, cold polar vortex, often distorted by a dominant blocking pattern in the troposphere. This study will examine several operational and research-level versions of the DAO's systems. The 70-level-TRMM-system with a resolution of 2-by-2.5 degrees and the 48-level, 1-by-l-degree resolution ''Terra'' system were operational in 1998/1999 and 1999/2000, respectively. Research versions of the system used a 48-level, 2-by-2.5-degree configuration, which facilitates studies of the impact of vertical resolution. The study includes checks against independent datasets and error analyses, as well as the main issue of troposphere-<span class="hlt">stratosphere</span> interactions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. Their policies may differ from this site.</small> </div> </center> <div id="footer-wrapper"> <div class="footer-content"> <div id="footerOSTI" class=""> <div class="row"> <div class="col-md-4 text-center col-md-push-4 footer-content-center"><small><a href="http://www.science.gov/disclaimer.html">Privacy and Security</a></small> <div class="visible-sm visible-xs push_footer"></div> </div> <div class="col-md-4 text-center col-md-pull-4 footer-content-left"> <img src="http://www.osti.gov/images/DOE_SC31.png" alt="U.S. Department of Energy" usemap="#doe" height="31" width="177"><map style="display:none;" name="doe" id="doe"><area shape="rect" coords="1,3,107,30" href="http://www.energy.gov" alt="U.S. Deparment of Energy"><area shape="rect" coords="114,3,165,30" href="http://www.science.energy.gov" alt="Office of Science"></map> <a ref="http://www.osti.gov" style="margin-left: 15px;"><img src="http://www.osti.gov/images/footerimages/ostigov53.png" alt="Office of Scientific and Technical Information" height="31" width="53"></a> <div class="visible-sm visible-xs push_footer"></div> </div> <div class="col-md-4 text-center footer-content-right"> <a href="http://www.osti.gov/nle"><img src="http://www.osti.gov/images/footerimages/NLElogo31.png" alt="National Library of Energy" height="31" width="79"></a> <a href="http://www.science.gov"><img src="http://www.osti.gov/images/footerimages/scigov77.png" alt="science.gov" height="31" width="98"></a> <a href="http://worldwidescience.org"><img src="http://www.osti.gov/images/footerimages/wws82.png" alt="WorldWideScience.org" height="31" width="90"></a> </div> </div> </div> </div> </div> <p><br></p> </div><!-- container --> </body> </html>