Science.gov

Sample records for stratospheric warmings ssws

  1. 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.

  2. The preconditioning of major sudden stratospheric warmings

    NASA Astrophysics Data System (ADS)

    Bancalá, S.; Krüger, K.; Giorgetta, M.

    2012-02-01

    The preconditioning of major sudden stratospheric warmings (SSWs) is investigated with two long time series using reanalysis (ERA-40) and model (MAECHAM5/MPI-OM) data. Applying planetary wave analysis, we distinguish between wavenumber-1 and wavenumber-2 major SSWs based on the wave activity of zonal wavenumbers 1 and 2 during the prewarming phase. For this analysis an objective criterion to identify and classify the preconditioning of major SSWs is developed. Major SSWs are found to occur with a frequency of six and seven events per decade in the reanalysis and in the model, respectively, thus highlighting the ability of MAECHAM5/MPI-OM to simulate the frequency of major SSWs realistically. However, from these events only one quarter are wavenumber-2 major warmings, representing a low (˜0.25) wavenumber-2 to wavenumber-1 major SSW ratio. Composite analyses for both data sets reveal that the two warming types have different dynamics; while wavenumber-1 major warmings are preceded only by an enhanced activity of the zonal wavenumber-1, wavenumber-2 events are either characterized by only the amplification of zonal wavenumber-2 or by both zonal wavenumber-1 and zonal wavenumber-2, albeit at different time intervals. The role of tropospheric blocking events influencing these two categories of major SSWs is evaluated in the next step. Here, the composite analyses of both reanalysis and model data reveal that blocking events in the Euro-Atlantic sector mostly lead to the development of wavenumber-1 major warmings. The blocking-wavenumber-2 major warming connection can only be statistical reliable analyzed with the model time series, demonstrating that blocking events in the Pacific region mostly precede wavenumber-2 major SSWs.

  3. Simple criteria to define stratospheric sudden warmings

    NASA Astrophysics Data System (ADS)

    Oates, Ryan Peter; Reichler, Thomas

    2015-04-01

    Research on future change of stratospheric sudden warmings (SSWs) shows somewhat mixed results in terms of the sign and magnitude of future SSW change. However, a significant number of studies has been based off of the absolute WMO SSW criterion, and there is some concern that potential change in future SSW frequency could be the byproduct of the criterion itself and not a real change in SSW frequency. In the present study we propose two alternative and relatively simple methods for identifying SSWs. We test the two methods and compare their outcomes against more conventional criteria using data from reanalysis and a climate model.

  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. Vertical coupling of the middle atmosphere during stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Miller, Andreas; Schmidt, Hauke; Bunzel, Felix

    2013-05-01

    A 20 year simulation of the high-top atmospheric General Circulation Model (GCM) HAMMONIA is used to investigate internally produced Sudden Stratospheric Warmings (SSWs). We detect 19 major SSWs and evaluate the model results by comparison to the ERA40 reanalysis dataset. Composites are built to analyze the climatological characteristics of SSWs, in particular to investigate the mesospheric precursors and differences between vortex splits and displacements. The vertical coupling processes from the stratosphere to the lower thermosphere are studied using transformed Eulerian-mean (TEM) analysis and diagnostics concerning the role of gravity waves. Consistent to recent studies, we find a mesospheric cooling and a weaker thermospheric warming accompanying the SSW. The large anomalies in the zonal mean winds and temperatures are explained by the interactions of EP-Flux divergence, mean flow advection and parameterized momentum deposition of gravity waves. We present an algorithm, based on geopotential height, to classify the events. Nine SSWs can be characterized as vortex splits, 10 as displacements. The differences between the two types are statistically significant suggesting splits are associated with larger anomalies in temperature and zonal wind. Investigation of the longitudinal dependence of zonal winds demonstrates the asymmetry of the climatological winter and of single events. Therefore, we do not find a criterion to sufficiently detect SSWs using mesospheric winds prior to the central date.

  6. Solar and lunar ionospheric electrodynamic effects during stratospheric sudden warmings

    NASA Astrophysics Data System (ADS)

    Yamazaki, Yosuke

    2014-11-01

    Both solar and lunar atmospheric tides are believed to drive ionospheric electrodynamic effects during stratospheric sudden warmings (SSWs), but their relative importance is not well understood. In this study, long-term records (1958-2007) of the geomagnetic field are analyzed to determine the average solar (S) and lunar (L) ionospheric current systems for SSW and non-SSW periods. It is found that the L current intensity is enhanced during SSWs approximately by 75%, while the relative change in the S current intensity is much smaller (~10%). Nonetheless, absolute changes are comparable in the S and L current intensities. At the magnetic equator, semidiurnal perturbations produced by S and L currents reinforce or cancel each other depending on the phase of the moon, creating lunar-dependent recurrent onset in the total effect. These results indicate that both S and L contributions need to be considered to understand ionospheric variability during SSWs.

  7. Do split and displacement sudden stratospheric warmings have different annular mode signatures?

    NASA Astrophysics Data System (ADS)

    Maycock, Amanda C.; Hitchcock, Peter

    2015-12-01

    Sudden stratospheric warmings (SSWs) contribute to intraseasonal tropospheric forecasting skill due to their surface impacts. Recent studies suggest these impacts depend upon whether the polar vortex splits or is displaced during the SSW. We analyze the annular mode signatures of SSWs in a 1000 year IPSL-CM5A-LR simulation. Although small differences in the mean surface Northern Annular Mode (NAM) index following splits and displacements are found, the sign is not consistent for two independent SSW algorithms, and over 50 events are required to distinguish the responses. We use the wintertime correlation between extratropical lower stratospheric wind anomalies and the surface NAM index as a metric for two-way stratosphere-troposphere coupling and find that the differences between splits and displacements, and between classification methodologies, can be simply understood in terms of their mean stratospheric wind anomalies. Predictability studies should therefore focus on understanding the factors that determine the persistence of these anomalies following SSWs.

  8. Effect of stratospheric sudden warmings on the predictability of the tropospheric NAM

    NASA Astrophysics Data System (ADS)

    Kuroda, Y.

    2012-04-01

    Impact of the stratospheric sudden warmings (SSWs) on the predictability of the tropospheric Northern Annular Mode (NAM) variability was examined for recent nine winters from 2001/2 to 2009/10 when we had eight major SSWs during this period. The predictability has been examined through sets of numerical experiments using an atmospheric general circulation model of the Meteorological Research Institute that includes well-resolved stratosphere and land processes. It is found that the timing of occurrence of SSW sometimes becomes an important turning date for the predictability of tropospheric NAM variability. In fact, for winters of 2003/4, 2005/6 and 2009/10, the predictability is very good and is more than a few months if prediction is initialized before the occurrence of the SSWs. However, it turns to be rather worse if it is initialized after the SSWs. These winters are characterized by the occurrence of quasi-periodic stratospheric variability called the polar-night jet oscillation (PJO), and the waves that create the SSWs were planetary wave of mainly zonal wavenumber one. On the other hand, the SSW of 2008/9 was created by almost pure planetary wave of zonal wavenumber two. In this winter, the predictability becomes better and have more than a few months only when prediction is initialized after the SSW. Effect of the SSWs on the predictability of the tropospheric NAM and its origin are discussed.

  9. Role of Stratospheric Sudden Warmings on the response to Central Pacific El Niño

    NASA Astrophysics Data System (ADS)

    Iza, Maddalen; Calvo, Natalia

    2015-04-01

    The Northern Hemisphere polar stratospheric response to Central Pacific El Niño (CP El Niño) remains unclear. Contradictory results have been found on its resemblance with the canonical East Pacific El Niño (EP El Niño), depending on the index used to characterize these events or the number of cases. Some studies found a stronger and colder polar vortex while others displayed a weaker and warmer polar stratosphere. Our results, based on reanalysis data, show that Stratospheric Sudden Warmings (SSWs) occurrence dominates the CP El Niño response in the Northern Hemisphere. A robust CP El Niño signal is observed when the events are classified according to the presence or absence of SSWs. CP El Niño winters without SSWs show significant cold anomalies in the Northern Hemisphere polar stratosphere in early winter. In contrast, CP El Niño winters with SSWs are associated with significant warm anomalies, which are in fact related to SSWs. Therefore, the polar stratospheric response to CP El Niño events is significant and opposite during winters with and without SSWs. In addition, and contrary to previous studies, CP and EP El Niño polar stratospheric responses are clearly distinguishable in early winter in the absence of SSWs. The analysis of the Pacific-North American (PNA) pattern and the tropospheric wave anomalies entering the stratosphere support the observed stratospheric signals. In the absence of SSWs, EP El Niño winters are characterized by a strengthened PNA pattern and enhanced propagation of planetary wave number 1 into the stratosphere, while during CP El Niño winters a weakened PNA pattern is resembled, related to inhibited upward wave propagation. This is consistent with a weaker polar vortex in EP El Niño winters and a stronger vortex in CP El Niño winters. Results are robust regardless of the CP El Niño definition or the size of the composite used. Similar conclusions are reached in CMIP5 historical simulations. Hence, our study reveals that the SSW occurrence needs to be taken into account when studying the CP El Niño stratospheric response and explain why different responses to CP El Niño were previously reported.

  10. Ionospheric effects of sudden stratospheric warmings in eastern Siberia region

    NASA Astrophysics Data System (ADS)

    Polyakova, A. S.; Chernigovskaya, M. A.; Perevalova, N. P.

    2014-12-01

    Ionospheric effects observed in Russia's Asia region during sudden stratospheric warmings (SSWs) in the winters 2008/2009 and 2012/2013 corresponding to both extreme solar minimum and moderate solar maximum conditions have been examined. To detect the ionospheric effects which must have been induced by the SSWs, we have carried out a joint analysis of total electron content (TEC) global ionospheric maps (GIM), MLS (Microwave Limb Sounder, EOS Aura) measurements of vertical temperature profiles, as well as NCEP/NCAR and UKMO Reanalysis data. It has been revealed for the first time that during strong SSWs the amplitude of diurnal variation of TEC decreases nearly by half in the mid-latitude ionosphere. Besides, the intensity of TEC deviations from the background level increases during SSWs. It has also revealed that during SSW peak the midday TEC maximum considerably decreases, and the night/morning TEC increases compared to quiet days. The pattern of TEC response to SSW is shown to be identical for both quiet and disturbed geophysical conditions.

  11. Stratospheric warmings and the geomagnetic lunar tide: 1958-2007

    NASA Astrophysics Data System (ADS)

    Yamazaki, Y.; Richmond, A. D.; Yumoto, K.

    2012-04-01

    A quantitative comparison of the geomagnetic lunar tide and lower stratospheric parameters (zonal mean air temperature T and zonal mean zonal wind U) is carried out for the period 1958-2007. The correlation between the amplitude of the geomagnetic lunar tide at an equatorial station, Addis Ababa, and the lower stratospheric parameters from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis is examined. It is found that the lunar tidal amplitude tends to be positively and negatively correlated with the stratospheric T and U, respectively, in high latitudes of the Northern Hemisphere during December and January. High correlations are observed in approximately 70% of stratospheric sudden warming (SSW) events. The results suggest that variability of the geomagnetic lunar tide during the northern winter is closely linked with dynamical changes in the lower stratospheric parameters associated with SSWs.

  12. 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 2? 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.

  13. Properties of stratospheric warming events during northern winter.

    NASA Astrophysics Data System (ADS)

    Maury, Pauline; Claud, Chantal; Manzini, Elisa; Hauchecorne, Alain; Keckhut, Philippe

    2015-04-01

    During wintertime the polar mid-stratosphere is characterized by the setting up of westerly winds around the pole; the so-called polar vortex. The polar vortex is one of the most variable features of the zonal-mean circulation of the earth atmosphere, due to a highly non linear interaction between planetary-scale Rossby waves and the zonal flow. Indeed, the interaction between the upward tropospheric propagating waves and the polar vortex leads to a zonal flow weakening, implying a large day to day vortex variability. In the most dramatic cases the polar vortex breaks down, the stratospheric polar flow can reverse its direction and the temperatures can rise locally by more than 50K in a span of a few days. Such phenomena are known as Sudden Stratospheric Warmings (SSWs) and constitute, since their discovery, the most impressive dynamical events in the physical climate system. There are however situations where the polar vortex does not break down, but temperatures increase dramatically. In this study, we propose a global characterization of stratospheric warmings situations based on a temperature threshold in the 50-10hPa layer, in order to assess the properties of daily stratospheric temperature variability during the northern winter. The originality of this approch consists in evaluating the wintertime positive temperature anomalies in terms of intensity and duration. We will show that there is a wide spectrum of warming types. The major SSWs are the most extreme, but there are other events that share some common properties with the major ones. Though neglected, these latter warmings may play a key role in the coupling of the stratosphere-troposphere system.

  14. 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, Hitchcock and Shepherd (2013). The zonal average distribution of gravity wave momentum fluxes during the recovery phase after major SSWs indicates that poleward propagation of gravity waves from midlatitudes likely contributes to the enhanced gravity wave drag on top of the re-established polar jets.

  15. Idealized Simulations of Sudden Stratospheric Warmings with an Ensemble of Dry GCM Dynamical Cores

    NASA Astrophysics Data System (ADS)

    Yao, W.; Jablonowski, C.

    2013-12-01

    The stratospheric circulation is most variable during Sudden Stratospheric Warmings (SSWs), when the polar vortex is disturbed by planetary-scale Rossby waves. The coupling between the stratosphere and troposphere is strongest before and after SSW events. SSWs are mainly generated and influenced by vertically propagating planetary-scale waves from the troposphere and their interaction with the zonal flow. In particular, orographically generated planetary waves are believed to play a major role. However, orographic gravity waves are not enough to explain SSWs in their entirety, and our understanding of the details of SSW precursors and their predictability is still incomplete. Our study sheds light on dynamical causes and effects of the SSWs by analyzing the wave-blocking events and the Northern Annular Mode (NAM) structure, especially the tropospheric response to the weakening of the lower stratospheric vortex. It discusses the onset and development of SSWs in idealized General Circulation Model (GCM) simulations that isolate the dynamical core from the physical parameterization package. In particular, SSWs are simulated with an ensemble of four dynamical cores that are part of the Community Atmosphere Model (CAM version 5) at the National Center for Atmospheric Research (NCAR). These are the spectral transform semi-Lagrangian (SLD), spectral transform Eulerian (EUL), Finite-Volume (FV), and CAM5's newest default Spectral Element (SE) dynamical cores. The simulations are configured for a dry and flat earth, and thereby omit typical wave triggering mechanisms like moist convection or orographic forcing. The dynamical cores are driven by Rayleigh damping near the surface and the model top, and a prescribed Newtonian temperature relaxation as suggested by Held and Suarez (1994) and Williamson et al. (1998). We demonstrate that SSWs can be simulated in both hemispheres at an equal rate, even in the absence of convectively or orographically forced waves. Wave analysis is performed to understand the driving mechanisms of SSWs in the different dynamical cores. In particular, the Transformed-Eulerian-Mean (TEM) analysis is used to explore the relative roles of the forcing by the resolved waves, the TEM advection terms and unresolved waves. It is shown that the choice of the numerical schemes in the dynamical cores greatly impacts their ability to resolve waves, and thereby trigger the SSW phenomenon in the simulations.

  16. 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.

  17. 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 identical for different geophysical conditions.

  18. Interannual and seasonal effects of sudden stratospheric warming events on gravity wave activity

    NASA Astrophysics Data System (ADS)

    Wing, R. J.; Collins, R. L.; Irving, B. K.; Titus, M. J.; Martus, C. M.; Krehlik, Z. A.; Mizutani, K.; Harvey, V.

    2013-12-01

    A significant correlation is found between the modulation of gravity wave activity and the level of disturbance in the middle atmosphere associated with sudden stratospheric warming (SSW) events. We report the variability of stratospheric and mesospheric (40-50 km) gravity wave activity, as measured at the Lidar Research Laboratory-Poker Flat Research Range, Chatanika, Alaska (65N, 147W), and the wind speed during SSWs. Using the Rayleigh lidar technique, measured relative density profiles are used to determine nightly temperature and density profiles. Gravity wave activity is characterized by calculating the potential energy density. The fluctuations in the lidar density profile and measurements of the buoyancy frequency are used to calculate potential energy density. Satellite and reanalysis data are used to characterize the synoptic conditions of the Arctic middle atmosphere and SSWs.

  19. Mesospheric intrusion and anomalous chemistry during and after a major stratospheric sudden warming

    NASA Astrophysics Data System (ADS)

    Kvissel, Ole-Kristian; Orsolini, Yvan J.; Stordal, Frode; Limpasuvan, Varavut; Richter, Jadwiga; Marsh, Dan R.

    2012-04-01

    Several major stratospheric sudden warmings (SSWs) characterized by a rapid vertical displacement of the winter polar stratopause are simulated in the National Center for Atmospheric Research's Whole Atmosphere Community Climate Model. The stratopause descends into the mid-stratosphere at the onset of the SSW, and then abruptly reforms near 70 km. The SSWs are accompanied by a strong equatorward and downward residual circulation between 40 and 60 km. The descent occurs mainly through the core of the highly displaced vortex, and is accompanied by an intrusion of air rich in carbon monoxide (CO) from the mesosphere into the mid-stratosphere. Around the periods when the stratopause undergoes rapid vertical displacement, the simulation shows that the air of mesospheric origin is being cut off and remains distinct from surrounding stratospheric air masses for at least a month after SSW onset. Such mesospheric cut-off intrusion of CO-rich appears to be a defining signature of winters with major SSWs. Due to its strong temperature dependency, the secondary ozone maximum (between 90 and 110 km) abruptly decreases in amplitude at the time of the high-altitude stratopause reformation that influences the thermal structure at these altitudes. The vertical location of the tertiary ozone maximum (between 70 and 75 km) shows significant variations in response to the changing vertical motion during SSW.

  20. Northern Hemisphere mid-winter vortex-displacement and vortex-split stratospheric sudden warmings: Influence of the Madden-Julian Oscillation and Quasi-Biennial Oscillation

    NASA Astrophysics Data System (ADS)

    Liu, Chuanxi; Tian, Baijun; Li, King-Fai; Manney, Gloria L.; Livesey, Nathaniel J.; Yung, Yuk L.; Waliser, Duane E.

    2014-11-01

    We investigate the connection between the equatorial Madden-Julian Oscillation (MJO) and different types of the Northern Hemisphere mid-winter major stratospheric sudden warmings (SSWs), i.e., vortex-displacement and vortex-split SSWs. The MJO-SSW relationship for vortex-split SSWs is stronger than that for vortex-displacement SSWs, as a result of the stronger and more coherent eastward propagating MJOs before vortex-split SSWs than those before vortex-displacement SSWs. Composite analysis indicates that both the intensity and propagation features of MJO may influence the MJO-related circulation pattern at high latitudes and the type of SSWs. A pronounced Quasi-Biennial Oscillation (QBO) dependence is found for vortex-displacement and vortex-split SSWs, with vortex-displacement (-split) SSWs occurring preferentially in easterly (westerly) QBO phases. The lagged composites suggest that the MJO-related anomalies in the Arctic are very likely initiated when the MJO-related convection is active over the equatorial Indian Ocean (around the MJO phase 3). Further analysis suggests that the QBO may modulate the MJO-related wave disturbances via its influence on the upper tropospheric subtropical jet. As a result, the MJO-related circulation pattern in the Arctic tends to be wave number-one/wave number-two ~25-30 days following phase 3 (i.e., approximately phases 7-8, when the MJO-related convection is active over the western Pacific) during easterly/westerly QBO phases, which resembles the circulation pattern associated with vortex-displacement/vortex-split SSWs.

  1. Analysis of data from spacecraft (stratospheric warmings)

    NASA Technical Reports Server (NTRS)

    Anderson, A. D.

    1974-01-01

    Links between the upper atmosphere and the stratosphere were studied to explain stratospheric warmings, and to correlate the warmings with other terrestrial and solar phenomena. Physical mechanisms for warming, or which may act as a trigger are discussed along with solar and geophysical indices. Two stratospheric warming cases are analyzed.

  2. Strong thermospheric cooling during the 2009 major stratosphere warming

    NASA Astrophysics Data System (ADS)

    Liu, Huixin; Doornbos, Eelco; Yamamoto, Mamoru; Tulasi Ram, S.

    2011-06-01

    Thermospheric density simultaneously observed by the CHAMP and GRACE satellites in both the pre-dawn and afternoon local time sectors undergoes significant decrease across both hemispheres during the major stratospheric sudden warming (SSW) in January 2009. This decrease is largest in the equatorial region near the subsolar latitude, reaching 30% at 325 km, and 45% at 475 km altitude in the afternoon sector. This large density drop demonstrates a substantial cooling of about 50 Kelvin in the equatorial upper thermosphere. Furthermore, the cooling varies clearly with longitude in terms of magnitude and the timing of the maximum cooling. Thermosphere cooling can have important impact on the ionosphere, as indicated by simultaneous plasma observations. Though many questions remain about what causes the cooling, our results open a new perspective for investigating the global coupling of the lower and upper atmosphere during SSWs.

  3. 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.

  4. Polar Stratospheric Warmings and their causality with Solar Proton Events

    NASA Astrophysics Data System (ADS)

    Kilifarska, Nataliya

    Although intensive observational and modelling studies since Matsuno's early model of stratospheric sudden warmings (SSW), the understanding of this phenomenon is still incomplete. Estimation of the capability of GCM to simulate SSWs [Charlton et. all, 2007] shows that there are some difficulties for the stratospheric resolving GCMs to reproduce the observed climatological polar vortex. The authors point out that the main reason for this model's deficiency is the luck of meridional heat flux in the lower stratosphere. Taking into account that the corpuscular particles showers are most intensive into the auroral oval (approximately 600 N) - it is quite naturally to suggest that the effect of their heating may affect the thermo-dynamical regime of the polar atmosphere. To test this hypothesis a detail statistical analysis of temperature, zonal wind and O3 profiles from ERA-40 reanalysis and satellite measurements is arrange. Composites of these parameters corresponding to negative anomalies of Arctic oscillation index (AO) less than -2 sigma have been created in order to analyze the situations preceding major warmings. We are looking for mechanisms responsible for existence of different types of major warmings, namely vortex displacement and vortex split. Preliminary results show that for east QBO phase of the equatorial stratospheric zonal wind and strong negative anomalies of AO index - more than 90% of total variability of polar cap temperature are described by O3 mixing ratio and the vertical profile of the zonal wind at 600 N. The lower stratospheric ozone is strongly influenced by the amplitude of AO anomaly. Unlike the temperature, the polar cap O3 profile is significantly related to the horizontal EP flux, while the strength of zonal wind at 600 N is significantly influenced by the amplitude of AO negative anomaly, the intensity of the particle precipitation within the auroral oval and F10.7 index (a proxy of solar irradiance activity). Results will be discussed in the light of different types of SSW, i.e. vortex displacement and vortex split.

  5. 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.

  6. The stratopause evolution during different types of sudden stratospheric warming event

    NASA Astrophysics Data System (ADS)

    Vignon, Etienne; Mitchell, Daniel M.

    2014-08-01

    Recent work has shown that the vertical structure of the Arctic polar vortex during different types of sudden stratospheric warming (SSW) events can be very distinctive. Specifically, SSWs can be classified into polar vortex displacement events or polar vortex splitting events. This paper aims to study the Arctic stratosphere during such events, with a focus on the stratopause using the Modern Era-Restrospective analysis for Research and Applications reanalysis data set. The reanalysis dataset is compared against two independent satellite reconstructions for validation purposes. During vortex displacement events, the stratopause temperature and pressure exhibit a wave-1 structure and are in quadrature whereas during vortex splitting events they exhibit a wave-2 structure. For both types of SSW the temperature anomalies at the stratopause are shown to be generated by ageostrophic vertical motions. Transformed Eulerian mean diagnostics are used to show differences in the planetary wave activity between displacement and splitting events. The convergence of Eliassen-Palm flux, which leads to SSWs is longer for displacement events and a persistent mesospheric Eliassen-Palm flux divergence can be observed about 20 days after displacement events. Finally, although this work focuses on the stratopause at high latitudes, associated observations of the equatorial middle atmosphere are also examined to explore links between the equator and polar evolution during SSWs.

  7. A minor sudden stratospheric warming with a major impact: Transport and polar processing in the 2014/2015 Arctic winter

    NASA Astrophysics Data System (ADS)

    Manney, Gloria L.; Lawrence, Zachary D.; Santee, Michelle L.; Read, William G.; Livesey, Nathaniel J.; Lambert, Alyn; Froidevaux, Lucien; Pumphrey, Hugh C.; Schwartz, Michael J.

    2015-09-01

    Stratospheric transport and polar processing during the 2014/2015 Arctic winter were strongly influenced by a minor sudden stratospheric warming (SSW) in early January. Disturbances to temperatures and trace gases in the middle and upper stratosphere were similar in character to those associated with major SSWs: The stratopause dropped, and vertical temperature gradients weakened, followed by renewed descent of mesospheric air. The lower stratospheric polar vortex was barely disrupted and remained unusually strong throughout the winter. The SSW did, however, cause lower stratospheric temperatures to rise well above chlorine activation thresholds; trace gas abundances from the Aura Microwave Limb Sounder (MLS) were consequently exceptional. The degree of chlorine activation in January was the smallest, and lower stratospheric ozone values in February were the highest, in the 11 year MLS record. The major role played by a minor SSW highlights the Arctic stratosphere's sensitivity to a spectrum of dynamical variability.

  8. The life cycle of a Sudden Stratospheric Warming from infrasonic ambient noise observations

    NASA Astrophysics Data System (ADS)

    Smets, Pieter; Evers, Lslo; Wapenaar, Kees

    2014-05-01

    Midwinter sudden stratospheric warmings (SSWs) leave a clear infrasonic signature, resulting from the drastic change in the stratosphere. This signature can be obtained passively by analysing the ambient infrasonic field. In this study, Arctic infrasound observations of stations IS18 and IS53 during the 2009 major SSW are re-analysed to better understand the signature of warming as a function of time. These stations are in place for the verification of the Comprehensive Nuclear-Test-Ban Treaty and part of the International Monitoring System. The back-azimuth shows the clearest effect, following the direction of the polar vortex. Directional time averaged amplitude plots reveal additional insight in the SSW life cycle, helping to better understand the phenomena. This technique can also be used to obtain information of the infrasound refraction altitude region, stratospheric or thermospheric, respectively, based on the presence of tidal fluctuations. A microbarom source model and atmospheric propagation model are used verify those findings.

  9. Effects of Major Sudden Stratospheric Warmings Identified in Midlatitude Mesospheric Rayleigh-Scatter Lidar Temperatures

    NASA Astrophysics Data System (ADS)

    Sox, L.; Wickwar, V. B.; Fish, C. S.; Herron, J. P.

    2014-12-01

    Mesospheric temperature anomalies associated with Sudden Stratospheric Warmings (SSWs) have been observed extensively in the polar regions. However, observations of these anomalies at midlatitudes are sparse. The very dense 11-year data set, collected between 1993-2004, with the Rayleigh-scatter lidar at the Atmospheric Lidar Observatory (ALO; 41.7°N, 111.8°W) at the Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU), has been carefully examined for such anomalies. The temperatures derived from these data extend over the mesosphere, from 45 to 90 km. During this period extensive data were acquired during seven major SSW events. In this work we aim to determine the characteristics of the midlatitude mesospheric temperatures during these seven major SSWs. To do this, comparisons were made between the temperature profiles on individual nights before, during, and after the SSW events and the corresponding derived climatological temperature profiles (31-day by 11-year average) for those nights. A consistent disturbance pattern was observed in the mesospheric temperatures during these SSWs. A distinct shift from the nominal winter temperature pattern to a pattern more characteristic of summer temperatures was seen in the midlatitude mesosphere close to when the zonal winds in the polar stratosphere (at 10 hPa, 60° N) reversed from eastward to westward. This shift lasted for several days. This change in pattern included coolings in the upper mesosphere, comparable to those seen in the polar regions, and warmings in the lower mesosphere.

  10. Signatures of the Sudden Stratospheric Warming events of January-February 2008 in Seoul, S. Korea

    NASA Astrophysics Data System (ADS)

    De Wachter, Evelyn; Hocke, Klemens; Flury, Thomas; Scheiben, Dominik; Kmpfer, Niklaus; Ka, Soohyun; Oh, Jung Jin

    2011-11-01

    The period January-February 2008 was characterized by four Sudden Stratospheric Warmings (SSWs) in the Northern Hemisphere, of which the last warming, at the end of February 2008, was a major warming. A significant decrease in mesospheric water vapour (H 2O) of more than 2 ppmv (40%) was observed by the ground-based microwave (GBMW) radiometer in Seoul, S. Korea [37.3N, 126.3E] during the major SSW. A comparison with ground-based mesospheric H 2O observations from the mid-latitude station in Bern [46.9N, 7E] revealed an anticorrelation in the mesospheric H 2O data during the major SSW. In addition, prior to the major warming, strong periodic fluctuations were recorded in the Aura MLS vertical temperature distribution between 15 and 0.05 hPa at Seoul. The mesospheric temperature oscillation was found to have a period of 10-14 days with a persistency of 3-4 cycles. The observed anticorrelation in mesospheric H 2O between the stations in Seoul and Bern is associated with an increased meridional flow. Trajectory calculations give evidence that H 2O-rich subtropical air had moved to Bern during the major SSW while H 2O-poor polar air was transported to Seoul. The results shown in this study are a possible indication of a strong coupling between the dynamic regimes of the low- and the high-latitude regions during SSWs.

  11. 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.

  12. Temperatures in the Mid-Latitude Mesosphere During Sudden Stratospheric Warmings as Determined from Rayleigh Lidar Data

    NASA Astrophysics Data System (ADS)

    Sox, L.; Wickwar, V. B.; Fish, C. S.; Heron, J. P.

    2013-12-01

    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 temperature data for 11 years, from 1993 through 2004. The temperatures derived from these data extended over the mesosphere, from 45 to 90 km. Recently, they were combined with other observations to examine the mid-latitude mesosphere's behavior during Sudden Stratospheric Warmings (SSWs). Other data utilized in this study include Imaging Doppler Interferometry (IDI) data from a dynasonde at Bear lake Observatory (BLO), a meteor wind radar at BLO, a Na lidar from Colorado State University (now at ALO), and the SABER instrument aboard the TIMED satellite. Extensive Rayleigh lidar observations were made during fourteen SSW events. In order to determine the characteristics of the mesospheric temperatures during SSWs, comparisons were made between the temperature profile on an individual night during a SSW event and the climatological (11-year average) temperature profile for that night. An overall disturbance pattern was observed in the mesospheric temperatures during these SSWs. It included coolings (sometimes very significant) in the upper mesosphere and warmings in the lower mesosphere.

  13. Variability of upper tropospheric clouds in the polar region during stratospheric sudden warmings

    NASA Astrophysics Data System (ADS)

    Kohma, Masashi; Sato, Kaoru

    2014-09-01

    The variability of upper tropospheric clouds during stratospheric sudden warmings (SSWs) in 2009, 2010, and 2012 in the Northern Hemisphere is examined using satellite observations and reanalysis data. It is shown that the zonal mean cloud frequency decreases in the altitude range of 8-12 km, and the mean cloud top height descends soon after an SSW. Following a sudden decrease in upper tropospheric cloud frequency, an increase in temperature and static stability around the tropopause and a downward shift of the tropopause height are simultaneously observed. These changes in the upper troposphere are observed when the downward residual mean flow associated with an SSW becomes stronger around the tropopause level. By means of analyses based on a recent theory of three-dimensional residual mean flow, it is shown that the horizontal structure of the vertical flow is consistent with the geographical distribution of clouds in the altitude range of 9-11 km. Another interesting feature is that the low cloud frequency in the upper troposphere that starts after an SSW continues for more than 1 month. Possible reasons are discussed in terms of a long radiative relaxation time and a change in the tropospheric wave activity. These findings indicate that SSWs can affect the tropospheric radiative budget through the modification of cloud frequency and cloud top heights.

  14. ODIN/SMR Observations Of A Particularly Strong Midwinter Stratospheric Sudden Warming In Early 2013

    NASA Astrophysics Data System (ADS)

    Perot, Kristell; Urban, Joachim; Murtagh, Donal

    2013-12-01

    The Sub-Millimetre Radiometer (SMR), on board the Odin satellite, observed a major stratospheric sudden warming (SSW) in the northern hemisphere in early January 2013. The provided measurements have been used to identify and characterize this event which seems to be the strongest of that kind in recent years. This paper is based on a comparison with the 2009 SSW which was so far considered as a record-breaking event. SSWs are an important manifestation of the coupling phenomena between the mesosphere / lower thermosphere and the lower atmospheric layers and can strongly affect the middle atmospheric composition. It is crucial to study these events in order to get a better understanding of the dynamical and chemical mechanisms that control this part of the atmosphere.

  15. Tidal Variability during Stratospheric Sudden Warmings: Comparison between a Whole Atmosphere Model and Satellite Observations

    NASA Astrophysics Data System (ADS)

    Jin, H.; Miyoshi, Y.; Pancheva, D.; Mukhtarov, P.; Fujiwara, H.; Shinagawa, H.; Murata, T.

    2012-12-01

    We compare results from a whole atmosphere-ionosphere coupled model, GAIA, and from the COSMIC and TIMED/SABER observations during 2008/2009 northern winter season. The GAIA model has assimilated meteorological reanalysis data by a nudging method. The comparison shows general agreements in the major features from the stratosphere to the ionosphere including the growth and decay of the major stratospheric sudden warming (SSW) event in 2009. During the major SSW period, a pronounced semidiurnal variation in the F-region electron density and its local-time phase shift similar to the previous observations are reproduced by the model and COSMIC observation. The model suggests that the TEC variation is caused by an enhanced semidiurnal variation in the EXB drift, which is probably related to an amplified semidiurnal migrating tide (SW2) in the lower thermosphere. The model and TIMED/SABER observation show that the SW2 tide amplifies at low latitudes from the stratosphere to the thermosphere as well as the phase variation. Possible sources of the SW2 variability could be related to the changing background wind and temperature distributions and/or to the stratospheric ozone variability. Cases of other SSWs are also studied.

  16. Stratospheric warming influence on the mesosphere/lower thermosphere as seen by the extended CMAM

    NASA Astrophysics Data System (ADS)

    Shepherd, M. G.; Beagley, S. R.; Fomichev, V. I.

    2014-06-01

    The response of the upper mesosphere/lower thermosphere region to major sudden stratospheric warming (SSW) is examined employing temperature, winds, NOX and CO constituents from the extended Canadian Middle Atmosphere Model (CMAM) with continuous incremental nudging below 10 hPa (~ 30 km). The model results considered cover high latitudes (60-85 N) from 10 to 150 km height for the December-March period of 2003/2004, 2005/2006 and 2008/2009, when some of the strongest SSWs in recent years were observed. NOX and CO are used as proxies for examining transport. Comparisons with ACE-FTS (Atmospheric Chemistry Experiment-Fourier Transform Spectrometer) satellite observations show that the model represents well the dynamics of the upper mesosphere/lower thermosphere region, the coupling of the stratosphere-mesosphere, and the NOX and CO transport. New information is obtained on the upper mesosphere/lower thermosphere up to 150 km showing that the NOX volume mixing ratio in the 2003/2004 winter was very perturbed indicating transport from the lower atmosphere and intense mixing with large NOX influx from the thermosphere compared to 2006 and 2009. These results, together with those from other models and observations, clearly show the impact of stratospheric warmings on the thermosphere.

  17. 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

  18. 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

  19. 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.

  20. Stratospheric warmings during February and March 1993

    SciTech Connect

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

    1994-05-01

    Two stratospheric warmings during February and March 1993 are described using UKMO analyses, calculated PV and diabatic heating, and N[sub 2]O observed by the CLAES instrument on the 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 N[sub 2]O 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 N[sub 2]O over a broad region near the edge of the polar vortex indicates the importance of horizontal transport. N[sub 2]O decreased in the vortex, consistent with enhanced diabatic descent during the warmings. 9 refs., 5 figs.

  1. The Response of Polar Mesosphere-Low Thermosphere (MLT) Ozone to Major Stratospheric Sudden Warming

    NASA Astrophysics Data System (ADS)

    Tweedy, O.; Limpasuvan, V.; Smith, A. K.; Randall, C. E.; Orsolini, Y.; Garcia, R. R.; Chandran, A.; Kinnison, D. E.; Kvissel, O.

    2012-12-01

    Stratospheric Sudden Warmings (SSWs) are dramatic natural phenomena that strongly impact the atmosphere from the ground up to the thermosphere. To date, the role of atmospheric dynamics on Northern Hemisphere polar ozone in the MLT during and after SSWs is not well understood. In this study, we investigate the SSW-induced changes in the night-time "tertiary" (near 75km) and "secondary" (90-105km) ozone maxima by making connections between dynamics, transport, and distributions of key species (like H, O, and NOx) important to ozone. We use output from NCAR's Whole Atmosphere Community Climate Model (WACCM3.5) to create a composite representation of six major warming events that were followed by an elevated stratopause and compare them to the model climatology as well as to individual SSW cases taken from the "specified dynamics" version of WACCM (WACCM-SD), in which the simulation is nudged toward NASA MERRA re-analyses. We attempt to validate WACCM3.5 and WACCM-SD results against satellite measurements taken by SABER and ACE-FTS. The composite evolution of NOx and ozone appears to be well connected with the anomalous vertical residual motion during and after SSWs. Just after the SSW onset, the tertiary ozone layer is displaced upward by nearly 10 km and the secondary ozone layer increases in concentration as it thickens. Rapid increase in the secondary ozone layer at SSW onset coincides well with a change in the direction of zonal mean zonal winds (from being westward to eastward) and the descent motion from above 100 km. About 50 days after SSW onset, a tongue of enhanced NOx concentration penetrates downward across 60 km with the descent of the reformed stratopause layer back to its climatological position. Assuming photochemical equilibrium for ozone, we compute the ozone budget of the secondary layer and test the relationship between ozone and variables involved in its production (O) and loss (H and temperature). Altitude-time evolution of SSW composite of night time zonal-mean ozone (color-filled contours in ppmv multiplied by a factor of ten) averaged from 60 to 80. Bold black line represents the stratopause layer and dashed white contour indicates the tertiary ozone layer

  2. 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 Andya (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.

  3. 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 warnings during February and March 1993 are described using UKMO analyses, calculated PV and diabatic heating, and N2O observed by the CLAES instrument on the 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.

  4. Equatorial middle atmospheric chemical composition changes during sudden stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Nath, O.; Sridharan, S.

    2015-09-01

    Chemical composition data obtained from the Microwave Limb Sounder (MLS) and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instruments onboard EOS-Aura and ENVISAT satellites are used to investigate the variation of ozone (O3), water vapor (H2O) and methane (CH4) volume mixing ratios (VMRs) in the height range 20-60 km over the equatorial region during the sudden stratospheric warmings (SSWs) of 2004, 2009 and 2012, the occurrence of which are identified using the ERA (European Center for Medium Range Weather Forecasting Reanalysis) Interim temperature and zonal wind data sets. It is found that the O3 VMR shows increment whereas H2O VMR shows decrement during the SSW event and the possible reasons for these changes in the VMRs are investigated. In the upper stratosphere, the source of water vapor is oxidation of CH4 which takes place either by hydroxyl (OH) or by atomic oxygen (O). However, the OH VMR available for the year 2009 SSW event does not show any significant variation. The decrease of zonal mean MLS temperature over the equator during the SSW suggests that the rate of the reaction of ozone production (O + O2 ⟶ O3 + M), which increases with decreasing temperature, shifts the O/O3 ratio towards O3, resulting in the decrease of CH4 oxidation and consequent decrease in water vapor.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Effects of stratospheric variability on El Niño teleconnections

    NASA Astrophysics Data System (ADS)

    Richter, J. H.; Deser, C.; Sun, L.

    2015-12-01

    The effects of the tropical Pacific El Niño Southern Oscillation (ENSO) phenomenon are communicated to the rest of the globe via atmospheric teleconnections. Traditionally, ENSO teleconnections have been viewed as tropospheric phenomena, propagating to higher latitudes as Rossby waves. Recent studies, however, suggest an influence of the stratosphere on extra-tropical ENSO teleconnections. The stratosphere is highly variable: in the tropics, the primary mode of variability is the quasi-biennial oscillation (QBO), and in the extra-tropics sudden stratospheric warmings (SSWs) regularly perturb the mean state. Here, we conduct a 10-member ensemble of simulations with a stratosphere-resolving atmospheric general circulation model forced with the observed evolution of sea surface temperatures during 1952–2001 to examine the effects of the QBO and SSWs on the zonal-mean circulation and temperature response to El Niño, with a focus on the northern extra-tropics during winter. We find that SSWs have a larger impact than the QBO on the composite El Niño responses. During El Niño winters with SSWs, the polar stratosphere shows positive temperature anomalies that propagate downward to the surface where they are associated with increased sea-level pressure over the Arctic. During El Niño winters without SSWs, the stratosphere and upper troposphere show negative temperature anomalies but these do not reach the surface. The QBO modulates the El Niño teleconnection primarily in winters without SSWs: the negative temperature anomalies in the polar stratosphere and upper troposphere are twice as large during QBO West compared to QBO East years. In addition, El Niño winters that coincide with the QBO West phase show stronger positive sea-level pressure anomalies over the eastern Atlantic and Northern Europe than those in the QBO East phase. The results imply that the stratosphere imparts considerable variability to ENSO teleconnections.

  12. Is there a stratospheric radiative feedback in global warming simulations?

    NASA Astrophysics Data System (ADS)

    Huang, Yi; Zhang, Minghong; Xia, Yan; Hu, Yongyun; Son, Seok-Woo

    2016-01-01

    The radiative impacts of the stratosphere in global warming simulations are investigated using abrupt CO2 quadrupling experiments of the Coupled Model Inter-comparison Project phase 5 (CMIP5), with a focus on stratospheric temperature and water vapor. It is found that the stratospheric temperature change has a robust bullhorn-like zonal-mean pattern due to a strengthening of the stratospheric overturning circulation. This temperature change modifies the zonal mean top-of-the-atmosphere energy balance, but the compensation of the regional effects leads to an insignificant global-mean radiative feedback (-0.02 ± 0.04 W m-2 K-1). The stratospheric water vapor concentration generally increases, which leads to a weak positive global-mean radiative feedback (0.02 ± 0.01 W m-2 K-1). The stratospheric moistening is related to mixing of elevated upper-tropospheric humidity, and, to a lesser extent, to change in tropical tropopause temperature. Our results indicate that the strength of the stratospheric water vapor feedback is noticeably larger in high-top models than in low-top ones. The results here indicate that although its radiative impact as a forcing adjustment is significant, the stratosphere makes a minor contribution to the overall climate feedback in CMIP5 models.

  13. Is there a stratospheric radiative feedback in global warming simulations?

    NASA Astrophysics Data System (ADS)

    Huang, Yi; Zhang, Minghong; Xia, Yan; Hu, Yongyun; Son, Seok-Woo

    2015-03-01

    The radiative impacts of the stratosphere in global warming simulations are investigated using abrupt CO2 quadrupling experiments of the Coupled Model Inter-comparison Project phase 5 (CMIP5), with a focus on stratospheric temperature and water vapor. It is found that the stratospheric temperature change has a robust bullhorn-like zonal-mean pattern due to a strengthening of the stratospheric overturning circulation. This temperature change modifies the zonal mean top-of-the-atmosphere energy balance, but the compensation of the regional effects leads to an insignificant global-mean radiative feedback (-0.02 0.04 W m-2 K-1). The stratospheric water vapor concentration generally increases, which leads to a weak positive global-mean radiative feedback (0.02 0.01 W m-2 K-1). The stratospheric moistening is related to mixing of elevated upper-tropospheric humidity, and, to a lesser extent, to change in tropical tropopause temperature. Our results indicate that the strength of the stratospheric water vapor feedback is noticeably larger in high-top models than in low-top ones. The results here indicate that although its radiative impact as a forcing adjustment is significant, the stratosphere makes a minor contribution to the overall climate feedback in CMIP5 models.

  14. 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.

  15. Numerical simulation of global ozone transport during stratospheric sudden warming

    SciTech Connect

    Liu, C.M.

    1982-01-01

    The variation of ozone distribution during a stratospheric sudden warming period was investigated through 3 numerical experiments. The first is a Lagrangian type particle tracing experiment. Air particles were released continuously from 5 different sources into the flows which were simulated from the global model (Koermer, 1980) for the study of the major warming and minor warming. The second was a numerical simulation of ozone transport in an Eulerian system (experiment P1). A 3-D ozone transport-diffusion model in an unequal-distanced vertical resolution system was developed. It was run for 29 consecutive days. In the model, the horizontal and vertical components of eddy diffusivity are computed from the model data (Koermer, 1980) in the case of major warming which was divided into 3 stages: prewarming, warming and after-warming stages. The third experiment was designed to include the photochemical reactions in our model (experiment P2). The computation has been performed for 2 days during the warming period. In the first experiment, air particles at upper levels tend to move poleward and upward (equatorward and downward) at higher (lower) latitudes. In the second experiment, a strong increase in ozone amount does occur at higher latitudes in the stratosphere during the warming period. In the third experiment, the inclusion of photochemical system in the model does not destroy but intensifies the ozone increasing. From the above results, the existence of the Lagrangian-mean indirect and direct circulations of the movements of air particles or ozone molecules caused by the planetary-scale wave activities in the upper and lower stratosphere, appears to explain the phenomenon of the ozone increasing at higher latitudes.

  16. 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.

  17. Stratospheric Warming Influence on the Thermosphere as seen by the Extended CMAM

    NASA Astrophysics Data System (ADS)

    Shepherd, Marianna; Shepherd, Gordon; Cho, Young-Min; Fomichev, Victor; Beagley, Stephen

    2012-07-01

    Ground-based observations of the OH and O2 (0,1) Atmospheric band airglow, nominally at 87 km and 94 km, respectively by a SATI (Spectral Airglow Temperature Imager) instrument installed at Resolute Bay (75N, 95W) and at the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka (80N, 86W) have shown that at the time of stratospheric warming events (e.g. 2004, 2009) (SSW) the airglow emissions and the derived rotational temperatures decreased, followed by an enhancement of the airglow emission rates during the SSW recovery phase, while the temperatures returned to their pre-event state. An empirical relationship between OH airglow peak altitude determined by SABER and SATI integrated emission rates allowed perturbed OH and O2 (0,1) airglow altitudes to be assigned to the SATI observations. From these the O volume mixing ratio (VMR), corresponding to the observed OH and O2 (0,1) airglow emission rates were modeled. A significant atomic oxygen depletion was observed during the SSW, while during the SSW recovery phase the O VMR giving rise to the observed O2 (0,1) airglow emission rates increased up to 17 times from that observed during the peak of the SSW. The effect of SSW on the thermosphere has also been examined through the response of thermospheric O(1S) dayglow as a proxy for SSW- induced variations in the O VMR observed by the WIND Imaging Interferometer on UARS, from 90 km to 280 km height. A depletion above 140 km in the daytime O(1S) volume emission rates was observed, which commenced around the onset of the SSW and lasted over a period of 3 -- 4 days before returning to and exceeding the pre-SSW values during the SSW recovery phase. Below 140 km height the effect was manifested by a four-fold enhancement in the O(1S) volume emission rate at 100 km, which correlated with the cold temperature anomaly of the SSW at and below the stratopause. The observed response of the MLT region to the major SSW is further examined employing temperature and wind fields, as well as NO, NOx and O constituents from the extended Canadian Middle Atmosphere Model (CMAM) at high latitudes from 10 to 220 km height. The study employs a ``nudged'' version of the extended CMAM for 2006, when one of the strongest SSWs in recent years was observed. NOx is used as a proxy for examining transport. Comparisons with ACE-FTS and SABER satellite observations show that the model well represents the dynamics of the MLT region and the coupling with the stratosphere and the NOx (and also NO) transport.

  18. 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 (54N) station and a high latitude (69N) 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 example, during SSW 2009, we found that M2 enhances many days before PVW which is not in agreement with most of our results.

  19. Large lunar tidal effects in the equatorial electrojet during northern winter and its relation to stratospheric sudden warming events

    NASA Astrophysics Data System (ADS)

    Yamazaki, Yosuke

    2013-11-01

    It has been known for many decades that lunar tidal effects in the equatorial electrojet are greatest during northern winter; the mechanism of which has never been identified. Recent findings of the lunar tidal amplification during stratospheric sudden warming (SSW) events raise the question: To what extent do SSWs contribute to the large lunar tide during northern winter? We use ground magnetometer data at Addis Ababa for the years 1958-2007 to determine the average M2 lunar tide in the equatorial electrojet at different seasons. When all the data are included, the amplitude of the lunar tide is largest during northern winter. However, when only the data for non-SSW winters are used, the amplitude during northern winter is not significantly larger than during other seasons. The M2 amplitude during SSW events is approximately 3 times as large as that for non-SSW winters, and it considerably increases the amplitude of the average lunar tide during northern winter. The M2 phase is not significantly affected by SSW events. These results indicate that the occurrence of SSW events significantly modulates the seasonal pattern of lunar tidal effects on the ionosphere.

  20. Uncertainties in modelling the stratospheric warming following Mt. Pinatubo eruption

    NASA Astrophysics Data System (ADS)

    Arfeuille, F.; Luo, B. P.; Heckendorn, P.; Weisenstein, D.; Sheng, J. X.; Rozanov, E.; Schraner, M.; Brönnimann, S.; Thomason, L. W.; Peter, T.

    2013-02-01

    In terms of atmospheric impact, the volcanic eruption of Mt. Pinatubo (1991) is the best characterized large eruption on record. We investigate here the stratospheric warming following the Pinatubo eruption derived from SAGE II extinction data including most recent improvements in the processing algorithm and a data filling procedure in the opacity-induced "gap" regions. From these data, which cover wavelengths of 1.024 micrometer and shorter, we derived aerosol size distributions which properly reproduce extinction coefficients at much longer wavelength. This provides a good basis for calculating the absorption of terrestrial infrared radiation and the resulting stratospheric heating. However, we also show that the use of this dataset in the global chemistry-climate model (CCM) SOCOL leads to exaggerated aerosol-induced stratospheric heating compared to observations, even partly larger than the already too high values found by many models in recent general circulation model (GCM) and CCM intercomparisons. This suggests that the overestimation of the stratospheric warming after the Pinatubo eruption arises from deficiencies in the model radiation codes rather than an insufficient observational data basis. Conversely, our approach reduces the infrared absorption in the tropical tropopause region, in better agreement with the post-volcanic temperature record at these altitudes.

  1. Equatorial stratospheric thermal structure and ozone variations during the sudden stratospheric warming of 2013

    NASA Astrophysics Data System (ADS)

    Nath, Oindrila; Sridharan, S.; Gadhavi, H.

    2015-01-01

    Ozone mass mixing ratio (OMMR) obtained from both European Centre for Medium Range Weather Forecasting (ECMWF) Reanalysis (ERA)-Interim and Sounding of Atmosphere by Broadband Emission Radiometry (SABER) instrument onboard Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite shows large values in the equatorial upper stratosphere during the occurrence of a major stratospheric sudden warming (SSW) in January 2013 preceded by a large reduction of planetary wave activity. However, surprisingly equatorial stratospheric temperature is found to decrease at pressure levels where the ozone mixing ratio is larger. The computed radiative heating rate using Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model also shows positive heating rate indicating that the temperature should increase in response to the ozone accumulation over equator. In addition to radiative heating due to ozone, heating rate due to other dominant factors, namely, ascending motion and convergence of meridional heat flux, which could influence the thermal structure of the equatorial stratosphere, are estimated. It is found that the observed low temperature during SSW is mainly due to large upward motions. The estimated heating rates agree reasonably well with the observed heating rates at 10-8 hPa indicating the dominance of transport at lower stratosphere. The large discrepancy between the estimated and observed heating rates in the upper stratosphere may be due to the dominance of photochemistry.

  2. The influence of the equatorial QBO on sudden stratospheric warmings

    NASA Technical Reports Server (NTRS)

    Holton, James R.; Austin, John

    1991-01-01

    A global primitive-equation model of the stratosphere and mesosphere is integrated for specified planetary-wave forcing at the 100-mb level with mean zonal flow conditions corresponding to the westerly and easterly phases of the equatorial QBO, respectively. The responses in the two QBO phases were compared for integrations with wavenumber-1 forcing-amplitude maxima at 100 mb and 60 deg N varying from 100 to 400 m. The phase of the QBO had little effect on the results in the weak-wave (100-m) cases, which did not produce warmings, and strong-wave (400-m) cases, which produced major sudden warmings.

  3. 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.

  4. 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.

  5. A multi tracer analysis of thermosphere to stratosphere descent triggered by the 2013 Stratospheric Sudden Warming

    NASA Astrophysics Data System (ADS)

    Bailey, S. M.; Thurairajah, B.; Randall, C. E.; Holt, L.; Siskind, D. E.; Harvey, V. L.; Venkataramani, K.; Hervig, M. E.; Rong, P.; Russell, J. M.

    2014-07-01

    Arctic winter observations in 2013 by the Solar Occultation for Ice Experiment (SOFIE) show significant transport from the lower-thermosphere to the stratosphere of air enriched in nitric oxide, but depleted in water and methane. The transport is triggered by the Stratospheric Sudden Warming (SSW) on 11 January and is continuously tracked for over 3 months. Ultimately, evidence for lower thermospheric air is seen at 40 km in mid-April. Area integrated nitric oxide (NO) fluxes are compared with previous events in 2004, 2006, and 2009, to show that this event is the second largest in the past 10 years. The SOFIE data are combined with a meteorological analysis to infer descent rates from 40 to 90 km. The descent profile initially peaks near 75 km, shifting downward by approximately 5 km per 10 days. Our work demonstrates the utility of SOFIE tracer measurements in diagnosing vertical transport from the stratosphere to the edge of space.

  6. Impact of the 2009 major sudden stratospheric warming on the composition of the stratosphere

    NASA Astrophysics Data System (ADS)

    Tao, M.; Konopka, P.; Ploeger, F.; Grooß, J.-U.; Müller, R.; Volk, C. M.; Walker, K. A.; Riese, M.

    2015-08-01

    In a case study of a remarkable major sudden stratospheric warming (SSW) during the boreal winter 2008/09, we investigate how transport and mixing triggered by this event affected the composition of the entire stratosphere in the Northern Hemisphere. We simulate this event with the Chemical Lagrangian Model of the Stratosphere (CLaMS), both with optimized mixing parameters and with no mixing, i.e. with transport occurring only along the Lagrangian trajectories. The results are investigated by using tracer-tracer correlations and by applying the transformed Eulerian-mean formalism. The CLaMS simulation of N2O and O3, and in particular of the O3-N2O tracer correlations with optimized mixing parameters, shows good agreement with the Aura Microwave Limb Sounder (MLS) data. The spatial distribution of mixing intensity in CLaMS correlates fairly well with the Eliassen-Palm flux convergence. This correlation illustrates how planetary waves drive mixing. By comparing simulations with and without mixing, we find that after the SSW, poleward transport of air increases, not only across the vortex edge but also across the subtropical transport barrier. Moreover, the SSW event, at the same time, accelerates polar descent and tropical ascent of the Brewer-Dobson circulation. The accelerated ascent in the tropics and descent at high latitudes first occurs in the upper stratosphere and then propagates downward to the lower stratosphere. This downward propagation takes over 1 month from the potential temperature level of 1000 to 400 K.

  7. Atmospheric Coupling Through Gravity Waves During Stratospheric Sudden Warmings: Gravity Wave Variations, Generation Mechanisms, and Impacts

    NASA Astrophysics Data System (ADS)

    Yamashita, Chihoko

    2011-12-01

    Full understanding of gravity wave influences on the middle and upper atmosphere remains an unresolved research topic. The goals of this work are two-fold. First, gravity wave sources and propagation characteristics are explored using assimilated meteorological analyses from the European Centre for Medium-Range Weather Forecasting (ECMWF) during the 2009 stratospheric sudden warming (SSW). Second, gravity wave impacts on polar temperatures in the middle and upper atmosphere are examined by modulating the gravity wave parameterization scheme in the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM). Gravity waves that are resolved in ECMWFT799 are validated with satellite and lidar observations. ECMWF gravity wave potential energy density (GW-Ep) shows two enhancements, on January 5 and 15--22, prior to the peak 2009 SSW on January 23--24. The two gravity wave enhancements are associated with the amplifications of planetary wave 1 and wave 2, respectively, and there is a sudden decay of GW-Ep after the peak 2009 SSW. GW-Ep enhancements prior to the SSW correspond well with the positive vertical gradients of total perturbation energy flux (FE), indicating an in-situ energy source. The spatial and temporal distributions of gravity wave activities correlate with those of the residual tendencies introduced by Snyder et al. [2009]. These results suggest that the two peaks of GW-Ep are caused by the enhancements of the wave excitation in the stratosphere due to the residual tendency forcings. The sudden decay of gravity wave amplitudes correlates well with the suppressions of gravity wave propagation from the troposphere to the stratosphere obtained from the ray-tracing model. In addition, the vertical derivatives of FE decay after January 22. These results indicate that the sudden decay of gravity waves after the wind reversal is likely due to suppressions of gravity wave propagation from the troposphere along with the reductions of in-situ gravity wave excitation by the polar night jet. The responses of the mesosphere and lower thermosphere (MLT) temperatures to gravity waves during SSWs are investigated using TIME-GCM through modifying gravity wave parameters. This study confirms that the height of gravity wave forcing region is mainly determined by gravity wave amplitude and wavelength, and the vertical depth is closely tied to the spectral width of gravity wave phase speed. The gravity wave forcings control the pattern and strength of residual circulation and thereby the characteristics of MLT cooling and warming regions. The planetary wave forcings in the MLT also affect the vertical depth and magnitude of MLT temperature anomalies through further modifying the residual circulation. These planetary wave forcings are likely generated in-situ by the gravity wave forcings at high latitudes. Therefore, the mechanisms of gravity wave controlling the MLT temperature during a SSW are directly through gravity wave forcing and indirectly through generating planetary waves in-situ. Realistic gravity wave variations during the 2009 SSW obtained from ECMWF-T799 are implemented in TIME-GCM. The following two simulations are examined. Case 1 includes the enhanced gravity waves with longitudinal variations. Case 2 suppresses gravity waves with horizontal wavelength longer than 150 km. Both cases improve the TIME-GCM simulations of the MLT temperature responses to the 2009 SSW, indicating that realistic gravity wave variations have impacts on the MLT thermal structure.

  8. Air Parcel Motions during a Numerically Simulated Sudden Stratospheric Warming.

    NASA Astrophysics Data System (ADS)

    Hsu, Chih-Ping F.

    1980-12-01

    The three-dimensional mass motions in a mechanistic numerical model of a sudden stratospheric warming are investigated by tracing a large number of marked particles. The model is adapted from that described by Holton (1976). A sudden stratospheric warming is simulated by allowing a large amplitude, single harmonic wave forced at the lower boundary of the model to interact with the zonal mean flow. The results of a model simulation involving zonal wavenumber 2 are reported.Rings of marked particles are placed along latitude circles at the time when the forcing is turned on at the lower boundary and their motions are traced for a period of 30 days. The particle displacements near the level of maximum warming are described in detail, the trajectories of particles exhibit two different types of characteristics depending upon whether the particles originate from high or low latitudes. The particle motions are therefore described in terms of two regimes, the polar and the tropical regimes.The polar regime is characterized by organized motions of the particles around the elongated polar cyclonic vortex. When projected onto the meridional plane, the rings of particles appear as ellipses whose centers of mass remain at the same location during the prewarming stage, but descend during the warming stage despite the fact that the zonal mean vertical velocities are directed upward in the same region at all times.The tropical regime is characterized by the trapping of some particles inside the cutoff anticyclones which first appear in middle latitudes and then migrate poleward. As a result, these particles spiral poleward and downward. Eventually the particles which originate from tropical latitudes are scattered all over the hemisphere. When projected onto the meridional plane, a cloud of particles spreads out poleward and downward until the particles are dispersed between the equator and the pole.These results of particle motions are interpreted in terms of the two quasi-conservative tracers, namely, potential temperature and potential vorticity. For conservative motions a thin tube bounded by two surfaces of constant potential temperature and two surfaces of constant potential vorticity always coincides with the same material line of air particles. These tubes bulge downward (upward) in the polar (tropical) stratosphere during the event of sudden stratospheric warming. It is shown that due to the Newtonian cooling processes the particles are displaced further downward (upward) away from the tubes from which they originate. The horizontal projections of these tubes are displayed and it is found that their shapes are much simpler than those of the material lines of air particles. The nonconservative processes which are responsible for these differences are discussed.

  9. Stratospheric aerosols and greenhouse warming of the lower troposphere

    NASA Astrophysics Data System (ADS)

    Karol', I. L.; Frol'Kis, V. A.

    1992-05-01

    The study calculates the radiation effects of sulfate and soot aerosols in different layers of the stratosphere and the radiation disturbances in the global mean annual atmosphere that were caused by an actual increase in the atmospheric greenhouse gas content since 1900. Aerosol masses compensating for the radiation greenhouse effect are estimated. Such aerosols as 75-percent H2SO4, soot, and oil-burning products which have standard or measured optical properties are considered. Numerical experiments with a radiative convective model of the atmospheric layer up to the 0.4-hPa level demonstrate that an annual emission of several megatons of sulfate aerosols and hundreds of kilotons of soot into the global stratosphere would be required to compensate for the greenhouse warming of the surface-layer air during the last few decades.

  10. High-midlatitude ionosphere response to major stratospheric warming

    NASA Astrophysics Data System (ADS)

    Shpynev, Boris G.; Kurkin, Vladimir I.; Ratovsky, Konstantin G.; Chernigovskaya, Marina A.; Belinskaya, Anastasiya Yu; Grigorieva, Svetlana A.; Stepanov, Alexander E.; Bychkov, Vasily V.; Pancheva, Dora; Mukhtarov, Plamen

    2015-12-01

    This study investigates the impact of dynamical processes in the neutral atmosphere on the high-midlatitude ionosphere during two sudden stratospheric warming (SSW) events. For this purpose, the reanalysis meteorological data of the National Centers for Environmental Prediction /National Center for Atmospheric Research (NCEP/NCAR) and UK Met Office (UKMO) were used in addition to that from the high-midlatitude chain of Russian ionosonde stations. The results show that the ionospheric response to the SSW events at high-midlatitudes depends on the position of the ionosonde stations relative to the stratospheric circulation pattern. Two well-pronounced effects were detected in this study. The first effect, observed in January 2009, was a negative effect in critical frequency (foF2) and a positive effect in F2 layer maximum (hmF2) above the border of a stratospheric cyclone and an anticyclone with northward flow direction. During a 6-day period, the ionosphere exhibited a sharply inhomogeneous longitudinal structure when ionosondes, displaced at a longitude of approximately 20, showed differences of approximately 1 MHz in foF2 and more than 50 km in hmF2. The second feature, which was clearly observed in January 2013, implied a positive effect in foF2 up to approximately 2.5 MHz and a negative effect in hmF2 at approximately 10 km above the center of the stratospheric cyclone. We conclude that these effects were caused by upward transport of molecular gas to the lower thermosphere for the first case and a pulldown forcing of molecular species above the low-pressure zone inside the cyclone for the second case. Changes in the O+/N2 ratio in the lower thermosphere altered the O+ recombination rate and the corresponding variations of ionosphere parameters.

  11. Dynamics of 2009 Stratospheric Major Warming and its Impact on Composition of Stratosphere

    NASA Astrophysics Data System (ADS)

    Tao, Mengchu; Konopka, Paul; Ploeger, Felix; Liu, Yi; Groo, Jens-Uwe; Mller, Rolf

    2014-05-01

    In a case study of a remarkable stratospheric Major Warming (MW) during the boreal winter 2008-09, we investigate how transport and mixing triggered by this event affect the composition of the whole stratosphere in the northern hemisphere. We simulate this event with the Chemical Lagrangian Model of the Stratosphere (CLaMS), which allows quantifying the effect of small-scale atmospheric mixing by varying the mixing intensity in the model (optimized mixing versus no mixing). The results are investigated by using the tracer-tracer correlation technique and by applying the Transformed Eulerian Mean formalism (TEM). The CLaMS simulation of N2O and O3 with optimized mixing parameters shows a good agreement with MLS observations. The comparison with CLaMS simulation without mixing shows that after the MW, i.e. around 23rd of January 2009, mixing of tracers increases at the polar vortex edge and at the extra-tropical transport barrier. The spatial distribution of the mixing intensity in CLaMS correlates fairly well with the EP flux convergence and illustrates that planetary waves drive mixing between the vortex and mid-latitude air as well as between the mid-latitude and tropical air under weak polar vortex condition. Moreover, the MW event also accelerates polar descent and tropical ascent of the Brewer-Dobson circulation. The accelerated ascent in the tropics and descent at high latitudes firstly occurs in the upper stratosphere and then propagates downward to the lower stratosphere. This downward propagation takes about one month from 1000K to 400K. In addition, as a consequence of the MW, negative anomalies of water vapor are found at low and mid latitudes of lower stratosphere during late winter and spring 2009 in MLS data counteracting the moistening effect of the westerly phase of the Quasi-Biennial Oscillation (QBO). The water vapor at the tropical tropopause is about 0.5 ppm lower than during the years with westerly QBO phase. This highly dehydrated air ascends into the lower stratosphere in late February of 2009, i.e. one month after the MW, and is consistent with accelerated upwelling branch of the Brewer-Dobson circulation due to intensified extratropical wave forcing during the MW.

  12. Stratospheric warming effects on thermospheric O(1S) dayglow dynamics

    NASA Astrophysics Data System (ADS)

    Shepherd, Marianna G.; Shepherd, Gordon G.

    2011-11-01

    This study examines the effect of a sudden stratospheric warming (SSW) on the thermosphere, and in particular the response of thermospheric O(1S) dayglow as a proxy for SSW-induced variations in the atomic oxygen volume mixing ratio. Thermospheric O(1S) volume emission rates and temperatures observed by the WIND Imaging Interferometer on UARS in February 1993 at latitudes from 50N to 70N and from 90 km to 280 km height have shown a depletion above 140 km in the daytime O(1S) volume emission rates, which commenced around the onset of the SSW and lasted over a period of 3-4 days before returning to and exceeding the pre-SSW values during the SSW recovery phase. Below 140 km height the effect was manifested by a fourfold enhancement in the O(1S) volume emission rate at 100 km, which correlated with the cold temperature anomaly of the SSW at and below the stratopause.

  13. Some Eulerian and Lagrangian Diagnostics for a Model Stratospheric Warming.

    NASA Astrophysics Data System (ADS)

    Dunkerton, T.; Hsu, C.-P. F.; McIntyre, M. E.

    1981-04-01

    Some new diagnostics are presented for a wavenumber-2 sudden warming, simulated by a version of Holton's semi-spectral, primitive-equation model. First, Eliassen-Palm cross sections exhibiting the Eliassen-Palm (EP) planetary-wave flux together with contours of the corresponding flux divergence, are presented for selected days of the simulation. Second, a description of zonal-mean-flow evolution in the model, simpler than the conventional Eulerian-mean description and qualitatively like Lagrangian- mean descriptions in some respects, is constructed from the transformed Eulerian-mean equations presented by Andrews and McIntyre (1976). In this description the mean warming is brought about by a thermally direct `residual meridional circulation' arising as an essentially adiabatic response to a wave-induced torque about the earth's axis. The torque itself is equal to the divergence of the EP wave flux and approximately proportional to the northward flux of quasi-geostrophic potential vorticity. Third, some true Lagrangian means and related diagnostics are presented and discussed.The EP cross sections strikingly display the effect of the mid-stratospheric zero-wind line which invades middle latitudes from the tropics during the first stage of substantial evolution of the mean state. This zero-wind line develops into a partial reflector of planetary waves, splitting the EP wave flux into two branches and deflecting one of them equatorward and the other to high polar altitudes. The consequent focusing of waves into a smaller horizontal area in the polar cap and into altitudes with lower densities helps bring about the reversal of the polar westerlies in the second stage of mean evolution. Focusing of planetary waves into the high-altitude polar cap should be similarly important for real warmings, but there is no evidence that subtropical zero-wind lines play any important role. Possible mechanisms leading to focusing and hence to warnings in the real atmosphere are discussed.To picture the model warming in Lagrangian terms, we first compare the shape of an isentropic surface near the level of maximum warming with the computed behavior of sets of air parcels. The isentropic surface is approximately a material surface over the short times concerned. As the warming develops the surface dips down over the pole and rises at the equator (and in the real atmosphere this leads to widespread cooling in the summer stratosphere as has often been observed). Thermally direct motion similarly appears in the residual, generalized Lagrangian-mean, and modified Lagrangian-mean meridional circulations near the level of maximum warming, as might have been expected from the theoretical results of Matsuno and Nakamura (1979). The divergence effect, or non-solenoidality of Lagrangian-mean motion, neglected in their study, is strong here because of the large north-south dispersion of air parcels accompanying the highly transient wave activity. Implications for modeling tracer transport are noted.

  14. 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.

  15. 61 FR 1284 - Protection of Stratospheric Ozone: Listing of Global Warming Potential for Ozone-Depleting...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1996-01-19

    ... (60 FR 24970). To meet EPA's statutory obligation under the CAA, this listing cites the global warming... AGENCY 40 CFR Part 82 RIN 2060-AF35 Protection of Stratospheric Ozone: Listing of Global Warming... the global warming potentials for ozone-depleting substances that are included as class I and class...

  16. 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.

  17. 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.

  18. The sun-weather connection - Sudden stratospheric warmings correlated with sudden commencements and solar proton events

    NASA Technical Reports Server (NTRS)

    Neubauer, L.

    1983-01-01

    It has been found that a strong correlation exists between sudden stratospheric warmings and sudden commencements of geomagnetic activity. This correlation follows a 22-yr cycle. The sudden warmings of the lower stratosphere occur near the north magnetic pole over Siberia and the Pacific, although occasionally they do occur over North America. A mechanism explaining how the solar wind ultimately affects the surface weather through its selective interaction with the middle atmosphere is outlined.

  19. Low-latitude scintillation weakening during sudden stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Paula, E. R.; Jonah, O. F.; Moraes, A. O.; Kherani, E. A.; Fejer, B. G.; Abdu, M. A.; Muella, M. T. A. H.; Batista, I. S.; Dutra, S. L. G.; Paes, R. R.

    2015-03-01

    Global Positioning System (GPS) L1-frequency (1.575 GHz) amplitude scintillations at So Jos dos Campos (23.1S, 45.8W, dip latitude 17.3S), located under the southern crest of the equatorial ionization anomaly, are analyzed during the Northern Hemisphere winter sudden stratospheric warming (SSW) events of 2001/2002, 2002/2003, and 2012/2013. The events occurred during a period when moderate to strong scintillations are normally observed in the Brazilian longitude sector. The selected SSW events were of moderate and major categories and under low Kp conditions. The most important result of the current study is the long-lasting (many weeks) weakening of scintillation amplitudes at this low-latitude station, compared to their pre-SSW periods. Ionosonde-derived evening vertical plasma drifts and meridional neutral wind effects inferred from total electron content measurements are consistent with the observed weakening of GPS scintillations during these SSW events. This work provides strong evidence of SSW effects on ionospheric scintillations and the potential consequences of such SSW events on Global Navigation Satellite System-based applications.

  20. The influence of natural and anthropogenic factors on major stratospheric sudden warmings

    NASA Astrophysics Data System (ADS)

    Hansen, F.; Matthes, K.; Petrick, C.; Wang, W.

    2014-07-01

    Major stratospheric sudden warmings are prominent disturbances of the Northern Hemisphere polar winter stratosphere. Understanding the factors controlling major warmings is required, since the associated circulation changes can propagate down into the troposphere and affect the surface climate, suggesting enhanced prediction skill when these processes are accurately represented in models. In this study we investigate how different natural and anthropogenic factors, namely, the quasi-biennial oscillation (QBO), sea surface temperatures (SSTs), anthropogenic greenhouse gases, and ozone-depleting substances, influence the frequency, variability, and life cycle of major warmings. This is done using sensitivity experiments performed with the National Center for Atmospheric Research's Community Earth System Model (CESM). CESM is able to simulate the life cycle of major warmings realistically. The QBO strengthens the climatological stratospheric polar night jet (PNJ) and significantly reduces the frequency of major warmings through reduction of planetary wave propagation into the PNJ region. Variability in SSTs weakens the PNJ and significantly increases the major warming frequency due to enhanced wave forcing. Even extreme climate change conditions (RCP8.5 scenario) do not influence the total frequency but determine the prewarming phase of major warmings. The amplitude and duration of major warmings seem to be mainly determined by internal stratospheric variability. We also suggest that SST variability, two-way ocean/atmosphere coupling, and hence the memory of the ocean are needed to reproduce the observed tropospheric negative Northern Annular Mode pattern after major warmings.

  1. Diagnostic Study of a Wavenumber-2 Stratospheric Sudden Warming in a Transformed Eulerian-Mean Formalism.

    NASA Astrophysics Data System (ADS)

    Palmer, T. N.

    1981-04-01

    The intense wavenumber-2 stratospheric warming of February 1979 is analyzed in a transformed Eulerian-mean formalism, and compared with diagnostics generated by the model warming of Dunkerton et al. (1981). Significant differences in the evolution of the zonal mean flow are found. The corresponding differences in wave, mean-flow interaction are examined by studying planetary wave activity in the troposphere and stratosphere, as measured by the Eliassen-Palm flux and its divergence. It is found that in the stratosphere, the direction of this flux changes several times during the warming. Zonal flow deceleration is most intense when the midlatitude stratospheric flux has positive poleward and upward components. Conversely, deceleration is smallest when the flux is directed equatorward. Some mechanisms that may account for this switching are discussed. However, unlike the model, the high-latitude zonal flow reversal does not arise from nonlinear critical layer interaction with the waves.

  2. The secondary ozone layer during major sudden stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Grygalashvyly, Mykhaylo; Sonnemann, Gerd; Zlicke, Christoph; Becker, Erich

    A sudden stratospheric warming (SSW) strongly affects the MLT-region in the northern hemisphere. Its influence on the secondary ozone layer gives a natural test for our understanding of the role of dynamics and temperature on ozone in the mesopause region. We investigate the SSW-induced variability of the nighttime secondary ozone maximum by using a comprehensive chemistry-transport model (CTM) that is driven by the Khlungsborn Mechanistic general Circulation Model (KMCM). The KMCM explicitly simulates mid-frequency gravity waves, as well as planetary waves and SSW events. Based on corresponding simulations of two events and using analytical expressions for the secondary ozone layer peak altitude and number density, we estimate the relative importance of atomic hydrogen, atomic oxygen, and temperature variability for the behavior of ozone. Our main finding is that the transport of atomic oxygen by the residual circulation is the main driver of the secondary ozone layer variability - as opposed to the previous assumption that the ozone variability is determined by the local temperature. From the modelling and analytically derived expression for the secondary ozone layer we conclude that the values are directly proportional to the atomic oxygen number density and inversely proportional to the temperature and atomic hydrogen. The response to the temperature change is instantaneous. The impact of atomic oxygen fluctuation is stronger but delayed by 4-5 days due to the long time scale of vertical transport. This often leads to some misinterpretation of the secondary ozone layer behavior. The impact of atomic hydrogen is negligible.

  3. 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.

  4. Differing tropospheric responses to stratospheric vortex splits and displacements in a global circulation model

    NASA Astrophysics Data System (ADS)

    O'Callaghan, Amee; Joshi, Manoj; Stevens, David; Mitchell, Daniel

    2014-05-01

    Sudden Stratospheric Warmings (SSWs) have become an increasingly popular topic of study due to the range of potential effects that they have on climate. Often stratospheric anomalies possess the ability to descend into the troposphere. These anomalies can then affect the surface climate for up to two months [Baldwin and Dunkerton, 2001] implying that improved scientific understanding could lead to extended forecasting. However, not all SSWs possess the ability to strongly affect the surface climate. Analysis of reanalysis data has shown that the behaviour of vortex splits and displacements (two classes of SSWs) is clearly distinct. Tropospheric anomalies associated with either type of event contain different spatial structures and often the response associated with vortex splits is stronger [Mitchell et al., 2013]. SSWs are identified in a 200 year integration of the Intermediate General Circulation Model (IGCM). The model's performance is evaluated following the benchmarks of Charlton et al. [2007], and is found to simulate both the frequency and the tropospheric response of SSWs well. Distinctive differences are found in the IGCM's responses to vortex splits and displacements. The vortex split composite displays a significant weakening of the Icelandic Low and Azores High for up to 60 days following an event, indicative of a negative NAM anomaly. On the other hand the vortex displacement composite displays little significant deviation from climatology, implying a lack of NAM anomaly descent. This reaffirms the findings from reanalysis and highlights the need to separate the distinct classes of Sudden Stratospheric Warming events in model studies. We discuss the sensitivity of the model response to other processes such as the parameterisation of gravity waves. References M Baldwin and T Dunkerton. Stratospheric harbingers of anomalous weather regimes. Science, 294:581-584, 2001. A Charlton and Coauthors. A new look at stratospheric sudden warmings. part II: Evaluation of numerical model simulations. J. Climate, 20:470-488, 2007. D Mitchell, L Gray, J Anstey, M Baldwin, and A Charlton-Perez. The influence of stratospheric vortex displacements and splits on surface climate. Geophys. Res. Lett., 26:2668-2682, 2013.

  5. 60 FR 52357 - Protection of Stratospheric Ozone: Listing of Global Warming Potential for Ozone-Depleting...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1995-10-06

    ... AGENCY 40 CFR Part 82 Protection of Stratospheric Ozone: Listing of Global Warming Potential for Ozone... global warming potentials for ozone- depleting substances that are included as class I and class II.... To meet EPA's statutory obligation under the CAA, this proposed listing cites the global...

  6. Studies of temperature disturbances of lower and middle atmosphere during stratospheric warmings 2006-2013

    NASA Astrophysics Data System (ADS)

    Medvedev, Andrey; Medvedeva, Irina; Ratovsky, Konstantin; Tolstikov, Maxim

    This paper was devoted to study of sudden winter stratospheric warmings 2006-2013. Initial data were vertical temperature profiles obtained by the Microwave Limb Sounder (MLS) aboard the spacecraft EOS Aura. Shown that the temperature disturbances, propagated during stratospheric warmings are result of interference of at least two waves. Two-wave interference model of stratospheric warming was developed. Characteristics of planetary waves were obtained by using this model. Periods of disturbances vary from 5 to 45 days. Vertical wave numbers range is 20-150 km. Amplitudes and horizontal wave numbers obtained by the two-wave model vary smoothly in space and time, forming vorticity-like structure. We compared warmings 2006-2013 by using global amplitude. Comparison of variations of ionospheric parameters and characteristics of planetary waves in the stratosphere during warmings was done. On the basis of regular, continuous observations of the Irkutsk ionosonde DSP-4, was shown that number of traveling ionospheric disturbances (TIDs) tend to increase during stratospheric warmings. Found correlations between the amount of traveling ionospheric disturbances and the temperature at 80 km, between the daily maximum electron concentration and global amplitude of wave with upward phase velocity between the ion temperature and the amplitude of wave with downward phase velocity over Irkutsk. The work was supported by Russian Foundation for Basic Research Grant 13-05-00153 and RF President Grant of Public Support for RF Leading Scientific Schools (NSh-2942.2014.5).

  7. Dynamical Coupling Between the Stratosphere and the Troposphere: The Influence of External Forcings

    NASA Astrophysics Data System (ADS)

    Hansen, Felicitas; Matthes, Katja

    2013-04-01

    The dynamical coupling between the stratosphere and the troposphere is dominated by planetary waves that are generated in the troposphere by orography and land-sea contrasts. These waves travel upward into the stratosphere where they either dissipate or are reflected downward to impact the troposphere again. Through the interaction with the zonal mean flow planetary waves can induce stratospheric sudden warmings (SSWs), i.e., conditions during NH winter where the stratospheric polar vortex is disturbed so that the zonal mean zonal wind in the NH stratospheric jet becomes easterly and the polar cap meridional temperature gradient reverses. Since strong major SSWs can propagate down into the troposphere and even affect surface weather, SSWs present a strong and clear manifestation of the dynamical coupling in the stratosphere-troposphere system. We will investigate the influence of some external forcings, namely sea surface temperatures (SSTs), anthropogenic greenhouse gases and the quasi-biennial oscillation (QBO), on these coupling processes. Thereby we are interested in how the distribution of SSWs in the winter months changes due to the different forcings, whether the events evolve differently, and whether they show differences in their preconditioning, e.g. a different wave geometry. We will also investigate whether and how vertical reflective surfaces in the stratosphere, which can reflect upward propagating planetary waves, influence the evolution of SSWs. To address these questions, we performed a set of model simulations with NCAR's Community Earth System Model (CESM), a coupled model system including an interactive ocean (POP2), land (CLM4), sea ice (CICE) and atmosphere (NCAR's Whole Atmosphere Community Climate Model (WACCM)) component. Our control experiment is a 140-year simulation with the fully coupled atmosphere-ocean version of CESM. A second experiment is a 55-year simulation with only CESM's atmospheric component WACCM, a fully interactive chemistry-climate model extending from the Earth's surface through the thermosphere (about 140 km), with underlying climatological SSTs obtained from the coupled CESM control run. A third 55-year simulation is performed without the nudging of the equatorial QBO. All three simulations develop under conditions where greenhouse gases are held constant at the 1960 level. In a fourth simulations, the greenhouse gases follow the RCP8.5 scenario. From the differences of the individual simulations to the control experiment we can estimate the respective roles of SSTs, the QBO and anthropogenic greenhouse gases for the stratosphere-troposphere coupling. The model results will be compared to the Modern Era Retrospective-Analysis for Research and Applications (MERRA) dataset.

  8. 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.

  9. 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 (23S 44W) 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.

  10. 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.

  11. Dynamical amplification of the stratospheric solar response simulated with the Chemistry-Climate Model LMDz-Reprobus

    NASA Astrophysics Data System (ADS)

    Marchand, M.; Keckhut, P.; Lefebvre, S.; Claud, C.; Cugnet, D.; Hauchecorne, A.; Lefvre, F.; Lefebvre, M.-P.; Jumelet, J.; Lott, F.; Hourdin, F.; Thuillier, G.; Poulain, V.; Bossay, S.; Lemennais, P.; David, C.; Bekki, S.

    2012-02-01

    The impact of the 11-year solar cycle on the stratosphere and, in particular, on the polar regions is investigated using simulations from the Chemistry Climate Model (CCM) LMDz-Reprobus. The annual solar signal clearly shows a stratospheric response largely driven by radiative and photochemical processes, especially in the upper stratosphere. A month-by-months analysis suggests that dynamical feedbacks play an important role in driving the stratospheric response on short timescales. CCM outputs on a 10 days frequency indicate how, in the northern hemisphere, changes in solar heating in the winter polar stratosphere may influence the upward propagation of planetary waves and thus their deposition of momentum, ultimately modifying the strength of the mean stratospheric overtuning circulation at middle and high latitudes. The model results emphasize that the main temperature and wind responses in the northern hemisphere can be explained by a different timing in the occurrence of Sudden Stratospheric Warmings (SSWs) that are caused by small changes in planetary wave propagation depending on solar conditions. The differences between simulations forced by different solar conditions indicate successive positive and negative responses during the course of the winter. The solar minimum simulation generally indicates a slightly stronger polar vortex early in the winter while the solar maximum simulation experiences more early SSWs with a stronger wave-mean flow interaction and reduced zonal wind at mid-latitudes in the upper stratosphere. The opposite response is observed during mid-winter, in February, with more SSWs simulated for solar minimum conditions while solar maximum conditions are associated with a damped planetary wave activity and a reinforced vortex after the initial stratospheric warming period. In late winter, the response is again reversed, as noticed in the temperature differences, with major SSW mostly observed in the solar maximum simulation and less intense final warmings simulated for solar minimum conditions. Due to the non-zonal nature of SSWs, the stratospheric response presents high regional variability during the northern hemisphere winter. As a result, successive positive and negative responses are observed during the course of the winter.

  12. 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

  13. The interaction of radiative and dynamical processes during a simulating sudden stratospheric warming

    SciTech Connect

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

    1993-12-01

    An analysis of a spontaneous sudden stratospheric warming that occurred during a 2-year integration of the Langley Research Center Atmospheric Simulation Model is presented. The simulated warming resembles observed [open quotes]wave 1[close quotes] 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 [open quotes]surf zone[close quotes] 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 LIMS analysis. 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. 27 refs., 25 figs.

  14. Vortex dynamics of stratospheric sudden warmings: a reanalysis data study using PV contour integral diagnostics

    NASA Astrophysics Data System (ADS)

    Beaumont, Robin; Thuburn, John; Kwasniok, Frank

    2015-04-01

    The dynamics of the polar vortex behind stratospheric sudden warming events is investigated in a data-based study. Potential vorticity contour integral diagnostics of mass and circulation are calculated from ERA-40 reanalysis data for the stratosphere. The edge of the vortex is easily identifiable in these diagnostics as a high gradient of potential vorticity, and the warming events are clearly visible. The amount of air stripped from the vortex as part of a preconditioning leading up to the warming events is determined using the balance equation of the mass integral. Significant persistent removal of mass from the vortex is found, with several such stripping events identifiable through the winter, especially in those during which a major sudden warming event occurred. These stripping episodes are visible in corresponding potential vorticity maps, where tongues of potential vorticity can be seen to be stripped from the vortex and mixed into the sorrounding surf zone of turbulent air.

  15. Impact of the stratospheric warming 2012/2013 on the upper mesosphere

    NASA Astrophysics Data System (ADS)

    Bittner, Michael; Lisa, Kuechelbacher; Carsten, Schmidt; Sabine, Wuest

    2014-05-01

    Impact of the stratospheric warming 2012 / 2013 on the upper mesosphere The effects of stratospheric warming events are not restricted to the stratosphere only. There is also considerable impact on the mesosphere. Remote-sensing data derived by satellite and ground-based instruments are analysed in order to dynamically characterize the stratospheric warming event which took place during winter 2012/2013. The temporal and spatial structure of planetary waves with zonal wave number 1 to 3 is studied from strato- to mesospheric heights using global ozone and temperature data from METOP-GOME-2 and TIMED-SABER, respectively. Ground-based infrared airglow spectrometer measurements (GRIPS) of OH rotational temperature in the mesopause region derived at European mid-latitude NDMC stations complete the data set. Planetary wave amplitudes show characteristic warming pulses whereby planetary wave with zonal wave number 3 significantly changes period and phase speed. The changing planetary wave regime obviously affects gravity wave propagation up to the mesosphere. Indication for varying mesopause airglow layer height is found.

  16. 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.

  17. Role of the stratosphere on the predictability of medium-range weather forecast: A case study of winter 2003-2004

    NASA Astrophysics Data System (ADS)

    Kuroda, Yuhji

    2008-10-01

    The role of the stratosphere on the predictability of medium-range weather forecast during the northern hemisphere winter is examined using numerical experiments with a middle atmosphere climate model of the Meteorological Research Institute. It is found that in the winter of 2003/04 when the stratosphere exhibited a large variability called the Polar-night Jet Oscillation (PJO), the predictability of the model tended to be very good for large-scale zonal variability if the prediction is performed just before the occurrence of stratospheric sudden warmings (SSWs). The role of the stratosphere is examined by comparing experiments for the 2002/03 year and using the model with and without the stratosphere included. The results of the study suggest that taking account of the role of stratospheric variability (PJO) is crucial for improving the predictability of medium-range weather forecast in certain winters.

  18. Connecting Stratospheric and Ionospheric Anomalies

    NASA Astrophysics Data System (ADS)

    Spraggs, M. E.; Goncharenko, L. P.; Zhang, S.; Coster, A. J.; Benkevitch, L. V.

    2014-12-01

    This study investigates any relationship between lunar phases and ionospheric anomalies that appear at low latitudes concurrently with sudden stratospheric warmings (SSWs). The study utilizes World-wide GPS Receiver Network Total Electron Content (TEC) data spanning 13 years (2001-2014) and focuses on the changes in the equatorial ionization anomaly the Western hemisphere. TEC is highly variable due to the influences of solar flux, geomagnetic activity, and seasonal variation and these influences are removed by the use of model. This empirical TEC model is a combination of linear dependencies of solar flux (F10.7) and geomagnetic activity (Ap3) with a third degree polynomial dependency for day-of-year (DOY). With such dependencies removed, the remaining TEC variation could be resolved and attributed to an appropriate mechanism. Lunar phase and apside was investigated in particular, especially the new and full moon phases during perigees when tidal forcing would be most powerful. Lunar tidal forcing on planetary waves is also examined as being physically responsible for setting up conditions that may give rise to SSWs and ionospheric anomalies. Preliminary results suggest that such anomalies may be enhanced in intensity during the full or new moon and even more so during perigee by different amounts depending on whether the SSW is a major (40-60%) or minor (20-45%) event.

  19. Comparison of stratospheric warming following Agung, El Chichon and Pinatubo volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Angell, J. K.

    1993-04-01

    Based on a 63-station radiosonde network and using 9-season-average temperatures to minimize the influence of the quasi-biennial oscillation, the 16-20 km warming following Agung and El Chichon was greatest in the equatorial zone and least in polar zones. The warming was not symmetric with respect to the equator, however, with greater warming south than north of the equator. In north extratropics and tropics, the warming following Pinatubo is indicated to be comparable to the warming following Agung and El Chichon. However, in south temperate and polar zones the warming is considerably greater following Pinatubo, perhaps reflecting a contribution from the eruption of Cerro Hudson in Chile. Globally, therefore, the low-stratospheric warming following Pinatubo is greater than following Agung or El Chichon. Based on a 10-station tropical radiosonde network with data to greater heights, the warming following El Chichon exceeded the warming following Agung to a height of at least 31 km, the difference in warming increasing with height. The warming following Pinatubo is similar to that following Agung to a height of 24 km, but thereafter is indicated to become less, an unexpected result to be reexamined as more data become available.

  20. Lidar studies of specific manifestation features of stratospheric warming in winter of 2014-2015

    NASA Astrophysics Data System (ADS)

    Marichev, V. N.; Bochkovskii, D. A.

    2015-11-01

    Studying the atmospheric thermal regime is one of important applications of lidar technologies. These studies in monitoring mode in Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences had been initiated since 1994 and continue until presently. A special attention is paid to studying the manifestations of sudden disturbances in the middle stratosphere, caused by wintertime stratospheric warmings (SWs). Reader can be acquainted with results on the subject in works [1-3]. In this paper, we present studies of SW during winter of 2014-2015.

  1. 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.

  2. 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.

  3. Numerical simulation of the 2013 stratospheric sudden warming by a mesoscale meteorological model

    NASA Astrophysics Data System (ADS)

    Heinrich, Philippe; Costantino, Lorenzo

    2014-05-01

    The major 2013 Stratospheric Sudden Warming was followed in the troposphere by cold air outbreaks over Western Europe from January 12 to 25. In the stratosphere, the polar vortex started moving towards Russia at the end of December 2012 and split on January 7. The vortex splitting was accompanied by an anticyclonic circulation above north Atlantic and Norwegian Sea. The meteorological situation in the troposphere from January 10 to 25 was characterized by a blocking ridge over eastern Atlantic and an anticyclonic cell over Norwegian Sea. This regime was associated to northerly and easterly flows over Western Europe that led to cold air outbreaks. For this event, WRF simulations (Weather, Research and Forecasting) are performed in a domain covering the northern Hemisphere with a resolution of 60 km and extending vertically from surface to 250 Pa. The model is nudged towards ECMWF meteorological analyses (91 levels) over a period extending from 1 to 5 January only, in order to leave the stratosphere-troposphere as unconstrained as possible. In this case, the model is able to approximately reproduce weather forecasts in the troposphere from January 5 to 15. Sensitivity experiments are performed consisting in perturbing the initial conditions on January 5 by adding a warm source in the stratosphere. Numerical results indicate that the Atlantic ridge is reinforced, which results in lower surface temperatures over Western Europe. This work has been performed as part of the european project ARISE.

  4. Modeling the stratospheric warming following the Mt. Pinatubo eruption: uncertainties in aerosol extinctions

    NASA Astrophysics Data System (ADS)

    Arfeuille, F.; Luo, B. P.; Heckendorn, P.; Weisenstein, D.; Sheng, J. X.; Rozanov, E.; Schraner, M.; Brönnimann, S.; Thomason, L. W.; Peter, T.

    2013-11-01

    In terms of atmospheric impact, the volcanic eruption of Mt. Pinatubo (1991) is the best characterized large eruption on record. We investigate here the model-derived stratospheric warming following the Pinatubo eruption as derived from SAGE II extinction data including recent improvements in the processing algorithm. This method, termed SAGE_4λ, makes use of the four wavelengths (385, 452, 525 and 1024 nm) of the SAGE II data when available, and uses a data-filling procedure in the opacity-induced "gap" regions. Using SAGE_4λ, we derived aerosol size distributions that properly reproduce extinction coefficients also at much longer wavelengths. This provides a good basis for calculating the absorption of terrestrial infrared radiation and the resulting stratospheric heating. However, we also show that the use of this data set in a global chemistry-climate model (CCM) still leads to stronger aerosol-induced stratospheric heating than observed, with temperatures partly even higher than the already too high values found by many models in recent general circulation model (GCM) and CCM intercomparisons. This suggests that the overestimation of the stratospheric warming after the Pinatubo eruption may not be ascribed to an insufficient observational database but instead to using outdated data sets, to deficiencies in the implementation of the forcing data, or to radiative or dynamical model artifacts. Conversely, the SAGE_4λ approach reduces the infrared absorption in the tropical tropopause region, resulting in a significantly better agreement with the post-volcanic temperature record at these altitudes.

  5. Wave-mean flow positive feedbacks associated with sudden stratospheric warmings

    NASA Astrophysics Data System (ADS)

    Sjoberg, Jeremiah P.

    Sudden stratospheric warmings -- most often characterized by zonal mean zonal wind easterlies at 60N, 10 hPa -- represent the largest dynamical perturbations to the wintertime polar stratosphere. Despite this, the predictability of sudden warmings remains low, in part because the forcing of these warming events involves a nonlinear positive feedback between planetary scale waves and the zonal wind of the stratosphere. In the wave-mean flow positive feedback, wave forcing decelerates the mean flow, allowing enhanced upward wave propagation, which then further decelerates the mean flow, etc., until the mean flow no longer supports wave propagation. This positive feedback process is crucial for the initiation of such events. Because the associated low predictability stems from poorly resolving initiation, this dissertation focuses on increasing mechanistic understanding of the wave-mean flow positive feedback associated with sudden stratospheric warmings. A simple model of wave-mean flow interaction is the first tool utilized here. In the original form of the model, constant bottom boundary wave forcing, set by geopotential height perturbations, results in a zonal wind state that oscillates between positive values (westerlies) and negative values (easterlies). We present a reformulation of the bottom boundary condition which allows for specification of the upward wave activity flux. Unlike with the original bottom boundary condition, we may precisely set the wave amplitudes propagating into the model domain. With this reformulated model, steady incoming wave fluxes lead to a steady zonal wind response. The oscillating state from the original model is found to rely on a representation of the positive feedback that is too strong. Transient forcing experiments in the reformulated simple model support previous results that there is a preferential wave forcing time scale on the order of 10 days for sudden stratospheric warmings. Forcing the model near this preferential time scale most efficiently drives the positive feedback. Lower stratospheric wave fields in reanalysis data show supporting evidence for these preferential wave forcing time scales prior to sudden stratospheric warmings. Pulses of wave activity flux are also analyzed in reanalysis data, and a set of pulses which are a novel proxy for strong wave-mean flow positive feedback are found. The zonal wind near these pulses display the expected characteristics of the positive feedback: strong precedent zonal winds and strong subsequent wind decelerations. This proxy is thus a useful diagnostic for the wave-mean flow positive feedback. A general circulation model forced by idealized planetary scale topography is employed to perform high order experiments. By stepwise increasing the height of the topography, we find that the frequency of sudden stratospheric warmings within the model increases nonlinearly to a maximum at moderate topographic heights and then strongly jumps down to a lower, steady value for still higher topography. Analyzing the proxy for positive feedback here reveals that the positive feedback is strongest in the range of topographic heights associated with the largest occurrence of sudden warmings, and also that preferential wave forcing time scales on the order of 10 days are upheld.

  6. Variability of the Brewer-Dobson circulation during Stratospheric Sudden Warmings

    NASA Astrophysics Data System (ADS)

    Chavez-Perez, Victor Manuel; de la Torre, Laura; Añel, Juan Antonio; Gimeno, Luis

    2015-04-01

    In this work we look for changes in the latitudinal distribution and intensity of the vertical branch of the Brewer-Dobson Circulation during the formation and development of the Stratospheric Sudden Warmings. Therefore we analyze the vertical component of the Transformed Eulerian-Mean residual circulation (w*,v*) from the lowermost stratosphere to the mesosphere. We use daily data from the ERA-Interim reanalysis and simulations with high vertical resolution performed with the Whole Atmosphere Community Climate Model (WACCM). Preliminary results show that, in the stratosphere, strong negative anomalies apppear at high latitudes around 20 days before the wind reversal. Thereafter, they shift to lower latitudes following the vortex, giving way to strong positive anomalies at high latitudes. In the lowermost stratosphere and in the mesosphere corresponding anomalies are also found. Associated to the positive anomalies at high latitudes, a weakening of the equatorial ascending branch of the Brewer-Dobson Circulation is found in the stratosphere. This equatorial signal is not so clear in the model as it is in the reanalysis.

  7. 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.

  8. Aspects of stratospheric sudden warmings studied from a transformed Eulerian-mean viewpoint

    NASA Astrophysics Data System (ADS)

    Palmer, T. N.

    1981-10-01

    One of the principal reasons for using the transformed Eulerian-mean formalism as a tool for diagnostic studies of the stratosphere is that it should be closer to the fundamental Lagrangian-mean description of the atmosphere than is the standard Eulerian-mean formalism. The wave 2 major warming of February 1979 and the wave 1 major warming of February 1980 are considered. It appears that a high latitude jet core may be a necessary precondition for a major warming and that the existence of such a jet can arise from the decay of an earlier warming pulse. It is pointed out that enhanced high latitude winds can arise from the convergence of wave activity in mid-latitudes that reverses the mid-latitude and enhances the high latitude thermal gradient.

  9. Energetics of a sudden stratospheric warming simulated with a three-dimensional, spectral, quasi-geostrophic model

    NASA Technical Reports Server (NTRS)

    Haggard, K. V.; Grose, W. L.

    1981-01-01

    The energetics of a three dimensional, quasi-geostrophic simulation of a sudden stratospheric warming which developed spontaneously during an annual cycle simulation are described. Daily values of the stratospheric temperatures, zonal winds, heating rates, energies, and energy conversions are discussed and compared with those for observed warmings. It is shown that, like observed warmings, the simulated warming was preceded by an increased vertical flux of eddy kinetic energy from the troposphere and the polar heating resulted because of the strong convergence of the horizontal, eddy heat flux which was only partially balanced by adiabatic and diabatic cooling. There is a significant similarity between the energetics of the simulated and observed warmings. In addition, the warming was spontaneous and the model did not develop a major warming in each winter of the simulation. These facts suggest that this model may be useful for studying not only the warming process but also the conditions that favor its development.

  10. Changes in the composition of the northern polar upper stratosphere in February 2009 after a sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Damiani, Alessandro; Funke, Bernd; Lpez Puertas, Manuel; Gardini, Angela; Clarmann, Thomas; Santee, Michelle L.; Froidevaux, Lucien; Cordero, Raul R.

    2014-10-01

    Variability in the chemistry of the upper stratosphere/lower mesosphere region has been analyzed focusing on high latitudes during the boreal winter in 2009 characterized by the strong sudden stratospheric warming (SSW) on 24 January. Data from Michelson Interferometer for Passive Atmospheric Sounding aboard Envisat and the Microwave Limb Sounder on Aura have been used to exemplify these changes. Record high (low) values of O3 and ClO (temperature and HCl) for the winters of 2005-2012, coupled with a simultaneous enhancement of ClONO2, have been observed in February 2009. This suggests that the very low temperatures favor a more effective ozone production and a greater O3/O ratio. The latter is the main factor controlling active chlorine partitioning. Increases of ClO lead to high ClONO2 concentrations in the upper stratosphere at high latitudes, where its photodissociation rate is smaller. Since this increase of ClONO2 happens at the expense of HCl, the region of high ClONO2 roughly coincides with the region of low HCl. Although this period was characterized by an elevated stratopause event, the investigated region was not influenced by the descent of mesospheric air rich in NOx. Some limited enhancements in NOx at ~1 hPa occurred at latitudes greater than 80N after about 20 February, but they became consistent only in March. Intrusion of midlatitude air mostly occurred between the SSW and early February. Then, the sum of volume mixing ratios of ClONO2 + ClO + HCl remained approximately constant and close to the values of the other years. In contrast, it was up to 0.2 ppbv lower during the SSW period. These atypical chemical conditions occurred also in February 2006, but 2009 stands out for its long-lasting effects, which persisted until late March.

  11. Ground-based microwave measuring of middle atmosphere ozone and temperature profiles during sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Feigin, A. M.; Shvetsov, A. A.; Krasilnikov, A. A.; Kulikov, M. Y.; Karashtin, D. A.; Mukhin, D.; Bolshakov, O. S.; Fedoseev, L. I.; Ryskin, V. G.; Belikovich, M. V.; Kukin, L. M.

    2012-12-01

    We carried out the experimental campaign aimed to study the response of middle atmosphere on a sudden stratospheric warming in winter 2011-2012 above Nizhny Novgorod, Russia (56N, 44E). We employed the ground-based microwave complex for remote sensing of middle atmosphere developed in the Institute of Applied Physics of the Russian Academy of Science. The complex combines two room-temperature radiometers, i.e. microwave ozonometer and the stratospheric thermometer. Ozonometer is a heterodyne spectroradiometer, operating in a range of frequencies that include the rotation transition of ozone molecules with resonance frequency 110.8 GHz. Operating frequency range of the stratospheric thermometer is 52.5-5.4 GHz and includes lower frequency edge of 5 mm molecular oxygen absorption bands and among them two relatively weak lines of O2 emission. Digital fast Fourier transform spectrometers developed by "Acqiris" are employed for signal spectral analysis. The spectrometers have frequency range 0.05-1 GHz and realizes the effective resolution about 61 KHz. For retrieval vertical profiles of ozone and temperature from radiometric data we applied novel method based on Bayesian approach to inverse problem solution, which assumed 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 introduce the results of the campaign in comparison with Aura MLS data. Presented data includes one sudden stratospheric warming event which took place in January 13-14 and was accompanied by temperature increasing up to 310 K at 45 km height. During measurement period, ozone and temperature variations were (almost) anti-correlated, and total ozone abundance achieved a local maxima during the stratosphere cooling phase. In general, results of ground-based measurements are in good agreement with satellite data. However, in opposite to satellite measurements, ground-based instrument registers properly daily variations of ozone concentration above 50 km.

  12. Forecasting the dynamic and electrodynamic response to the January 2009 sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Fuller-Rowell, Tim; Wang, Houjun; Akmaev, Rashid; Wu, Fei; Fang, Tzu-Wei; Iredell, Mark; Richmond, Arthur

    2011-07-01

    A whole atmosphere model has been used to simulate the changes in the global atmosphere dynamics and electrodynamics during the January 2009 sudden stratospheric warming (SSW). In a companion paper, it has been demonstrated that the neutral atmosphere response to the 2009 warming can be simulated with high fidelity and can be forecast several days ahead. The 2009 warming was a major event with the polar stratospheric temperature increasing by 70 K. The neutral dynamics from the whole atmosphere model (WAM) was used to drive the response of the electrodynamics. The WAM simulation predicted a substantial increase in the amplitude of the 8-hour terdiurnal tide in the lower thermosphere dynamo region in response to the warming, at the expense of the more typical semidiurnal tides. The increase in the terdiurnal mode had a significant impact on the diurnal variation of the electrodynamics at low latitude. The changes in the winds in the dayside ionospheric E region increased the eastward electric field early in the morning, and drove a westward electric field in the afternoon. The initial large increase in upward drifts gradually moved to later local times, and decreased in magnitude. The change in the amplitude and phase of the electrodynamic response to the SSW is in good agreement with observations from the Jicamarca radar. The agreement with observations serves to validate the whole atmosphere dynamic response. Since WAM can forecast the neutral dynamics several days ahead, the simulations indicate that the electrodynamic response can also be predicted.

  13. The 2009 stratospheric major warming described from synergistic use of BASCOE water vapour analyses and MLS observations

    NASA Astrophysics Data System (ADS)

    Lahoz, W. A.; Errera, Q.; Viscardy, S.; Manney, G. L.

    2010-10-01

    The record-breaking major stratospheric warming of northern winter 2009 (January-February) is studied using BASCOE (Belgian Assimilation System for Chemical ObsErvation) stratospheric water vapour analyses and MLS (Microwave Limb Sounder) water vapour observations, together with meteorological data from the European Centre for Medium-Range Weather Forecasts (ECMWF) and potential vorticity derived from ECMWF meteorological data. We focus on the interaction between the cyclonic wintertime stratospheric polar vortex and subsidiary anticyclonic stratospheric circulations during the build-up, peak and aftermath of the major warming. We show dynamical consistency between the water vapour analysed fields, and the meteorological and PV fields. New results include the analysis of water vapour during the major warming and demonstration of the benefit of assimilating MLS satellite data into the BASCOE model.

  14. Impact of the Stratospheric Warming 2012 / 2013 on the Middle Atmosphere

    NASA Astrophysics Data System (ADS)

    Bittner, M.; Kchelbacher, L.; Schmidt, C.; Wst, S.; Eriksen Holmen, S.; Espy, P. J.; Gavrilyeva, G.; Yee, J. H.; Mlynczak, M. G.; Russell, J. M., III

    2014-12-01

    The effects of stratospheric warming events are not restricted to the stratosphere only. There is considerable impact on the mesosphere. Global ozone and temperature data derived from the METOP-A-GOME-2 and TIMED-SABER satellites, respectively, and rotational temperatures obtained by ground-based infrared airglow spectrometer measurements (GRIPS) including polar stations within the Network for Mesospheric Change, NDMC, are analyzed in order to characterize both larger scale (planetary waves) and smaller scale (gravity waves) atmospheric dynamics during minor and major stratospheric warming events which took place in winter 2012/2013 in the Northern Hemisphere. The planetary wave regime is found being dominated by zonal wavenumbers 1 and 2 which significantly trigger the observed stratwarming; induced momentum on the background zonal flow due to wave breaking is estimated. As a consequence of the stratwarming the planetary wave number 3 is found being modified significantly in its wave characteristics (phase speed, frequency). Impact of the stratwarming on the upper mesosphere / lower thermosphere is discussed. Evidence for some mesospheric cooling prior to the stratwarming is found. Gravity wave characteristics in that altitude regime seem to be altered. There is also evidence that the mesopause airglow layer might have changed its geometric height during these events.

  15. The Antarctic stratospheric sudden warming of 2002: A self-tuned resonance?

    NASA Astrophysics Data System (ADS)

    Esler, J. G.; Polvani, L. M.; Scott, R. K.

    2006-06-01

    The extraordinary Antarctic stratospheric warming event of 2002 was characterized by a remarkable vertical structure, with the vortex observed to divide at upper levels in the stratosphere but not at lower levels: such `partially' split vortex events are relatively rare. A simple, yet fully three-dimensional, model is constructed to investigate the dynamics of this unique event. Planetary waves are excited on the model vortex edge by a lower boundary forcing characterized by two parameters: an amplitude hF and a frequency ?F, measured relative to a stationary frame. For realistic forcing amplitudes, a partial vortex split resembling that observed during the 2002 event is found only within a specific, narrow band of forcing frequencies. Exploiting the relative simplicity of our model, these frequencies are shown to be those causing a `self-tuning' resonant excitation of the gravest linear mode, during which nonlinear feedback causes an initially off-resonant forcing to approach resonance.

  16. Equatorial ionization anomaly variability over the Brazilian region during boreal sudden stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Paes, R. R.; Batista, I. S.; Candido, C. M. N.; Jonah, O. F.; Santos, P. C. P.

    2014-09-01

    This study refers to the connection between the stratosphere and ionosphere, investigating, specifically, the behavior of the equatorial ionization anomaly (EIA) and ionospheric effects over the Brazilian region during sudden stratospheric warming (SSW) events. We studied three major warmings that occurred in the Northern Hemisphere winter 2007-2008, 2008-2009, and 2009-2010 and a minor warming that occurred in 2010-2011. The solar activity was low for the first two cases and relatively moderate for the last two. In this study the EIA behavior was investigated using the ?TEC (total electron content) parameter, which expresses the EIA relative intensity for the Brazilian sector. The results for the Brazilian region show, mainly after SSW temperature peak, an increase in the EIA intensity in the morning, followed by a decrease in the afternoon. As identified through ?TEC signatures and consistently confirmed through wavelet power spectra analysis, this semidiurnal behavior is preserved for a number of days equal to the polar region thermal stabilization phase and it is very similar to the results obtained in pioneer studies in the Peruvian sector, in which TEC data was also used. In some cases the TEC negative variation is stronger than the positive, being noticeably more intense around the prereversal enhancement time, when the EIA is strongly suppressed in the Brazilian sector.

  17. Mesospheric temperature and metal densities during the major stratospheric warming in 2009

    NASA Astrophysics Data System (ADS)

    Kaifler, Bernd; Hffner, Josef; Baumgarten, Gerd; Williams, Bifford; Hoppe, Ulf-Peter; Lbken, Franz-Josef

    Sudden stratospheric warmings are usually accompanied by a strong cooling in the mesosphere. As this happens within the time frame of a few days, the cooling represents an excellent case to study the influence of the temperature on metal layers in absence of seasonal variations of the metal sources. The major stratospheric warming in January 2009 was the strongest and most prolonged on record. Impacts on the mesosphere include a cooling in excess of 50 K at 87 km altitude in conjunction with a dramatic reduction in atomic metal abundances. We will report on measurements taken with three different lidar systems (ALOMAR Na-Lidar, mobile Fe-Lidar, ALOMAR RMR-Lidar) which were colocated at the ALOMAR observatory in Northern Norway (69 N) at that time. As the instruments were operated simultaneously most of the time, the combination of all three data sets offers a unique and so far unsurpassed view on the thermal structure within the MLT region during a major warming.

  18. 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 0.16C/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 0.2C in global-mean when the model reaches equilibrium. Conversely, the sudden drop of SWV from 2000 to 2004 would cause a surface cooling about -0.08C 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 0.04C/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, suggesting a close coupling between surface temperature and SWV.

  19. Equatorial Circulation Changes up to the Mesosopause during Stratospheric Sudden Warming Events

    NASA Astrophysics Data System (ADS)

    Hirooka, T.; Ohata, T.; Eguchi, N.

    2014-12-01

    Significant general circulation changes are brought about in the equatorial region as well as in the polar region during stratospheric sudden warming (SSW) events. Many studies have been devoted for the region up to the stratopause level from both observational and theoretical aspects. However, observational evidence is still fragmentary in the region above the stratopause, because global data capable of comprehensive analyses are still insufficient for the region. In this study, we make global gridpoint data derived from Aura Microwave Limb Sounder (MLS) observations for geopotential and temperature fields up to the mesopause level. Using these data, we make dynamical analyses for equatorial zonal wind and temperature changes since June 2004 to present. During SSW events, poleward flows of the residual mean meridional circulation are enhanced to lead to equatorial temperature perturbations consisting of a cooling in the upper stratosphere and a warming in the lower mesosphere. These temperature perturbations are found to strengthen the equatorial semiannual oscillation (SAO) with two separate out-of-phase amplitude maxima centered near the stratopause (SSAO) and the middle mesosphere (MSAO) through the thermal wind balance at the equator. In particular, the large amplification of the SAO is clearly observed during mid-winter SSW events when the SSAO and the MSAO have eastely and westerly maxima respectively. Moreover, we compare the results with simulated ones by a general circulation model.

  20. Equatorial ionization anomaly variability over the Brazilian region during boreal sudden stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Da Rosa Paes, Ricardo; Candido, Claudia; Folarin Jonah, Olusegun; Batista, Inez S.; Pernomian dos Santos, Paulo C.

    This study refers to the connection between the stratosphere and ionosphere, investigating, specifically, the behavior of the equatorial ionization anomaly (EIA) and ionospheric effects over the Brazilian region during major sudden stratospheric warming (SSW) events occurred in the northern hemisphere winter 2007-2008, 2008-2009, 2009-2010 and a minor warming occurred in 2010-2011, when the solar activity was low for the first two cases and relatively moderate for the last two. In this study the EIA behavior was investigated using the ?TEC parameter, which expresses the EIA relative intensity for the Brazilian sector. The results for the Brazilian region show, mainly after SSW temperature peak, an increase in the EIA intensity in the morning, followed by a decrease in the afternoon. As identified through ?TEC signatures and consistently confirmed through wavelet power spectra analysis, this semidiurnal behavior is preserved for a number of days equal to the polar region thermal stabilization phase and it is very similar to the results obtained in pioneer studies in the Peruvian sector, in which TEC data was also used. In some cases the TEC negative variation is stronger than the positive, being noticeably more intense around the pre-reversal enhancement time, when the EIA is strongly suppressed in the Brazilian sector.

  1. 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.; Thlix, L.; Kyrl, E.; Backman, L.; Karpechko, A. Yu.; Seppl, 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 related to the descent but are due to solar activation of halogen and NOx chemistry.

  2. 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.

  3. Stratosphere-troposphere evolution during polar vortex intensification

    NASA Astrophysics Data System (ADS)

    Limpasuvan, Varavut; Hartmann, Dennis L.; Thompson, David W. J.; Jeev, Kumar; Yung, Yuk L.

    2005-12-01

    Stratosphere-troposphere evolution associated with polar vortex intensification (VI) events is examined during the Northern Hemisphere winter. The incipient stage of a VI event is marked by anomalously low wave activity and descending westerly anomalies over the depth of the polar stratosphere. Reduced poleward planetary wave heat flux occurs as the circumpolar wind becomes strongest and pressure anomalies penetrate toward the surface. Descending pressure patterns project strongly onto the positive state of the Northern Hemisphere Annular Mode (NAM). Concurrently, anomalous poleward momentum flux develops in the upper troposphere, and the related tropospheric mean meridional circulation maintains the attendant wind and temperature anomalies against surface drag. The gross behavior of the composite VI event is similar in shape but opposite in sign to that associated with sudden stratospheric warming events (SSWs). However, the descent of the wind and temperature anomalies over the VI life cycle is generally weaker and slower than its SSW counterpart preceding the maximum vortex anomaly. Similarly, after the maximum wind event, the weakening of the winds is faster than the strengthening of the winds after a SSW. This is because stratospheric wind reduction anomalies are produced by wave driving, which can be rapid, and increases in wind speed are associated with the radiative cooling of the polar cap, which happens more gradually. While the contributions of the anomalous momentum fluxes by the quasi-stationary and synoptic eddies are similar to SSWs, the much stronger anomalous momentum flux observed during VI can be attributed to the larger role of eddies with timescales between 15 and 40 days and of wave number 2 scale. Notable differences between VI and SSW appear in the tropical region. In particular, anomalous vortex intensification seems to occur preferentially during La Nia conditions.

  4. Equatorial and low-latitude ionospheric response due to 2009 sudden stratospheric warming, South American sector.

    NASA Astrophysics Data System (ADS)

    Fagundes, Paulo Roberto; Gende, Mauricio; De Jesus, Rodolfo; Goncharenko, Larisa; Coster, Anthea; Kavutarapu, Venkatesh; De Abreu, Alessandro; Pillat, ValdirGil; Pezzopane, Michael

    The equatorial and low-latitude ionosphere/thermosphere system is permanently 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. Until recently 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 electroject. 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, recently an unexpected coupling between high latitude, -mid latitude, and -equatorial/low-latitude was discovered during sudden stratospheric warming (SSW). The exploration of all aspects involved in this process must be investigated in order to improve our knowledge about the Earth's atmosphere. This investigation, studies the consequences of the vertical coupling from lower to upper atmosphere during a major Northern Hemisphere sudden stratospheric warming, which took place in January 2009, on the equatorial and low-latitude ionosphere in the Southern Hemisphere. Using 16 ground-based GPS stations over the Brazilian sector, spanning from latitude 2.8N to 30.1S and longitude 62.0W to 37.7W, it was possible to notice that the ionosphere was disturbed by SSW from the Equator to low latitude. The TEC at all 16 stations was severely disturbed during several days after the SSW temperature peak.

  5. The 2009 stratospheric major warming described from synergistic use of BASCOE water vapour analyses and MLS observations

    NASA Astrophysics Data System (ADS)

    Lahoz, W. A.; Errera, Q.; Viscardy, S.; Manney, G. L.

    2011-05-01

    The record-breaking major stratospheric warming of northern winter 2009 (January-February) is studied using BASCOE (Belgian Assimilation System for Chemical ObsErvation) stratospheric water vapour analyses and MLS (Microwave Limb Sounder) water vapour observations, together with meteorological data from the European Centre for Medium-Range Weather Forecasts (ECMWF) and potential vorticity (PV) derived from ECMWF meteorological data. We focus on the interaction between the cyclonic wintertime stratospheric polar vortex and subsidiary anticyclonic stratospheric circulations during the build-up, peak and aftermath of the major warming. We show dynamical consistency between the water vapour analysed fields and the meteorological and PV fields. Using various approaches, we use the analysed water vapour fields to estimate descent in the polar vortex during this period of between ~0.5 km day-1 and ~0.7 km day-1. New results include the analysis of water vapour during the major warming and demonstration of the benefit of assimilating MLS satellite data into the BASCOE model.

  6. Impacts of sudden stratospheric warming on general circulation of the thermosphere

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Impacts of sudden stratospheric warming (SSW) on the thermosphere were studied using a gravity wave (GW)-resolving whole atmosphere model. During an SSW event, the mesosphere at high latitudes cools, and the lower thermosphere becomes warm. At the peak of the SSW event, a temperature drop occurs above an altitude of 150 km at high latitudes. Our results indicate that the SSW event strongly affects meridional circulation and GW drag in the thermosphere. In the lower thermosphere, upward wind in the Arctic region, southward wind in the region between the North Pole and the South Pole, and downward wind in the Antarctic region are dominant before SSW occurs. The SSW event reverses meridional circulation at altitudes between 90 and 125 km in the Northern Hemisphere. During the SSW event, downward wind in the Arctic region and northward wind in the Northern Hemisphere prevail in the lower thermosphere. A detailed analysis revealed that during the SSW event, the change in meridional circulation is caused by the attenuation of the GW drag, and we identified the mechanism responsible for this attenuation. Moreover, we assessed the impacts of SSW on temperatures in the equatorial region and Southern Hemisphere.

  7. Equatorial and Low Latitude Ionospheric Effects During Sudden Stratospheric Warming Events. Ionospheric Effects During SSW Events

    NASA Astrophysics Data System (ADS)

    Chau, Jorge L.; Goncharenko, Larisa P.; Fejer, Bela G.; Liu, Han-Li

    2012-06-01

    There are several external sources of ionospheric forcing, including these are solar wind-magnetospheric processes and lower atmospheric winds and waves. In this work we review the observed ion-neutral coupling effects at equatorial and low latitudes during large meteorological events called sudden stratospheric warming (SSW). Research in this direction has been accelerated in recent years mainly due to: (1) extensive observing campaigns, and (2) solar minimum conditions. The former has been instrumental to capture the events before, during, and after the peak SSW temperatures and wind perturbations. The latter has permitted a reduced forcing contribution from solar wind-magnetospheric processes. The main ionospheric effects are clearly observed in the zonal electric fields (or vertical E B drifts), total electron content, and electron and neutral densities. We include results from different ground- and satellite-based observations, covering different longitudes and years. We also present and discuss the modeling efforts that support most of the observations. Given that SSW can be forecasted with a few days in advance, there is potential for using the connection with the ionosphere for forecasting the occurrence and evolution of electrodynamic perturbations at low latitudes, and sometimes also mid latitudes, during arctic winter warmings.

  8. Structure and Evolution of Singular Vectors in a Global Forecast Model during the January 2009 Stratospheric Sudden Warming

    NASA Astrophysics Data System (ADS)

    Eckermann, S. D.; Reynolds, C. A.; Coy, L.

    2012-12-01

    Singular vectors (SV) of a global forecast model are computed over deep domains of the Northern Hemisphere throughout January 2009 to investigate rapidly-growing perturbations and troposphere-stratosphere predictability. In early-to-mid January, when the stratospheric vortex was relatively undisturbed, the fastest growing stratospheric SV perturbations form initially on the equatorward flanks of the vortex jet as isolated tilted packet-like structures that grow rapidly in energy and horizontal scale, propagate into the core of the vortex jet and self-organize into quasi-barotropic Rossby-wave trains. From 22-28 January, a period characterized by a major wave-2 stratospheric sudden warming (SSW), stratospheric SV structure and evolution change dramatically. SV energy growth increases and the leading stratospheric SV (SV1) assumes an hemispheric geopotential height structure closely resembling a negative anomaly in the northern annular mode (NAM). Forecasts with atmospheric initial conditions perturbed with initial SV1 perturbations produce rapid growth of this hemispheric annular perturbation, which in turn either enhances or suppresses the forecast strength of the SSW. Relative to a control forecast, +SV1-perturbed forecasts increase the strength of the forecast SSW, as reflected in the rate and degree of vortex splitting, the magnitude of forced mean stratospheric easterlies and the descent rate of easterly shear zones, leading to mean easterlies in the high-latitude troposphere and stratosphere after 3-4 days. Conversely, -SV1-perturbed forecasts weaken and then halt the warming, yielding a minor SSW with mean westerlies throughout the high-latitude troposphere and stratosphere after ~4 days.This forecast SSW sensitivity to growing SV1 perturbations arises in each case as a positive feedback driven by large reinforcing changes in planetary-wave Eliassen-Palm (EP) fluxes, with +SV1-perturbed forecasts increasing poleward EP fluxes and -SV1-perturbed forecasts increasing equatorward and decreasing poleward EP fluxes. Sea-level pressures also show NAM-like perturbation structure and growth, consistent with deep NAM coupling between the troposphere and stratosphere during the SSW period. Inferred dynamical pathways driving deep NAM-like perturbation growth and forecast sensitivity during the 2009 SSW are compared and contrasted to corresponding conceptual models of how the NAM controls climate variability.

  9. Quantifying the response strength of the southern stratospheric polar vortex to Indian Ocean warming in austral summer

    NASA Astrophysics Data System (ADS)

    Li, Shuanglin; Chen, Xiaoting

    2014-03-01

    A previous multiple-AGCM study suggested that Indian Ocean Warming (IOW) tends to warm and weaken the southern polar vortex. Such an impact is robust because of a qualitative consistency among the five AGCMs used. However, a significant difference exists in the modeled strengths, particularly in the stratosphere, with those in three of the AGCMs (CCM3, CAM3, and GFS) being four to five times as strong as those in the two other models (GFDL AM2, ECHAM5). As to which case reflects reality is an important issue not only for quantifying the role of tropical ocean warming in the recent modest recovery of the ozone hole over the Antarctic, but also for projecting its future trend. This issue is addressed in the present study through comparing the models' climatological mean states and intrinsic variability, particularly those influencing tropospheric signals to propagate upward and reach the stratosphere. The results suggest that differences in intrinsic variability of model atmospheres provide implications for the difference. Based on a comparison with observations, it is speculated that the impact in the real world may be closer to the modest one simulated by GFDL AM2 and ECHAM5, rather than the strong one simulated by the three other models (CCM3, CAM3 and GFS). In particular, IOW during the past 50 years may have dynamically induced a 1.0C warming in the polar lower stratosphere ( 100 hPa), which canceled a fraction of radiative cooling due to ozone depletion.

  10. On the latitudinal distribution of mesospheric temperatures during sudden stratospheric warming events

    NASA Astrophysics Data System (ADS)

    Singh, Ravindra P.; Pallamraju, Duggirala

    2015-04-01

    Mesospheric rotational temperatures from O2(0-1) and OH(6-2) band nightglow emissions that originate from 94 and 87 km altitudes, respectively, were obtained from a low-latitude location, Mount Abu (24.6N, 72.8E), in India using a high spectral resolution grating spectrograph, which showed significant enhancements during the major sudden stratospheric warming (SSW) event of January 2013. To investigate the relationship of these enhancements in the context of SSW occurrences, a detailed study was carried out for 11 SSW events that occurred during 2004-2013 using SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) data. In addition to SABER, Optical Spectrograph and Infrared Imaging System and Solar Occultation For Ice Experiment mesospheric temperatures were also used which showed similar latitudinal behavior as obtained by SABER. The longitudinal mean mesospheric temperatures at different latitudes of Northern and Southern Hemispheres have been derived. It is found that during SSW events the well-known mesospheric cooling over the Northern Hemispheric high latitudes turns to heating over midlatitudes and then reverts to cooling closer to equatorial regions. This trend continues into the Southern Hemisphere as well. These variations in the mesospheric temperatures at different latitudes have been characterized based on northern hemispheric stratospheric temperature enhancements at high latitudes during SSW periods. In comparison with the COSPAR International Reference Atmosphere-86-derived temperatures, the SABER temperatures show an increase/decrease in Southern/Northern Hemisphere. Such a characterization in mesospheric temperatures with respect to latitudes reveals a hitherto unknown intriguing nature of the latitudinal coupling in the mesosphere that gets set up during the SSW events.

  11. Subtropical influence on January 2009 major sudden stratospheric warming event: diagnostic analysis

    NASA Astrophysics Data System (ADS)

    Schneidereit, Andrea; Peters, Dieter; Grams, Christian; Wolf, Gabriel; Riemer, Michael; Gierth, Franziska; Quinting, Julian; Keller, Julia; Martius, Olivia

    2015-04-01

    In January 2009 a major sudden stratospheric warming (MSSW) event occurred with the strongest NAM anomaly ever observed at 10 hPa. Also stratospheric 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 Nia), 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 warm 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 system. The evolution of these links is examined in its importance for the forcing of the MSSW 2009.

  12. Transport of atmospheric tracers by planetary waves during a winter stratospheric warming event - A three-dimensional model simulation

    NASA Astrophysics Data System (ADS)

    Kouker, W.; Brasseur, G.

    1986-11-01

    In a simple three-dimensional primitive equation model, a wave number 1 major stratospheric warming is simulated. With the aid of two idealized tracers it is shown that the transport during a major warming event is characterized by a small, well-organized tongue of subtropical air flowing around the displaced winter vortex into the polar cap and by a wide area with strong quasi-horizontal mixing (surf zone). The description of these dynamical processes requires a full three-dimensional space resolution.

  13. Observational evidence of ionospheric migrating tide modification during the 2009 stratospheric sudden warming

    NASA Astrophysics Data System (ADS)

    Lin, J. T.; Lin, C. H.; Chang, L. C.; Huang, H. H.; Liu, J. Y.; Chen, A. B.; Chen, C. H.; Liu, C. H.

    2012-01-01

    In this paper, modifications of the ionospheric tidal signatures during the 2009 stratospheric sudden warming (SSW) event are studied by applying atmospheric tidal analysis to ionospheric electron densities observed using radio occultation soundings of FORMOSAT-3/COSMIC. The tidal analysis indicates that the zonal mean and major migrating tidal components (DW1, SW2 and TW3) decrease around the time of the SSW, with 1.5-4 hour time shifts in the daily time of maximum around EIA and middle latitudes. The typical ionospheric SSW signature: a semi-diurnal variation of the ionospheric electron density, featuring an earlier commencement and subsidence of EIA, can be reproduced by differencing the migrating tides before and during the SSW period. Our results also indicate that the migrating tides represent ˜80% of the ionospheric tidal components at specific longitudes, suggesting that modifications of the migrating tides may be the major driver for producing ionospheric changes observed during SSW events, accounting for greater variability than the nonmigrating tides that have been the focus of previous studies.

  14. Mesospheric and Thermospheric Observations of the January 2010 Stratospheric Warming Event

    NASA Astrophysics Data System (ADS)

    Wu, Q.; Nozawa, S.

    2013-12-01

    We use two ground based Fabry-Perot interferometers (FPI) at Boulder (40N, 105W), Resolute (75N, 95W), and a meteor radar at Bear Island (75N, 19E) to examine the mesospheric and thermospheric winds during a sudden stratospheric warming (SSW) event in January 2010. The two high latitude wind instruments allow us, for the first time, to compute the zonal wavenumber of the semidiurnal tide on a daily basis during an SSW event. The ground based FPIs recorded enhanced lower thermosphere semidiurnal tide before and during the SSW. A substorm on January 20 strongly affected the thermospheric winds from high latitudes to mid-latitudes. A 6-hour wave was observed in the polar lower thermospheric winds during the SSW. The two high latitude stations did not show much westward propagating semidiurnal tide with zonal wavenumber one (SW1) as predicted by model simulations. Several indications of westward propagating zonal wavenumber three semidiurnal tide (SW3) require further verification. Enhancements in the mid-latitude thermospheric semidiurnal and teridiurnal tides during the SSW were observed.

  15. Equatorial electrodynamics and neutral background in the Asian sector during the 2009 stratospheric sudden warming

    NASA Astrophysics Data System (ADS)

    Liu, Huixin; Yamamoto, Mamoru; Tulasi Ram, S.; Tsugawa, Takuya; Otsuka, Yuichi; Stolle, Claudia; Doornbos, Eelco; Yumoto, Kiyohumi; Nagatsuma, Tsutomu

    2011-08-01

    Using ground observations of total electron content (TEC) and equatorial electrojet (EEJ) in the Asian sector, along with plasma and neutral densities obtained from the CHAMP satellite, we investigate the ionospheric electrodynamics and neutral background in this longitude sector during the major stratospheric sudden warming (SSW) in January 2009. Our analysis reveals the following prominent features. First, the TEC response in tropical regions is strongly latitude dependent, with monotonic depletion at the dip equator but a semidiurnal perturbation at low latitudes. Second, the TEC semidiurnal perturbation possesses a significant hemispheric asymmetry in terms of onset date and magnitude. It starts on the same day as the SSW peak in the Northern Hemisphere but 2 days later in the Southern Hemisphere. Its magnitude is twice as strong in the north than in the south. Third, strong counter electrojet occurs in the afternoon, following the strengthening of the eastward EEJ in the morning. Fourth, semidiurnal perturbation in both TEC and EEJ possesses a phase shift, at a rate of about 0.7 h/day. Comparisons with results reported in the Peruvian sector reveal clear longitude dependence in the amplitude and hemispheric asymmetry of the semidiurnal perturbation. Finally, thermospheric density undergoes 25% decrease at low latitudes in the afternoon local time sector during the SSW, indicating significant cooling effects in the tropical upper thermosphere.

  16. Coupling between mesosphere and ionosphere over Beijing through semidiurnal tides during the 2009 sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Xiong, Jiangang; Wan, Weixing; Ding, Feng; Liu, Libo; Ning, Baiqi; Niu, Xiaojuan

    2013-05-01

    Sudden stratospheric warming (SSW) in the winter of 2008/2009 is the strongest recorded SSW event. The enhancement in semidiurnal variation of ionospheric TEC (total electron content) with phase shift forward is shown during 22 to 27 January 2009, based on the TEC observations in Beijing (40.30°N, 116.19°E geographic, 39.73°N dip latitude). We focus on finding the reason for the TEC variation. Winds observed by an all-sky meteor radar in the same observatory are used to study mesospheric variation. The semidiurnal solar tide in the mesosphere starts to increase before the SSW and maintains oscillation with period 16-20 days during the SSW. The semidiurnal lunar tides in TEC and wind start to increase on 17 and 15 January, respectively. Although the semidiurnal lunar tide in TEC over Beijing almost dies out on 1 February, that over equatorial ionospheric anomaly crest does not vanish until 15 February when lunar tide in wind tends to be very weak. The maximum of lunar tide in wind appears on 2 February at 96 km with amplitudes of 15 m/s and 21 m/s for zonal and meridional winds. The phase comparison shows that lunar tides in TEC and zonal wind reach their maxima at almost the same time, which is 2-4 h lag behind the meridional wind. The coupling between the mesosphere and ionosphere contributes to the semidiurnal variation of TEC through both solar and semidiurnal lunar tides. The enhancement in semidiurnal lunar tide is responsible for the TEC peak shift forward during the SSW.

  17. Ionospheric variability over Indian low latitude linked with the 2009 sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Patra, Amit; Alex, Sobhana; Samireddipalle, Sripathi; Peddapati, PavanChaitanya

    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 stratospheric warming (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.

  18. Ionospheric variability over Indian low latitude linked with the 2009 sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Patra, A. K.; Pavan Chaitanya, P.; Sripathi, S.; Alex, S.

    2014-05-01

    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 stratospheric warming (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.

  19. Atmospheric and Ionospheric Response to Stratospheric Sudden Warming of January 2013.

    NASA Astrophysics Data System (ADS)

    Jonah, Olusegun Folarin; De Paula, Eurico; Kherani, Esfhan alam; Severino, Dutra

    In this work, we examine the atmospheric and ionospheric responses to the January 2013 Stratospheric Sudden Warming (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 (9.9S, 55.9W, dip lat: 1.96) and an off equatorial station Cuiaba (15.3S, 56.0W, dip lat: 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 mid-latitude Santa Maria (29.4S, 53.3W, dip lat: 17.8). 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].

  20. Atmospheric and ionospheric response to sudden stratospheric warming of January 2013

    NASA Astrophysics Data System (ADS)

    Jonah, O. F.; Paula, E. R.; Kherani, E. A.; Dutra, S. L. G.; Paes, R. R.

    2014-06-01

    In this work, we examine the atmospheric and ionospheric responses to the January 2013 sudden stratospheric warming (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 (9.9S, 55.9W, dip latitude 1.96) and an off-equatorial station Cuiaba (15.3S, 56.0W, 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 (29.4S, 53.3W, 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 30S. 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.

  1. Vertical coupling of atmospheres: dependence on strength of sudden stratospheric warming and solar activity

    NASA Astrophysics Data System (ADS)

    Laskar, Fazlul I.; Pallamraju, Duggirala; Veenadhari, Bhaskara

    2014-12-01

    Comprehensive behavior of the low-latitude upper atmosphere during sudden stratospheric warming (SSW) events at varying levels of solar activity has been investigated. The equatorial electrojet (EEJ) strength and the total electron content (TEC) data from low latitudes over Indian longitudes during the mid-winter season in the years 2005 to 2013 are used in this study. Five major and three minor SSW events occurred in the observation duration, wherein the solar activity had varied from minimum (almost no sunspots) to mini-maximum (approximately 50 sunspots of the solar cycle 24). Spectral powers of the large-scale planetary wave (PW) features in the EEJ and the TEC have been found to be varying with solar activity and SSW strengths. Specially, the spectral powers of quasi-16-day wave variations during the three very strong SSW events in the years 2006, 2009, and 2013 were found to be very high in comparison with those of other years. For these major events, the amplitudes of the semi-diurnal tides and quasi-16-day waves were found to be highly correlated and were maximum around the peak of SSW, suggesting a strong interaction between the two waves. However, this correlation was poor and the quasi-16-day spectral power was low for the minor events. A strong coupling of atmospheres was noted during a relatively high solar activity epoch of 2013 SSW, which was, however, explained to be due to the occurrence of a strong SSW event. These results suggest that the vertical coupling of atmospheres is stronger during strong major SSW events and these events play an important role in enabling the coupling even during high solar activity.

  2. The Major Stratospheric Sudden Warming of January 2013: Analyses and Forecasts in the GEOS-5 Data Assimilation System

    NASA Technical Reports Server (NTRS)

    Coy, Lawrence; Pawson, Steven

    2014-01-01

    We examine the major stratosphere sudden warming (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 stratosphere 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 warming. The overall success of the 5-day forecasts provides motivation to produce regular 10-day forecasts with GEOS-5, to better support studies of stratosphere-troposphere interaction.

  3. The Tropospheric cooling and the Stratospheric warming at Tirunelveli during the Annular Solar Eclipse of 15 January, 2010

    NASA Astrophysics Data System (ADS)

    Nelli, Narendra Reddy; Choudhary, Raj Kumar; Rao, Kusuma

    The UTLS region, a transition region between the troposphere and the stratosphere 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 warming and cooling of the troposphere and the stratosphere. To examine, the temperature variations from surface to lower stratosphere,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 warming in the stratosphere is observed with the peak warming 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 stratospheric warming. 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 variations in turbulent parameters during ASE window using the high resolution GPS Radiosonde data.

  4. Stratospheric Warmings Diagnosed Using the Transformed Eulerian-Mean Equations and the Effect of the Mean State on Wave Propagation.

    NASA Astrophysics Data System (ADS)

    O'Neill, A.; Youngblut, C. E.

    1982-06-01

    Terms in the transformed Eulerian mean equations are computed for the stratospheric warmings of December and January, 1976-77, together with cross sections showing the directions of the Eliassen-Palm (EP) fluxes and residual mean meridional circulations. The picture of warmings that emerges from them transformed diagnostics is compared and contrasted with that presented for the same events by O'Neill and Taylor (1979), whose analysis was based on the traditional momentum and heat budgets. The transformed equations lead to a simpler interpretation of warmings mainly because one term, the convergence of the EP flux, embodies to good approximation the total effect of the waves in forcing the mean flow. Zonal mean temperature changes occur essentially as an adiabatic response to the wave-induced, residual mean meridional circulation. Some evidence that critical lines may act to absorb rather than to reflect planetary waves an a short time-scale is presented.One aspect of these and other warmings of dynamical importance is the switching of the EP fluxes which occurs from an upward and equatorward direction to an upward and poleward direction. It is proposed that this represents a feedback effect on wave propagation of an evolving mean flow. Some support for this idea comes from an analysis of ray paths in the meridional plane. They are computed for different mean wind fields which arise during a warming, and give the direction of wave propagation according to a linear theory based on the WKB approximation. Within the approximations of the theory, the mean state determines how the planetary waves propagate meridionally and vertically through a quantity Q which may be termed a refractive index. Rays are refracted poleward or equatorward according to whether Q increases poleward or equatorward. After a minor warming when the stratospheric jet has been replaced by weak westerlies, a local minimum in Q occurs in the stratosphere and rays reaching upper levels are refracted equatorward. They are refracted poleward when a strong jet is established at high latitudes, which implies that subsequent wave disturbances are focused into the polar cap, leading there to a deceleration of the mean wind. The ray paths are compared with the directions of wave propagation as given by the observed EP fluxes. Good qualitative agreement is found.

  5. HALO aircraft measurements of East Asian anthropogenic SO2 import into the lower stratosphere by a warm conveyor belt uplift

    NASA Astrophysics Data System (ADS)

    Schlager, H.; Arnold, F.; Aufmhoff, H.; Baumann, R.; Pirjola, L.; Roiger, A.; Sailer, T.; Wirth, M.; Schumann, U.

    2012-04-01

    We report on a case study of anthropogenic SO2 pollution transport into the lower stratosphere 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 warm conveyor belt associated with a West-Pacific cyclone and finally injected into the lower stratosphere. 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 stratosphere presented in this study will be discussed.

  6. Tidal variability during stratospheric sudden warming in 2009: Comparison between GAIA model and COSMIC and TIMED/SABER observations

    NASA Astrophysics Data System (ADS)

    Jin, Hidekatsu; Miyoshi, Yasunobu; Fujiwara, Hitoshi; Shinagawa, Hiroyuki; Pancheva, Dora; Mukhtarov, Plamen

    2012-07-01

    We compare results from a whole atmosphere-ionosphere coupled model, GAIA, and from the COSMIC and TIMED/SABER observations during 2008/2009 northern winter season. The GAIA model has assimilated meteorological reanalysis data by a nudging method. The comparison shows excellent agreements in the major features from the stratosphere to the ionosphere including the growth and decay of the major stratospheric sudden warming (SSW) event in 2009. During the major SSW period, a pronounced semidiurnal variation in the F-region electron density and its local-time phase shift similar to the previous observations are reproduced by the model and COSMIC observation. The model suggests that the TEC variation is caused by an enhanced semidiurnal variation in the EXB drift, which is probably related to an amplified semidiurnal migrating tide (SW2) in the lower thermosphere. The model and TIMED/SABER observation show that the SW2 tide amplifies at low latitudes from the stratosphere to the thermosphere as well as the phase variation. Possible mechanisms will be discussed in the presentation.

  7. Relation between stratospheric sudden warming and the lunar effect on the equatorial electrojet based on Huancayo recordings

    NASA Astrophysics Data System (ADS)

    Adnan Siddiqui, Tarique; Lhr, Hermann; Stolle, Claudia; Park, Jaeheung

    2015-04-01

    It has been known for many decades that the lunar tidal influence in the equatorial electrojet (EEJ) is noticeably enhanced during northern hemisphere winters. Recent literature has discussed the role of stratospheric sudden warming (SSW) events behind the enhancement of lunar tides and their findings suggest a positive correlation between the lunar tidal amplitude and lower stratospheric parameters (zonal mean air temperature and zonal mean zonal wind) during SSW events. The positive correlation raises the question whether an inverse approach could also be developed which makes it possible to deduce the occurrence of SSW events before their direct observations (before 1952) from the amplitude of the lunar tides. This study presents an analysis technique based on the phase of the semi-monthly lunar tide to determine the lunar tidal modulation of the equatorial electrojet (EEJ). A statistical approach using the superposed epoch analysis is also carried out to formulate a relation between the EEJ tidal amplitude and lower stratospheric parameters. Using these results, we have estimated a threshold value for the tidal wave power that could be used to identify years with SSW events from magnetic field observations.

  8. Relation between stratospheric sudden warming and the lunar effect on the equatorial electrojet based on Huancayo recordings

    NASA Astrophysics Data System (ADS)

    Siddiqui, T. A.; Lhr, H.; Stolle, C.; Park, J.

    2015-02-01

    It has been known for many decades that the lunar tidal influence in the equatorial electrojet (EEJ) is noticeably enhanced during Northern Hemisphere winters. Recent literature has discussed the role of stratospheric sudden warming (SSW) events behind the enhancement of lunar tides and the findings suggest a positive correlation between the lunar tidal amplitude and lower stratospheric parameters (zonal mean air temperature and zonal mean zonal wind) during SSW events. The positive correlation raises the question whether an inverse approach could also be developed which makes it possible to deduce the occurrence of SSW events before their direct observations (before 1952) from the amplitude of the lunar tides. This study presents an analysis technique based on the phase of the semi-monthly lunar tide to determine the lunar tidal modulation of the EEJ. A statistical approach using the superposed epoch analysis is also carried out to formulate a relation between the EEJ tidal amplitude and lower stratospheric parameters. Using these results, we have estimated a threshold value for the tidal wave power that could be used to identify years with SSW events from magnetic field observations.

  9. Geographical dependence observed in blocking high influence on the stratospheric variability through enhancement and suppression of upward planetary-wave propagation

    NASA Astrophysics Data System (ADS)

    Nishii, K.; Nakamura, H.; Orsolini, Y. J.

    2012-04-01

    Previous studies have suggested the importance of blocking high (BH) development for the occurrence of stratospheric sudden warming (SSW), while there is a recent study that failed to identify their statistical linkage. Through composite analysis applied to high-amplitude anticyclonic anomaly events observed around every grid point over the extratropical Northern Hemisphere, the present study reveals distinct geographical dependence of BH influence on upward propagation of planetary waves (PWs) into the stratosphere. Tropospheric BHs that develop over the Euro-Atlantic sector tend to enhance upward PW propagation, leading to the warming in the polar stratosphere and, in some occasions, to major SSW events. In contrast, the upward PW propagation tends to be suppressed by BHs developing over the western Pacific and the Far East, resulting in the polar stratospheric cooling. This dependence is found to arise mainly from the sensitivity of the interference between the climatological PWs and upward-propagating Rossby wave packets emanating from BHs to their geographical locations. This study also reveals that whether a BH over the eastern Pacific and Alaska can enhance or reduce the upward PW propagation is case-dependent. It is suggested that BHs that induce the stratospheric cooling can weaken statistical relationship between BHs and SSWs.

  10. Combined model-data analysis during the recent stratospheric warming events: WACCM-X predictions and upper atmosphere data assimilation

    NASA Astrophysics Data System (ADS)

    Yudin, V.; Liu, H.; Goncharenko, L.

    2012-12-01

    The paper will present the initial investigations of predictability of the Mesosphere and Thermosphere (MT) region and examination of the physical mechanisms of variability in the community MT models governed and constrained by two important sources of information, (1) lower atmosphere weather patterns and (2) Middle Atmosphere (MA) observations. To relate explicitly Numerical Weather and Space Weather predictions, this study explores the novel framework for constraining the Whole Atmosphere Community Climate Model (WACCM) and its extension in the thermosphere and ionosphere, WACCM-X, by the meteorological analyses (MERRA and GEOS-5) of Global Modeling and Assimilation Office (GMAO). During the recent stratospheric warming events the research satellite data from NASA's TIMED (SABER and TIDI) and EOS-Aura (HIRDLS and MLS) instruments resolve the vertical structures of mean flow, waves and composition providing additional constraints for modeling of the lower-upper atmosphere coupling. Their sequential assimilation in the WACCM-X/MERRA will allow data constrained predictions of tides, planetary waves, and neutral-ion chemistry with the realistic weather in the lower atmosphere. For constraining the fast varying wave dynamics and composition novel aspects of the upper atmosphere data assimilation will be discussed including recreation of the fast diurnal variations in WACCM-X. The model and analysis results will be compared with independent ground-based and space-borne observations during stratospheric warming events.

  11. Can the GEOS CCM Simulate the Temperature Response to Warm Pool El Nino Events in the Antarctic Stratosphere?

    NASA Technical Reports Server (NTRS)

    Hurwitz, M. M.; Song, I.-S.; Oman, L. D.; Newman, P. A.; Molod, A. M.; Frith, S. M.; Nielsen, J. E.

    2010-01-01

    "Warm 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 stratosphere. These conditions lead to higher polar stratospheric 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 warming 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.

  12. Can the GEOS CCM Simulate the Temperature Response to Warm Pool El Nino Events in the Antarctic Stratosphere?

    NASA Technical Reports Server (NTRS)

    Hurwitz, M. M.; Song, I.-S.; Oman, L. D.; Newman, P. A.; Molod, A. M.; Frith, S. M.; Nielsen, J. E.

    2011-01-01

    "Warm 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 stratosphere. These conditions lead to higher polar stratospheric 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 warming 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.

  13. Comprehensive study of disturbances of the neutral atmosphere and ionosphere parameters over Eastern Siberia during major sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Medvedeva, Irina; Medvedev, Andrey; Ratovsky, Konstantin; Tolstikov, Maxim; Shcherbakov, Alexander

    We investigated the disturbances of the neutral atmosphere and ionosphere parameters in a large range of heights in the region of Eastern Siberia during the period of the 2013 January sudden stratospheric warming (SSW). The analysis based on the data from spectrometric measurements of the OH and O2 upper atmospheric emissions obtained at the ISTP Geophysical Observatory (52E, 103N), data from Irkutsk DPS-4 Digisonde, data from Irkutsk Incoherent Scatter Radar, and satellite data on vertical temperature distribution in the atmosphere from Aura MLS v3.3. Also, the data of NCEP / NCAR and MERRA reanalysis were involved. The 2013 January major sudden stratospheric warming (SSW) was accompanied by significant disturbances of zonal characteristics of the lower and middle atmosphere, zonal circulation reversal at the 10-hPa level at 60N, and splitting of the polar vortex. Comprehensive analysis of the neutral atmosphere and ionosphere parameters revealed the SSW manifestations in a large height range. Disturbances of the neutral atmosphere temperature from the stratosphere to the mesosphere and lower thermosphere (MLT) were detected. At the MLT heights, revealed was an increase in the intensities of the OH (~87 km) and O2 (~94 km) emissions by a factor of 2-2.5 relative to the undisturbed conditions. At the F2-layer peak height, found were disturbances of the plasma parameters: electron density, electron and ion temperatures, and decrease in the daily rate of meridional component of the neutral wind. We assume that the observed effects can be caused by atmospheric circulation disturbances and amplification of vertical transfer. The disturbances in the upper atmosphere and ionosphere parameters during SSW can be evidence of the coupling between the lower and upper atmosphere. The work was supported by Russian Foundation for Basic Research Grant 13-05-00153 and RF President Grant of Public Support for RF Leading Scientific Schools (NSh-2942.2014.5).

  14. Predictability of the stratospheric sudden warming and its impact on the tropospheric climate in January 2009 -Comparison with the warmings of 2004 and 2006-

    NASA Astrophysics Data System (ADS)

    Kuroda, Y.

    2010-12-01

    Predictability of the stratospheric sudden warming (SSW) and its following Northern Annular Mode (NAM) variability in the troposphere is examined for the winter of 2009, and comparison is made with other warmings of 2004 and 2006. The predictability was examined using sets of ensemble runs of a climate model of our institute. The SSW of 2009 is very unusual in the sense that it is caused by almost pure planetary wave of zonal-wavenumber 2 and such SSW is the only one that appears in the past. So it will be interesting to see how extend can we predict the occurrence of the SSW and following impact on the troposphere with the climate model. The result shows that the occurrence of the SSW can be predicted if prediction is initialized within 8 days before the peaked day. The limit is rather short compared with the one found in the previous studies, which shows limit longer than about 2 weeks. The predictability of the downward propagating tropospheric NAM variability following the SSW shows that very long predictability of a few months cannot be obtained even if the forecast is performed before the occurrence of the SSW. Predictability is limited to almost half months regardless of the initial time of the prediction. The situation was very different to the typical PJO-type warmings of 2004 and 2006.

  15. Mesoscale Simulations of Gravity Waves During the 2008-2009 Major Stratospheric Sudden Warming

    NASA Technical Reports Server (NTRS)

    Limpasuvan, Varavut; Alexander, M. Joan; Orsolini, Yvan J.; Wu, Dong L.; Xue, Ming; Richter, Jadwiga H.; Yamashita, Chihoko

    2011-01-01

    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 stratospheric 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 stratosphere 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 stratosphere. 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 stratosphere or by secondary GW breaking. The simulated large-scale features agree well with those resolved in satellite observations and analysis products.

  16. Modeling and mechanisms of polar winter upper stratosphere/lower mesosphere disturbances in WACCM

    NASA Astrophysics Data System (ADS)

    Greer, K. R.; Thayer, J. P.; Harvey, V. L.; Peck, E. D.

    2015-08-01

    This work focuses on the characteristics and mechanisms of upper stratosphere/lower mesosphere (USLM) disturbances in the polar winter as simulated by a free-running 40 year run of the Whole Atmosphere Community Climate Model (WACCM) version 4. USLM disturbances have been shown to precede the development of every major sudden stratospheric warming (SSW), thus potentially increasing the predictability of SSWs. WACCM4 is shown to internally and spontaneously generate polar USLM disturbances that are consistent with an established USLM climatology based on the UK Meteorological Office stratospheric assimilation. Arctic USLM disturbances in WACCM4 occur on average 2.65 times per winter season; are most frequently generated in the months of December, January, and February; and are preferentially located in the longitude band between 30E and 120E, poleward of 40 latitude, all in good agreement with observations. Analysis of composite USLM events corroborates the underlying mechanism responsible for their formation as planetary wave breaking between ~45 km and 65 km that decelerates the mean flow, induces vertical air motion, and causes regions of adiabatic heating in a limited longitude band. These conditions are suitable for the growth of a baroclinic instability at the stratopause level. Using the Trenberth localized three-dimensional Eliassen-Palm flux along with the Charney-Stern criteria, a WACCM4 case study of an independent USLM event implicates baroclinic instability as a critical process in the development of the USLM thermal structure.

  17. The life cycle of a sudden stratospheric warming from infrasonic ambient noise observations

    NASA Astrophysics Data System (ADS)

    Smets, P. S. M.; Evers, L. G.

    2014-11-01

    A method is presented to study the life cycle of a SSW using infrasonic ambient noise observations. The potential of infrasound is shown to provide the missing observations required by numerical weather prediction to better resolve the upper atmosphere. The 2009 major SSW is reanalyzed using the Evers and Siegmund (2009) data set. Microbarom observations are evaluated to identify detections that cannot be explained by the analysis of the European Centre for Medium-Range Weather Forecasts. Identified differences can be related to either the altitude limit of the analysis, not resolving thermospheric ducts, or to an actual error in the analysis. Therefore, a first-order model is used to relate observations with the analysis, existing of the Waxler et al. (2007) microbarom source model, including bathymetry to allow column resonances, and an atmospheric propagation model using 3-D ray tracing. Daily normalized spectral powers are proposed to distinguish stratospheric from thermospheric return height, based on the different signature of solar tidal amplitude fluctuations. It is shown that a SSW is not a smooth event as following from the analysis but a series of abrupt changes with a period of 10 to 16 days, increasing in intensity and duration. This is in agreement with the wave period of Rossby waves, interacting with the stratospheric circumpolar vortex. The type of vortex disturbance, split or reversal, can be deduced from the combined effect of the change in back-azimuth direction, solar tidal signature type, and/or phase variation of the amplitude variation of the observed microbaroms.

  18. Ionospheric response to the 2009 sudden stratospheric warming over the equatorial, low, and middle latitudes in the South American sector

    NASA Astrophysics Data System (ADS)

    Fagundes, P. R.; Goncharenko, L. P.; Abreu, A. J.; Venkatesh, K.; Pezzopane, M.; Jesus, R.; Gende, M.; Coster, A. J.; Pillat, V. G.

    2015-09-01

    The present study investigates the ionospheric total electron content (TEC) and F-layer response in the Southern Hemisphere equatorial, low, and middle latitudes due to major sudden stratospheric warming (SSW) event, which took place during January-February 2009 in the Northern Hemisphere. In this study, using 17 ground-based dual frequency GPS stations and two ionosonde stations spanning latitudes from 2.8N to 53.8S, longitudes from 36.7W to 67.8W over the South American sector, it is observed that the ionosphere was significantly disturbed by the SSW event from the equator to the midlatitudes. During day of year 26 and 27 at 14:00 UT, the TEC was two times larger than that observed during average quiet days. The vertical TEC at all 17 GPS and two ionosonde stations shows significant deviations lasting for several days after the SSW temperature peak. Using one GPS station located at Rio Grande (53.8S, 67.8W, midlatitude South America sector), it is reported for the first time that the midlatitude in the Southern Hemisphere was disturbed by the SSW event in the Northern Hemisphere.

  19. Scenarios for halocarbon emissions in Finland and estimates of their impact on global warming and chlorine loading in the stratosphere

    SciTech Connect

    Pipatti, R.; Sinisalo, J.

    1994-07-01

    Finnish halocarbon (CFC, HCFC and HFC) emissions and their impact on global warming and chlorine loading in the stratosphere have been estimated. CFC consumption is estimated to have begun in the 1960s in Finland. CFCs deplete ozone and are therefore being phased out. In Finland, the deadline is the year 1995. The total Finnish CFC consumption during 1960-1994 is estimated to be about 70,000 tonnes. The yearly consumption has been, at most, about 3000 tonnes. CFCs will be partly substituted by HCFCs and HFCs. The yearly HCFC consumption has been around 300 tonnes since the mid 1980s. HFCs are new products and their use has been minor. Both HCFC and HFC consumption is assumed to increase. HCFCs will be gradually phased out between 1996 and 2030 because they also deplete ozone. No restrictions are planned for HFCs. CFC emissions are evaluated in two scenarios. In the base scenario, all the consumed amount is expected to be released to the atmosphere. In the recovery scenario, 75% of the amount now stored in equipment and products (about 10,000 tonnes) is assumed to be recovered. Even if consumption is phased out in 1994, emissions continue until the next century. 15 refs., 6 figs., 5 tabs.

  20. Ionospheric Effects of Sudden Stratospheric Warming During Moderate-to-High Solar Activity: Case Study of January 2013

    NASA Astrophysics Data System (ADS)

    Goncharenko, L. P.; Chau, J. L.; Condor Patilongo, P. J.; Coster, A. J.; Benkevitch, L. V.

    2013-12-01

    A major and long-lasting sudden stratospheric warming occurred in January 2013 during moderate-to-high solar activity conditions. Analysis of experimental observations of ionospheric parameters during the winter of 2012/13 reveals strong ionospheric disturbances associated with this event. Anomalous variations in vertical ion drift measured at the geomagnetic equator at Jicamarca (12S, 75W) are observed for over 40 days from mid-December 2012 to the end of January 2013. We report strong perturbations in the total electron content (TEC) obtained with global network of GPS receivers. These perturbations maximize in the crests of equatorial ionization anomaly, reach 100% of the background TEC value, exhibit significant longitudinal and hemispheric asymmetry, and last for over 40 days. The magnitude of ionospheric anomalies in both vertical drifts and TEC during the January 2013 SSW is comparable to the anomalies observed during the record-strong SSW of January 2009 that coincided with extreme solar minimum. This observation contrasts with results of numerical simulations that predict a weaker ionospheric response to the tidal forcing during high solar activity due to the higher F-region Pedersen conductivity. The temporal behavior of anomalous variations in both vertical drift and TEC is consistent with the phase change of lunar semidiurnal tide and could result from the superposition of amplified solar and lunar tides.

  1. Indirect global warming effects of ozone and stratospheric water vapor induced by surface methane emission

    SciTech Connect

    Wuebbles, D.J.; Grossman, A.S.; Tamaresis, J.S.; Patten, K.O. Jr.; Jain, A.; Grant, K.A.

    1994-07-01

    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 stratospheric 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%).

  2. Wave Driven Disturbances of the Thermal Structure in the Polar Winter Upper Stratosphere and Lower Mesosphere

    NASA Astrophysics Data System (ADS)

    Greer, Katelynn R.

    The polar winter middle atmosphere is a dynamically active region that is driven primarily by wave activity. Planetary waves intermittently disturbed the region at different levels and the most spectacular type of disturbance is a major Sudden Stratospheric Warming (SSW). However, other types of extreme disturbances occur on a more frequent, intraseasonal basis. One such disturbance is a synoptic-scale "weather event" observed in lidar and rocket soundings, soundings from the TIMED/SABER instrument and UK Meteorological Office (MetO) assimilated data. These disturbances are most easily identified near 42 km where temperatures are elevated over baseline conditions by a remarkable 50 K and an associated cooling is observed near 75 km. As these disturbances have a coupled vertical structure extending into the lower mesosphere, they are termed Upper Stratospheric/Lower Mesospheric (USLM) disturbances. This research begins with description of the phenomenology of USLM events in observations and the assimilated data set MetO, develops a description of the dynamics responsible for their development and places them in the context of the family of polar winter middle atmospheric disturbances. Climatologies indicates that USLM disturbances are commonly occurring polar wintertime disturbances of the middle atmosphere, have a remarkably repeating thermal structure, are located on the East side of the polar low and are related planetary wave activity. Using the same methodology for identifying USLM events and building climatologies of these events, the Whole Atmosphere Community Climate Model WACCM version 4 is established to spontaneously and internally generate USLM disturbances. Planetary waves are seen to break at a level just above the stratopause and convergence of the EP-flux vector is occurring in this region, decelerating the eastward zonal-mean wind and inducing ageostrophic vertical motion to maintain mass continuity. The descending air increases the horizontal temperature gradient at 2 hPa and is responsible for the stratopause warming. Embedded in this planetary wave breaking process is baroclinic instability, as indicated by the Charney-Stern criteria and an EP-flux analysis decomposed by planetary and synoptic-scale waves. It is recognized that USLM events are part of a family of disturbances that occur in the polar winter middle atmosphere which have the potential to impact the entire atmospheric column. Relationships between USLM events, minor SSWs and major SSWs are examined and displayed through a Venn diagram which looked for events that were linked to each other (or not) by temporal evolution of the polar vortex within 14 days. Critically, every identified major SSW (in both MetO and WACCM) is preceded by a USLM disturbance, and the baroclinic instability that is embedded in the planetary wave breaking of USLM disturbances mark significant disruption to the middle atmosphere, which may aid in the forecast of major SSWs. This leads to the proposal of new dynamics based definitions of minor and major SSWs.

  3. Ionospheric Effects of Sudden Stratospheric Warming During Solar Maximum and Minimum Periods: What Do We See from Puerto Rico?

    NASA Astrophysics Data System (ADS)

    Hernandez-Espiet, A.; Goncharenko, L. P.; Spraggs, M. E.; Coster, A. J.; Galkin, I. A.; Aponte, N.

    2014-12-01

    Some of the main factors that contribute to changes in multiple ionospheric parameters are solar flux, geomagnetic activity, seasonal behavior, and coupling with lower atmosphere, which is particularly strong during sudden stratospheric warming events (SSW). Studying the way that these factors induce changes in the ionosphere is important, since these changes can have a negative effect on different types of communication systems. Multiple case studies have demonstrated large variations in ionospheric electron density in association with SSW in the low-latitude ionosphere, in particular near the crests of the equatorial ionization anomaly. However, the latitudinal extend of these variations was not addressed. In this study, we utilize data obtained in Puerto Rico by three instruments - Ramey digisonde, Arecibo Incoherent Scatter Radar (ISR) and GPS receivers to analyze four winter-time periods: two years with major SSW events (2005-2006, 2012-2013) and two years with minor SSW events (2006-2007, 2013-2014). In addition, selected cases represent two winters with low solar activity and two winters with moderate to high solar activity. The study focuses on the location of Arecibo, Puerto Rico (18.34N, 66.75W), ~15 to the north of the northern crest of the equatorial ionization anomaly. We report good agreement in ionospheric parameters between all three instruments. To investigate possible association with SSW events, we remove influences of seasonal behavior, solar flux, and geomagnetic activity by building empirical model and subtracting expected variations from the observational data. The analysis of residuals between the data and the model shows that ionospheric disturbances were observed in Puerto Rico for both minor and major SSW events in the ISR, digisonde and GPS Total Electron Content (TEC) data. We report 20-60% variations in NmF2 and TEC due to SSW effects. Large variations are also observed in electron density, electron temperature and plasma velocity during both daytime and nighttime.

  4. Thermal and dynamical perturbations in the winter polar mesosphere-lower thermosphere region associated with sudden stratospheric warmings under conditions of low solar activity

    NASA Astrophysics Data System (ADS)

    Lukianova, Renata; Kozlovsky, Alexander; Shalimov, Sergey; Ulich, Thomas; Lester, Mark

    2015-06-01

    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 stratospheric warming (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 stratospheric maximum, and the mesospheric cooling is almost of the same value as the stratospheric warming (~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.

  5. Signatures of the two day wave and sudden stratospheric warmings in Arctic water vapour observed by ground-based microwave radiometry

    NASA Astrophysics Data System (ADS)

    Tschanz, B.; Kmpfer, N.

    2015-01-01

    The ground-based microwave radiometer MIAWARA-C recorded the upper stratospheric and lower mesospheric water vapour distribution continuously from June 2011 to March 2013 above the Arctic station of Sodankyl, Finland (67.4 N, 26.6 E) without major interruptions and offers water vapour profiles with temporal resolution of one hour for average conditions. Over the measurement period, the instrument monitored the changes in water vapour linked to two sudden stratospheric warmings in early 2012 and 2013. Based on the water vapour measurements, the descent rate in the vortex after the warmings is 364 m d-1 for 2012 and 315 m d-1 for 2013. The water vapour time series of MIAWARA-C shows strong periodic variations in both summer and winter related to the quasi two day wave. In the mesosphere the amplitudes are strongest in summer. The stratospheric wintertime two day wave is pronounced for both winters and reaches a maximum amplitude of 0.8 ppmv in November 2011.

  6. Signatures of the 2-day wave and sudden stratospheric warmings in Arctic water vapour observed by ground-based microwave radiometry

    NASA Astrophysics Data System (ADS)

    Tschanz, B.; Kmpfer, N.

    2015-05-01

    The ground-based microwave radiometer MIAWARA-C recorded the upper stratospheric and lower mesospheric water vapour distribution continuously from June 2011 to March 2013 above the Arctic station of Sodankyl, Finland (67.4 N, 26.6 E) without major interruptions and offers water vapour profiles with temporal resolution of 1 h for average conditions. The water vapour time series of MIAWARA-C shows strong periodic variations in both summer and winter related to the quasi-2-day wave. Above 0.1 hPa the amplitudes are strongest in summer. The stratospheric wintertime 2-day wave is pronounced for both winters on altitudes below 0.1 hPa and reaches a maximum amplitude of 0.8 ppmv in November 2011. Over the measurement period, the instrument monitored the changes in water vapour linked to two sudden stratospheric warmings in early 2012 and 2013. Based on the water vapour measurements, the descent rate in the vortex after the warmings is 364 m d-1 for 2012 and 315 m d-1 for 2013.

  7. Ionospheric Response to the 2009 Sudden Stratospheric Warming over the Equatorial, Low- and Mid-Latitudes in American Sector.

    NASA Astrophysics Data System (ADS)

    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.

    2014-12-01

    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 stratospheric warming (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 lasting for several days after the SSW temperature peak.

  8. Sudden Stratospheric Warming Effects over L1 Scintillation at Low Latitude During Quiet and Magnetically Disturbed Periods

    NASA Astrophysics Data System (ADS)

    Paula, E. R.; Jonah, O. F.; Moraes, A. O.; Kherani, E. A.; Fejer, B. G.; Abdu, M. A.; Batista, I. S.; Negreti, P. M. D. S.; Dutra, S. L. G.; Paes, R. D. R.

    2014-12-01

    Small scale irregularities of hundred of meters, associated with bubbles cause scattering and diffraction of radio waves crossing the ionosphere and produces scintillation in amplitude and/or phase of the GNSS signal that can cause loss of lock of its code and/or carrier, affecting the positioning determination. The L1 band GPS amplitude scintillation intensities, represented by the S4 scintillation index, at the low latitude station of So Jos dos Campos (23.1 S, 45.8 W, dip latitude 17.3 S), located under the southern crest of the EIA, were analyzed during two northern hemisphere Sudden Stratospheric Warming (SSW) events. These events occurred during the northern winter months of 2003/2004 marked by moderate magnetic disturbances and 2012/2013 during a very quiet magnetic period. Normally during these months (January to February) moderate to strong scintillation occurs in this Brazilian station for moderate and high solar flux. Long lasting weakening of the scintillation amplitude at this low latitude station was observed during these two SSW events, compared to the pre-SSW periods, however stronger S4 weakening was observed during 2003/2004. The main mechanisms that can lead to scintillation weakening are the meridional neutral wind and the equatorial vertical plasma drift. Since no wind data is available during pre-SSW and SSW periods, we have sought to identify its signature in the latitudinal distribution of the TEC along the 60o magnetic meridian and we suggest that a SSW induced southward meridional wind had a large contribution to the S4 weakening. The other mechanism that could have contributed to S4 weakening is the vertical plasma drift. This parameter, inferred from So Lus (2.52S, 44.3W, dip latitude 1.73S) digisonde data for the 17 to 21 LT period during the SSW events, showed predominant decreases around the prereversal hours relative to their pre-SSW periods. The vertical drift during the period of the 2003/2004 SSW event presented a large flattening and remained constant at about 10 m/s. We suggest that this larger drift decrease during the magnetic storm, compared to the 2012/2013 SSW period, is caused by the SSW effects reinforced by the disturbance dynamo and overshielding westward polarity electric fields associated with the storm.

  9. Enhanced long-range forecast skill in boreal winter following stratospheric strong vortex conditions

    NASA Astrophysics Data System (ADS)

    Tripathi, Om P.; Charlton-Perez, Andrew; Sigmond, Michael; Vitart, Frederic

    2015-10-01

    There has been a great deal of recent interest in producing weather forecasts on the 2-6 week sub-seasonal timescale, which bridges the gap between medium-range (0-10 day) and seasonal (3-6 month) forecasts. While much of this interest is focused on the potential applications of skilful forecasts on the sub-seasonal range, understanding the potential sources of sub-seasonal forecast skill is a challenging and interesting problem, particularly because of the likely state-dependence of this skill (Hudson et al 2011). One such potential source of state-dependent skill for the Northern Hemisphere in winter is the occurrence of stratospheric sudden warming (SSW) events (Sigmond et al 2013). Here we show, by analysing a set of sub-seasonal hindcasts, that there is enhanced predictability of surface circulation not only when the stratospheric vortex is anomalously weak following SSWs but also when the vortex is extremely strong. Sub-seasonal forecasts initialized during strong vortex events are able to successfully capture the associated surface temperature and circulation anomalies. This results in an enhancement of Northern annular mode forecast skill compared to forecasts initialized during the cases when the stratospheric state is close to climatology. We demonstrate that the enhancement of skill for forecasts initialized during periods of strong vortex conditions is comparable to that achieved for forecasts initialized during weak events. This result indicates that additional confidence can be placed in sub-seasonal forecasts when the stratospheric polar vortex is significantly disturbed from its normal state.

  10. Chemistry and dynamics of the secondary ozone layer during the sudden stratospheric warming in the southern hemisphere in 2002, using WACCM-SD

    NASA Astrophysics Data System (ADS)

    Smith-Johnsen, Christine; Limpasuvan, Varavut; Yvan, Orsolini; Frode, Stordal

    2015-04-01

    A sudden stratospheric warming (SSW) will affect the chemistry and dynamics of the middle atmosphere, and up to the thermosphere. The major warmings 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 warming 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.

  11. Stratospheric ozone, global warming, and the principle of unintended consequences--an ongoing science and policy success story.

    PubMed

    Andersen, Stephen O; Halberstadt, Marcel L; Borgford-Parnell, Nathan

    2013-06-01

    In 1974, Mario Molina and F. Sherwood Rowland warned that chlorofluorocarbons (CFCs) could destroy the stratospheric 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 stratosphere 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 stratospheric 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 stratospheric 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:23858990

  12. Study of the thermospheric and ionospheric response to the 2009 sudden stratospheric warming using TIME-GCM and GSM TIP models: First results

    NASA Astrophysics Data System (ADS)

    Klimenko, M. V.; Klimenko, V. V.; Bessarab, F. S.; Korenkov, Yu N.; Liu, Hanli; Goncharenko, L. P.; Tolstikov, M. V.

    2015-09-01

    This paper presents a study of mesosphere and low thermosphere influence on ionospheric disturbances during 2009 major sudden stratospheric warming (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 stratospheric 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.

  13. Global ionospheric response to the 2009 sudden stratospheric warming event using Ionospheric Data Assimilation Four-Dimensional (IDA4D) algorithm

    NASA Astrophysics Data System (ADS)

    Azeem, I.; Crowley, G.; Honniball, C.

    2015-05-01

    A data assimilation algorithm is used to delineate the time-dependent three-dimensional ionospheric response to the 2009 sudden stratospheric warming (SSW) event. We use the Ionospheric Data Assimilation Four-Dimensional (IDA4D) algorithm to study the global ionospheric response to the 2009 SSW. This is the first study to utilize global ionospheric measurements in a data assimilation framework to unambiguously characterize atmosphere-ionosphere coupling via tidal modifications during the 2009 SSW event. Model results reveal that the dominant mode of ionospheric variability during the 2009 SSW is driven by the enhancements in westward propagating semidiurnal tide with zonal wave number 1. The IDA4D results completely characterize the tidal perturbation during the 2009 SSW for the first time and show the global 3-D structure of the tide in total electron content (TEC) and electron density. The largest ionospheric responses were seen at low latitudes, where ionospheric plasma is extremely sensitive to the zonal electric field and susceptible to modifications by tidal winds in the lower thermosphere. The ionospheric response to the warming was characterized by an increase in TEC in the morning/early afternoon sector and a decrease during the late afternoon/evening period. The effects of coupling between the stratosphere and ionosphere were strongest between 220 km and 380 km. The IDA4D results also show a reversal of asymmetry in the equatorial ionization anomaly crests occurring several days after the peak of the 2009 SSW event. We suggest that this could be a result of the equatorial fountain effect being further modified by the summer-to-winter meridional neutral winds.

  14. Sporadic mesoscale variability of stratospheric aerosol

    NASA Astrophysics Data System (ADS)

    Megrelishvili, T. G.; Melnikova, I. G.; Rozenberg, G. V.

    1982-05-01

    Twilight measurements made at the Abastumani Astrophysical Observatory are examined, and Salyut-6 observations of the optical structure of the sunset are analyzed. These data disclose the existence of sporadic mesoscale variations of stratospheric aerosol, including rapid processes of stratospheric 'self-cleaning' which is long-lasting. The short-term disappearance of stratospheric aerosol during stratospheric winter warmings is also disclosed.

  15. Comprehensive study of disturbances of the neutral atmosphere and ionosphere parameters over Eastern Siberia during the 2013 January major sudden stratospheric warming

    NASA Astrophysics Data System (ADS)

    Medvedeva, Irina; Medvedev, Andrey; Ratovsky, Konstantin; Shcherbakov, Alexandr; Tolstikov, Maxim

    2015-11-01

    We investigated variations in the neutral atmosphere and ionosphere parameters within a large range of heights in the Eastern Siberia region during the 2013 January sudden stratospheric warming (SSW). The analysis is based on: the data from spectrometric measurements of OH (?87 km, 834.0 nm, (6-2)) and At O2 (?94 km, 864.5 nm, (0-1)) upper atmospheric emissions, the data from the Irkutsk DPS-4 Digisonde, the data on electron and ion temperatures and the meridional component of the neutral wind from the Irkutsk Incoherent Scatter Radar, the satellite data on the vertical temperature distribution in the atmosphere from Aura MLS v3.3, and the MERRA reanalysis data. We detected the disturbances of the neutral atmosphere temperature from the stratosphere to the mesosphere and lower thermosphere (MLT). The temperature at 10 hPa (?32 km) increased by ?70 K up to ?270 K, the temperature at 0.01 hPa (?80 km) decreased by 50 K, and reached ?170 K. At the MLT heights, an increase in the intensities of the OH and O2 emissions by a factor of 2-2.5 relative to the undisturbed conditions was revealed. At the F2-layer height, the plasma parameter disturbances were found. After 2013 January 10, interruption of the correlation between NmF2 and hmF2 occurred. Ion temperature cooling reaching 50 K was observed on January 1-10, changing to a quick increase by 50 K for several days after January 10. The neutral wind meridional component and the electron temperature decreased over January 1-21. The observed effects can be probably caused by atmospheric circulation disturbances and amplification in the vertical transfer. The disturbances in the upper atmospheric and in ionospheric parameters during SSW can evidence the coupling between the lower and upper atmosphere.

  16. Response of migrating tides to the stratospheric sudden warming in 2009 and their effects on the ionosphere studied by a whole atmosphere-ionosphere model GAIA with COSMIC and TIMED/SABER observations

    NASA Astrophysics Data System (ADS)

    Jin, H.; Miyoshi, Y.; Pancheva, D.; Mukhtarov, P.; Fujiwara, H.; Shinagawa, H.

    2012-10-01

    This paper compares results from a whole atmosphere-ionosphere coupled model, GAIA, with the COSMIC and TIMED/SABER observations during the 2008/2009 northern winter season. The GAIA model has assimilated meteorological reanalysis data by a nudging method. The comparison shows general agreement in the major features from the stratosphere to the ionosphere including the growth and decay of the major stratospheric sudden warming (SSW) event in 2009. During this period, a pronounced semidiurnal variation in the F region electron density and its local-time phase shift similar to the previous observations are reproduced by the model and COSMIC observation. The model suggests that the electron density variation is caused by an enhanced semidiurnal variation in the E B drift, which is probably related to an amplified semidiurnal migrating tide (SW2) in the lower thermosphere. The model and TIMED/SABER observation show that the SW2 tide amplifies at low latitudes from the stratosphere to the thermosphere as well as the phase variation. Possible mechanisms for the SW2 variability in the low latitude stratosphere could be the change of its propagation condition, especially the (2, 2) mode, due to changing zonal background wind and meridional temperature gradient, and/or an enhancement of its source due to redistribution of stratospheric ozone. Present results also show a prominent long-term variation of the terdiurnal migrating component (TW3) in the ionosphere and atmosphere.

  17. Variabilities of mesospheric tides during sudden stratospheric warming events of 2006 and 2009 and their relationship with ozone and water vapour

    NASA Astrophysics Data System (ADS)

    Sridharan, S.; Sathishkumar, S.; Gurubaran, S.

    2012-04-01

    The present study demonstrates how the relationship between the high latitude northern hemispheric major sudden stratospheric warming (SSW) events of 2006 and 2009 and low-latitude mesospheric tidal variability in zonal winds observed by the MF radar at Tirunelveli (8.70N, 77.8E) exists. It is found that the ozone mixing ratio increases at low latitudes during the SSW and it could probably be due to the SSW induced reversal of meridional circulation towards southward, which may aid the transport of ozone from high to low latitudes, but prevent the same from low to high latitudes. As semi-diurnal tide is produced due to solar insolation absorption of ozone and the increase in the ozone mixing ratio could be a reason for the increase in the semi-diurnal tidal amplitude. The variabilities of diurnal tide appear to be governed mostly by variation of specific humidity at 300 hPa over equator and intraseasonal variability dominates the variabilities in both the parameters.

  18. Impacts of stratospheric ozone depletion and recovery on wave propagation in the boreal winter stratosphere

    NASA Astrophysics Data System (ADS)

    Hu, Dingzhu; Tian, Wenshou; Xie, Fei; Wang, Chunxiao; Zhang, Jiankai

    2015-08-01

    This paper uses a state-of-the-art general circulation model to study the impacts of the stratospheric 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 stratospheric ozone depletion leads to a cooler and stronger Antarctic stratosphere, while the stratospheric ozone recovery has the opposite effects. In the Northern Hemisphere (NH), the impacts of the stratospheric ozone depletion on polar stratospheric temperature are not opposite to that of the stratospheric ozone recovery; i.e., the stratospheric ozone depletion causes a weak cooling and the stratospheric ozone recovery causes a statistically significant cooling. The stratospheric ozone depletion leads to a weakening of the Arctic polar vortex, while the stratospheric 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 stratospheric ozone increases. Particularly interesting is that stratospheric ozone changes have opposite effects on the stationary and transient wave fluxes in the NH stratosphere. The analysis of the wave refractive index and Eliassen-Palm flux in the NH indicates (1) that the wave refraction in the stratosphere cannot fully explain wave flux changes in the Arctic stratosphere and (2) that stratospheric ozone changes can cause changes in wave propagation in the northern midlatitude troposphere which in turn affect wave fluxes in the NH stratosphere. In the SH, the radiative cooling (warming) caused by stratospheric 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 propagating into the stratosphere. The dynamical warming (cooling) caused by stratospheric ozone decreases (increases) partly offsets their radiative cooling (warming).

  19. Stratospheric chemistry

    SciTech Connect

    Brune, W.H. )

    1991-01-01

    Advances in stratospheric chemistry made by investigators in the United States from 1987 to 1990 are reviewed. Subject areas under consideration include photochemistry of the polar stratosphere, photochemistry of the global stratosphere, and assessments of inadvertent modification of the stratosphere 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 stratospheric ozone, and reactive nitrogen effects.

  20. Stratospheric temperatures during the 88-89 Northern Hemisphere winter

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.; Lait, Leslie R.; Schoeberl, Mark R.; Nagatani, Ronald M.

    1990-01-01

    The Airborne Arctic Stratospheric Expedition (AASE) was conducted during January and February 1989. The polar stratosphere during this period was characterized by cold conditions from January to mid-February. A mid-February wave 2 major warming considerably warmed the polar stratosphere, but did not immediately lead to a lower stratospheric vortex breakup. As inferred from temperature data, January temperatures were sufficient for polar stratospheric cloud (PSC) formation. PSC regional extent was greater than the long-term average, but not significantly larger than in previous years.

  1. Stratospheric temperatures during the 88-89 northern hemisphere winter

    SciTech Connect

    Newman, P.A.; Lait, L.R.; Schoeberl, M.R. ); Nagatani, R.M. )

    1990-03-01

    The Airborne Arctic Stratospheric Expedition (AASE) was conducted during January and February 1989. The polar stratosphere during this period was characterized by cold conditions from January to mid-February. A mid-February wave 2 major warming considerably warmed the polar stratosphere, but did not immediately lead to a lower stratospheric vortex breakup. As inferred from temperature data, January temperatures were sufficient for polar stratospheric cloud (PSC) formation. PSC regional extent was greater than the long-term average, but not significantly larger than in previous years.

  2. Stratospheric aerosol geoengineering

    SciTech Connect

    Robock, Alan

    2015-03-30

    The Geoengineering Model Intercomparison Project, conducting climate model experiments with standard stratospheric 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 warm, 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 warming. 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 warming.

  3. Stratospheric aerosol geoengineering

    NASA Astrophysics Data System (ADS)

    Robock, Alan

    2015-03-01

    The Geoengineering Model Intercomparison Project, conducting climate model experiments with standard stratospheric 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 warm, 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 warming. 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 warming.

  4. Atmospheric responses to stratospheric aerosol geoengineering

    NASA Astrophysics Data System (ADS)

    Ferraro, Angus; Highwood, Eleanor; Charlton-Perez, Andrew

    2013-04-01

    Stratospheric aerosol geoengineering, also called solar radiation management (SRM), involves the injection of aerosol into the stratosphere to increase the planetary albedo. It has been conceieved as a policy option in response to human-induced global warming. It is well-established from modelling studies and observations following volcanic eruptions that stratospheric sulphate aerosols cause global cooling. Some aspects of the climate response, especially those involving large-scale dynamical changes, are more uncertain. This work attempts to identify the physical mechanisms operating in the climate response to stratospheric aerosol geoengineering using idealised model experiments. The radiative forcing produced by the aerosol depends on its type (species) and size. Aerosols absorb terrestrial and solar radiation, which drives stratospheric temperature change. The stratospheric temperature change also depends on aerosol type and size. We calculate the stratospheric temperature change due to geoengineering with sulphate, titania, limestone and soot in a fixed-dynamical-heating radiative model. Sulphate produces tropical heating of up to ~6 K. Titania produces much less heating, whereas soot produces much more. Most aerosols increase the meridional temperature gradient in the lower stratosphere which, by thermal wind balance, would be expected to intensify the zonal winds in the polar vortex. An intermediate-complexity general circulation model is used to investigate the dynamical response to geoengineering aerosols. Atmospheric carbon dioxide concentrations are quadrupled. The carbon dioxide forcing is then balanced using stratospheric sulphate aerosol. We assess dynamical changes in the stratosphere, for example, the frequency of stratospheric sudden warmings and the strength of the Brewer-Dobson overturning circulation. We also assess changes in the strength and position of the tropospheric jets. We compare results for sulphate with those for titania.

  5. Stratospheric ozone depletion.

    PubMed

    Rowland, F Sherwood

    2006-05-29

    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 warms the air, creating the stratosphere 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 stratospheric ozone layer. The growing emissions of synthetic chlorofluorocarbon molecules cause a significant diminution in the ozone content of the stratosphere, 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 stratosphere 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

  6. Stratospheric ozone depletion

    PubMed Central

    Rowland, F. Sherwood

    2006-01-01

    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 warms the air, creating the stratosphere 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 stratospheric ozone layer. The growing emissions of synthetic chlorofluorocarbon molecules cause a significant diminution in the ozone content of the stratosphere, 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 stratosphere 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

  7. The Future of the Stratosphere and the Ozone Layer

    NASA Astrophysics Data System (ADS)

    Newman, P. A.; Oman, L.; Pawson, S.; Fleming, E. L.; Li, F.; Jackman, C. H.

    2014-12-01

    Stratospheric 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 stratospheric 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 stratospheric circulation and chemistry changes induced by Greenhouse Gas increases (the "GHG era"). The stratosphere 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 stratospheric ozone levels and the basic stratospheric climatology: CO2 and CH4 increases will increase stratospheric ozone, while N2O increases will decrease stratospheric ozone. In particular, GHG increases and the associated warming of the troposphere will modify stratospheric transport and cool the upper stratosphere. 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 stratosphere evolves under future GHG projections from the various Representative Concentration Pathways, illustrating the different changes in stratospheric ozone caused by the concurrent radiative, chemical and dynamical impacts of GHG changes.

  8. Aspects of the stratospheric circulation as derived from SSU data

    NASA Technical Reports Server (NTRS)

    Michaelis, V.; Oneill, A.

    1985-01-01

    Five years of global data are available for the stratosphere up to 1 mb from Stratospheric Sounding Units (SSUs) on board NOAA satellites. These data form the basis for a climatological study which concentrates on the seasonal and inter-annual variability of the stratosphere and the connection between the stratospheric circulation and that of the troposphere. Particular emphasis is on the structure of the Southern Hemisphere and how it compares with that of the Northern Hemisphere. The characteristic difference in the vertical structure and propagation of disturbances in the two hemispheres is related to differences in the tropospheric flow and the long-term variation of the basic state of the stratosphere. Disturbances in both hemispheres occur in preferred geographical locations. The final warming, marking the transition from westerly to easterly winds, is an example. These occur asymmetrically with respect to the pole as warm air moves over the pole, usually from the same region.

  9. Global Warming: Lessons from Ozone Depletion

    ERIC Educational Resources Information Center

    Hobson, Art

    2010-01-01

    My teaching and textbook have always covered many physics-related social issues, including stratospheric ozone depletion and global warming. The ozone saga is an inspiring good-news story that's instructive for solving the similar but bigger problem of global warming. Thus, as soon as students in my physics literacy course at the University of…

  10. Global Warming: Lessons from Ozone Depletion

    ERIC Educational Resources Information Center

    Hobson, Art

    2010-01-01

    My teaching and textbook have always covered many physics-related social issues, including stratospheric ozone depletion and global warming. The ozone saga is an inspiring good-news story that's instructive for solving the similar but bigger problem of global warming. Thus, as soon as students in my physics literacy course at the University of

  11. Stratospheric aircraft: Impact on the stratosphere?

    SciTech Connect

    Johnston, H.

    1992-02-01

    The steady-state distribution of natural stratospheric 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 stratosphere. Nitrogen oxides from the exhausts of a commercially viable fleet of supersonic transports would exceed the natural source of stratospheric 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 stratospheric 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 stratospheric 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 stratosphere, 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 stratosphere and to broaden our knowledge of hetergeneous stratospheric chemistry. This article reviews recently proposed new mechanisms for heterogeneous reactions on the global stratospheric sulfate aerosols.

  12. Stratospheric aircraft: Impact on the stratosphere

    SciTech Connect

    Johnston, H.

    1992-02-01

    The steady-state distribution of natural stratospheric 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 stratosphere. Nitrogen oxides from the exhausts of a commercially viable fleet of supersonic transports would exceed the natural source of stratospheric 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 stratospheric 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 stratospheric 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 stratosphere, 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 stratosphere and to broaden our knowledge of hetergeneous stratospheric chemistry. This article reviews recently proposed new mechanisms for heterogeneous reactions on the global stratospheric sulfate aerosols.

  13. Interannual and intraseasonal variability of stratospheric dynamics and stratosphere-troposphere coupling during northern winter

    NASA Astrophysics Data System (ADS)

    Pogoreltsev, A. I.; Savenkova, E. N.; Aniskina, O. G.; Ermakova, T. S.; Chen, W.; Wei, K.

    2015-12-01

    The UK Met Office reanalysis data have been used to investigate the interannual and intraseasonal variability of the stratospheric 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 stratosphere, 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 stratospheric warmings (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 stratosphere 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 stratosphere 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 stratosphere in another region occurs. The secondary enhancement of the planetary wave activity in the stratosphere is accompanied by the heating of the polar region and the weakening, or even reversal of the stratospheric jet. Additionally to the well-known result that meridional refraction of SPW to the polar region in stratosphere 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 stratosphere can be considered as the region where SPW2 is generated during SSW.

  14. Weakened stratospheric quasibiennial oscillation driven by increased tropical mean upwelling.

    PubMed

    Kawatani, Yoshio; Hamilton, Kevin

    2013-05-23

    The zonal wind in the tropical stratosphere switches between prevailing easterlies and westerlies with a period of about 28 months. In the lowermost stratosphere, the vertical structure of this quasibiennial oscillation (QBO) is linked to the mean upwelling, which itself is a key factor in determining stratospheric composition. Evidence for changes in the QBO have until now been equivocal, raising questions as to the extent of stratospheric circulation changes in a global warming 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 stratosphere. 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 warming 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 stratosphere. Almost all comprehensive climate models have projected an intensifying tropical upwelling in global warming 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-stratosphere QBO amplitude provides strong support for the existence of a long-term trend of enhanced upwelling near the tropical tropopause. PMID:23698448

  15. Significant radiative impact of volcanic aerosol in the lowermost stratosphere

    NASA Astrophysics Data System (ADS)

    Andersson, Sandra M.; Martinsson, Bengt G.; Vernier, Jean-Paul; Friberg, Johan; Brenninkmeijer, Carl A. M.; Hermann, Markus; van Velthoven, Peter F. J.; Zahn, Andreas

    2015-07-01

    Despite their potential to slow global warming, until recently, the radiative forcing associated with volcanic aerosols in the lowermost stratosphere (LMS) had not been considered. Here we study volcanic aerosol changes in the stratosphere 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 stratosphere aerosol loadings, whereas the Southern Hemisphere generally had loadings close to background conditions. We show that half of the global stratospheric aerosol optical depth following the Kasatochi, Sarychev and Nabro eruptions is attributable to LMS aerosol. On average, 30% of the global stratospheric 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.

  16. Significant radiative impact of volcanic aerosol in the lowermost stratosphere

    PubMed Central

    Andersson, Sandra M.; Martinsson, Bengt G.; Vernier, Jean-Paul; Friberg, Johan; Brenninkmeijer, Carl A. M.; Hermann, Markus; van Velthoven, Peter F. J.; Zahn, Andreas

    2015-01-01

    Despite their potential to slow global warming, until recently, the radiative forcing associated with volcanic aerosols in the lowermost stratosphere (LMS) had not been considered. Here we study volcanic aerosol changes in the stratosphere 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 stratosphere aerosol loadings, whereas the Southern Hemisphere generally had loadings close to background conditions. We show that half of the global stratospheric aerosol optical depth following the Kasatochi, Sarychev and Nabro eruptions is attributable to LMS aerosol. On average, 30% of the global stratospheric aerosol optical depth originated in the LMS during the period 20082011. 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

  17. Studying Stratospheric Temperature Variation with Cosmic Ray Measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaohang; He, Xiaochun

    2015-04-01

    The long term stratospheric cooling in recent decades is believed to be equally important as surface warming as evidence of influences of human activities on the climate system. Un- fortunatly, there are some discrepancies among different measurements of stratospheric 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 stratospheric 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 stratospheric temperature will be discussed. We verify this method by comparing the stratospheric tem- perature measured by radiosonde with the ones derived from cosmic ray measurement at multiple locations around the globe.

  18. Significant radiative impact of volcanic aerosol in the lowermost stratosphere.

    PubMed

    Andersson, Sandra M; Martinsson, Bengt G; Vernier, Jean-Paul; Friberg, Johan; Brenninkmeijer, Carl A M; Hermann, Markus; van Velthoven, Peter F J; Zahn, Andreas

    2015-01-01

    Despite their potential to slow global warming, until recently, the radiative forcing associated with volcanic aerosols in the lowermost stratosphere (LMS) had not been considered. Here we study volcanic aerosol changes in the stratosphere 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 stratosphere aerosol loadings, whereas the Southern Hemisphere generally had loadings close to background conditions. We show that half of the global stratospheric aerosol optical depth following the Kasatochi, Sarychev and Nabro eruptions is attributable to LMS aerosol. On average, 30% of the global stratospheric 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

  19. Downward-Propagating Temperature Anomalies in the Preconditioned Polar Stratosphere.

    NASA Astrophysics Data System (ADS)

    Zhou, Shuntai; Miller, Alvin J.; Wang, Julian; Angell, James K.

    2002-04-01

    Dynamical links of the Northern Hemisphere stratosphere and troposphere are studied, with an emphasis on whether stratospheric changes have a direct effect on tropospheric weather and climate. In particular, downward propagation of stratospheric anomalies of polar temperature in the winter-spring season is examined based upon 22 years of NCEP-NCAR reanalysis data. It is found that the polar stratosphere is sometimes preconditioned, which allows a warm anomaly to propagate from the upper stratosphere to the troposphere, and sometimes it prohibits downward propagation. The Arctic Oscillation (AO) is more clearly seen in the former case. To understand what dynamical conditions dictate the stratospheric property of downward propagation, the upper-stratospheric warming episodes with very large anomalies (such as stratospheric sudden warming) are selected and divided into two categories according to their downward-propagating features. Eliassen-Palm (E-P) diagnostics and wave propagation theories are used to examine the characteristics of wave-mean flow interactions in the two different categories. It is found that in the propagating case the initial wave forcing is very large and the polar westerly wind is reversed. As a result, dynamically induced anomalies propagate down as the critical line descends. A positive feedback is that the dramatic change in zonal wind alters the refractive index in a way favorable for continuous poleward transport of wave energy. The second pulse of wave flux conducts polar warm anomalies farther down. Consequently, the upper-tropospheric circulations are changed, in particular, the subtropical North Atlantic jet stream shifts to the south by 5 degrees of latitude, and the alignment of the jet stream becomes more zonal, which is similar to the negative phase of the North Atlantic Oscillation (NAO).

  20. Benefits, risks, and costs of stratospheric geoengineering

    NASA Astrophysics Data System (ADS)

    Robock, Alan; Marquardt, Allison; Kravitz, Ben; Stenchikov, Georgiy

    2009-10-01

    Injecting sulfate aerosol precursors into the stratosphere has been suggested as a means of geoengineering to cool the planet and reduce global warming. The decision to implement such a scheme would require a comparison of its benefits, dangers, and costs to those of other responses to global warming, including doing nothing. Here we evaluate those factors for stratospheric geoengineering with sulfate aerosols. Using existing U.S. military fighter and tanker planes, the annual costs of injecting aerosol precursors into the lower stratosphere would be several billion dollars. Using artillery or balloons to loft the gas would be much more expensive. We do not have enough information to evaluate more exotic techniques, such as pumping the gas up through a hose attached to a tower or balloon system. Anthropogenic stratospheric aerosol injection would cool the planet, stop the melting of sea ice and land-based glaciers, slow sea level rise, and increase the terrestrial carbon sink, but produce regional drought, ozone depletion, less sunlight for solar power, and make skies less blue. Furthermore it would hamper Earth-based optical astronomy, do nothing to stop ocean acidification, and present many ethical and moral issues. Further work is needed to quantify many of these factors to allow informed decision-making.

  1. Stratospheric response to intraseasonal changes in incoming solar radiation

    NASA Astrophysics Data System (ADS)

    Garfinkel, C. I.; Silverman, V.; Harnik, N.; Haspel, C.; Riz, Y.

    2015-08-01

    Superposed epoch analysis of meteorological reanalysis data is used to demonstrate a significant connection between intraseasonal solar variability and temperatures in the stratosphere. Decreasing solar flux leads to a cooling of the tropical upper stratosphere above 7 hPa, while increasing solar flux leads to a warming of the tropical upper stratosphere above 7 hPa, after a lag of approximately 6-10 days. Late winter (February-March) Arctic stratospheric temperatures also change in response to changing incoming solar flux in a manner consistent with that seen on the 11 year timescale: 10-30 days after the start of decreasing solar flux, the polar cap warms during the easterly phase of the quasi-biennial oscillation. In contrast, cooling is present after decreasing solar flux during the westerly phase of the quasi-biennial oscillation (though it is less robust than the warming during the easterly phase). The estimated composite mean changes in Northern Hemisphere upper stratospheric ( 5 hPa) polar temperatures exceed 8 K 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 stratosphere.

  2. Weather from the Stratosphere?

    NASA Technical Reports Server (NTRS)

    Baldwin, Mark P.; Thompson, David W. J.; Shuckburgh, Emily F.; Norton, Warwick A.; Gillett, Nathan P.

    2006-01-01

    Is the stratosphere, the atmospheric layer between about 10 and 50 km, important for predicting changes in weather and climate? The traditional view is that the stratosphere 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 stratosphere 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 stratosphere above it is less dense and less turbulent (see the figure). Variability in the stratosphere is dominated by hemispheric-scale changes in airflow on time scales of a week to several months. Occasionally, however, stratospheric 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 stratosphere mainly through atmospheric waves that propagate upward. Recent evidence shows that the stratosphere organizes this chaotic wave forcing from below to create long-lived changes in the stratospheric circulation. These stratospheric changes can feed back to affect weather and climate in the troposphere.

  3. Climate and Ozone Response to Increased Stratospheric Water Vapor

    NASA Technical Reports Server (NTRS)

    Shindell, Drew T.

    2001-01-01

    Stratospheric water vapor abundance affects ozone, surface climate, and stratospheric 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 stratospheric water vapor is allowed to increase. Observations suggest that stratospheric 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 stratosphere, suggesting that ongoing climate change may be altering tropospheric input. The calculated stratospheric water vapor increase contributes an additional approximately equals 24% (approximately equals 0.2 W/m(exp 2)) to the global warming 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 warming and impede stratospheric ozone recovery.

  4. How stratospheric are deep stratospheric intrusions?

    NASA Astrophysics Data System (ADS)

    Trickl, T.; Vogelmann, H.; Giehl, H.; Scheel, H.-E.; Sprenger, M.; Stohl, A.

    2014-09-01

    Preliminary attempts of quantifying the stratospheric ozone contribution in the observations at the Zugspitze summit (2962 m a.s.l.) next to Garmisch-Partenkirchen in the German Alps had yielded an approximate doubling of the stratospheric fraction of the Zugspitze ozone during the time period 1978 to 2004. These investigations had been based on data filtering by using low relative humidity (RH) and elevated 7Be as the criteria for selecting half-hour intervals of ozone data representative of stratospheric intrusion air. To quantify the residual stratospheric component in stratospherically influenced air masses, however, the mixing of tropospheric air into the stratospheric intrusion layers must be taken into account. In fact, the dewpoint mirror instrument at the Zugspitze summit station rarely registers RH values lower than 10% in stratospheric air intrusions. Since 2007 a programme of routine lidar sounding of ozone, water vapour and aerosol has been conducted in the Garmisch-Partenkirchen area. The lidar results demonstrate that the intrusion layers are drier by roughly one order of magnitude than indicated in the in situ measurements. Even in thin layers RH values clearly below 1% have frequently been observed. These thin, undiluted layers present an important challenge for atmospheric modelling. Although the ozone values never reach values typical of the lower-stratosphere it becomes, thus, obvious that, without strong wind shear or convective processes, mixing of stratospheric and tropospheric air must be very slow in most of the free troposphere. As a consequence, the analysis the Zugspitze data can be assumed to be more reliable than anticipated. Finally, the concentrations of Zugspitze carbon monoxide rarely drop inside intrusion layers and normally stay clearly above full stratospheric values. This indicates that most of the CO, and thus the intrusion air mass, originates in the shallow "mixing layer" around the thermal tropopause. The CO mixing ratio in these descending layers between 1990 and 2004 exhibits a slightly positive trend indicating some Asian influence on the lowermost stratosphere in the high-latitude source region of most intrusions reaching the station.

  5. How stratospheric are deep stratospheric intrusions?

    NASA Astrophysics Data System (ADS)

    Trickl, T.; Vogelmann, H.; Giehl, H.; Scheel, H.-E.; Sprenger, M.; Stohl, A.

    2014-06-01

    Preliminary attempts of quantifying the stratospheric ozone contribution in the observations at the Zugspitze summit (2962 m a.s.l.) next to Garmisch-Partenkirchen in the German Alps had yielded an approximate doubling of the stratospheric fraction of the Zugspitze ozone during the time period 1978 and 2004. These investigations had been based on data filtering by using low relative humidity and elevated 7Be as the criteria for selecting half-hour intervals of ozone data representative of stratospheric intrusion air. For quantifying the residual stratospheric component in stratospherically influenced air masses, however, the mixing of tropospheric air into the stratospheric intrusion layers must be taken into account. In fact, the dew-point-mirror instrument at the Zugspitze summit station rarely registers relative humidity (RH) values lower than 10% in stratospheric air intrusions. Since 2007 a programme of routine lidar sounding of ozone, water vapour and aerosol has been conducted in the Garmisch-Partenkirchen area. The lidar results demonstrate that the intrusion layers are dryer by roughly one order of magnitude than indicated in the in-situ measurements. Even in thin layers frequently RH values clearly below 1% have been observed. These thin, undiluted layers present an important challenge for atmospheric modelling. Although the ozone values never reach values typical of the lower-stratosphere it becomes, thus, obvious that, without strong wind shear or convective processes, mixing of stratospheric and tropospheric air must be very slow in most of the free troposphere. As a consequence, the analysis the Zugspitze data can be assumed to be more reliable than anticipated. Finally, the concentrations of Zugspitze carbon monoxide rarely drop inside intrusion layers and normally stay clearly above full stratospheric values. This indicates that most of the CO and, thus, the intrusion air mass originate in the shallow "mixing layer" around the thermal tropopause. The CO mixing ratio in these descending layers between 1990 and 2004 exhibits a slightly positive trend indicating some Asian influence on the lowermost stratosphere in the high-latitude source region of most intrusions reaching the station.

  6. The radiative impact of Polar Stratospheric Clouds

    NASA Astrophysics Data System (ADS)

    Wegner, T.; Merrelli, A. J.; Poole, L. R.; Pitts, M. C.

    2014-12-01

    Polar Stratospheric Clouds (PSCs) are an ubiquitous feature in the stratosphere over the polar regions on the winter hemisphere. Heterogeneous chemistry and microphysics of these clouds play a pivotal role in the formation of the ozone hole. We constrain the radiative impact of these clouds utilizing observations from the space-borne lidar CALIPSO and the state of the art radiative transfer model LBLDIS.In addition to spatial and vertical distribution of PSCs, CALIPSO also provides their composition which is used in LBLDIS to calculate their radiative impact.This analysis focuses on the Antarctic winter season of 2008. Here, CALIPSO shows a distinct maximum in integrated optical depth of PSCs east of the Antarctic peninsula which is present throughout the entire winter season. Under clear-sky conditions PSCs can warm the lower stratosphere by several K/day in this region. However, the radiative impact of PSCs is greatly reduced in the presence of underlying tropospheric clouds. With tropospheric cloud parameters provided by CALIPSO we calculate the radiative impact of PSCs for several tropospheric cloud conditions to constrain the potential impact of PSCs on stratospheric temperatures.We find that high tropospheric clouds reduce the heating effect of PSCs and eventually PSCs have a cooling effect on lower stratospheric temperatures. We investigate how the radiative impact of PSCs changes throughout the winter with changing tropospheric conditions and how these locally forced temperature fluctuations impact the formation of PSCs.

  7. Light Absorption in the Stratosphere: Trend, Soot Aerosol Concentration and Contribution by...

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Verma, S.; Strwwa, A. W.; Ferry, G. V.; Hamill, P.; Vay, S.; Gore, Warren J. Y. (Technical Monitor)

    1997-01-01

    The light absorption coefficient, Beta(a) of the stratospheric aerosol is an important quantity that determines its radiative effects. When combined with the aerosol scattering coefficient, Beta(a) it becomes possible to evaluate the aerosol single scatter albedo, omega = Beta(s)/(Beta(s) + Beta(a)) which is essential for modeling the overall radiative effects of the stratospheric aerosol. Pollack1 determined that omega = 0.98 is a critical value that separates stratospheric cooling from warming.

  8. Dynamic characteristics of observed sudden warmings

    NASA Technical Reports Server (NTRS)

    Dartt, D. G.; Venne, D. E.

    1986-01-01

    The planetary wave dynamics of stratospheric sudden warmings in the Northern Hemisphere for a large number of observed events that occurred during winters from 1970 to 1975 and 1978 to 1981 are investigated. The analysis describes wave propagation and zonal flow interaction from the troposphere upwards to near 50 km, and in some years to near 80 km. Three primary topics are covered here: (1) the interaction of zonally propagating and quasi-stationary planetary waves during warming events; (2) planetary wave influence on zonal flow near the stratopause; and (3) planetary wave propagation to near 80 km as seen from Stratospheric and Mesospheric Sounder (SAMS) data.

  9. Stratospheric water vapor feedback

    PubMed Central

    Dessler, A. E.; Schoeberl, M. R.; Wang, T.; Davis, S. M.; Rosenlof, K. H.

    2013-01-01

    We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric water vapor feedback. We estimate the strength of this feedback in a chemistryclimate 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 stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause. PMID:24082126

  10. On the connection between stratospheric water vapour changes and widespread severe denitrification in the Arctic

    NASA Astrophysics Data System (ADS)

    Khosrawi, Farahnaz; Urban, Jo; Lossow, Stefan; Stiller, Gabi; Murtagh, Donal

    2013-04-01

    Water vapour is one of the most important greenhouse gases and plays a key role in the chemistry of the upper troposphere and lower stratosphere (UT/LS). Any changes in atmospheric water vapour bring important implications for the global climate. Long-term ground-based and satellite measurements indicate an increase of stratospheric water vapour abundance by an average of 1 ppmv during the last 30 years (1980-2010). Increases in stratospheric water vapour cool the stratosphere but warm the troposphere. Both the cooling of the stratosphere and the increase in water vapour enhance the potential for the formation of polar stratospheric clouds. More than a decade ago it already was suggested that a cooling of stratospheric temperatures by 1 K or an increase of 1 ppmv of stratospheric water vapor could promote denitrification, the permanent removal of nitrogen species from the stratosphere by solid polar stratospheric cloud particles. In fact, during the two recent Arctic winter 2009/2010 and 2010/2011 the strongest denitrification in the recent decade was measured by Odin/SMR. In the latter winter denitrification lead also to severe ozone depletion with similar extensions as the Antarctic "ozone hole". In this study, the correlation between observed water vapour trends and the recent temperature evolution in the Arctic together with trace gas measurements and PSC observations are considered to investigate a possible connection between the increase in stratospheric water vapour and polar stratospheric cloud formation/denitrification.

  11. Contrasting Effects of Central Pacific and Eastern Pacific El Nino on Stratospheric Water Vapor

    NASA Technical Reports Server (NTRS)

    Garfinkel, Chaim I.; Hurwitz, Margaret M.; Oman, Luke D.; Waugh, Darryn W.

    2013-01-01

    Targeted experiments with a comprehensive chemistry-climate model are used to demonstrate that seasonality and the location of the peak warming of sea surface temperatures dictate the response of stratospheric water vapor to El Nino. In spring, El Nino events in which sea surface temperature anomalies peak in the eastern Pacific lead to a warming at the tropopause above the warm pool region, and subsequently to more stratospheric 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 warm pool region are nonuniform and less water vapor enters the stratosphere. The difference in water vapor in the lower stratosphere between the two variants of El Nino approaches 0.3 ppmv, while the difference between the winter and spring responses exceeds 0.5 ppmv.

  12. Stratospheric Airships: New Opportunities

    NASA Astrophysics Data System (ADS)

    Smith, Ira; Perry, William; West, Mark

    Southwest Research Institute (SwRI) and Aerostar International, Inc. have been involved in developing a lightweight, expendable stratospheric airship since 1997. The concept of a stratospheric airship has been around almost as long as stratospheric free balloons. Airships are defined as lighter-than-air vehicles with propulsion and steering systems. The basic technology that makes stratospheric airships possible is rooted in the free floating stratospheric 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, stratospheric 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 stratospheric airship development, a discussion of the flight environment, key technologies and performance trade study results for stratospheric airships. An overview of the application of this technology to Earth and Space Sciences will be presented.

  13. Trends in stratospheric temperature

    NASA Technical Reports Server (NTRS)

    Schoeberl, M. R.; Newman, P. A.; Rosenfield, J. E.; Angell, J.; Barnett, J.; Boville, B. A.; Chandra, S.; Fels, S.; Fleming, E.; Gelman, M.

    1989-01-01

    Stratospheric temperatures for long-term and recent trends and the determination of whether observed changes in upper stratospheric 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 stratosphere 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 stratospheric ozone changes reported by the Solar Backscatter Ultraviolet (SBUV) instrument aboard Nimbus-7 and the Stratospheric Aerosol and Gas Experiment (SAGE) instruments.

  14. Stratospheric-Tropospheric Interaction and the 2002 Ozone Hole

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.

    2003-01-01

    The 2002 ozone hole was remarkable for its small size and early break-up. This small size resulted from a series of wave events over the course of the 2002 winter. The major event of the 2002 winter was the major warming in late September 2002. This warming resulted from an extremely strong wave event that propagated out of the troposphere, reversed the zonal mean flow, and warmed the polar vortex. This late-September event was the culmination of a series of large wave events which occurred over the course of the 2002 winter. These waves collectively warmed the vortex and decelerated the stratospheric flow. In this talk, we will trace the origin of these wave events, and we will also analyze the feedback of the large disruption of the stratospheric flow on the troposphere.

  15. Satellite stratospheric aerosol measurement validation

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Mccormick, M. P.

    1984-01-01

    The validity of the stratospheric aerosol measurements made by the satellite sensors SAM II and SAGE was tested by comparing their results with each other and with results obtained by other techniques (lider, dustsonde, filter, and impactor). The latter type of comparison required the development of special techniques that convert the quantity measured by the correlative sensor (e.g. particle backscatter, number, or mass) to that measured by the satellite sensor (extinction) and quantitatively estimate the uncertainty in the conversion process. The results of both types of comparisons show agreement within the measurement and conversion uncertainties. Moreover, the satellite uncertainty is small compared to aerosol natural variability (caused by seasonal changes, volcanoes, sudden warmings, and vortex structure). It was concluded that the satellite measurements are valid.

  16. Satellite stratospheric aerosol measurement validation

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Mccormick, M. P.

    1984-01-01

    The validity of the stratospheric aerosol measurements made by the satellite sensors SAM II and SAGE was tested by comparing their results with each other and with results obtained by other techniques (lider, dustsonde, filter, and impactor). The latter type of comparison required the development of special techniques that convert the quantity measured by the correlative sensor (e.g., particle backscatter, number, or mass) to that measured by the satellite sensor (extinction) and quantitatively estimate the uncertainty in the conversion process. The results of both types of comparisons show agreement within the measurement and conversion uncertainties. Moreover, the satellite uncertainty is small compared to aerosol natural variability (caused by seasonal changes, volcanoes, sudden warmings, and vortex structure). It was concluded that the satellite measurements are valid.

  17. The impacts of Unilateral Stratospheric Geoengineering

    NASA Astrophysics Data System (ADS)

    Jones, A.; Haywood, J. M.; Bellouin, N.; Stephenson, D.

    2013-12-01

    Stratospheric 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 warming. Here, we examine both the impacts of hemispherically asymmetric volcanoes in the observational record and the impact of prolonged deliberate injection of stratospheric aerosol into either the northern or southern hemisphere stratosphere 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 stratospheric geoengineering. Figure 1 shows the impacts of the geoengineering simulations which show that stratospheric 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 stratospheric aerosols impacts Sahelian drought, Nature Climate Change, Vol 3, No 7, 660-665, doi: 10.1038/NCLIMATE1857, 2013.

  18. Stratospheric Data Analysis System (STRATAN)

    NASA Technical Reports Server (NTRS)

    Rood, Richard B.; Fox-Rabinovitz, Michael; Lamich, David J.; Newman, Paul A.; Pfaendtner, James W.

    1990-01-01

    A state of the art stratospheric analyses using a coupled stratosphere/troposphere data assimilation system is produced. These analyses can be applied to stratospheric studies of all types. Of importance to this effort is the application of the Stratospheric Data Analysis System (STRATAN) to constituent transport and chemistry problems.

  19. Triton - Stratospheric molecules and organic sediments

    NASA Technical Reports Server (NTRS)

    Thompson, W. Reid; Singh, Sushil K.; Khare, B. N.; Sagan, Carl

    1989-01-01

    Continuous-flow plasma discharge techniques show production rates of hydrocarbons and nitriles in N2 + CH4 atmospheres appropriate to the stratosphere 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 stratosphere. 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 stratosphere 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 stratosphere is as warm as expected. Both organic haze and condensed gases will provide a substantial UV and visible opacity in Triton's atmosphere.

  20. Global Warming.

    ERIC Educational Resources Information Center

    Hileman, Bette

    1989-01-01

    States the foundations of the theory of global warming. Describes methodologies used to measure the changes in the atmosphere. Discusses steps currently being taken in the United States and the world to slow the warming trend. Recognizes many sources for the warming and the possible effects on the earth. (MVL)

  1. LINKAGE BETWEEN CLIMATE CHANGE AND STRATOSPHERIC OZONE DEPLETION

    EPA Science Inventory

    Two primary areas link the issue of stratospheric 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 warming and in depleting the ozon...

  2. Software development: Stratosphere modeling

    NASA Technical Reports Server (NTRS)

    Chen, H. C.

    1977-01-01

    A more comprehensive model for stratospheric chemistry and transport theory was developed for the purpose of aiding predictions of changes in the stratospheric ozone content as a consequence of natural and anthropogenic processes. This new and more advanced stratospheric model is time dependent and the dependent variables are zonal means of the relevant meteorological quantities which are functions of latitude and height. The model was constructed by the best mathematical approach on a large IBM S360 in American National Standard FORTRAN. It will be both a scientific tool and an assessment device used to evaluate other models. The interactions of dynamics, photochemistry and radiation in the stratosphere can be governed by a set of fundamental dynamical equations.

  3. Stratospheric water vapor feedback.

    PubMed

    Dessler, A E; Schoeberl, M R; Wang, T; Davis, S M; Rosenlof, K H

    2013-11-01

    We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric 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 stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause. PMID:24082126

  4. Influence of Stratospheric Ozone Distribution on Tropospheric Circulation Patterns

    NASA Astrophysics Data System (ADS)

    Barodka, Siarhei; Krasouski, Aliaksandr; Mitskevich, Yaroslav; Shalamyansky, Arkady

    2015-04-01

    In the present study we investigate the cause-and-effect relationship between the stratospheric ozone distribution and tropospheric circulation, focusing our attention mainly on the possible "top-down" side of this interaction: the impact of the stratosphere 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 stratospheric ozone distribution, temperature field of the lower stratosphere 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 stratospheric 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 stratospheric 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 stratospheric 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 stratospheric warming (SSW) events. In particular, the November 2013 SSW over Eastern Siberia, which is characterized by abrupt stratospheric temperatures change in the course of one day, can be seen as the origin of the subsequent southward shift of both polar and subtropical fronts in NH with a succeeding displacement of the Intertropical Convergence Zone (ITCZ) and changes of atmospheric circulation pattern in the Southern Hemisphere (SH).

  5. Characteristics of cirrus clouds in the tropical lower stratosphere

    NASA Astrophysics Data System (ADS)

    Iwasaki, Suginori; Luo, Zhengzhao Johnny; Kubota, Hisayuki; Shibata, Takashi; Okamoto, Hajime; Ishimoto, Hiroshi

    2015-10-01

    A unique type of cloud in the tropical lower stratosphere, which we call "stratospheric cirrus", is described in this study. Stratospheric 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 stratospheric cirrus in the tropical and subtropical lower stratosphere 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 stratospheric 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 stratospheric cirrus clouds are likely from an overshooting plume, pushed up into the stratosphere in an overshoot when warm stratospheric air is inhomogeneously mixed with cold overshooting air. The single-layer stratospheric 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 stratospheric 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 stratospheric cirrus clouds occur on the order of 3.0 × 103 times a year between 30 °S and 30 °N. Many of the stratospheric cirrus clouds are found in the pre-monsoon season in the South and Southeast Asia, where convection is deep and intense.

  6. Impact of Oceanic Front on the Northern Hemispheric Coupled Stratosphere/Troposphere-System

    NASA Astrophysics Data System (ADS)

    Nour-Eddine, Omrani; Ogawa, Fumiaki; Nakamura, Hisashi; Keenlyside, Noel; Matthes, Katja

    2014-05-01

    The impact of southern hemisphere oceanic fronts on the large-scale tropospheric circulation and its variability in aquaplanet configurations has widely been studied. For the Northern hemisphere, however, the dynamical and climatic impact of oceanic fronts and their signature in the stratosphere/troposphere coupled system are still poorly understood. Using a set of semi-idealized experiments with a stratosphere-resolving AGCM, it is shown that the extratropical northern hemisphere oceanic fronts play a fundamental role in shaping the large-scale atmospheric circulation and transferring the stratospheric circulation changes into the troposphere. The impact of Northern hemispheric extratropical oceanic fronts on the stratosphere is shown to be dominated by the Kuroshio-Oyashio front and it is similar to the simultaneous impact of land/sea contrast and orography. It is associated with a strong adiabatic stratospheric warming, vortex weakening and a strengthening of the Brower-Dobson circulation, which are all caused mainly by resolved and partially by unresolved wave forcing. The stratospheric signature of oceanic fronts is shown to be important for understanding the very weak ozone destruction seen in the northern hemisphere. Regarding the stratosphere/troposphere coupling it is shown that the northern hemisphere oceanic fronts play a crucial role in transferring the stationary wave-induced stratospheric perturbations into the troposphere and dictating the latitudinal position of the stratosphere/troposphere coupling. The implications of our results for the mechanisms of the stratosphere/troposphere coupling are discussed.

  7. Disentangling the Roles of Various Forcing Mechanisms on Stratospheric Temperature Changes Since 1979 with the NASA GEOSCCM

    NASA Technical Reports Server (NTRS)

    Aquila, Valentina; Swartz, W.; Colarco, P.; Pawson, S.; Polvani, L.; Stolarski, R.; Waugh, D.

    2015-01-01

    Observations show that the cooling of global stratospheric 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 stratospheric 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 stratospheric temperatures, where the decrease in ozone depleting substances due to the Montreal Protocol slowed ozone depletion and therefore also the cooling of the stratosphere. Volcanic eruptions also caused a significant warming of the stratosphere after 1995. The observed general cooling is mainly caused by increasing ozone depleting substances in the lower stratosphere, and greenhouse gases in the middle and upper stratosphere.

  8. Stratospheric benzene and hydrocarbon aerosols detected in Saturn's auroral regions

    NASA Astrophysics Data System (ADS)

    Guerlet, S.; Fouchet, T.; Vinatier, S.; Simon, A. A.; Dartois, E.; Spiga, A.

    2015-08-01

    Context. Saturn's polar upper atmosphere exhibits significant auroral activity; however, its impact on stratospheric 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 stratosphere, 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 (80S), 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 80S than at the equator. This advocates for the inclusion of ion-related reactions in Saturn's chemical models. The polar stratosphere 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 stratosphere. The aerosol mass loading at 80S 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 warms the middle stratosphere by 6 K in summer and cools the upper stratosphere by 5 K in winter. Hence, aerosols linked with auroral activity can partly account for the warm polar hood observed in Saturn's summer stratosphere.

  9. Analysis of the Interactions of Planetary Waves with the Mean Flow of the Stratosphere

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.

    2007-01-01

    During the winter period, large scale waves (planetary waves) are observed to propagate from the troposphere into the stratosphere. Such wave events have been recognized since the 1 950s. The very largest wave events result in major stratospheric warmings. These large scale wave events have typical durations of a few days to 2 weeks. The wave events deposit easterly momentum in the stratosphere, decelerating the polar night jet and warming 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 warmings. We will illustrate some of the differences between major and minor warming wave events. We will further illustrate the feedback by the mean flow on subsequent wave events.

  10. Stratospheric Airship Design Sensitivity

    NASA Astrophysics Data System (ADS)

    Smith, Ira Steve; Fortenberry, Michael; Noll, . James; Perry, William

    2012-07-01

    The concept of a stratospheric or high altitude powered platform has been around almost as long as stratospheric 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 stratospheric 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 stratosphere 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 stratospheric 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.

  11. Urban warming

    SciTech Connect

    Kukla, G.; Gavin, J.; Karl, T.R.

    1986-09-01

    Meteorological stations located in an urban environment in North America warmed between 1941 and 1980, compared to the countryside, at an average rate of about 0,12 /sup 0/C per decade. Secular trends of surface air temperature computed predominately from such station data are likely to have a serious warm bias.

  12. On the feedback of stratospheric clouds on polar climate

    NASA Astrophysics Data System (ADS)

    Kirk-Davidoff, Daniel B.; Schrag, Daniel P.; Anderson, James G.

    2002-06-01

    Past climates, such as the Eocene (55 - 38 Ma), experienced dramatically warmer polar winters. Global climate models run with Eocene-like boundary conditions have under-predicted polar temperatures, a discrepancy which has stimulated a recent hypothesis that polar stratospheric clouds may have been important. We propose that such clouds form in response to higher CO2 via changes in stratospheric circulation and water content. We show that the absence of this mechanism from models of Eocene climate may be attributable to poor vertical resolution in the neighborhood of the tropical tropopause. This may cause the models to underestimate future greenhouse warming.

  13. Human Health Effects of Ozone Depletion From Stratospheric Aircraft

    NASA Technical Reports Server (NTRS)

    Wey, Chowen (Technical Monitor)

    2001-01-01

    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 stratospheric ozone impacts of a hypothetical HSCT fleet, although recent research indicates that a fleet of HSCT is predicted to contribute to climate warming as well. This report also briefly describes the international and domestic institutional frameworks established to address stratospheric ozone depletion, as well as those established to control pollution from aircraft engine exhaust emissions.

  14. Stratospheric dynamics and midlatitude jets under geoengineering with space mirrors and sulfate and titania aerosols

    NASA Astrophysics Data System (ADS)

    Ferraro, A. J.; Charlton-Perez, A. J.; Highwood, E. J.

    2015-01-01

    The impact on the dynamics of the stratosphere of three approaches to geoengineering by solar radiation management is investigated using idealized simulations of a global climate model. The approaches are geoengineering with sulfate aerosols, titania aerosols, and reduction in total solar irradiance (representing mirrors placed in space). If it were possible to use stratospheric aerosols to counterbalance the surface warming produced by a quadrupling of atmospheric carbon dioxide concentrations, tropical lower stratospheric radiative heating would drive a thermal wind response which would intensify the stratospheric polar vortices. In the Northern Hemisphere this intensification results in strong dynamical cooling of the polar stratosphere. Northern Hemisphere stratospheric sudden warming events become rare (one and two in 65 years for sulfate and titania, respectively). The intensification of the polar vortices results in a poleward shift of the tropospheric midlatitude jets in winter. The aerosol radiative heating enhances the tropical upwelling in the lower stratosphere, influencing the strength of the Brewer-Dobson circulation. In contrast, solar dimming does not produce heating of the tropical lower stratosphere, and so there is little intensification of the polar vortex and no enhanced tropical upwelling. The dynamical response to titania aerosol is qualitatively similar to the response to sulfate.

  15. Ozone and the stratosphere

    NASA Technical Reports Server (NTRS)

    Shimazaki, Tatsuo

    1987-01-01

    It is shown that the stratospheric 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 stratosphere, 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 stratospheric ozone layer and thus have a profound impact on the world climate and on life.

  16. Measurements of stratospheric bromine

    NASA Technical Reports Server (NTRS)

    Sedlacek, W. A.; Lazrus, A. L.; Gandrud, B. W.

    1984-01-01

    From 1974 to 1977, molecules containing acidic bromine were sampled in the stratosphere 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 stratosphere. Seasonal variability seems to be small.

  17. A consistent definition of the Arctic polar vortex breakup in both the lower and upper stratosphere

    NASA Astrophysics Data System (ADS)

    Choi, W.; Seo, J.

    2014-12-01

    Breakup of the polar vortex is a dominant feature of the seasonal transition from winter to summer in the stratosphere, which significantly affects stratospheric O3 concentration and tropospheric weather. Previously several criteria for the vortex breakup have been suggested based on the potential vorticity (PV) and wind speed, however, those mainly have focused on the lower stratospheric vortex of which spatiotemporal evolution and decay are more continuous than those of the upper stratospheric vortex. To find a consistent criterion for the vortex breakup in both the lower and upper stratosphere, the present study defined a polar vortex breakup day as when PV gradient at the polar vortex edge becomes lower than that at the subtropical edge on the area equivalent latitude based on PV. With applying the new definition to the UK Met Office reanalysis data, the breakup days of the Arctic polar vortices on 18 isentropic levels from 450 K to 1300 K were calculated for the period of 1993-2005. In comparison with CH4, N2O and O3 measured by the ILAS and POAM II/III satellite instruments, the breakup days are well consistent with changes in the distribution of such tracers as well as their zonal standard deviations associated with the vortex structure breaking and irreversible mixing. The vortex breakup in the upper stratosphere occurs more or less a month prior to that in the middle and lower stratosphere while the stratospheric final warming events occurs simultaneously in the upper and lower stratosphere.

  18. Northern Winter Climate Change: Assessment of Uncertainty in CMIP5 Projections Related to Stratosphere-Troposphere Coupling

    NASA Technical Reports Server (NTRS)

    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.

    2014-01-01

    Future changes in the stratospheric 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-stratosphere circulation. Here we assess northern winter stratospheric change and its potential to influence surface climate change in the Coupled Model Intercomparison Project-Phase 5 (CMIP5) multimodel ensemble. In the stratosphere 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 stratospheric easterly change is common feature in future climate projections. This stratospheric wind change, however, shows a significant spread among the models. By using linear regression, we quantify the impact of tropical upper troposphere warming, polar amplification, and the stratospheric wind change on SLP. We find that the intermodel spread in stratospheric wind change contributes substantially to the intermodel spread in Arctic SLP change. The role of the stratosphere in determining part of the spread in SLP change is supported by the fact that the SLP change lags the stratospheric zonally averaged wind change. Taken together, these findings provide further support for the importance of simulating the coupling between the stratosphere and the troposphere, to narrow the uncertainty in the future projection of tropospheric circulation changes.

  19. Northern winter climate change: Assessment of uncertainty in CMIP5 projections related to stratosphere-troposphere coupling

    NASA Astrophysics Data System (ADS)

    Manzini, E.; Karpechko, A. Yu.; Anstey, J.; 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, D.; Son, S.-W.; Watanabe, S.; Zappa, G.

    2014-07-01

    Future changes in the stratospheric 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-stratosphere circulation. Here we assess northern winter stratospheric change and its potential to influence surface climate change in the Coupled Model Intercomparison Project-Phase 5 (CMIP5) multimodel ensemble. In the stratosphere 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 stratospheric easterly change is common feature in future climate projections. This stratospheric wind change, however, shows a significant spread among the models. By using linear regression, we quantify the impact of tropical upper troposphere warming, polar amplification, and the stratospheric wind change on SLP. We find that the intermodel spread in stratospheric wind change contributes substantially to the intermodel spread in Arctic SLP change. The role of the stratosphere in determining part of the spread in SLP change is supported by the fact that the SLP change lags the stratospheric zonally averaged wind change. Taken together, these findings provide further support for the importance of simulating the coupling between the stratosphere and the troposphere, to narrow the uncertainty in the future projection of tropospheric circulation changes.

  20. Stratospheric temperature increases due to Pinatubo aerosols

    NASA Technical Reports Server (NTRS)

    Labitzke, K.; Mccormick, M. P.

    1992-01-01

    Northern-Hemisphere stratospheric temperatures at 30 and 50 mb beginning in June 1991 are compared with 20-year (1965-1984) and 26-year (1964-1989) monthly means. Significant temperature increases are shown in July, August, September, and October for latitudes from approximately 30 deg N to the equator. In September and October deviations are observed for large areas between the equator and 30 deg N, with temperature increases as high as + 3.5 C occurring at some locations. The monthly averaged zonal mean 30-mb temperatures at 20 deg N in September and October were approximately 2.5 C higher that the 26-year mean, with some daily zonal mean increases of almost 3 C. Higher values occurred equatorward of 20 deg N. These warmings are due to absorption of radiation by the aerosols produced from the June eruptions of the volcano Pinatubo (15.1 deg N, 120.4 deg E) in the Philippines. Stratospheric warmings are expected to be occurring simultaneously at southern latitudes, especially from the equator to about 20 deg S, based on satellite and lidar measurements of the locations of the new aerosol layers. These localized temperature increases should decrease in magnitude and become more global as the cloud disperses globally and spreads in altitude.

  1. Radiative effects of polar stratospheric clouds

    SciTech Connect

    Kinne, S.; Toon, O.B. )

    1990-03-01

    Radiative transfer calculations are performed for polar stratospheric clouds (PSCs) using newly acquired PSC properties and polar atmospheric data. PSC radiative effects depend strongly on upwelling thermal radiation and vary from infrared heating over warm polar surfaces, such as oceans, to cooling over cold surfaces, such as the Antarctic plateau. Heating and cooling rates of nitric acid PSCs are smaller than {plus minus}0.1K/day. Rates for optically thicker ice PSCs vary from 1.0 to {minus}0.2K/day, those for orographically forced ice PSCs even from 3.0 to {minus}0.5K/day. Frequently observed optically thick cirrus decks near the tropopause provide a very cold radiative surface. These clouds not only act to prevent heating and enhance cooling in ice PSCs to {minus}0.5K/day and orographic ice PSCs to {minus}2K/day, but such cirrus cloud decks also cool the entire stratosphere by up to {minus}0.5K/day over warm surfaces, even in the absence of PSCs.

  2. Chlorofluoromethanes and the Stratosphere

    NASA Technical Reports Server (NTRS)

    Hudson, R. D. (Editor)

    1977-01-01

    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 stratospheric 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.

  3. Probing stratospheric ozone

    SciTech Connect

    Rodriguez, J.M. )

    1993-08-27

    This paper is a review of research and present knowledge on ozone layer losses during the winter in the Arctic and Antarctic. Heterogeneous chemical reactions in polar stratospheric clouds and sulfate aerosols are discussed. Methods for determining actual ozone losses are discussed, with particular emphasis on the Arctic ozone layer.

  4. Stratospheric halogens from the western Pacific ocean

    NASA Astrophysics Data System (ADS)

    Quack, B.; Krueger, K.; Tegtmeier, S.; Atlas, E. L.; Bracher, A.; Dinter, T.; Wache, S.; Wallace, D.

    2010-12-01

    Natural, short-lived halocarbons play a role in the stratospheric ozone budget, besides the anthropogenic emitted long-lived chlorine- and bromine fluorocarbons. The tropical oceans are a known source of reactive iodine and bromine to the atmosphere in the form of iodinated and brominated methanes (VSLS), as methyl iodide (CH3I), dibromomethane (CH2Br2) and bromoform (CHBr3), which contributes to reactive bromine within the lower stratosphere. Elevated atmospheric concentrations above the oceans are related to oceanic super-saturations of the compounds, caused by photochemical and biological production. The tropical Western Pacific is of special interest since it is a largely uncharacterized region for the oceanic compounds and in certain regions a projected hot spot for their emissions and transport pathways into the stratosphere. Under the leadership of IFM-GEOMAR (Kiel, Germany) a cruise with RV Sonne was conducted from 9 to 25 October 2009 in the tropical western Pacific to investigate trace gas emissions on a 4030 nm (7,500 km) and 60 degrees latitude covering transit between Tomakomai (Japan, 4235,4N/ 14137,5E) and Townsville (Australia, 1906,6S/ 14650,5E). The ships cruise crossed various biogeochemical regimes of the northern and southern western Pacific Ocean, which differ in seawater properties, currents, productivity and atmospheric dynamics (e.g. Kuroshio Front, Northern Pacific Gyre, Pacific warm pool and Coral Seas). We will present highlights of the oceanic and atmospheric halocarbon measurements during the ships campaign, halocarbon emissions from the western Pacific Ocean, sources and transport calculations, including contributions to stratospheric bromine.

  5. Scientific assessment of stratospheric ozone: 1989, volume 1

    SciTech Connect

    Not Available

    1989-01-01

    A review is presented of the current understanding of stratospheric 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 warming potentials. Other ozone related topics are also discussed: (1) the trends of stratospheric temperature, stratospheric 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.

  6. A Tropical West Pacific OH minimum and implications for stratospheric composition

    NASA Astrophysics Data System (ADS)

    Rex, M.; Wohltmann, I.; Ridder, T.; Lehmann, R.; Rosenlof, K.; Wennberg, P.; Weisenstein, D.; Notholt, J.; Krüger, K.; Mohr, V.; Tegtmeier, S.

    2013-11-01

    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 stratosphere. 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 stratospheric air. We show that this amplifies the impact of surface emissions on the stratospheric composition. Specifically, emissions of biogenic halogenated species from natural sources and from kelp and seaweed farming can have a larger effect on stratospheric ozone depletion. Increasing anthropogenic emissions of SO2 in South East Asia or from minor volcanic eruptions can play a larger role for the stratospheric aerosol budget, a key element for explaining the recently observed decrease in global warming rates (Solomon et al., 2011).

  7. Mesosphere-Stratosphere Coupling: Implications for Climate Variability and Trends

    NASA Technical Reports Server (NTRS)

    Baldwin, Mark P.

    2004-01-01

    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 stratosphere to the troposphere. The observational link for stratospheric sudden warmings 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 stratosphere 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 warming 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 stratosphere evolve through the winter and affect the polar vortex.

  8. In-situ observations of mid-latitude forest fire plumes deep in the stratosphere

    NASA Astrophysics Data System (ADS)

    Jost, Hans-Jürg; Drdla, Katja; Stohl, Andreas; Pfister, Leonhard; Loewenstein, Max; Lopez, Jimena P.; Hudson, Paula K.; Murphy, Daniel M.; Cziczo, Daniel J.; Fromm, Michael; Bui, T. Paul; Dean-Day, J.; Gerbig, Christoph; Mahoney, M. J.; Richard, Erik C.; Spichtinger, Nicole; Pittman, Jasna Vellovic; Weinstock, Elliot M.; Wilson, James C.; Xueref, Irène

    2004-06-01

    We observed a plume of air highly enriched in carbon monoxide and particles in the stratosphere at altitudes up to 15.8 km. It can be unambiguously attributed to North American forest fires. This plume demonstrates an extra-tropical direct transport path from the planetary boundary layer several kilometers deep into the stratosphere, which is not fully captured by large-scale atmospheric transport models. This process indicates that the stratospheric ozone layer could be sensitive to changes in forest burning associated with climatic warming.

  9. In-situ Observations of Mid-latitude Forest Fire Plumes Deep in the Stratosphere

    NASA Technical Reports Server (NTRS)

    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

    2004-01-01

    We observed a plume of air highly enriched in carbon monoxide and particles in the stratosphere 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 stratosphere, which is not fully captured by large-scale atmospheric transport models. This process indicates that the stratospheric ozone layer could be sensitive to changes in forest burning associated with climatic warming.

  10. Sensitivity of Stratospheric Geoengineering with Black Carbon to Aerosol Size and Altitude of Injection

    NASA Technical Reports Server (NTRS)

    Kravitz, Ben; Robock, Alan; Shindell, Drew T.; Miller, Mark A.

    2012-01-01

    Simulations of stratospheric 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 stratosphere would cause little surface cooling for large radii but a large amount of surface cooling for small radii and stratospheric warming of over 60 C. With the exception of small particles, increasing the altitude of injection increases surface cooling and stratospheric warming. Stratospheric warming causes global ozone loss by up to 50% in the small radius case. The Antarctic shows less ozone loss due to reduction of polar stratospheric 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.

  11. Stratospheric geoengineering impacts on El Nio/Southern Oscillation

    NASA Astrophysics Data System (ADS)

    Gabriel, C. J.; Robock, A.

    2015-03-01

    To examine the impact of proposed stratospheric geoengineering schemes on the amplitude and frequency of El Nio/Southern Oscillation (ENSO) variations we examine climate model simulations from the Geoengineering Model Intercomparison Project (GeoMIP) G1-G4 experiments. Here we compare tropical Pacific behavior under anthropogenic global warming (AGW) using the representative concentration pathway resulting in 4.5 W m-2 radiative forcing at the end of the 21st Century, the RCP4.5 scenario, with that under G1-G4 and under historical model simulations. Climate models under AGW project relatively uniform warming across the tropical Pacific over the next several decades. We find no statistically significant change in ENSO frequency or amplitude under stratospheric geoengineering as compared with those that would occur under ongoing AGW.

  12. Surface response to stratospheric aerosol changes in a coupled atmosphere-ocean model

    NASA Astrophysics Data System (ADS)

    Fyfe, J. C.; Salzen, K.; Cole, J. N. S.; Gillett, N. P.; Vernier, J.-P.

    2013-02-01

    Abstract Previous work with a simple climate model has suggested a global cooling impact of increasing <span class="hlt">stratospheric</span> aerosol. Here we use a comprehensive Earth System Model including coupled atmosphere and ocean components to show that increasing <span class="hlt">stratospheric</span> aerosol since the late 1990s has reduced global <span class="hlt">warming</span> by at least 0.07 C to present and that a further global cooling impact will occur if the observed <span class="hlt">stratospheric</span> aerosol trend continues to the end of this decade. This result confirms the previous work and suggests that climate models that do not account for <span class="hlt">stratospheric</span> aerosol increase will overestimate global <span class="hlt">warming</span> to a small but notable degree. An additional new finding is that increasing <span class="hlt">stratospheric</span> aerosol since the late 1990s has reduced the rise in global mean precipitation. Finally, regional patterns of change in simulations with <span class="hlt">stratospheric</span> aerosol increase to year 2020 show ~40% less equatorial precipitation increase and ~60% greater surface pressure decrease around Antarctica, relative to simulations without such <span class="hlt">stratospheric</span> aerosol changes.</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 Nio 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 Nio 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 Nio 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/2015JASTP.136..201S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JASTP.136..201S"><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://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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM21C2206B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM21C2206B"><span id="translatedtitle">Oxygen Compounds in Saturn's <span class="hlt">Stratosphere</span> During the 2010 Northern Storm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bjoraker, G. L.; Hesman, B. E.; Achterberg, R. K.; Jennings, D. E.; Romani, P. N.; Fletcher, L. N.; Irwin, P.</p> <p>2013-12-01</p> <p>The massive storm at 40N on Saturn that began in December 2010 has produced significant and long-lived changes in temperature and species abundances in the <span class="hlt">stratosphere</span> throughout the northern hemisphere (Hesman et al. 2012a, Fletcher et al. 2012). The northern storm region has been observed on many occasions between January 2011 and January 2013 by Cassini's Composite Infrared Spectrometer (CIRS). In this time period, temperatures in regions referred to as 'beacons' (<span class="hlt">warm</span> regions in the <span class="hlt">stratosphere</span> at certain longitudes in the storm latitude) became significantly warmer than pre-storm values of 140K, peaking at 220K in May 2011 followed by gradual cooling. Hydrocarbon emission greatly increased over pre-storm values and then slowly decayed as the beacon cooled. Radiative transfer modeling has revealed that this increased emission is due to enhanced gas abundances for many of these species, rather than simply due to the temperature changes alone (Hesman et al. 2012b, Bjoraker et al 2012). In order to build a comprehensive picture of the changes to the <span class="hlt">stratosphere</span> due to the 2010 northern storm we are now investigating the oxygen compounds in Saturn's <span class="hlt">stratosphere</span> to determine if similar changes in these species were measured. The time evolution of <span class="hlt">stratospheric</span> CO2 and H2O abundances in the beacon regions throughout 2011 and 2012 will be presented and compared with pre-storm measurements made in 2010.</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://ntrs.nasa.gov/search.jsp?R=19890040765&hterms=lait&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dlait','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19890040765&hterms=lait&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dlait"><span id="translatedtitle">Fast, long-lived features in the polar <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>Lait, Leslie R.; Stanford, John L.</p> <p>1988-01-01</p> <p>The analysis method of Salby (1982) is applied to <span class="hlt">Stratospheric</span> Sounding Unit brightness temperatures from the TIROS-N and NOAA-6 satellites. The resulting spectra are used to present further evidence for the wave two and three oscillations found by Prata (1984) and to demonstrate the existence of a wave four feature. Maps of synoptic reconstructions of the brightness temperature fields from the spectra are then used to further characterize the <span class="hlt">warm</span> pools.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/166222','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/166222"><span id="translatedtitle">Carbonyl sulfide: No remedy for global <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Taubman, S.J.; Kasting, J.F.</p> <p>1995-04-01</p> <p>The authors look at the possibility of counteracting global <span class="hlt">warming</span> forces by the injection of carbonyl sulfide (OCS) into the <span class="hlt">stratosphere</span> at levels high enough to balance the impact say of a doubling of carbon dioxide concentrations, which are projected to result in a global 3{degrees} C <span class="hlt">warming</span>. OCS injections at densities to provide such cooling will result a 30 percent impact of global ozone, whereas the carbon dioxide only made a 5% impact. In addition levels which would be found on the earths surface would be in the range 10 ppmv which is questionable as a safe exposure limit for humans, in addition to its impact on the ph of rainwater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930016055','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930016055"><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> </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_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_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" 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_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820010902&hterms=High-resolution+Interferometer+Sounder&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DHigh-resolution%2BInterferometer%2BSounder','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820010902&hterms=High-resolution+Interferometer+Sounder&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DHigh-resolution%2BInterferometer%2BSounder"><span id="translatedtitle"><span class="hlt">Stratospheric</span> instruments and analyses</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1982-01-01</p> <p>The Instruments are divided into two groups, ground based instruments and satellite-borne instruments. The ground based instruments include a Dobson ozone spectrophotometer, a filter ozonometer, and ozonesondes. The satellite-borne instruments include: a backscatter ultraviolet spectrometer, a high resolution infrared radiation sounder, a infrared interferometer spectrometer, a limb radiance inversion radiometer, and multichannel filter radiometer. A list of investigations using <span class="hlt">stratospheric</span> satellite data is presented.</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://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://adsabs.harvard.edu/abs/2009EGUGA..11.9917L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.9917L"><span id="translatedtitle">GEMS <span class="hlt">stratospheric</span> ozone evaluation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lefever, K.; Daerden, F.; Chabrillat, S.; Flentje, H.; Stein, O.; Moinat, P.; Huijnen, V.; Flemming, J.; Schulz, M.; Gems Grg Team</p> <p>2009-04-01</p> <p>The EU FP6 Integrated Project "Global Earth-system (atmosphere) Monitoring using Satellite and in-situ data" (GEMS, http://gems.ecmwf.int/) aims at developing the world's first operational chemical weather system, providing daily analyzes and forecasts for trace atmospheric constituents which are important for climate, air quality and UV radiation. It concerns simulations from the lower troposphere up to the <span class="hlt">stratosphere</span>, on the global as well as on the regional scale. The present poster presents the evaluation of <span class="hlt">stratospheric</span> ozone simulations in the GEMS system during the chosen test year 2003. 4D <span class="hlt">stratospheric</span> ozone fields produced by several development phases of the GEMS system will be assessed. These comprise the standalone CTMs driven by offline meteorological data, forecasts by the coupled GEMS GRG system for global reactive gases and the GEMS GRG reanalyzes, resulting from the assimilation of ozone from SCIAMACHY, MIPAS, GOME and SBUV. To evaluate the performance of each individual run, we compare the ozone fields with both an independent assimilation system (BASCOE) and independent satellite data (TOMS, POAM and HALOE). We present the standardized evaluation routines we developed to this end and the methods we applied to optimally assess the differences between the chemical models and the observational data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=global+AND+heating&id=EJ484206','ERIC'); return false;" href="http://eric.ed.gov/?q=global+AND+heating&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/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/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://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 overall feasibility of such an approach to climate change mitigation.</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://ntrs.nasa.gov/search.jsp?R=19760087420&hterms=climate+change+solutions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dclimate%2Bchange%2Bsolutions','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19760087420&hterms=climate+change+solutions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dclimate%2Bchange%2Bsolutions"><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=Vortex+motion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528Vortex%2Bmotion%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950036038&hterms=Vortex+motion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528Vortex%2Bmotion%2529"><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://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://ntrs.nasa.gov/search.jsp?R=19870057798&hterms=global+warming+effect&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dglobal%2Bwarming%2Beffect','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870057798&hterms=global+warming+effect&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dglobal%2Bwarming%2Beffect"><span id="translatedtitle">Global features of the semiannual oscillation in <span class="hlt">stratospheric</span> temperatures and comparison between seasons and hemispheres</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gao, Xin-Hai; Yu, Wen-Bi; Stanford, John L.</p> <p>1987-01-01</p> <p>Four years of satellite-derived microwave and infrared radiances are analyzed for the three-dimensional and seasonal variation of semiannual oscillations (SAO) in <span class="hlt">stratospheric</span> temperatures, with particular focus on high latitudes, to investigate the effect of <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> on SAO. Separate analyses of individual seasons in each hemisphere reveal that the strongest SAO in temperature occur in the Northern Hemisphere (NH) winter polar upper <span class="hlt">stratosphere</span>. These results, together with the latitudinal structure of the temperature SAO and the fact that the NH polar SAO is nearly out of phase with the lower latitude SAO, are consistent with the existence of a global-scale, meridional circulation on the SAO time scale. The results suggest that polar <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> are an important source of SAO in both high and low latitude <span class="hlt">stratospheric</span> temperature fields. Interannual variations, three-dimensional phase structure, and zonal asymmetry of SAO are also detailed. The SH <span class="hlt">stratospheric</span> SAO is dominated by a localized feature in the high-latitude, eastern hemisphere which tilts westward with height.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20070034992&hterms=climate+changes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dclimate%2Bchanges','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20070034992&hterms=climate+changes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dclimate%2Bchanges"><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://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/abs/1987JAtS...44.2252L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987JAtS...44.2252L"><span id="translatedtitle">Lagrangian Mean Circulations 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>Lyjak, Lawrence V.; Smith, Anne K.</p> <p>1987-08-01</p> <p>Three-dimensional winds derived from LIMS satellite observations for the 1978/79 winter are used to compute the mean Lagrangian motion in the winter <span class="hlt">stratosphere</span>. Material tubes of air parcels are initialized every 4 days and followed for periods of 10 days each. The initial positions of the tubes are chosen so that they lie along contours of constant geopotential and potential temperature. Maps of air parcel distributions give a qualitative picture of the degree of deformation of the material tubes with time. In addition, quantitative measures of the Lagrangian mean velocity and dispersion are computed.During quiet periods, when the zonal wind is strong and the vortex is nearly axisymmetric, the air parcel tubes tend to remain coherent for the full 10 days of the integration. When the wave amplitudes are large, many of the tubes break and the parcels disperse. During the observed minor sudden <span class="hlt">warming</span>, those tubes closest to the vortex center remained coherent with little distortion. In contrast, during the major sudden <span class="hlt">warming</span> every material tube in the <span class="hlt">stratosphere</span> was broken, and there was extensive mixing between air parcels from low and high latitudes.Lagrangian mean vertical motion tended to be smaller than the motion in the transformed Eulerian coordinate system, which is sometimes used to represent the mean Lagrangian flow. The horizontal velocities determined from the Lagrangian parcel trajectories do not in general correspond well with the transformed Eulerian velocities. Largest differences in horizontal winds occur for situations during which the tubes underwent extensive deformation and the dispersion of air parcels was large. This suggests that the transformed Eulerian circulation is not capable of representing the horizontal Lagrangian motion when a large part of the latter is due to dispersive motion rather than to net displacements of coherent material tube.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15..483B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15..483B"><span id="translatedtitle">Retrieval and variability of <span class="hlt">stratospheric</span> aerosols from SCIAMACHY limb-scatter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brinkhoff, Lena A.; Ernst, Florian; Rozanov, Alexei; von Savigny, Christian; Hommel, René; Burrows, John P.</p> <p>2013-04-01</p> <p>SCIAMACHY was one of ten instruments onboard the Envisat spacecraft, detecting the sunlight in the wavelength range from 214 to 2386 nm with three different viewing geometries: nadir, limb and occultation. Limb-scatter measurements have the advantage of high vertical resolution, compared to nadir measurements, and a near-global coverage on the dayside of the Earth, in contrast to solar occultation measurements. We report on the <span class="hlt">stratospheric</span> aerosol retrieval from SCIAMACHY limb-scatter observations. <span class="hlt">Stratospheric</span> aerosols are of scientific interest, as they primarily scatter solar radiation, and therefore increase the Earth's planetary albedo. The permanent aerosol background in the <span class="hlt">stratosphere</span> is due to tropical injection of tropospheric air containing SO2, COS and sulphate particles, which are precursors for <span class="hlt">stratospheric</span> aerosols. An additional contribution is sporadically caused by an uplift of SO2 after a strong volcanic eruption. Especially after strong volcanic eruptions, the consequential effect of <span class="hlt">stratospheric</span> aerosols on the Earth's radiation budget is <span class="hlt">stratospheric</span> <span class="hlt">warming</span> and tropospheric cooling. Furthermore, they have an impact on <span class="hlt">stratospheric</span> chemistry: <span class="hlt">Stratospheric</span> aerosols are precursors for polar <span class="hlt">stratospheric</span> clouds and thus support the destruction of ozone inside the polar vortex. They even lead to a halogen-driven ozone destruction outside polar vortices. On account of these properties, <span class="hlt">stratospheric</span> aerosols concern to the so-called Essential Climate Variables. The present SCIAMACHY aerosol product from 2002 to 2012 will be presented, including validation with co-located SAGE II solar occultation measurements from 2002-05, i.e. for background aerosol. From the data, interesting signatures of volcanic eruptions and bushfires as well as a seasonal cycle and biennial variation in the aerosol load can be identified. However, an improvement of the data quality is planned by using multi-wavelength observations from SCIAMACHY in order to optimize the used phase function, which turned out to be a very influential factor in the retrieval.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMGC22A..09X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMGC22A..09X"><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 of agricultural technology, <span class="hlt">stratospheric</span> geoengineering reduces the yields and productions of major crops in China, especially northeastern China, where the frequency of drought increases. Fertilizer and irrigation both increase crop yields significantly. However, irrigation increases are more important than the fertilizer increases, because the irrigation system can efficiently redistribute water resources during drought and flood. In summary, agricultural technology (e.g., fertilizer and irrigation) largely compensates the effects of <span class="hlt">stratospheric</span> geoengineering on Chinese agriculture, except in some extreme climate events.</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_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" 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_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <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://www.ncbi.nlm.nih.gov/pubmed/21778361','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21778361"><span id="translatedtitle">The persistently variable "background" <span class="hlt">stratospheric</span> aerosol layer and global climate change.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Solomon, S; Daniel, J S; Neely, R R; Vernier, J-P; Dutton, E G; Thomason, L W</p> <p>2011-08-12</p> <p>Recent measurements demonstrate that the "background" <span class="hlt">stratospheric</span> aerosol layer is persistently variable rather than constant, even in the absence of major volcanic eruptions. Several independent data sets show that <span class="hlt">stratospheric</span> aerosols have increased in abundance since 2000. Near-global satellite aerosol data imply a negative radiative forcing due to <span class="hlt">stratospheric</span> aerosol changes over this period of about -0.1 watt per square meter, reducing the recent global <span class="hlt">warming</span> that would otherwise have occurred. Observations from earlier periods are limited but suggest an additional negative radiative forcing of about -0.1 watt per square meter from 1960 to 1990. Climate model projections neglecting these changes would continue to overestimate the radiative forcing and global <span class="hlt">warming</span> in coming decades if these aerosols remain present at current values or increase. PMID:21778361</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950033288&hterms=global+warming+temperature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dglobal%2Bwarming%2Btemperature','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950033288&hterms=global+warming+temperature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dglobal%2Bwarming%2Btemperature"><span id="translatedtitle">Variability in daily, zonal mean lower-<span class="hlt">stratospheric</span> temperatures</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Christy, John R.; Drouilhet, S. James, Jr.</p> <p>1994-01-01</p> <p>Satellite data from the microwave sounding unit (MSU) channel 4, when carefully merged, provide daily zonal anomalies of lower-<span class="hlt">stratosphere</span> temperature with a level of precision between 0.01 and 0.08 C per 2.5 deg latitude band. Global averages of these daily zonal anomalies reveal the prominent <span class="hlt">warming</span> events due to volcanic aerosol in 1982 (El Chichon) and 1991 (Mt. Pinatubo), which are on the order of 1 C. The quasibiennial oscillation (QBO) may be extracted from these zonal data by applying a spatial filter between 15 deg N and 15 deg S latitude, which resembles the meridional curvature. Previously published relationships between the QBO and the north polar <span class="hlt">stratospheric</span> temperatures during northern winter are examined but were not found to be reproduced in the MSU4 data. Sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> in the north polar region are represented in the MSU4 data for latitudes poleward of 70 deg N. In the Southern Hemisphere, there appears to be a moderate relationship between total ozone concentration and MSU4 temperatures, though it has been less apparent in 1991 and 1992. In terms of empirical modes of variability, the authors find a strong tendency in EOF 1 (39.2% of the variance) for anomalies in the Northern Hemisphere polar regions to be counterbalanced by anomalies equatorward of 40 deg N and 40 deg S latitudes. In addition, most of the modes revealed significant power in the 15-20 day period band.</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://www.osti.gov/scitech/biblio/7071585','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7071585"><span id="translatedtitle">Variability in daily, zonal mean lower-<span class="hlt">stratospheric</span> temperatures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Christy, J.R. ); Drouilhet, S.J. Jr. )</p> <p>1994-01-01</p> <p>Satellite data from the microwave sounding unit (MSU) channel 4, when carefully merged, provide daily zonal anomalies of lower-<span class="hlt">stratosphere</span> temperature with a level of precision between 0.01[degrees] and 0.08[degrees]C per 2.5[degrees] latitude band. Global averages of these daily zonal anomalies reveal the prominent <span class="hlt">warming</span> events due to volcanic aerosol in 1982 (El Chichon) and 1991 (Mt. Pinatubo), which are on the order of 1[degrees]C. The quasibiennel oscillation (QBO) may be extracted from these zonal data by applying a spatial filter between 15[degrees]N and 15[degrees]S latitude, which resembles the meridional curvature. Previously published relationships between the QBO and the north polar <span class="hlt">stratospheric</span> temperatures during northern winter are examined but were not found to be reproduced in the MSU4 data. Sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> in the north polar region are represented in the MSU4 data for latitudes poleward of 70[degrees]N. In the Southern Hemisphere, there appears to be a moderate relationship between total ozone concentration and MSU4 temperatures, though it has been less apparent in 1991 and 1992. In terms of empirical modes of variability revealed significant power in the 15-20 day period band.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013DPS....4550907F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013DPS....4550907F"><span id="translatedtitle">IRTF/TEXES observations of Saturns <span class="hlt">stratospheric</span> beacon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fouchet, Thierry; Greathouse, T. K.; Richter, M. J.; Lacy, J.; Fletcher, L.; Spiga, A.</p> <p>2013-10-01</p> <p>On December 5th, 2010, a giant convective storm erupted in Saturns Northern Hemisphere as each Saturnian year at least since 1876. For the first time, a huge thermal and chemical <span class="hlt">stratospheric</span> disturbance associated with this large convective event was detected from ground-based and Cassini observations (Fletcher et al. 2011). This <span class="hlt">stratospheric</span> disturbance is named the beacon. Here, we present high spectral resolution observations of the beacon obtained by the Texas Echelon Cross Echelle Spectrograph (TEXES) mounted on the IRTF during 6 nights from July 15th, 2011 to July 20th, 2011. We targeted several different CH4 lines between 1230 and 1280 cm-1, probing the <span class="hlt">stratospheric</span> temperature between 5 hPa and 0.05 hPa, and the H2 S(1) quadrupolar and collision-induced lines at 587 cm-1, probing the <span class="hlt">stratospheric</span> temperature between 150 hPa and 5 hPa. The <span class="hlt">stratospheric</span> temperatures are retrieved from the dataset using a forward radiative model coupled with a constrained linear inverse method. Within the core of the beacon the maximum temperature inferred from the data is 178K at 40N, hence about 50K warmer than the mean temperature measured before the occurrence of the storm. However, the TEXES data unambiguously demonstrate that this <span class="hlt">warming</span> is not vertically homogeneous but rather confined in a specific pressure range between 1-5 hPa, overhung by a cold layer between 0.1 and 1 hPa. This vertical behavior is evident from the CH4 line spectral profiles with the core of the lines in absorption and the wings in emission. Moreover, our data demonstrate that the altitude of the local temperature maximum increases northwards. We will present how this thermal structure can help deciphering the <span class="hlt">stratospheric</span> heating sources. On the western side of the beacon, the <span class="hlt">stratospheric</span> heating is concentrated at lower pressures, hence higher altitudes, than within the beacon, between 0.1 and 0.01 hPa. We interpret this structure as being caused by convective motions within the beacon, and westward advection associated with a vertical shear of <span class="hlt">stratospheric</span> zonal winds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19730040971&hterms=earth+layers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dearth%2527s%2Blayers','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19730040971&hterms=earth+layers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dearth%2527s%2Blayers"><span id="translatedtitle"><span class="hlt">Stratospheric</span> aerosol layer detection.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cunnold, D. M.; Gray, C. R.; Merritt, D. C.</p> <p>1973-01-01</p> <p>The earth's daytime horizon was scanned on several occasions between 1963 and 1968. The limb was observed at six wavelengths in the ultraviolet and visible spectrum with a narrow field of view instrument on the X-15 aircraft. The inversion of such horizon observations to yield atmospheric density and the concentrations of ozone and aerosol extinctions is discussed. The most significant features of the X-15 data are effects attributed to <span class="hlt">stratospheric</span> aerosols. Observations of both the 20-km aerosol layer and a layer at approximately 50 km are inferred from the data. Both layers apparently possess considerable variability. It is pointed out that the existence of substantial aerosol concentrations above 30 km is an important limitation of the nadir technique of determining ozone concentrations in which the earth's radiance is observed at ultraviolet wavelengths from a satellite.</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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930062150&hterms=Polar+Stratospheric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DPolar%2BStratospheric','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930062150&hterms=Polar+Stratospheric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DPolar%2BStratospheric"><span id="translatedtitle">Radiative feedback of polar <span class="hlt">stratospheric</span> clouds on Antarctic temperatures</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rosenfeld, Joan E.</p> <p>1993-01-01</p> <p>A one-dimensional time marching radiative transfer model has been used to investigate the potential effects of polar <span class="hlt">stratospheric</span> clouds (PSCs) on winter and spring temperatures in the Antarctic lower <span class="hlt">stratosphere</span>. High, middle, and low PSC amounts were specified from lidar backscatter profiles and were chosen to represent the likely range of PSC amounts present in the Antarctic region. The computed effects of the PSCs on temperatures depend strongly on the surface temperature and on the extent of tropospheric cloudiness, and range from a maximum increase of 6 K for a high amount of PSCs over a <span class="hlt">warm</span> surface and clear troposphere to a maximum decrease of 2 K for a high amount of PSCs over a cold surface and a troposphere with high clouds. The average effect is unlikely to be more than a 1 or 2 K temperature change.</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/2014AGUFMGC43B0711G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGC43B0711G"><span id="translatedtitle">Attributing the Global <span class="hlt">Warming</span> Slowdown of the Last Decade</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guemas, V.; Doblas-Reyes, F.</p> <p>2014-12-01</p> <p>Despite a sustained production of anthropogenic greenhouse gases, the Earth's mean near-surface temperature paused its rise from 2000 onward. To explain such a pause, an increase in ocean heat uptake below the superficial ocean layer has been hypothesized to overcompensate for the Earth's heat storage. Contributions have also been suggested from the deep prolonged solar minimum, the <span class="hlt">stratospheric</span> water vapor, the <span class="hlt">stratospheric</span> and tropospheric aerosols. This presentation will illustrate how successful retrospective climate predictions of this <span class="hlt">warming</span> slowdown up to 5 years ahead can be exploited to attribute this slowdown through sensitivity experiments and heat budget analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.A42C..04S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.A42C..04S"><span id="translatedtitle">The Surface Impacts of Arctic <span class="hlt">Stratospheric</span> Ozone Variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, K. L.; Polvani, L. M.; Correa, G. J.</p> <p>2013-12-01</p> <p>Unlike the near complete destruction of <span class="hlt">stratospheric</span> ozone in the Antarctic every spring due to anthropogenic cholorofluorocarbon emissions, ozone concentrations in the Arctic <span class="hlt">stratosphere</span> in winter and spring are highly variable from year to year. Most global climate models (GCMs) prescribe the seasonal cycle of and the trend in ozone but do not include its interannual variability. Here, we investigate the extent to which this variability in Arctic <span class="hlt">stratospheric</span> ozone influences the surface climate of the Northern Hemisphere. To do this, we examine the difference between model integrations with prescribed low (LO; -25% relative to the 1980-2000 climatological model ozone) and high (HI; +25%) winter/spring <span class="hlt">stratospheric</span> ozone from 50-90N, using the Community Atmosphere Model Version 3. The most striking differences between the LO and HI ensembles occur in April and May with significant cooling in the Arctic lower <span class="hlt">stratosphere</span> and a strengthening of the polar vortex, resulting in a delayed final <span class="hlt">warming</span> in the LO ozone ensemble relative to the HI ensemble by approximately two weeks. In the zonal mean, the LO minus HI response resembles the positive phase of the Northern Annular Mode, with low (high) sea level pressure over the poles (mid-latitudes) and a poleward shift of the mid-latitude jet. The poleward shifted jet in the LO integration is accompanied by a significant poleward shift in extratropical precipitation in spring. Regionally, the most significant changes in the tropospheric zonal winds, precipitation and surface temperature occur in Eastern North America and over the North Atlantic. Our work suggests that, by lacking interannual stratosheric ozone variability, most present generation GCMs may be missing an important source of natural, extratropical variability.</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 for billions of people. These regional climate anomalies are but one of many reasons why geoengineering may be a bad idea. I also discuss 19 other reasons. Global efforts to mitigate anthropogenic emissions and to adapt to climate change are a much better way to channel our resources to address anthropogenic global <span class="hlt">warming</span>.</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 Earths 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 ones 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, which should be not less than 10 m. A brief description of this instrument is provided in the report. The SBMG is certified for the use in Russia for "zero-pressure" balloon "VAL 120" capable of drifting at about 30 km height. The obtained data are used in solving the problems of deep sounding of the Earths crust magnetic structure - an extraction of magnetic anomalies, determination of a depth of bedding of magnetoactive rocks and others. Examples of the experiments (data) obtained by SBMG (including along the 9000 km flight track), as a new opportunities in geomagnetism for researchers that could use this device, are shown here. To avoid magnetic noise the sensor of the upper magnetometer is located at 35 meters above the main suspension basket of the balloon (in the small magnetic noise place). As we know, people have a problem to find such places (with a relatively low level of magnetic noise) at other types of balloons. So, for the other types of balloons we have developed and investigated balloon gradiometer with sensors located at a distance of 50 m down from the main suspension basket of the balloon. This decision is optimal for the "superpressure" balloons. The developed launching technology, deployment in flight, assembly, data processing, transfer and landing the containers with the equipment can be used for other similar problems of monitoring and sounding an environment. Useful flight weights of each of three instrumental containers (uniformly placed along a vertical 6 km line) may be reaching 50 kg. More than ten testing flights (1986-2013) at <span class="hlt">stratospheric</span> altitudes (20-30 km) have proven the reliability of this system.</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, larger injections might be required than previously assumed. Rasch et al. (2008) showed that smaller particles would be advantageous in terms of cooling the surface. However, with a continuous injection of sulphur dioxide into to lower tropical <span class="hlt">stratosphere</span> aerosol size distributions with mode radii larger than 0.5 microns are likely to form. An additional complication is that the sedimenting particles tend to heat the tropical tropopause region and as a consequence the entry mixing ratio of water vapour increases. For the extreme scenario of 10 Mt/year injection SOCOL predicts an enhancement of the water vapour entry mixing ratio by more than 1 ppmv. This is predicted to have a significant impact on the radiative forcing and the total ozone, because of enhanced heterogeneous reactions and because the increased water vapour intensifies the hydrogen and chlorine catalysed ozone destruction cycles. The intense <span class="hlt">warming</span> of the lower <span class="hlt">stratosphere</span> further intensifies the catalytic ozone destruction cycles. Furthermore, the <span class="hlt">stratospheric</span> circulation is predicted to change due to the strong heating of the lower <span class="hlt">stratosphere</span>. As a consequence of the intensified meridional temperature gradient the polar vortices are strengthened with enhanced formation of polar <span class="hlt">stratospheric</span> clouds and ozone depletion. The ozone loss due to changed <span class="hlt">stratospheric</span> dynamic is four times larger than the ozone loss caused by the increase of aerosol surface for heterogeneous reactions, which would postpone the recovery of the ozone hole even more as already pointed out by Tilmes et al. [2008]. At the same time the uncertainties involved in the different modelling steps are tremendous. Model validation, by comparing model runs of the 1991 Mt. Pinatubo eruption with observations, reveals that the temperature increase in the lower <span class="hlt">stratosphere</span> and the tropopause region is probably overestimated by SOCOL. Other CCMs show similar behaviour. This lets us conclude that with the present modelling tools we are not capable to reliably predict the changes in <span class="hlt">stratospheric</span> climate following geoengineering applications. Rasch, P. J. et al. (2008), Exploring the geoengineering of climate using <span class="hlt">stratospheric</span> sulfate aerosols: The role of particle size, Geophysical Research Letters, 35 (2), L02,809. Tilmes, S. et al. (2008), The sensitivity of polar ozone depletion to proposed geoengineering schemes, Science, 320 (5880), 1201-1204.</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_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" 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_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12..918A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12..918A"><span id="translatedtitle"><span class="hlt">Stratospheric</span> ozone loss and Antarctic climate change: an update from a <span class="hlt">stratosphere</span> resolving Chemistry Climate Model simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abalichin, Janna; Kubin, Anne; Grieger, Jens; Langematz, Ulrike; Leckebusch, Gregor C.; Joeckel, Patrick; Brhl, Christoph</p> <p>2010-05-01</p> <p>The evolution of Antarctic climate during the past four decades was characterized by enhanced tropospheric westerlies and a negative trend in near-surface temperature over the Antarctic plateau during the austral summer, while the Antarctic Peninsula showed a <span class="hlt">warming</span> (Thompson and Solomon, 2002). Model simulations suggested that these trends are most certainly attributable to the Antarctic ozone depletion since the early 1980s (Gillett and Thompson, 2003). However, the more recent publication of Steig et al. (2009) finds a <span class="hlt">warming</span> of the whole Antarctic continent since 1957 in data from satellites and automatic weather stations. Motivated by this discussion we have analysed changes in <span class="hlt">stratospheric</span> ozone, temperature and dynamics, and the corresponding signal in Antarctic climate in a transient simulation of the period 1960 to 2000, performed with the <span class="hlt">stratosphere</span>-troposphere Chemistry-Climate Model (CCM) EMAC. The model has been integrated following the SCN2d scenario recommendations of the SPARC CCMVal initiative for the temporal evolution of greenhouse gases, ozone depleting substances and sea surface temperatures/sea ice. The model reproduces the main observed features of the Antarctic <span class="hlt">stratosphere</span> since the 1960s, e.g. the establishment of the ozone hole in the 1980s, a negative <span class="hlt">stratospheric</span> temperature trend, and a longer lived and deeper polar vortex and its more intense breakdown. The enhancement of the tropospheric jet is well reproduced as well. With respect to the near surface trends the model seems to support the recently published results of a weak positive temperature trend all over Antarctica. Analyses of heat and humidity fluxes will be used to support the interpretation of the model results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/166245','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/166245"><span id="translatedtitle">Modeled impacts of <span class="hlt">stratospheric</span> ozone and water vapor perturbations with implications for high-speed civil transport aircraft</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rind, D.; Lonergan, P.</p> <p>1995-04-20</p> <p>Ozone and water vapor perturbations are explored in a series of experiments with the Goddard Institute for Space Studies climate/middle atmosphere model. Large perturbations, and realistic perturbations, to <span class="hlt">stratospheric</span> ozone and water vapor are investigated, with and without allowing sea surface temperatures to change, to illuminate the nature of the dynamic and climatic impact. Removing ozone in the lower <span class="hlt">stratosphere</span> without allowing sea surface temperatures to change results in in situ cooling of up to 10{degrees}C in the tropical lower <span class="hlt">stratosphere</span>, with radiative <span class="hlt">warming</span> about half as large in the middle <span class="hlt">stratosphere</span>. The temperature changes induce increases in tropospheric and lower <span class="hlt">stratospheric</span> eddy energy and in the lower <span class="hlt">stratosphere</span> residual circulation of the order of 10%. When sea surface temperatures are allowed to respond to this forcing, the global, annual-average surface air temperature cools by about 1{degrees}C as a result of the decreased ozone greenhouse capacity, reduced tropospheric water vapor, and increased cloud cover. For more realistic ozone changes, as defined in the High-Speed Research Program/Atmospheric Effects of <span class="hlt">Stratospheric</span> Aircraft reports, the <span class="hlt">stratosphere</span> generally cools by a few tenths degrees Celsius. In this case, the surface air temperature change is not significant, due to the conflicting influences of <span class="hlt">stratospheric</span> ozone reduction and tropospheric ozone increase, although high-latitude cooling of close to 0.5{degrees}C does occur consistently. With a more realistic increase of <span class="hlt">stratospheric</span> water vapor of 7%, the middle atmosphere cools by 0.5{degrees}C or less, and the surface temperature change is neither significant nor consistent. Overall, the experiments emphasize that <span class="hlt">stratospheric</span> changes affect tropospheric dynamics, and that tropospheric feedback processes and natural variability are important when assessing the climatic response to aircraft emissions. 21 refs., 20 figs., 3 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930001903','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930001903"><span id="translatedtitle"><span class="hlt">Stratospheric</span> processes: Observations and interpretation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brune, William H.; Cox, R. Anthony; Turco, Richard; Brasseur, Guy P.; Matthews, W. Andrew; Zhou, Xiuji; Douglass, Anne; Zander, Rudi J.; Prendez, Margarita; Rodriguez, Jose M.</p> <p>1991-01-01</p> <p>Explaining the observed ozone trends discussed in an earlier update and predicting future trends requires an understanding of the <span class="hlt">stratospheric</span> processes that affect ozone. <span class="hlt">Stratospheric</span> processes occur on both large and small spatial scales and over both long and short periods of time. Because these diverse processes interact with each other, only in rare cases can individual processes be studied by direct observation. Generally the cause and effect relationships for ozone changes were established by comparisons between observations and model simulations. Increasingly, these comparisons rely on the developing, observed relationships among trace gases and dynamical quantities to initialize and constrain the simulations. The goal of this discussion of <span class="hlt">stratospheric</span> processes is to describe the causes for the observed ozone trends as they are currently understood. At present, we understand with considerable confidence the <span class="hlt">stratospheric</span> processes responsible for the Antarctic ozone hole but are only beginning to understand the causes of the ozone trends at middle latitudes. Even though the causes of the ozone trends at middle latitudes were not clearly determined, it is likely that they, just as those over Antarctica, involved chlorine and bromine chemistry that was enhanced by heterogeneous processes. This discussion generally presents only an update of the observations that have occurred for <span class="hlt">stratospheric</span> processes since the last assessment (World Meteorological Organization (WMO), 1990), and is not a complete review of all the new information about <span class="hlt">stratospheric</span> processes. It begins with an update of the previous assessment of polar <span class="hlt">stratospheres</span> (WMO, 1990), followed by a discussion on the possible causes for the ozone trends at middle latitudes and on the effects of bromine and of volcanoes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6488246','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6488246"><span id="translatedtitle">Superpressure <span class="hlt">stratospheric</span> vehicle</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chocol, C.; Robinson, W.; Epley, L.</p> <p>1990-09-15</p> <p>Our need for wide-band global communications, earth imaging and sensing, atmospheric measurements and military reconnaissance is extensive, but growing dependence on space-based systems raises concerns about vulnerability. Military commanders require space assets that are more accessible and under local control. As a result, a robust and low cost access to space-like capability has become a national priority. Free floating buoyant vehicles in the middle <span class="hlt">stratosphere</span> can provide the kind of cost effective access to space-like capability needed for a variety of missions. These vehicles are inexpensive, invisible, and easily launched. Developments in payload electronics, atmospheric modeling, and materials combined with improving communications and navigation infrastructure are making balloon-borne concepts more attractive. The important milestone accomplished by this project was the planned test flight over the continental United States. This document is specifically intended to review the technology development and preparations leading up to the test flight. Although the test flight experienced a payload failure just before entering its assent altitude, significant data were gathered. The results of the test flight are presented here. Important factors included in this report include quality assurance testing of the balloon, payload definition and characteristics, systems integration, preflight testing procedures, range operations, data collection, and post-flight analysis. 41 figs., 5 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993AdSpR..13...33R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993AdSpR..13...33R"><span id="translatedtitle">The superpressure <span class="hlt">stratospheric</span> vehicle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rand, J. L.; Seely, L. G.; Lew, T. M.</p> <p>1993-02-01</p> <p>The scientific community has been interested for many years in obtaining a reliable, long duration platform in the <span class="hlt">stratosphere</span> from which measurements could be made of transient events. In addition, other applications have been envisioned which may include anything from communication relays to environmental sampling. Because of the wide variety of applications possible, Winzen International has undertaken the task of developing a balloon system which will not exhibit the failure modes of prior attempts and has the potential to be scaled up to sizes comparable to zero pressure balloons. In addition, new manufacturing techniques have been developed which will permit these balloons to be built almost as economically as polyethylene balloons. This paper will describe the use of biaxially oriented nylon film in the development of this unique system. This film exhibits a number of properties, both optical and mechanical, which work together to produce a feasible system. A method was then found to adapt the construction techniques with proven reliability for zero pressure balloons to this design to produce a leak free system. The results of inflation testing and flight testing will be presented along with plans for further flight testing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19810037718&hterms=Mount+St+Helens&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2528%2528Mount%2BSt%2529%2BHelens%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810037718&hterms=Mount+St+Helens&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2528%2528Mount%2BSt%2529%2BHelens%2529"><span id="translatedtitle">Long-wave <span class="hlt">stratospheric</span> transmission of Mount St. Helens ejecta</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kuhn, P. M.; Haughney, L. C.; Innis, R. C.</p> <p>1981-01-01</p> <p>The NASA/Ames Research C-141 aircraft underflew the Mount St. Helens ejecta plume in Utah three days after the eruption. Upward-looking 20-40-microns on-board radiometry provided data resulting in a calculated long-wave transmission of 0.93. From this value, an optical depth of 0.073 is inferred. This value is compared with an accepted background, <span class="hlt">stratospheric</span> infrared optical depth of 0.06. Assumptions on particle size, shortwave albedo, and thermal <span class="hlt">warming</span> imply little surface temperature change caused by the ejecta on the third day immediately following the eruption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6848426','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6848426"><span id="translatedtitle">Long-wave <span class="hlt">stratospheric</span> transmission of Mount St. Helens ejecta</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kuhn, P.M.; Haughney, L.C.; Innis, R.C.</p> <p>1981-01-01</p> <p>The NASA/Ames Research C-141 aircraft underflew the Mount St. Helens ejecta plume in Utah three days after the eruption. Upward-looking 20--40-..mu..m on-board radiometry provided data resulting in a calculated long-wave transmission of 0.93. From this value, an optical depth of 0.073 is inferred. This value is compared with an accepted background, <span class="hlt">stratospheric</span> infrared optical depth of 0.06. Assumptions on particle size, shortwave albedo, and thermal <span class="hlt">warming</span> imply little surface temperature change caused by the ejecta on the third day immediately following the eruption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1710223L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1710223L"><span id="translatedtitle">Optimizing <span class="hlt">stratospheric</span> sulfur geoengineering by seasonally changing sulfur injections</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laakso, Anton; Partanen, Antti-Ilari; Kokkola, Harri; Lehtinen, Kari; Korhonen, Hannele</p> <p>2015-04-01</p> <p>Solar radiation management (SRM) by <span class="hlt">stratospheric</span> sulfur injection has been shown to have potential in counteracting global <span class="hlt">warming</span> if reducing of greenhouse gases has not been achieved fast enough and if climate <span class="hlt">warming</span> will continue. Injecting large amounts of sulfate particles to the <span class="hlt">stratosphere</span> would increase the reflectivity of the atmosphere and less sunlight would reach the surface. However, the effectivity (per injected sulphur mass unit) of this kind of geoengineering would decrease when amount of injected sulfur is increased. When sulfur concentration increases, <span class="hlt">stratospheric</span> particles would grow to larger sizes which have larger gravitational settling velocity and which do not reflect radiation as efficiently as smaller particles. In many previous studies, sulfur has been assumed to be injected along the equator where yearly mean solar intensity is the highest and from where sulfur is spread equally to both hemispheres. However, the solar intensity will change locally during the year and sulfate has been assumed to be injected and spread to the hemisphere also during winter time, when the solar intensity is low. Thus sulfate injection could be expected to be more effective, if sulfur injection area is changed seasonally. Here we study effects of the different SRM injection scenarios by using two versions of the MPI climate models. First, aerosol spatial and temporal distributions as well as the resulting radiative properties from the SRM are defined by using the global aerosol-climate model ECHAM6.1-HAM2.2-SALSA. After that, the global and regional climate effects from different injection scenarios are predicted by using the Max Planck Institute's Earth System Model (MPI-ESM). We carried out simulations, where 8 Tg of sulfur is injected as SO2 to the <span class="hlt">stratosphere</span> at height of 20-22 km in an area ranging over a 20 degree wide latitude band. Results show that changing the sulfur injection area seasonally would lead to similar global mean shortwave radiative forcing (-4.41 W/m2 at top of atmosphere) as if sulfur is injected only to the equator (-4.40 W/m2). However zonal mean distribution would be different and forcing is concentrated relatively more to the midlatitudes and less to the equator. Cooling effect from the geoengineering and <span class="hlt">warming</span> effect from the increased greenhouse gas has been shown in many studies to lead to cooling in the equator and <span class="hlt">warming</span> in the poles compared the preindustrial conditions. Changing the injection area seasonally might prevent this from happening and lead globally to more homogeneous temperature change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.5224D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.5224D"><span id="translatedtitle">Boreal winter modes of circulation in the <span class="hlt">stratosphere</span>-troposphere system under the influence of the ENSO polarity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de La Cmara, lvaro; Garca-Serrano, Javier; Serrano, Encarna</p> <p>2010-05-01</p> <p>The <span class="hlt">stratospheric</span> circulation has been recently proposed to play an important role in transmitting the ENSO signal to the Euro-Atlantic region, which projects on annular-like patterns. In this context, the influence of the ENSO polarity on the winter circulation modes in the <span class="hlt">stratosphere</span>-troposphere system over the Northern Hemisphere is studied. Principal Component Analysis of the geopotential at different levels is performed partitioning the data into El Nio and La Nia winters (DJFM; 1957/58-2001/02 period). On the one hand, it is found that the 20-hPa annular mode retains almost a 10% more variance of the geopotential in cold-La Nia than in <span class="hlt">warm</span>-El Nio winters. However, <span class="hlt">stratospheric</span> zonal-wavenumber-1 modes accumulate more variability for <span class="hlt">warm</span>-El Nio winters. Our results support the presence of more <span class="hlt">stratospheric</span> wave-like anomalies coming from the troposphere during <span class="hlt">warm</span>-El Nio conditions. On the other hand, the spatial structure of the surface annular-like mode during <span class="hlt">warm</span>-El Nio winters presents a clear difference with the neutral-conditions pattern, which is well-known to have a weak (but statistically significant) Azores-Aleutian positive correlation. Concretely, El Nio case shows anticorrelated anomalies between the Azores and Aleutian centres, which implies the presence of anomalies of the same sign at middle and high latitudes in the North Pacific. During La Nia winters, the Aleutian centre in the annular mode reinforces. The discrepancy between El Nio and La Nia surface patterns is also found in the surface signature associated with the corresponding <span class="hlt">stratospheric</span> annular mode. Our results point to a <span class="hlt">stratosphere</span>-troposphere interaction in the mentioned differences, which agrees with previous works that highlight the role of the <span class="hlt">stratosphere</span> in connecting the North Pacific and the North Atlantic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16..419D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16..419D"><span id="translatedtitle">The effects of <span class="hlt">stratosphere</span>-troposphere coupling on the decadal predictability of the climate system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>D'Errico, Miriam; Bellucci, Alessio; Cagniazzo, Chiara; Gualdi, Silvio</p> <p>2014-05-01</p> <p>The coupled ocean-atmosphere CMCC-CMS model is used to investigate the influence of the <span class="hlt">stratosphere</span> on the decadal predictability. As part of the EU-funded COMBINE Project, a set of decadal prediction experiments are performed for the 1960-2005 period, following the CMIP5 protocol using historical radiative forcing conditions, followed by RCP4.5 scenario settings from 2006 onward. The decadal predictions consist in 3-member ensembles of 10-year simulations starting at 5-year intervals, with the ocean initial states provided by ocean reanalyses differing by assimilation methods and assimilated data. A purpose of this work is to asses the impact of the initialization to reproduce climate variations with respect to an uninitialized climate simulation performed for the same time period of the predictions using identical forcing conditions. Focus is also laid on the differences between simulations by high-top configuration (CMCC-CMS), including a well-resolved <span class="hlt">stratosphere</span> and equivalent simulations using a low top model differing only in vertical extent and vertical resolution, to estimate how the inclusion of a well-represented <span class="hlt">stratosphere</span> could impact climate predictability on the decadal time scale. The <span class="hlt">stratospheric</span> predictability was further examined by focusing on the statistics of sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) events considered one of the most important <span class="hlt">stratosphere</span>-troposphere dynamical coupling processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880050731&hterms=GLA&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DGLA','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880050731&hterms=GLA&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DGLA"><span id="translatedtitle">Forecast experiments with the NASA/GLA <span class="hlt">stratospheric</span>/tropospheric 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>Takano, Kenji; Baker, Wayman E.; Kalnay, Eugenia; Lamich, David J.; Rosenfield, Joan E.</p> <p>1987-01-01</p> <p>For the first time, a four-dimensional <span class="hlt">stratospheric</span>/tropospheric data assimilation system with a top analysis level at 0.4 mb has been developed and used to produce physically consistent gridded analyses for the <span class="hlt">stratosphere</span> as well as the troposphere for a period during the First GARP Global Experiment (FGGE) and Limb Infrared Monitor of the <span class="hlt">Stratosphere</span> (LIMS) (November 1978-May 1979). The system consists of a two-dimensional optimum interpolation analysis with 18 mandatory pressure levels and a 19-level fourth order <span class="hlt">stratospheric</span>/tropospheric general circulation model with a horizontal resolution of 4 (latitude) by 5 deg (longitude) and a top at 0.3 mb. The system allows the utilization of <span class="hlt">stratospheric</span> data including LIMS, Tiros-N retrievals, rocketsondes and vertical temperature profile radiometer soundings in addition to the other FGGE level 2b data. These data are analyzed every six hours. In order to examine the quality of the analyzed data, forecast experiments starting from different analyses are performed for the period of the <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span> of late February 1979. The results indicate that by employing the present four-dimensional assimilation approach, the medium-range forecast skill for this event is improved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A11J0177S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A11J0177S"><span id="translatedtitle">The Role of <span class="hlt">Stratospheric</span> Vortex Breakdown in Southern Hemisphere Climate Trends</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, L.; Chen, G.; Robinson, W. A.</p> <p>2012-12-01</p> <p>Observations indicate that the final breakdown of the <span class="hlt">stratospheric</span> polar vortex, the <span class="hlt">stratospheric</span> final <span class="hlt">warming</span> (SFW), in the Southern Hemisphere was increasingly delayed in the late 20th century, presumably a consequence of anthropogenic ozone depletion. This paper investigates the connection between this delay and climate trends in the austral <span class="hlt">stratosphere</span> and troposphere. We present a new way to characterize the downward influence of <span class="hlt">stratospheric</span> ozone depletion on tropospheric climate trends, based on the trend in the date of the SFW. Trends in zonal winds in the <span class="hlt">stratosphere</span> and troposphere are decomposed into two components: those due to the change in the SFW date and those resulting from the change in the speed with which the vortex breaks down. In the reanalysis and in climate model output, the trend in the <span class="hlt">stratosphere</span> is primarily associated with the delayed date of the vortex breakdown, while slowing and weakening of SFW events explains much of the downward influence of ozone depletion into the troposphere. The climate trends reproduce the association, observed in interannual variability, between the late and weak SFW events, and weaker/slower events have a smaller influence on the tropospheric circulation than stronger/faster ones. Thus, most of the late 20th century climate trends in the Southern Hemisphere can be understood as a consequence of delayed SFWs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20020050917&hterms=absorption+cooling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dabsorption%2Bcooling','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20020050917&hterms=absorption+cooling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dabsorption%2Bcooling"><span id="translatedtitle">Light Absorption of <span class="hlt">Stratospheric</span> Aerosols: Long-Term Trend and Contribution by Aircraft</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pueschel , R. F.; Gore, Waren J. Y. (Technical Monitor)</p> <p>1997-01-01</p> <p>Measurements of aerosol light-absorption coefficients are useful for studies of radiative transfer and heating rates. Ogren appears to have published the first light- absorption coefficients in the <span class="hlt">stratosphere</span> in 1981, followed by Clarke in 1983 and Pueschel in 1992. Because most <span class="hlt">stratospheric</span> soot appears to be due to aircraft operations, application of an aircraft soot aerosol emission index to projected fuel consumption suggests a threefold increase of soot loading and light absorption by 2025. Together, those four data sets indicate an increase in mid-visible light extinction at a rate of 6 % per year. This trend is similar to the increase per year of sulfuric acid aerosol and of commercial fleet size. The proportionality between stepped-up aircraft operations above the tropopause and increases in <span class="hlt">stratospheric</span> soot and sulfuric acid aerosol implicate aircraft as a source of <span class="hlt">stratospheric</span> pollution. Because the strongly light-absorbing soot and the predominantly light-scattering sulfuric acid aerosol increase at similar rates, however, the mid-visible <span class="hlt">stratospheric</span> aerosol single scatter albedo is expected to remain constant and not approach a critical value of 0.98 at which <span class="hlt">stratospheric</span> cooling could change to <span class="hlt">warming</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850019103','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850019103"><span id="translatedtitle">Measurement of Elements 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>Anderson, J. G.</p> <p>1985-01-01</p> <p>Balloon-borne winch system; <span class="hlt">stratospheric</span> free radicals; <span class="hlt">stratospheric</span> sounding; copper vapor lasers; ozone measurement; NO2 analysis; chlorine chemistry; trace elements; and ClO observations are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=35285&keyword=stratosphere&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=50569182&CFTOKEN=77847468','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=35285&keyword=stratosphere&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=50569182&CFTOKEN=77847468"><span id="translatedtitle"><span class="hlt">STRATOSPHERIC</span> OZONE DEPLETION: IMPLICATIONS FOR MARINE ECOSYSTEMS</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>The <span class="hlt">stratospheric</span> ozone layer shields the earth from biologically damaging solar ultraviolet radiation. Chlorofluorocarbons (CFCs), used in refrigerants, etc. and halons, used in fire extinguishers, escape into the lower atmosphere and migrate to the <span class="hlt">stratosphere</span>, destroying the ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940033440&hterms=lait&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dlait','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940033440&hterms=lait&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dlait"><span id="translatedtitle"><span class="hlt">Stratospheric</span> meteorological conditions in the Arctic polar vortex, 1991 to 1992</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Newman, P.; Lait, L. R.; Schoeberl, M.; Nash, E. R.; Kelly, K.; Fahey, D. W.; Nagatani, R.; Toohey, D.; Avallone, L.; Anderson, J.</p> <p>1993-01-01</p> <p><span class="hlt">Stratospheric</span> meteorological conditions during the Airborne Arctic <span class="hlt">Stratospheric</span> Expedition II (AASE II) presented excellent observational opportunities from Bangor, Maine, because the polar vortex was located over southeastern Canada for significant periods during the 1991-1992 winter. Temperature analyses showed that nitric acid trihydrates (NAT temperatures below 195 K) should have formed over small regions in early December. The temperatures in the polar vortex <span class="hlt">warmed</span> beyond NAT temperatures by late January (earlier than normal). Perturbed chemistry was found to be associated with these cold temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5108477','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5108477"><span id="translatedtitle">Wintertime measurements of <span class="hlt">stratospheric</span> HNO[sub 3] as part of the ISY polar ozone project</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fast, H.; McElroy, C.T.; Wardle, D.I. ); Rosen, J.M. )</p> <p>1993-11-19</p> <p>Atmospheric infrared emission has been recorded with a scanning variable-filter radiometer on eight <span class="hlt">stratospheric</span> balloon flights at Alert, inside the arctic vortex, from Dec. 1991 to Mar. 1992. The radiometer and the data analysis for the determination of the altitude distribution of nitric acid vapour are described. The time development of the nitric acid altitude profile at Alert is presented. A sudden change in the profile and vertical column density appears to be associated with the mid-January <span class="hlt">stratospheric</span> <span class="hlt">warming</span>. There is good overall agreement between these results and other arctic winter measurements. 11 refs., 4 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5648925','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5648925"><span id="translatedtitle"><span class="hlt">Stratospheric</span> meterological conditions in the Arctic polar vortex, 1991 to 1992</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Newman, P.; Lait, L.R.; Schoeberl, M. ); Nash, E.R. ); Kelly, K.; Fahey, D.W. ); Nagatani, R. ); Toohey, D.; Avallone, L. ); Anderson, J. )</p> <p>1993-08-27</p> <p><span class="hlt">Stratospheric</span> meterological conditions during the Airborne Arctic <span class="hlt">Stratospheric</span> Expedition II (AASE II) presented excellent observational opportunities from Bangor, Maine, because the polar vortex was located over southeastern Canada for significant periods during the 1991-1992 winter. Temperature analyses showed that nitric acid trihydrates (NAT temperatures below 195 k) should have formed over small regions in early December. The temperatures in the polar vortex <span class="hlt">warmed</span> beyond NAT temperatures by late January (earlier than normal). Perturbed chemistry was found to be associated with these cold temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38...41B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38...41B"><span id="translatedtitle">OSIRIS Measurements of <span class="hlt">Stratospheric</span> Aerosol</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bourassa, Adam; Degenstein, Doug; Llewellyn, Edward J.</p> <p></p> <p>The Canadian built OSIRIS instrument, currently in operation on the Swedish Odin satel-lite, has collected over nine years of limb radiance spectra at UV, visible and near infrared wavelengths. These measurements are used to retrieve vertical profiles of <span class="hlt">stratospheric</span> aerosol extinction. The relatively high horizontal sampling of the limb scatter technique, which pro-vides nearly global coverage, combined with the almost decade long duration of the mission, makes this an increasingly useful and important data set. This work shows comparisons with coincident measurements and highlights the features of the OSIRIS <span class="hlt">stratospheric</span> aerosol data product including the potential for studies of long term trends, <span class="hlt">stratospheric</span> dynamics, and the effect of recent volcanic eruptions on climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920052898&hterms=ozone+concentration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dozone%2Bconcentration','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920052898&hterms=ozone+concentration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dozone%2Bconcentration"><span id="translatedtitle">Measured trends in <span class="hlt">stratospheric</span> ozone</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stolarski, Richard; Bojkov, Rumen; Bishop, Lane; Zerefos, Christos; Staehelin, Johannes; Zawodny, Joseph</p> <p>1992-01-01</p> <p>Recent findings, based on both ground-based and satellite measurements, have established that there has been an apparent downward trend in the total column amount of ozone over mid-latitude areas of the Northern Hemisphere in all seasons. Measurements of the altitude profile of the change in the ozone concentration have established that decreases are taking place in the lower <span class="hlt">stratosphere</span> in the region of highest ozone concentration. Analysis of updated ozone records, through March of 1991, including 29 stations in the former Soviet Union, and analysis of independently calibrated satellite data records from the Total Ozone Mapping Spectrometer and <span class="hlt">Stratospheric</span> Aerosol and Gas Experiment instruments confirm many of the findings originally derived from the Dobson record concerning northern midlatitude changes in ozone. The data from many instruments now provide a fairly consistent picture of the change that has occurred in <span class="hlt">stratospheric</span> ozone levels.</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_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" 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_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910018326','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910018326"><span id="translatedtitle">Background <span class="hlt">stratospheric</span> aerosol reference model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mccormick, M. P.; Wang, P.</p> <p>1989-01-01</p> <p>In this analysis, a reference background <span class="hlt">stratospheric</span> aerosol optical model is developed based on the nearly global SAGE 1 satellite observations in the non-volcanic period from March 1979 to February 1980. Zonally averaged profiles of the 1.0 micron aerosol extinction for the tropics and the mid- and high-altitudes for both hemispheres are obtained and presented in graphical and tabulated form for the different seasons. In addition, analytic expressions for these seasonal global zonal means, as well as the yearly global mean, are determined according to a third order polynomial fit to the vertical profile data set. This proposed background <span class="hlt">stratospheric</span> aerosol model can be useful in modeling studies of <span class="hlt">stratospheric</span> aerosols and for simulations of atmospheric radiative transfer and radiance calculations in atmospheric remote sensing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=stratosphere&id=EJ191220','ERIC'); return false;" href="http://eric.ed.gov/?q=stratosphere&id=EJ191220"><span id="translatedtitle">Chemistry and Pollution of the <span class="hlt">Stratosphere</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>Donovan, R. J.</p> <p>1978-01-01</p> <p>Presents an outline of the chemistry involved and the steps which are being taken to gain a better understanding of the <span class="hlt">stratosphere</span>. Chemical composition of natural <span class="hlt">stratosphere</span> and depletion of ozone in the <span class="hlt">stratosphere</span> by man-made pollutants are covered. (HM)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990103360','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990103360"><span id="translatedtitle">Statistical Perspectives on <span class="hlt">Stratospheric</span> Transport</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sparling, L. C.</p> <p>1999-01-01</p> <p>Long-lived tropospheric source gases, such as nitrous oxide, enter the <span class="hlt">stratosphere</span> through the tropical tropopause, are transported throughout the <span class="hlt">stratosphere</span> by the Brewer-Dobson circulation, and are photochemically destroyed in the upper <span class="hlt">stratosphere</span>. These chemical constituents, or "tracers" can be used to track mixing and transport by the <span class="hlt">stratospheric</span> winds. Much of our understanding about the <span class="hlt">stratospheric</span> circulation is based on large scale gradients and other spatial features in tracer fields constructed from satellite measurements. The point of view presented in this paper is different, but complementary, in that transport is described in terms of tracer probability distribution functions (PDFs). The PDF is computed from the measurements, and is proportional to the area occupied by tracer values in a given range. The flavor of this paper is tutorial, and the ideas are illustrated with several examples of transport-related phenomena, annotated with remarks that summarize the main point or suggest new directions. One example shows how the multimodal shape of the PDF gives information about the different branches of the circulation. Another example shows how the statistics of fluctuations from the most probable tracer value give insight into mixing between different regions of the atmosphere. Also included is an analysis of the time-dependence of the PDF during the onset and decline of the winter circulation, and a study of how "bursts" in the circulation are reflected in transient periods of rapid evolution of the PDF. The dependence of the statistics on location and time are also shown to be important for practical problems related to statistical robustness and satellite sampling. The examples illustrate how physically-based statistical analysis can shed some light on aspects of <span class="hlt">stratospheric</span> transport that may not be obvious or quantifiable with other types of analyses. An important motivation for the work presented here is the need for synthesis of the large and growing database of observations of the atmosphere and the vast quantities of output generated by atmospheric models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20020041487&hterms=aerosol+compounds&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Daerosol%2Bcompounds','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20020041487&hterms=aerosol+compounds&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Daerosol%2Bcompounds"><span id="translatedtitle">Pole-to-Pole Distribution of <span class="hlt">Stratospheric</span> Black Carbon (Soot) Aerosol from Aircraft</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pueschel, R. F.; Ferry, G. V.; Verma, S.; Howard, S. D.; Strawa, Anthony W. (Technical Monitor)</p> <p>1995-01-01</p> <p>The distribution of black carbon (soot) aerosol (BCA) in the atmosphere is of interest for several reasons: (1) Because BCA has the highest absorption cross section of any compound known, it can absorb solar radiation to cause atmospheric <span class="hlt">warming</span>. (2) Because it is a strong adsorber of gases, it can catalyze heterogeneous reactions to change the chemical composition of the atmosphere.(3) If aircraft are a major source of BCA, it is an important tracer of aircraft emissions. Analysis for BCA of impactor samples from Arctic and Antarctic deployments, utilizing particle morphology of scanning electron microscopy images, permits the following conclusions: (1) The BCA concentration in the northern <span class="hlt">stratosphere</span> varies between 0 and 2.6 ng m-3 averaging 0.6 ng/cu m. (2) This BCA loading is commensurate with estimated fuel consumptions in the <span class="hlt">stratosphere</span> by the current commercial fleet and an emission index E=0.03 g BCA per kg fuel burnt which was measured in jet exhaust at al titude.Thus, most <span class="hlt">stratospheric</span> BCA in the northern <span class="hlt">stratosphere</span> results from aircraft emissions. The background BCA concentration in the southern <span class="hlt">stratosphere</span> varies between 0 and 0.6 ng cu m averaging 0.1 ng/cu m. This strong meridional gradient implies that <span class="hlt">stratospheric</span> BCA residence time- is shorter than are mixing times between hemispheres. Projected annual fuel consumption of a future supersonic commercial fleet is 7E13 g. This fleet would increase <span class="hlt">stratospheric</span> BCA loadings by a factor of 2-3, because almost all fuel would be burnt above the tropopause. An improved EI(BCA) by a factor of ten would result in an increase of <span class="hlt">stratospheric</span> BCA loadings by approximately 50 %.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JASTP.132...74S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JASTP.132...74S"><span id="translatedtitle">Extreme <span class="hlt">stratospheric</span> springs and their consequences for the onset of polar mesospheric clouds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Siskind, David E.; Allen, Douglas R.; Randall, Cora E.; Harvey, V. Lynn; Hervig, Mark E.; Lumpe, Jerry; Thurairajah, Brentha; Bailey, Scott M.; Russell, James M.</p> <p>2015-09-01</p> <p>We use data from the Aeronomy of Ice in the Mesosphere (AIM) explorer and from the NASA Modern Era Retrospective Analysis for Research and Applications (MERRA) <span class="hlt">stratospheric</span> analysis to explore the variability in the onset of the Northern Hemisphere (NH) Polar Mesospheric Cloud (PMC) season. Consistent with recently published results, we show that the early onset of the NH PMC season in 2013 was accompanied by a <span class="hlt">warm</span> springtime <span class="hlt">stratosphere</span>; conversely, we show that the late onset in 2008 coincides with a very cold springtime <span class="hlt">stratosphere</span>. Similar <span class="hlt">stratospheric</span> temperature anomalies for 1997 and 2011 also are connected either directly, through observed temperatures, or indirectly, through an early PMC onset, to conditions near the mesopause. These 4 years, 2008, 1997, 2011, and 2013 represent the extremes of <span class="hlt">stratospheric</span> springtime temperatures seen in the MERRA analysis and correspond to analogous extrema in planetary wave activity. The three years with enhanced planetary wave activity (1997, 2011 and 2013) are shown to coincide with the recently identified <span class="hlt">stratospheric</span> Frozen In Anticyclone (FrIAC) phenomenon. FrIACs in 1997 and 2013 are associated with early PMC onsets; however, the dramatic FrIAC of 2011 is not. This may be because the 2011 FrIAC occurred too early in the spring. The link between NH PMC onset and <span class="hlt">stratospheric</span> FrIAC occurrences represents a new mode of coupling between the <span class="hlt">stratosphere</span> and mesosphere. Since FrIACs appear to be more frequent in recent years, we speculate that as a result, PMCs may occur earlier as well. Finally we compare the zonal mean zonal winds and observed gravity wave activity for the FrIACs of 2011 and 2013. We find no evidence that gravity wave activity was favored in 2013 relative to 2011, thus suggesting that direct forcing by planetary waves was the key mechanism in accelerating the cooling and moistening of the NH mesopause region in May of 2013.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992GeoRL..19.1607L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992GeoRL..19.1607L"><span id="translatedtitle">Climate forcing by <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>Lacis, Andrew; Hansen, James; Sato, Makiko</p> <p>1992-08-01</p> <p>We illustrate how climate forcing by <span class="hlt">stratospheric</span> aerosols depends on aerosol properties. The climate forcing is a function of aerosol size distribution, but the size dependence can be described well by a single parameter: the area-weighted mean radius, reff.If reff is greater than about 2 ?m, the global average greenhouse effect of the aerosols exceeds the albedo effect, causing a surface heating. The aerosol climate forcing is less sensitive to other characteristics of the size distribution, the aerosol composition, and the altitude of the aerosols. Thus <span class="hlt">stratospheric</span> aerosol forcing can be defined accurately from measurements of aerosol, extinction over a broad wavelength range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920069671&hterms=hansen+james&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dhansen%252C%2Bjames','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920069671&hterms=hansen+james&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dhansen%252C%2Bjames"><span id="translatedtitle">Climate forcing by <span class="hlt">stratospheric</span> aerosols</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lacis, Andrew; Hansen, James; Sato, Makiko</p> <p>1992-01-01</p> <p>It is illustrated how climate forcing by <span class="hlt">stratospheric</span> aerosols depends on aerosol properties. The climate forcing is a function of aerosols size distribution, but the size dependence can be described well by a single parameter: the area-weighted mean radius, r(eff). If r(eff) is greater than about 2 microns, the global average greenhouse effect of the aerosols exceeds the albedo effect, causing a surface heating. The aerosol climate forcing is less sensitive to other characteristics of the size distribution, the aerosol composition, and the altitude of the aerosols. Thus <span class="hlt">stratospheric</span> aerosol forcing can be defined accurately from measurements of aerosol extinction over a broad wavelength range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880059899&hterms=extinction+events&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dextinction%2Bevents','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880059899&hterms=extinction+events&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dextinction%2Bevents"><span id="translatedtitle">The relationship of satellite-inferred <span class="hlt">stratospheric</span> aerosol extinction to the position of the 50-mb north polar jet stream</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Livingston, John M.; Endlich, Roy M.</p> <p>1988-01-01</p> <p>The relationship between <span class="hlt">stratospheric</span> aerosols and the location of the north polar night <span class="hlt">stratospheric</span> jet stream was investigated for selected periods of four successive winters (1979-1982), using measurements from SAM II (<span class="hlt">Stratospheric</span> Aerosol Measurement II) and SAGE I (<span class="hlt">Stratospheric</span> Aerosol and Gas Experiment I) satellite-borne sun photometers and corresponding meteorological observations. Each period investigated included a polar <span class="hlt">stratospheric</span> <span class="hlt">warming</span> during which major dynamic meteorological changes are known to have perturbed the structure of the polar vortex. The analysis of variations in aerosol extinction mixing ratio patterns among winters and during major <span class="hlt">stratospheric</span> <span class="hlt">warming</span> events within separate winters showed a well-defined positive gradient in extinction mixing ratio and temperature across the jet stream from the cyclonic side to the anticyclonic side at altitudes between 20 and 30 km during each winter period. Estimates of extinction mixing ratio profiles measured near the center of the polar vortex suggest that a gradual subsidence took place within the polar vortex during at least three of the four winter periods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920006216','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920006216"><span id="translatedtitle">Halocarbon ozone depletion and global <span class="hlt">warming</span> potentials</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cox, Richard A.; Wuebbles, D.; Atkinson, R.; Connell, Peter S.; Dorn, H. P.; Derudder, A.; Derwent, Richard G.; Fehsenfeld, F. C.; Fisher, D.; Isaksen, Ivar S. A.</p> <p>1990-01-01</p> <p>Concern over the global environmental consequences of fully halogenated chlorofluorocarbons (CFCs) has created a need to determine the potential impacts of other halogenated organic compounds on <span class="hlt">stratospheric</span> ozone and climate. The CFCs, which do not contain an H atom, are not oxidized or photolyzed in the troposphere. These compounds are transported into the <span class="hlt">stratosphere</span> where they decompose and can lead to chlorine catalyzed ozone depletion. The hydrochlorofluorocarbons (HCFCs or HFCs), in particular those proposed as substitutes for CFCs, contain at least one hydrogen atom in the molecule, which confers on these compounds a much greater sensitivity toward oxidation by hydroxyl radicals in the troposphere, resulting in much shorter atmospheric lifetimes than CFCs, and consequently lower potential for depleting ozone. The available information is reviewed which relates to the lifetime of these compounds (HCFCs and HFCs) in the troposphere, and up-to-date assessments are reported of the potential relative effects of CFCs, HCFCs, HFCs, and halons on <span class="hlt">stratospheric</span> ozone and global climate (through 'greenhouse' global <span class="hlt">warming</span>).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGC13I0781S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGC13I0781S"><span id="translatedtitle">Comparing the Responses of <span class="hlt">Stratospheric</span> Dynamics to Volcanic Eruptions and Sulfate Climate Engineering in CMIP5 and Geomip Simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmidt, H.; Bittner, M.</p> <p>2014-12-01</p> <p>The suggestion of injecting sulfur into the <span class="hlt">stratosphere</span> to cool the climate is motivated by the response of the climate system to large volcanic eruptions. But can we expect that the effects observed after eruptions accurately describe the effects of sulfate climate engineering? Here we discuss the response of <span class="hlt">stratospheric</span> dynamics to both types of forcing as simulated in state-of-the-art climate models. The cooling observed after volcanic eruptions is not homogeneous in space and time. An anomalous <span class="hlt">warming</span> has been observed after several big tropical eruptions during boreal winter in northern Europe and Asia. In general, this <span class="hlt">warming</span> is attributed to a strengthening of the <span class="hlt">stratospheric</span> polar night jet, related to the <span class="hlt">stratospheric</span> effects of volcanic aerosol, and a subsequent downward propagation of this dynamical signal. Here we use the Geoengineering Intercomparison Model Project (GeoMIP) G3 and G4 simulations where sulfur is injected to reduce <span class="hlt">warming</span> during the 21st century to study the potential response of <span class="hlt">stratospheric</span> dynamics to this type of climate engineering and compare it with the response to volcanic eruptions simulated by the same models in the CMIP5 historical simulations. Unfortunately, in general the CMIP5 models do not reproduce the strengthening of the polar night jet well. Potential reasons for this will be discussed. Furthermore we show that due to the different time scales involved in volcanic eruptions in comparison to assumed climate engineering the dynamical responses may differ.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ACP....1511949G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ACP....1511949G"><span id="translatedtitle"><span class="hlt">Stratospheric</span> geoengineering impacts on El Nio/Southern Oscillation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gabriel, C. J.; Robock, A.</p> <p>2015-10-01</p> <p>To examine the impact of proposed <span class="hlt">stratospheric</span> geoengineering schemes on the amplitude and frequency of El Nio/Southern Oscillation (ENSO) variations we examine climate model simulations from the Geoengineering Model Intercomparison Project (GeoMIP) G1-G4 experiments. Here we compare tropical Pacific behavior under anthropogenic global <span class="hlt">warming</span> (AGW) using several scenarios: an instantaneous quadrupling of the atmosphere's CO2 concentration, a 1 % annual increase in CO2 concentration, and the representative concentration pathway resulting in 4.5 W m-2 radiative forcing at the end of the 21st century, the Representative Concentration Pathway 4.5 scenario, with that under G1-G4 and under historical model simulations. Climate models under AGW project relatively uniform <span class="hlt">warming</span> across the tropical Pacific over the next several decades. We find no statistically significant change in ENSO frequency or amplitude under <span class="hlt">stratospheric</span> geoengineering as compared with those that would occur under ongoing AGW, although the relative brevity of the G1-G4 simulations may have limited detectability of such changes. We also find that the amplitude and frequency of ENSO events do not vary significantly under either AGW scenarios or G1-G4 from the variability found within historical simulations or observations going back to the mid-19th century. Finally, while <span class="hlt">warming</span> of the Nio3.4 region in the tropical Pacific is fully offset in G1 and G2 during the 40-year simulations, the region continues to <span class="hlt">warm</span> significantly in G3 and G4, which both start from a present-day climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRD..117.4104Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRD..117.4104Z"><span id="translatedtitle">The El Nio-Southern Oscillation (ENSO) Modoki signal 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>Zubiaurre, I.; Calvo, N.</p> <p>2012-02-01</p> <p>El Nino-Southern Oscillation (ENSO) is known to be the largest source of interannual variability in the tropical troposphere. However, the variability in the tropical Pacific since 1979 seems to be associated not only with "canonical" ENSO events but also with a variation thereof known as ENSO Modoki, which is characterized by <span class="hlt">warm</span> anomalies in the central Pacific, west from those occurring during a typical ENSO. This works analyzes the signal of ENSO Modoki in the <span class="hlt">stratosphere</span> and compares it to canonical ENSO by using the chemistry-climate Whole Atmosphere Community Climate Model (WACCM3.5). The results reveal a significant <span class="hlt">warming</span> in the Southern Hemisphere polar <span class="hlt">stratosphere</span> during boreal winter months, which propagates downward in early spring; this is absent during canonical <span class="hlt">warm</span> ENSO events. On the other hand, in the Northern Hemisphere <span class="hlt">stratosphere</span>, the anomalous <span class="hlt">warming</span> typical of canonical El Nio episodes during boreal winter is not statistically significant during El Nio Modoki events. These differences are related in WACCM3.5 to changes in tropical convection and tropospheric teleconnections associated with each type of event. In particular, an enhancement and westward displacement of the anomalous convective area during El Nio Modoki episodes is related to an intensification of the Pacific South American teleconnection pattern and a weakening of the Aleutian Low. During cold ENSO Modoki events a significant anomalous cooling is present in the model simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920035310&hterms=ozone+hole&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dozone%2Bhole','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920035310&hterms=ozone+hole&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dozone%2Bhole"><span id="translatedtitle">Polar <span class="hlt">stratospheric</span> clouds and the ozone hole</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamill, Patrick; Toon, Owen B.</p> <p>1991-01-01</p> <p>An account is given of physical processes governing the formation of <span class="hlt">stratospheric</span> particles, in order to dramatize the interactions between polar <span class="hlt">stratospheric</span> clouds and the Antarctic ozone-destruction mechanism. Attention is given to the successive stages of particle nucleation, condensation/evaporation and sedimentation/coagulation phenomena, and the ways in which polar <span class="hlt">stratospheric</span> clouds are observed. Considerable evidence exists that polar <span class="hlt">stratospheric</span> cloud particles are composed of nitric acid. The relatively small Arctic ozone hole depletion is due to the much smaller duration of Arctic <span class="hlt">stratospheric</span> clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920005298','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920005298"><span id="translatedtitle">Aircraft deployment, and airborne arctic <span class="hlt">stratospheric</span> expedition</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Condon, Estelle; Tuck, Adrian; Hipskind, Steve; Toon, Brian; Wegener, Steve</p> <p>1990-01-01</p> <p>The Airborne Arctic <span class="hlt">Stratospheric</span> Expedition had two primary objectives: to study the production and loss mechanisms of ozone in the north polar <span class="hlt">stratosphere</span> and to study the effect on ozone distribution of the Arctic Polar Vortex and of the cold temperatures associated with the formation of Polar <span class="hlt">Stratospheric</span> Clouds. Two specially instrumented NASA aircraft were flown over the Arctic region. Each aircraft flew to acquire data on the meteorological, chemical and cloud physical phenomena that occur in the polar <span class="hlt">stratosphere</span> during winter. The chemical processes which occur in the polar <span class="hlt">stratosphere</span> during winter were also observed and studied. The data acquired are being analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRD..119.1340M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRD..119.1340M"><span id="translatedtitle">Northern hemispheric winter <span class="hlt">warming</span> pattern after tropical volcanic eruptions: Sensitivity to the ozone climatology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muthers, S.; Anet, J. G.; Raible, C. C.; Brönnimann, S.; Rozanov, E.; Arfeuille, F.; Peter, T.; Shapiro, A. I.; Beer, J.; Steinhilber, F.; Brugnara, Y.; Schmutz, W.</p> <p>2014-02-01</p> <p>An important key for the understanding of the dynamic response to large tropical volcanic eruptions is the <span class="hlt">warming</span> of the tropical lower <span class="hlt">stratosphere</span> and the concomitant intensification of the polar vortices. Although this mechanism is reproduced by most general circulation models today, most models still fail in producing an appropriate winter <span class="hlt">warming</span> pattern in the Northern Hemisphere. In this study ensemble sensitivity experiments were carried out with a coupled atmosphere-ocean model to assess the influence of different ozone climatologies on the atmospheric dynamics and in particular on the northern hemispheric winter <span class="hlt">warming</span>. The ensemble experiments were perturbed by a single Tambora-like eruption. Larger meridional gradients in the lower <span class="hlt">stratospheric</span> ozone favor the coupling of zonal wind anomalies between the <span class="hlt">stratosphere</span> and the troposphere after the eruption. The associated sea level pressure, temperature, and precipitation patterns are more pronounced and the northern hemispheric winter <span class="hlt">warming</span> is highly significant. Conversely, weaker meridional ozone gradients lead to a weaker response of the winter <span class="hlt">warming</span> and the associated patterns. The differences in the number of <span class="hlt">stratosphere</span>-troposphere coupling events between the ensembles experiments indicate a nonlinear response behavior of the dynamics with respect to the ozone and the volcanic forcing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030053448','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030053448"><span id="translatedtitle">The Unusual Southern Hemisphere <span class="hlt">Stratosphere</span> Winter of 2002</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.</p> <p>2003-01-01</p> <p>The southern hemisphere <span class="hlt">stratospheric</span> winter of 2002 was the most unusual winter yet observed in the southern hemisphere climate record. Temperatures near the edge of the Antarctic polar vortex were considerably warmer than normal over the entire course of the winter. The polar night jet was considerably weaker than normal, and was displaced more poleward than has been observed in previous winters. These record high temperatures and weak jet resulted from a series of wave events that took place over the course of the winter. The first large event occurred on 15 May, and the final <span class="hlt">warming</span> occurred on 25 October. The propagation of these wave events from the troposphere is diagnosed from time series of Eliassen-Palm flux vectors. The wave events tended to occur irregularly over the course of the winter, and pre-conditioned the polar night jet for the extremely large wave event of 22 September. This large wave event resulted in the first ever observed major <span class="hlt">stratospheric</span> <span class="hlt">warming</span> in the southern hemisphere. This wave event split the Antarctic ozone hole. The combined effect of the wave events of the 2002 winter resulted in the smallest ozone hole observed since 1988.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850013561','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850013561"><span id="translatedtitle">21 Layer troposphere-<span class="hlt">stratosphere</span> climate model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rind, D.; Suozzo, R.; Lacis, A.; Russell, G.; Hansen, J.</p> <p>1984-01-01</p> <p>The global climate model is extended through the <span class="hlt">stratosphere</span> by increasing the vertical resolution and raising the rigid model top to the 0.01 mb (75 km) level. The inclusion of a realistic <span class="hlt">stratosphere</span> is necessary for the investigation of the climate effects of <span class="hlt">stratospheric</span> perturbations, such as changes of ozone, aerosols or solar ultraviolet irradiance, as well as for studying the effect on the <span class="hlt">stratosphere</span> of tropospheric climate changes. The observed temperature and wind patterns throughout the troposphere and <span class="hlt">stratosphere</span> are simulated. In addition to the excess planetary wave amplitude in the upper <span class="hlt">stratosphere</span>, other model deficiences include the Northern Hemisphere lower <span class="hlt">stratospheric</span> temperatures being 5 to 10 C too cold in winter at high latitudes and the temperature at 50 to 60 km altitude near the equator are too cold. Methods of correcting these deficiencies are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...813L...3K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...813L...3K"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Temperatures and Water Loss from Moist Greenhouse Atmospheres of Earth-like Planets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kasting, James F.; Chen, Howard; Kopparapu, Ravi K.</p> <p>2015-11-01</p> <p>A radiative-convective climate model is used to calculate <span class="hlt">stratospheric</span> temperatures and water vapor concentrations for ozone-free atmospheres warmer than that of modern Earth. Cold, dry <span class="hlt">stratospheres</span> are predicted at low surface temperatures, in agreement with recent 3D calculations. However, at surface temperatures above 350 K, the <span class="hlt">stratosphere</span> <span class="hlt">warms</span> and water vapor becomes a major upper atmospheric constituent, allowing water to be lost by photodissociation and hydrogen escape. Hence, a moist greenhouse explanation for loss of water from Venus, or some exoplanet receiving a comparable amount of stellar radiation, remains a viable hypothesis. Temperatures in the upper parts of such atmospheres are well below those estimated for a gray atmosphere, and this factor should be taken into account when performing inverse climate calculations to determine habitable zone boundaries using 1D models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DPS....4731116H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DPS....4731116H"><span id="translatedtitle">Saturn's <span class="hlt">Stratospheric</span> Water Vapor Distribution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hesman, Brigette E.; Bjoraker, Gordon L.; Achterberg, Richard K.; Romani, Paul N.; Irwin, Patrick G. J.</p> <p>2015-11-01</p> <p>Water is a sought after commodity in the solar system. It is used as an indication of life, planetary formation timescales, and signatures of past cometary impacts. In Saturn’s atmosphere there are two sources of water: an internal primordial reservoir that is confined to the troposphere, and an external source of unknown origin that delivers water to the <span class="hlt">stratosphere</span>. Potential sources of <span class="hlt">stratospheric</span> water include: Saturn’s main rings (via neutral infall and/or ions transported along magnetic field lines - “Ring Rain”), interplanetary dust particles, and the E-ring that is supplied with water from the plumes of Enceladus. Measuring the latitudinal and seasonal variation of H2O on Saturn will constrain the source of Saturn’s <span class="hlt">stratospheric</span> water.Cassini’s Composite InfraRed Spectrometer (CIRS) has detected emission lines of H2O on Saturn at wavelengths of 40 and 50 microns. CIRS also retrieves the temperature of the <span class="hlt">stratosphere</span> using CH4 lines at 7.7 microns. Using our retrieved temperatures, we derive the mole fraction of H2O at the 0.5-5 mbar level for comparison with water-source models. The latitudinal variation of <span class="hlt">stratospheric</span> water vapor will be presented as a first step in understanding the external source of water on Saturn. The observed local maximum near Saturn’s equator supports either a neutral infall from the rings or a source in the E-ring. We will look for secondary maxima at mid-latitudes to determine whether “Ring Rain” also contributes to the inventory of water in Saturn’s upper atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040074999&hterms=ultraviolet+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dultraviolet%2Bwaves','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040074999&hterms=ultraviolet+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dultraviolet%2Bwaves"><span id="translatedtitle">Ultraviolet Radiation and <span class="hlt">Stratospheric</span> Ozone</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stolarski, R.</p> <p>2003-01-01</p> <p>Ultraviolet radiation from the sun produces ozone in the <span class="hlt">stratosphere</span> and it participates in the destruction of ozone. Absorption of solar ultraviolet radiation by ozone is the primary heating mechanism leading to the maximum in temperature at the stratopause. Variations of solar ultraviolet radiation on both the 27-day solar rotation period and the 11-year solar cycle affect ozone by several mechanisms. The temperature and ozone in the upper <span class="hlt">stratosphere</span> respond to solar uv variations as a coupled system. An increase in uv leads to an increase in the production of ozone through the photolysis of molecular oxygen. An increase in uv leads to an increase in temperature through the heating by ozone photolysis. The increase in temperature leads to a partially-offsetting decrease in ozone through temperature-dependent reaction rate coefficients. The ozone variation modulates the heating by ozone photolysis. The increase in ozone at solar maximum enhances the uv heating. The processes are understood and supported by long-term data sets. Variation in the upper <span class="hlt">stratospheric</span> temperatures will lead to a change in the behavior of waves propagating upward from the troposphere. Changes in the pattern of wave dissipation will lead to acceleration or deceleration of the mean flow and changes in the residual or transport circulation. This mechanism could lead to the propagation of the solar cycle uv variation from the upper <span class="hlt">stratosphere</span> downward to the lower <span class="hlt">stratosphere</span>. This process is not well-understood and has been the subject of an increasing number of model studies. I will review the data analyses for solar cycle and their comparison to model results.</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_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" 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_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRD..120.5404G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRD..120.5404G"><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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garfinkel, C. I.; Hurwitz, M. M.; Oman, L. D.</p> <p>2015-06-01</p> <p>Comprehensive chemistry-climate model experiments and observational data are used to show that up to 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. 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 loss is larger in the presence of changing concentrations of ozone-depleting substances and greenhouse gases. 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://adsabs.harvard.edu/abs/2016ERL....11c4012F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ERL....11c4012F"><span id="translatedtitle">Quantifying the temperature-independent effect of <span class="hlt">stratospheric</span> aerosol geoengineering on global-mean precipitation in a multi-model ensemble</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferraro, Angus J.; Griffiths, Hannah G.</p> <p>2016-03-01</p> <p>The reduction in global-mean precipitation when <span class="hlt">stratospheric</span> aerosol geoengineering is used to counterbalance global <span class="hlt">warming</span> from increasing carbon dioxide (CO2) concentrations has been mainly attributed to the temperature-independent effect of CO2 on atmospheric radiative cooling. We demonstrate here that <span class="hlt">stratospheric</span> sulphate aerosol itself also acts to reduce global-mean precipitation independent of its effects on temperature. The temperature-independent effect of <span class="hlt">stratospheric</span> aerosol geoenginering on global-mean precipitation is calculated by removing temperature-dependent effects from climate model simulations of the Geoengineering Model Intercomparison Project (GeoMIP). When sulphate aerosol is injected into the <span class="hlt">stratosphere</span> at a rate of 5 Tg SO2 per year the aerosol reduces global-mean precipitation by approximately 0.2 %, though multiple ensemble members are required to separate this effect from internal variability. For comparison, the precipitation reduction from the temperature-independent effect of increasing CO2 concentrations under the RCP4.5 scenario of the future is approximately 0.5 %. The temperature-independent effect of <span class="hlt">stratospheric</span> sulphate aerosol arises from the aerosol’s effect on tropospheric radiative cooling. Radiative transfer calculations show this is mainly due to increasing downward emission of infrared radiation by the aerosol, but there is also a contribution from the <span class="hlt">stratospheric</span> <span class="hlt">warming</span> the aerosol causes. Our results suggest climate model simulations of solar dimming can capture the main features of the global-mean precipitation response to <span class="hlt">stratospheric</span> aerosol geoengineering.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.A13A0204A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.A13A0204A"><span id="translatedtitle">CFC Destruction of Ozone - Major Cause of Recent 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>Ashworth, R. A.</p> <p>2008-12-01</p> <p>There has been a lot of discussion about global <span class="hlt">warming</span>. Some say anthropogenic carbon dioxide (CO2) emissions caused the earth to <span class="hlt">warm</span>. Others say there is no abnormality at all, that it is just natural <span class="hlt">warming</span>. As you will see from the data presented and analyzed, a greater than normal <span class="hlt">warming</span> did occur in recent times but no measurements confirm an increase in CO2, whether anthropogenic or natural, had any effect on global temperatures. There is however, strong evidence that anthropogenic emissions of chlorofluorocarbons (CFCs) were the major cause of the recent abnormal <span class="hlt">warming</span>. CFCs have created both unnatural atmospheric cooling and <span class="hlt">warming</span> based on these facts: CFCs have destroyed ozone in the lower <span class="hlt">stratosphere</span>/ upper troposphere causing these zones in the atmosphere to cool 1.37C from 1966 to 1998. This time span was selected to eliminate the effect of the natural solar irradiance (cooling-<span class="hlt">warming</span>) cycle effect on the earth's temperature. The loss of ozone allowed more UV light to pass through the <span class="hlt">stratosphere</span> at a sufficient rate to <span class="hlt">warm</span> the lower troposphere plus 8-3/4" of the earth by 0.48C (1966 to 1998). Mass and energy balances show that the energy that was absorbed in the lower <span class="hlt">stratosphere</span> and upper troposphere hit the lower troposphere/earth at a sustainable level of 1.69 10 18 Btu more in 1998 than it did in 1966. Greater ozone depletion in the Polar Regions has caused these areas to <span class="hlt">warm</span> some two and one-half (2 1/2) times that of the average earth temperature -1.2C versus 0.48C. This has caused permafrost to melt, which is releasing copious quantities of methane, estimated at 100 times that of manmade CO2 release, to the atmosphere. Methane in the atmosphere slowly converts to CO2 and water vapor and its release has contributed to higher CO2 concentrations in the atmosphere. There is a temperature anomaly in Antarctica. The Signey Island landmass further north, <span class="hlt">warmed</span> like the rest of the Polar Regions; but south at Vostok, there has been a cooling effect. Although the cooling at Vostok needs to be analyzed in more detail, because of the large ozone hole there, black body radiation from Vostok, some 11,400 feet above sea level, to outer space is most likely the cause. Especially, since this phenomenon occurred over the same period that <span class="hlt">stratospheric</span> ozone destruction took place. Chlorofluorocarbon destruction of <span class="hlt">stratospheric</span> ozone can be correlated nicely with both the cooling and <span class="hlt">warming</span> temperature anomalies seen over the time span from 1966 to 1998 and compared to actual temperature measurements, the ozone signature for global <span class="hlt">warming</span> is the closest of the five signature impacts developed by the IPCC. Further,the "greenhouse signature" is not seen at all. One can account for most, if not all, of the 0.48C rise in earth's temperature from 1966 to 1998 with the additional UV light that hit the earth due to ozone destruction in the upper atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.1395T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.1395T"><span id="translatedtitle">Impacts of <span class="hlt">Stratospheric</span> Particles Injection on <span class="hlt">Stratospheric</span> Ozone: Laboratory Studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tang, Mingjin; Rkiouak, Laylla; Fuller, Steve; Pope, Francis; Cox, Tony; Watson, Matt; Kalberer, Markus</p> <p>2013-04-01</p> <p>The <span class="hlt">stratospheric</span> injection of aerosols is a geoengineering scheme designed to reduce the impacts of climate change. The injected particles scatter solar radiation back to space and hence reduce the radiative forcing of the Earth. The scattering ability of a particle depends on both its size and composition. Particles composed of titania (TiO2) have recently been highlighted as a possible candidate aerosol because of their impressive light scattering ability by virtue of a high refractive index (Pope et al. 2012). The impact of particles injection on <span class="hlt">stratospheric</span> ozone needs to be systematically assessed via laboratory and modelling studies. In this work, the heterogeneous reactions of airborne TiO2 particles with N2O5 and HCl are investigated by using an atmospheric pressure aerosol flow tube. A Chemical Ionization Mass Spectrometer is used to detect trace gases, and a Scanning Mobility Particle Sizer is used to measure aerosol number concentration and size distribution. The kinetics of the uptake of N2O5 onto TiO2 particles and the influence of HCl will be presented, and the result will be compared to the uptake onto natural sulphate <span class="hlt">stratospheric</span> particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20100031244&hterms=Asten&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D*Asten','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20100031244&hterms=Asten&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D*Asten"><span id="translatedtitle">QBO Influence on Polar <span class="hlt">Stratospheric</span> Variability in the GEOS Chemistry-Climate Model</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.; Oman, L. D.; Li, F.; Slong, I.-S.; Newman, P. A.; Nielsen, J. E.</p> <p>2010-01-01</p> <p>The quasi-biennial oscillation modulates the strength of both the Arctic and Antarctic <span class="hlt">stratospheric</span> vortices. Model and observational studies have found that the phase and characteristics of the quasi-biennial oscillation (QBO) contribute to the high degree of variability in the Arctic <span class="hlt">stratosphere</span> in winter. While the Antarctic <span class="hlt">stratosphere</span> is less variable, recent work has shown that Southern Hemisphere planetary wave driving increases in response to "<span class="hlt">warm</span> pool" El Nino events that are coincident with the easterly phase of the QBO. These events hasten the breakup of the Antarctic polar vortex. The Goddard Earth Observing System (GEOS) chemistry-climate model (CCM) is now capable of generating a realistic QBO, due a new parameterization of gravity wave drag. In this presentation, we will use this new model capability to assess the influence of the QBO on polar <span class="hlt">stratospheric</span> variability. Using simulations of the recent past, we will compare the modeled relationship between QBO phase and mid-winter vortex strength with the observed Holton-Tan relation, in both hemispheres. We will use simulations of the 21 St century to estimate future trends in the relationship between QBO phase and vortex strength. In addition, we will evaluate the combined influence of the QBO and El Nino/Southern Oscillation (ENSO) on the timing of the breakup of the polar <span class="hlt">stratospheric</span> vortices in the GEOS CCM. We will compare the influence of these two natural phenomena with trends in the vortex breakup associated with ozone recovery and increasing greenhouse gas concentrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.U43A0047T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.U43A0047T"><span id="translatedtitle">Impact Of Geo-engineered Aerosols On <span class="hlt">Stratospheric</span> Chemistry And Dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tilmes, S.; Garcia, R. R.; Kinnison, D. E.; Gettelman, A.; Rasch, P. J.</p> <p>2008-12-01</p> <p>Geo-engineering schemes have been proposed to alleviate the consequences of global <span class="hlt">warming</span>; one proposed scheme is to inject sulfur into the <span class="hlt">stratosphere</span> so as to mimic the effects of large volcanic eruptions. Past volcanic eruptions have shown that strongly enhanced sulfate aerosols in the <span class="hlt">stratosphere</span> result in a higher planetary albedo, leading to surface cooling. However, the increase of sulfate aerosol surface area enhances heterogeneous reactions in the <span class="hlt">stratosphere</span> that lead to ozone loss. The potential for high Arctic ozone depletion in the context of geo-engineering is known. On the other hand, halogen compounds are now decreasing in the atmosphere as a result of the enforcement of the Montreal Protocol and its amendments, and this is expected to bring about the recovery of the ozone layer and to lessen the potential impact of aerosols. In this study we present results of calculations made with NCAR's Whole Atmosphere Community Climate Model (WACCM), focusing on the impact of Geo-engineering on <span class="hlt">stratospheric</span> chemistry and dynamics. Aside from changes in heterogeneous reactions, changes in <span class="hlt">stratospheric</span> dynamics have a significant impact on ozone. On average, changes of both chemistry and dynamics result in a slowdown of the recovery of ozone for mid- and high latitudes. An increase of ozone depletion as a result of geo-engineering was found in both polar regions for the period between 2040-2050.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4408860','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4408860"><span id="translatedtitle"><span class="hlt">Stratospheric</span> sulfur and its implications for radiative forcing simulated by the chemistry climate model EMAC</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Brühl, C; Lelieveld, J; Tost, H; Höpfner, M; Glatthor, N</p> <p>2015-01-01</p> <p>Multiyear simulations with the atmospheric chemistry general circulation model EMAC with a microphysical modal aerosol module at high vertical resolution demonstrate that the sulfur gases COS and SO2, the latter from low-latitude and midlatitude volcanic eruptions, predominantly control the formation of <span class="hlt">stratospheric</span> aerosol. Marine dimethyl sulfide (DMS) and other SO2 sources, including strong anthropogenic emissions in China, are found to play a minor role except in the lowermost <span class="hlt">stratosphere</span>. Estimates of volcanic SO2 emissions are based on satellite observations using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument for total injected mass and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat or <span class="hlt">Stratospheric</span> Aerosol and Gases Experiment for the spatial distribution. The 10 year SO2 and COS data set of MIPAS is also used for model evaluation. The calculated radiative forcing of <span class="hlt">stratospheric</span> background aerosol including sulfate from COS and small contributions by DMS oxidation, and organic aerosol from biomass burning, is about 0.07W/m2. For <span class="hlt">stratospheric</span> sulfate aerosol from medium and small volcanic eruptions between 2005 and 2011 a global radiative forcing up to 0.2W/m2 is calculated, moderating climate <span class="hlt">warming</span>, while for the major Pinatubo eruption the simulated forcing reaches 5W/m2, leading to temporary climate cooling. The Pinatubo simulation demonstrates the importance of radiative feedback on dynamics, e.g., enhanced tropical upwelling, for large volcanic eruptions. PMID:25932352</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.A43E0329S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.A43E0329S"><span id="translatedtitle">Tropospheric response to an 'ozone depletion'-like polar <span class="hlt">stratospheric</span> cooling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, L.; Chen, G.; Robinson, W. A.</p> <p>2013-12-01</p> <p>By following the setup of Kushner and Polvani (2006) in a simplified dynamical model, we add a polar <span class="hlt">stratospheric</span> cooling in the springtime to mimic the ozone depletion, and try to investigate the role of polar vortex breakdown, also known as <span class="hlt">stratospheric</span> final <span class="hlt">warming</span> (SFW), in the tropospheric response to <span class="hlt">stratospheric</span> changes. Overall, the circulation anomaly associated with such cooling bears a remarkable resemblance to the Southern Hemisphere climate trends due to ozone depletion, including poleward shift of the tropospheric jet and poleward expansion of the Hadley cell. We then categorize the 80 members into those SFWs are delayed, and those SFWs are not, and calculate the response separately. The response for the years in which SFWs are delayed are very similar to the total one, while the <span class="hlt">stratosphere</span> is only characterized by the localized cooling for those years in which SFWs are not delayed, without any clear downward influence. This suggests that ozone depletion affects the Southern Hemisphere climate through delaying the SFWs. We also find that interannual variability in the <span class="hlt">stratospheric</span> and tropospheric circulation can be organized by the timing of SFWs, similar to the observed climate trends.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.9794H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.9794H"><span id="translatedtitle">Ozone as a tracer of short period gravity waves in the <span class="hlt">stratosphere</span> and lower mesosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hocke, K.; Kmpfer, N.; Flury, T.</p> <p>2009-04-01</p> <p>One of the earliest works on atmospheric gravity waves reports about remarkable surface pressure oscillations with periods from 5 to 15 minutes in presence of large temperature inversions which are usually accompanied by fog or low stratus (Gossard and Munk, 1954). Gravity waves with similar periods also have been observed in mesospheric airglow. On the other hand, observations of short period gravity waves and associated ozone perturbations at <span class="hlt">stratospheric</span> altitudes are almost not available yet though numerical simulations predict an upward propagation of tropospheric short period gravity waves through the <span class="hlt">stratosphere</span> and mesosphere. Ozone profiles with a unique time resolution of 3 min, covering the altitude range from 20 to 70 km are provided by ozone microwave radiometers operated by the Institute of Applied Physics (University of Bern) and MeteoSwiss (Payerne). We have started to investigate if the continuous ozone observations are appropriate to monitor short period gravity waves in the <span class="hlt">stratosphere</span> and lower mesosphere. The gravity wave-ozone perturbation relationship and the measurement principle of ground-based microwave radiometry are sketched. An example is shown for a gravity wave-induced ozone perturbation in the lower <span class="hlt">stratosphere</span>. Results of the time evolution of gravity wave flux over Switzerland during the sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> of February 2008 are presented as well as initial validation work of the temporally high resolution ozone profiles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995JCli....8.2281P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995JCli....8.2281P"><span id="translatedtitle">The Statistical Connection between Tropospheric and <span class="hlt">Stratospheric</span> Circulation of the Northern Hemisphere in Winter.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perlwitz, Judith; Graf, Hans-F.</p> <p>1995-10-01</p> <p>The associated anomaly patterns of the <span class="hlt">stratospheric</span> geopotential height field and the tropospheric geopetential and temperature height fields of the Northern Hemisphere are determined applying the canonical correlation analysis. With this linear multivariate technique the coupled modes of variability of lime series of two fields are isolated in the space of empirical orthogonal functions. The one dataset is the 50-hPa geopotential height field; the other set consists of different height fields of the tropospheric pressure levels (200, 500, 700, and 850 hPa) and the temperature of the 850-hPa pressure level. For the winter months (December, January, February) two natural coupled modes, a barotropic and a baroclinic one, of linear relationship between <span class="hlt">stratospheric</span> and tropospheric circulation are found. The baroclinic mode describes a connection between the strength of the <span class="hlt">stratospheric</span> cyclonic winter vortex and the tropospheric circulation over the North Atlantic. The corresponding temperature pattern for an anomalously strong <span class="hlt">stratospheric</span> cyclonic vortex is characterized by positive temperature anomalies over higher latitudes of Eurasia. These `Winter <span class="hlt">Warmings</span>' are observed, for example, after violent volcanic eruptions. The barotropic mode is characterized by a zonal wavenumber 1 in the lower <span class="hlt">stratosphere</span> and by a PNA-like pattern in the troposphere. It was shown by van Loon and Labitzke that this mode can be enhanced, for example, by El Nios via the intensification of the Aleutian low.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ACP....14.7705Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ACP....14.7705Z"><span id="translatedtitle">Evidence for an earlier greenhouse cooling effect in the <span class="hlt">stratosphere</span> before 1980 over the Northern Hemisphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zerefos, C. S.; Tourpali, K.; Zanis, P.; Eleftheratos, K.; Repapis, C.; Goodman, A.; Wuebbles, D.; Isaksen, I. S. A.; Luterbacher, J.</p> <p>2014-08-01</p> <p>This study provides a new look at the observed and calculated long-term temperature changes from the lower troposphere to the lower <span class="hlt">stratosphere</span> since 1958 over the Northern Hemisphere. The data sets include the NCEP/NCAR reanalysis, the Free University of Berlin (FU-Berlin) and the RICH radiosonde data sets as well as historical simulations with the CESM1-WACCM global model participating in CMIP5. The analysis is mainly based on monthly layer mean temperatures derived from geopotential height thicknesses in order to take advantage of the use of the independent FU-Berlin <span class="hlt">stratospheric</span> data set of geopotential height data since 1957. This approach was followed to extend the records for the investigation of the <span class="hlt">stratospheric</span> temperature trends to the earliest possible time. After removing the natural variability with an autoregressive multiple regression model our analysis shows that the period 1958-2011 can be divided into two distinct sub-periods of long-term temperature variability and trends: before and after 1980. By calculating trends for the summer time to reduce interannual variability, the two periods are as follows. From 1958 until 1979, a non-significant trend (0.06 ± 0.06 °C decade-1 for NCEP) and slightly cooling trends (-0.12 ± 0.06 °C decade-1 for RICH) are found in the lower troposphere. The second period from 1980 to the end of the records shows significant <span class="hlt">warming</span> (0.25 ± 0.05 °C decade-1 for both NCEP and RICH). Above the tropopause a significant cooling trend is clearly seen in the lower <span class="hlt">stratosphere</span> both in the pre-1980 period (-0.58 ± 0.17 °C decade-1 for NCEP, -0.30 ± 0.16 °C decade-1 for RICH and -0.48 ± 0.20 °C decade-1 for FU-Berlin) and the post-1980 period (-0.79 ± 0.18 °C decade-1 for NCEP, -0.66 ± 0.16 °C decade-1 for RICH and -0.82 ± 0.19 °C decade-1 for FU-Berlin). The cooling in the lower <span class="hlt">stratosphere</span> persists throughout the year from the tropics up to 60° N. At polar latitudes competing dynamical and radiative processes reduce the statistical significance of these trends. Model results are in line with reanalysis and the observations, indicating a persistent cooling (-0.33 °C decade-1) in the lower <span class="hlt">stratosphere</span> during summer before and after 1980; a feature that is also seen throughout the year. However, the lower <span class="hlt">stratosphere</span> CESM1-WACCM modelled trends are generally lower than reanalysis and the observations. The contrasting effects of ozone depletion at polar latitudes in winter/spring and the anticipated strengthening of the Brewer-Dobson circulation from man-made global <span class="hlt">warming</span> at polar latitudes are discussed. Our results provide additional evidence for an early greenhouse cooling signal in the lower <span class="hlt">stratosphere</span> before 1980, which appears well in advance relative to the tropospheric greenhouse <span class="hlt">warming</span> signal. The suitability of early warning signals in the <span class="hlt">stratosphere</span> relative to the troposphere is supported by the fact that the <span class="hlt">stratosphere</span> is less sensitive to changes due to cloudiness, humidity and man-made aerosols. Our analysis also indicates that the relative contribution of the lower <span class="hlt">stratosphere</span> versus the upper troposphere low-frequency variability is important for understanding the added value of the long-term tropopause variability related to human-induced global <span class="hlt">warming</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740008999','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740008999"><span id="translatedtitle">Mean meridional circulation in the Southern Hemisphere <span class="hlt">stratosphere</span> during the polar night</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Adler, R. F.</p> <p>1973-01-01</p> <p>Atmospheric structure derived from satellite, multichannel radiance data is used to calculate zonally averaged vertical motions in the wintertime <span class="hlt">stratosphere</span> of both hemispheres. The Northern Hemisphere calculations confirm the two celled meridional circulation calculated by previous authors. The Southern Hemisphere results show a three celled structure with descending motion over the South Pole. The variability of the mean meridional circulation in the Southern Hemisphere in relation to the presence or absence of a minor midwinter <span class="hlt">warming</span> is also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850012159&hterms=winter+1980&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwinter%2B1980','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850012159&hterms=winter+1980&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dwinter%2B1980"><span id="translatedtitle">Changes in the Ozone Content over Central Europe During Reversals of <span class="hlt">Stratospheric</span> Circulation in Late Winter</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Entzian, G.; Grasnick, K. H.</p> <p>1984-01-01</p> <p>A superposed epoch analysis during late winter zonal wind reversals was carried out from 18 year observation series (1963 to 1980) of the meridional geopotential height gradient in the 30 mb level (latitude mean) and of the ozone content over central Europe. Experimental data suggest that if planetary waves are responsible for the additional meridional ozone transport during <span class="hlt">stratospheric</span> <span class="hlt">warmings</span>, this transport has to take place at heights other than those up to the ozone maximum in the middle latitudes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140013023','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140013023"><span id="translatedtitle">Temperature Trends in the Tropical Upper Troposphere and Lower <span class="hlt">Stratosphere</span>: Connections with Sea Surface Temperatures and Implications for Water Vapor and Ozone</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Garfinkel, C. I.; Waugh, D. W.; Oman, L. D.; Wang, L.; Hurwitz, M. M.</p> <p>2013-01-01</p> <p>Satellite observations and chemistry-climate model experiments are used to understand the zonal structure of tropical lower <span class="hlt">stratospheric</span> temperature, water vapor, and ozone trends. The <span class="hlt">warming</span> in the tropical upper troposphere over the past 30 years is strongest near the Indo-Pacific <span class="hlt">warm</span> pool, while the <span class="hlt">warming</span> trend in the western and central Pacific is much weaker. In the lower <span class="hlt">stratosphere</span>, these trends are reversed: the historical cooling trend is strongest over the Indo-Pacific <span class="hlt">warm</span> pool and is weakest in the western and central Pacific. These zonal variations are stronger than the zonal-mean response in boreal winter. Targeted experiments with a chemistry-climate model are used to demonstrate that sea surface temperature (hereafter SST) trends are driving the zonal asymmetry in upper tropospheric and lower <span class="hlt">stratospheric</span> tropical temperature trends. <span class="hlt">Warming</span> SSTs in the Indian Ocean and in the <span class="hlt">warm</span> pool region have led to enhanced moist heating in the upper troposphere, and in turn to a Gill-like response that extends into the lower <span class="hlt">stratosphere</span>. The anomalous circulation has led to zonal structure in the ozone and water vapor trends near the tropopause, and subsequently to less water vapor entering the <span class="hlt">stratosphere</span>. The radiative impact of these changes in trace gases is smaller than the direct impact of the moist heating. Projected future SSTs appear to drive a temperature and water vapor response whose zonal structure is similar to the historical response. In the lower <span class="hlt">stratosphere</span>, the changes in water vapor and temperature due to projected future SSTs are of similar strength to, though slightly weaker than, that due directly to projected future CO2, ozone, and methane.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940033096','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940033096"><span id="translatedtitle"><span class="hlt">Stratospheric</span> emissions effects database development</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baughcum, Steven L.; Henderson, Stephen C.; Hertel, Peter S.; Maggiora, Debra R.; Oncina, Carlos A.</p> <p>1994-01-01</p> <p>This report describes the development of a <span class="hlt">stratospheric</span> emissions effects database (SEED) of aircraft fuel burn and emissions from projected Year 2015 subsonic aircraft fleets and from projected fleets of high-speed civil transports (HSCT's). This report also describes the development of a similar database of emissions from Year 1990 scheduled commercial passenger airline and air cargo traffic. The objective of this work was to initiate, develop, and maintain an engineering database for use by atmospheric scientists conducting the Atmospheric Effects of <span class="hlt">Stratospheric</span> Aircraft (AESA) modeling studies. Fuel burn and emissions of nitrogen oxides (NO(x) as NO2), carbon monoxide, and hydrocarbons (as CH4) have been calculated on a 1-degree latitude x 1-degree longitude x 1-kilometer altitude grid and delivered to NASA as electronic files. This report describes the assumptions and methodology for the calculations and summarizes the results of these calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6952854','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6952854"><span id="translatedtitle"><span class="hlt">Stratospheric</span> emissions effects database development</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Baughcum, S.L.; Henderson, S.C.; Hertel, P.S.; Maggiora, D.R.; Oncina, C.A.</p> <p>1994-07-01</p> <p>This report describes the development of a <span class="hlt">stratospheric</span> emissions effects database (SEED) of aircraft fuel burn and emissions from projected Year 2015 subsonic aircraft fleets and from projected fleets of high-speed civil transports (HSCT's). This report also describes the development of a similar database of emissions from Year 1990 scheduled commercial passenger airline and air cargo traffic. The objective of this work was to initiate, develop, and maintain an engineering database for use by atmospheric scientists conducting the Atmospheric Effects of <span class="hlt">Stratospheric</span> Aircraft (AESA) modeling studies. Fuel burn and emissions of nitrogen oxides (NO(x) as NO2), carbon monoxide, and hydrocarbons (as CH4) have been calculated on a 1-degree latitude x 1-degree longitude x 1-kilometer altitude grid and delivered to NASA as electronic files. This report describes the assumptions and methodology for the calculations and summarizes the results of these calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110005651','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110005651"><span id="translatedtitle">Ices in Titan's Lower <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>Anderson, Carrie</p> <p>2010-01-01</p> <p>Analyses of Cassini CIRS far-infrared limb spectra of Titan at 15N, 15S, and 58S reveal a broad emission feature between 70 and 270/cm, restricted to altitudes between 60 and 100 km. This emission feature is chemically different from Titan's photochemical aerosol, which has an emission feature peak around 145 cm-1. The shape of the observed broad emission feature resembles a mixture of the solid component of the two most abundant nitrites in Titan's <span class="hlt">stratosphere</span>, that of HCN and HC3N. Following the saturation vapor pressure vertical profiles of HCN and HC3N, the 60 to 100 km altitude range corresponds closely to the vertical location where these nitriles are expected to condense out and form small, suspended ice particles. This is the first time ices in Titan's <span class="hlt">stratosphere</span> have been identified at latitudes south of 50N. Results and physical implications will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004RvGeo..42.3003M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004RvGeo..42.3003M"><span id="translatedtitle">Mesosphere inversion layers and <span class="hlt">stratosphere</span> temperature enhancements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meriwether, John W.; Gerrard, Andrew J.</p> <p>2004-09-01</p> <p>It has been known for at least 30 years that vertically narrow thermal layers form within the middle atmosphere. Two types of temperature enhancements, the low-latitude to midlatitude mesosphere inversion layer (MIL) and the high-latitude winter <span class="hlt">stratosphere</span> temperature enhancement (STE), have both received much attention within the atmospheric science community because of their unexplained formation mechanisms and potential impacts on the middle-atmosphere global circulation. Numerous experimental, numerical, and theoretical studies have attempted to explain certain aspects of these respective thermal layers, but no one theory consistently and satisfactorily describes all the features observed. We present a review of the literature and explicitly propose a classification scheme based on the different formation mechanisms suspected to cause these events. For the MIL we demonstrate that there are two subtypes. The first one is tidally driven and tends to occur above ~85 km. This MIL originates from large-amplitude tidal waves propagating into the mesosphere and their subsequent nonlinear interactions with gravity waves, which can often create the appearance of a ``double MIL'' separated by approximately one vertical tidal wavelength (~25 km). The other subtype of MIL is formed by a climatological planetary wave dissipation mechanism that occurs at a zero-wind line. The dissipation of the planetary wave tends to generate a mesoscale (~1000 km) inversion layer in the range of 65-80 km. These two formation mechanisms explain a host of observed characteristics, including the reason behind the downward progression of some MILs and not others, the different climatological nature of the two forms of MIL events, and the relative scarcity of MIL observations at high latitudes. The STE is believed to be generated by an altogether different process, namely, the nonlinear interaction between the polar vortex and planetary waves/Aleutian High. The induced temperatures typically peak around 40 km and often exceed 300 K, generating what appears to be a ``low, hot stratopause.'' When vertical temperature profiles are combined with synoptic analyses, one observes that the STE is the consequence of high-latitude vortex interactions creating a baroclinic atmosphere, i.e., a downward adiabatic compression induced by an ageostropic flow. We summarize the details of the relationship between this feature and sudden <span class="hlt">stratospheric</span> <span class="hlt">warmings</span>, as well as the potential for in situ gravity wave generation. We close with a review of currently unexplained MIL/STE features and offer new directions for future middle-atmosphere thermal layer research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900032321&hterms=cfcs&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcfcs','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900032321&hterms=cfcs&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcfcs"><span id="translatedtitle">Laboratory chemistry and <span class="hlt">stratospheric</span> clouds</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Molina, Mario J.</p> <p>1989-01-01</p> <p>Results are presented from laboratory experiments on the chemistry of ice particles to study the role of HCl and ClONO2 from CFCs in <span class="hlt">stratospheric</span> ozone depletion over Antarctica. It is found that gaseous HCl is scavenged with high efficiency by the ice and the gas phase chlorine nitrate may react with the HCL-containing ice to produce Cl2. Also, consideration is given ot the behavior of solid nitric acid trihydrate and sulfuric acid aerosols.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/45755','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/45755"><span id="translatedtitle">A climatology of <span class="hlt">stratospheric</span> aerosol</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hitchman, M.H.; Mckay, M.; Trepte, C.R.</p> <p>1994-10-01</p> <p>A global climatology of <span class="hlt">stratospheric</span> aerosol is created by combining nearly a decade (1979-1981 and 1984-1990) of contemporaneous observations from the <span class="hlt">Stratospheric</span> Aerosol and Gas Experiment (SAGE I and II) and <span class="hlt">Stratospheric</span> Aerosol Measurement (SAM II) instruments. One goal of this work is to provide a representative distribution of the aerosol layer for use in radiative and chemical modeling. A table of decadal average 1 micron extinction values is included, extending from the tropopause to 35 km and 80 deg S to 85 deg N, which allows estimation of surface area density. We find that the aerosol layer is distinctly volcanic in nature and suggest that the decadal average is a more useful estimate of future aerosol loading than a `background` loading, which is never clearly achieved during the data record. This climatology lends insight into the general circulation of the <span class="hlt">stratosphere</span>. Latitude - altitude sections of extinction radio at 1 micron are shown, average by decade, season, and phase of the quasi-biennial oscillation (QBO). A tropical reservoir region is diagnosed, with an `upper` and a `lower` transport regime. In the tropics above 22 km (upper regime), enhanced lofting occurs in the summer, with suppressed lofting or eddy dilution in the winter. In the extratropics within two scale heights of the tropopause (lower regime), poleward and downward transport is most robust during winter, especially in the northern hemisphere. The transport patterns persist into the subsequent equinoctial season. Ascent associated with QBO easterly shear favors detrainment in the upper regime, while relative descent and poleward spreading during QBO westerly shear favors detrainment in the lower regime. Extinction radio differences between the winter-spring and summer-fall hemispheres, and differences between the two phases of the QBO, are typically 20-50%.</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_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" 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_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoRL..42.4989M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoRL..42.4989M"><span id="translatedtitle">Inability of <span class="hlt">stratospheric</span> sulfate aerosol injections to preserve the West Antarctic Ice Sheet</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>2015-06-01</p> <p>Injection of sulfate aerosols into the <span class="hlt">stratosphere</span> has the potential to reduce the climate impacts of global <span class="hlt">warming</span>, including sea level rise (SLR). However, changes in atmospheric and oceanic circulation that can significantly influence the rate of basal melting of Antarctic marine ice shelves and the associated SLR have not previously been considered. Here we use a fully coupled global climate model to investigate whether rapidly increasing <span class="hlt">stratospheric</span> sulfate aerosol concentrations after a period of global <span class="hlt">warming</span> could preserve Antarctic ice sheets by cooling subsurface ocean temperatures. We contrast this climate engineering method with an alternative strategy in which all greenhouse gases (GHG) are returned to preindustrial levels. We find that the rapid addition of a <span class="hlt">stratospheric</span> aerosol layer does not effectively counteract surface and upper level atmospheric circulation changes caused by increasing GHGs, resulting in continued upwelling of <span class="hlt">warm</span> water in proximity of ice shelves, especially in the vicinity of the already unstable Pine Island Glacier in West Antarctica. By contrast, removal of GHGs restores the circulation, yielding relatively cooler subsurface ocean temperatures to better preserve West Antarctica.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009DPS....41.3905F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009DPS....41.3905F"><span id="translatedtitle">Modeling Transport in Saturn's <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>Friedson, Andrew James; Moses, J. I.</p> <p>2009-09-01</p> <p>Recent Cassini and groundbased observations provide strong evidence that temperature and constituent distributions in the <span class="hlt">stratosphere</span> of Saturn are controlled by a complex interaction between photochemical, radiative, and dynamical processes. Knowledge of the mass transport circulation in the upper troposphere and <span class="hlt">stratosphere</span> is therefore indispensable for a full and correct interpretation of spatial maps of trace species concentrations. In this work, a three-dimensional outer-planet general circulation model (OPGCM) is used to compute the thermal structure and dynamics in Saturn's troposphere and <span class="hlt">stratosphere</span>. The model includes a rigorous treatment of radiative transfer and diabatic heating. The effective zonal-mean advective meridional circulation and eddy transport coefficients required by zonally symmetric two-dimensional models are derived from OPGCM tracer experiments. The OPGCM also allows investigation of the relationship between observed temporal and spatial variations of temperatures, winds, and composition in terms of coupling between photochemistry, radiation, and dynamics. The overall methodology and some preliminary results will be presented at the meeting. This work is supported by the NASA Planetary Atmospheres Program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20070025103&hterms=CORA&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DCORA','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20070025103&hterms=CORA&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DCORA"><span id="translatedtitle">Simulations of Dynamics and Transport during the September 2002 Antarctic Major <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>Manney, Gloria L.; Sabutis, Joseph L.; Allen, Douglas R.; Lahoz, Willian A.; Scaife, Adam A.; Randall, Cora E.; Pawson, Steven; Naujokat, Barbara; Swinbank, Richard</p> <p>2005-01-01</p> <p>A mechanistic model simulation initialized on 14 September 2002, forced by 100-hPa geopotential heights from Met Office analyses, reproduced the dynamical features of the 2002 Antarctic major <span class="hlt">warming</span>. The vortex split on approx.25 September; recovery after the <span class="hlt">warming</span>, westward and equatorward tilting vortices, and strong baroclinic zones in temperature associated with a dipole pattern of upward and downward vertical velocities were all captured in the simulation. Model results and analyses show a pattern of strong upward wave propagation throughout the <span class="hlt">warming</span>, with zonal wind deceleration throughout the <span class="hlt">stratosphere</span> at high latitudes before the vortex split, continuing in the middle and upper <span class="hlt">stratosphere</span> and spreading to lower latitudes after the split. Three-dimensional Eliassen-Palm fluxes show the largest upward and poleward wave propagation in the 0(deg)-90(deg)E sector prior to the vortex split (coincident with the location of strongest cyclogenesis at the model's lower boundary), with an additional region of strong upward propagation developing near 180(deg)-270(deg)E. These characteristics are similar to those of Arctic wave-2 major <span class="hlt">warmings</span>, except that during this <span class="hlt">warming</span>, the vortex did not split below approx.600 K. The effects of poleward transport and mixing dominate modeled trace gas evolution through most of the mid- to high-latitude <span class="hlt">stratosphere</span>, with a core region in the lower-<span class="hlt">stratospheric</span> vortex where enhanced descent dominates and the vortex remains isolated. Strongly tilted vortices led to low-latitude air overlying vortex air, resulting in highly unusual trace gas profiles. Simulations driven with several meteorological datasets reproduced the major <span class="hlt">warming</span>, but in others, stronger latitudinal gradients at high latitudes at the model boundary resulted in simulations without a complete vortex split in the midstratosphere. Numerous tests indicate very high sensitivity to the boundary fields, especially the wave-2 amplitude. Major <span class="hlt">warmings</span> occurred for initial fields with stronger winds and larger vortices, but not smaller vortices, consistent with the initiation of wind-deceleration by upward-propagating waves near the poleward edge of the region where wave 2 can propagate above the jet core. Thus, given the observed 100-hPa boundary forcing, <span class="hlt">stratospheric</span> preconditioning is not needed to reproduce a major <span class="hlt">warming</span> similar to that observed. The anomalously strong forcing in the lower <span class="hlt">stratosphere</span> can be viewed as the primary direct cause of the major <span class="hlt">warming</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006IJAsB...5...13W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006IJAsB...5...13W"><span id="translatedtitle">How do microorganisms reach 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>Wainwright, M.; Alharbi, S.; Wickramasinghe, N. C.</p> <p>2006-04-01</p> <p>A number of studies have demonstrated that bacteria and fungi are present in the <span class="hlt">stratosphere</span>. Since the tropopause is generally regarded as a barrier to the upward movement of particles it is difficult to see how such microorganisms can reach heights above 17 km. Volcanoes provide an obvious means by which this could be achieved, but these occur infrequently and any microorganisms entering the <span class="hlt">stratosphere</span> from this source will rapidly fall out of the <span class="hlt">stratosphere</span>. Here, we suggest mechanisms by which microorganisms might reach the <span class="hlt">stratosphere</span> on a more regular basis; such mechanisms are, however, likely only to explain how micrometre to submicrometre particles could be elevated into the <span class="hlt">stratosphere</span>. Intriguingly, clumps of bacteria of size in excess of 10 ?m have been found in <span class="hlt">stratospheric</span> samples. It is difficult to understand how such clumps could be ejected from the Earth to this height, suggesting that such bacterial masses may be incoming to Earth. We suggest that the <span class="hlt">stratospheric</span> microflora is made up of two components: (a) a mixed population of bacteria and fungi derived from Earth, which can occasionally be cultured; and (b) a population made up of clumps of, viable but non-culturable, bacteria which are too large to have originated from Earth; these, we suggest, have arrived in the <span class="hlt">stratosphere</span> from space. Finally, we speculate on the possibility that the transfer of bacteria from the Earth to the highly mutagenic <span class="hlt">stratosphere</span> may have played a role in bacterial evolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990099126','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990099126"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Temperature Changes: Observations and Model Simulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ramaswamy, V.; Chanin, M.-L.; Angell, J.; Barnett, J.; Gaffen, D.; Gelman, M.; Keckhut, P.; Koshelkov, Y.; Labitzke, K.; Lin, J.-J. R.</p> <p>1999-01-01</p> <p>This paper reviews observations of <span class="hlt">stratospheric</span> temperatures that have been made over a period of several decades. Those observed temperatures have been used to assess variations and trends in <span class="hlt">stratospheric</span> temperatures. A wide range of observation datasets have been used, comprising measurements by radiosonde (1940s to the present), satellite (1979 - present), lidar (1979 - present) and rocketsonde (periods varying with location, but most terminating by about the mid-1990s). In addition, trends have also been assessed from meteorological analyses, based on radiosonde and/or satellite data, and products based on assimilating observations into a general circulation model. Radiosonde and satellite data indicate a cooling trend of the annual-mean lower <span class="hlt">stratosphere</span> since about 1980. Over the period 1979-1994, the trend is 0.6K/decade. For the period prior to 1980, the radiosonde data exhibit a substantially weaker long-term cooling trend. In the northern hemisphere, the cooling trend is about 0.75K/decade in the lower <span class="hlt">stratosphere</span>, with a reduction in the cooling in mid-<span class="hlt">stratosphere</span> (near 35 km), and increased cooling in the upper <span class="hlt">stratosphere</span> (approximately 2 K per decade at 50 km). Model simulations indicate that the depletion of lower <span class="hlt">stratospheric</span> ozone is the dominant factor in the observed lower <span class="hlt">stratospheric</span> cooling. In the middle and upper <span class="hlt">stratosphere</span> both the well-mixed greenhouse gases (such as CO) and ozone changes contribute in an important manner to the cooling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850017663','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850017663"><span id="translatedtitle">Development of algorithms for using satellite meteorological data sets to study global transport of <span class="hlt">stratospheric</span> aerosols and ozone</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Want, P. H.; Deepak, A.</p> <p>1985-01-01</p> <p>The utilization of <span class="hlt">stratospheric</span> aerosol and ozone measurements obtained from the NASA developed SAM II and SAGE satellite instruments were investigated for their global scale transports. The <span class="hlt">stratospheric</span> aerosols showed that during the <span class="hlt">stratospheric</span> <span class="hlt">warming</span> of the winter 1978 to 1979, the distribution of the zonal mean aerosol extinction ratio in the northern high latitude exhibited distinct changes. Dynamic processes might have played an important role in maintenance role in maintenance of this zonal mean distribution. As to the <span class="hlt">stratospheric</span> ozone, large poleward ozone transports are shown to occur in the altitude region from 24 km to 38 km near 55N during this <span class="hlt">warming</span>. This altitude region is shown to be a transition region of the phase relationship between ozone and temperature waves from an in-phase one above 38 km. It is shown that the ozone solar heating in the upper <span class="hlt">stratosphere</span> might lead to enhancement of the damping rate of the planetary waves due to infrared radiation alone in agreement with theoretical analyses and an earlier observational study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5458515','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5458515"><span id="translatedtitle">Balloon borne observations of backscatter, frost point and ozone in polar <span class="hlt">stratospheric</span> clouds at the South Pole</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rosen, J.M.; Kjome, N.T. ); Oltmans, S.J. )</p> <p>1991-02-01</p> <p>Concurrent backscatter and ozone measurements were made with near-simultaneous frost point soundings over the South Pole when the center of the 1990 winter vortex was at or very near that location. The initial water vapor concentration in the <span class="hlt">stratosphere</span> was {approximately}5ppmv and decreased to {approximately}1.5-2.0 ppmv as cooling took place. By mid-July the <span class="hlt">stratospheric</span> temperature had decreased to the frost point and heavy polar <span class="hlt">stratospheric</span> cloud (PSC) activity was observed presumably due to the condensation of water vapor. The lowest water vapor concentrations observed correspond to saturated air at the lowest temperatures encountered. The slow recovery of the water vapor concentration during spring <span class="hlt">warming</span> indicates that the 12 to 22 km altitude region in the vortex is not readily penetrated by outside air. The observed large decrease in PSC backscatter above {approximately}14 km before the <span class="hlt">stratosphere</span> began to <span class="hlt">warm</span> is consistent with loss of particles by sedimentation leading to significant dehydration and denitrification. The region of PSC activity in July is noted to be in the same region in which ozone depletion and the persistent dehydration is observed later in the year. At the end of August heavy PSC activity was observed in the lower <span class="hlt">stratosphere</span> and upper troposphere, consistent with earlier observations from NASA aircraft. These lower clouds were in a region that apparently was still experiencing cooling. No compelling evidence was found surrounding earlier claims that PSC layers are anti-correlated with ozone inside the vortex.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DPS....4740008S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DPS....4740008S"><span id="translatedtitle">Seasonal evolution of Saturn's <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>Sylvestre, Melody; Fouchet, Thierry; Spiga, Aymeric; Guerlet, Sandrine</p> <p>2015-11-01</p> <p>The exceptional duration of the Cassini-Huygens mission enables unprecedented study of Saturn's atmospheric dynamics and chemistry. In Saturn's <span class="hlt">stratosphere</span> (from 20 hPa to 10-4 hPa), photochemical and radiative timescales are in the same order as Saturn's revolution period (29.5 years). Consequently, the large seasonal insolation variations experienced by this planet are expected to influence significantly temperatures and abundances of photochemical by-products in this region. We investigate the seasonal evolution of Saturn's <span class="hlt">stratosphere</span> by measuring meridional and seasonal variations (from 2005 to 2012) of temperature and C2H6, C2H2, and C3H8 abundances using Cassini/CIRS limb observations. We complete this study with the development of a GCM (Global Climate Model), in order to understand the physical processes behind this seasonal evolution.The analysis of the CIRS limb observations show that the lower and upper <span class="hlt">stratospheres</span> do not exhibit the same trends in their seasonal variations, especially for temperature. In the lower <span class="hlt">stratosphere</span>, the seasonal temperature contrast is maximal (at 1 hPa) and can be explained by the radiative contributions included in our GCM. In contrast, upper <span class="hlt">stratospheric</span> temperatures (at 0.01 hPa) are constant from northern winter to spring, at odds with our GCM predictions. This behavior indicates that other physical processes such as gravity waves breaking may be at play. At 1 hPa, C2H6, C2H2, and C3H8 abundances exhibit a striking seasonal stability, consistently with the predictions of the photochemical models of Moses and Greathouse, 2005 and Hue et al., 2015. However, the meridional distributions of these species do not follow the predicted trends, which gives insight on atmospheric dynamics. We perform numerical simulations with the GCM to better understand dynamical phenomena in Saturn's atmosphere. We investigate how the large insolation variations induced by the shadow of the rings influence temperatures and atmospheric dynamics. We also study the characteristics of atmospheric waves in the numerical simulations and compare them to existing observations (Achterberg and Flasar, 1996 ; Orton et al., 2013).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989PhDT........81F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989PhDT........81F"><span id="translatedtitle">A Observational Study of the Circulation in the Southern Hemisphere <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>Farrara, John Damon</p> <p></p> <p>The dynamical processes that shape the three-dimensional evolution of the circulation in the Southern Hemisphere <span class="hlt">stratosphere</span> during winter and spring are studied using observational data. Limited use is also made of a three -dimensional, primitive-equation model of the circulation in the middle atmosphere. The final <span class="hlt">warming</span> during spring 1982 is analyzed in detail and other events from an eight-year set are briefly surveyed. The zonal mean westerly jet moves poleward and downward in spring as strong, planetary-scale disturbances develop which contribute to the weakening of the <span class="hlt">stratospheric</span> westerly vortex. The processes governing this weakening are discussed by reference to isentropic maps of Ertel's potential vorticity. Repeating life cycles of growth, eastward-movement and decay of anticyclones in the <span class="hlt">stratosphere</span> are described and related to the behavior of quasi-stationary wave 1 and eastward-traveling wave 2. Evidence that the orography exerts a strong influence on the evolution of the final <span class="hlt">warming</span> is presented. During the winter the <span class="hlt">stratospheric</span> jet stream shifts downward and poleward in response to seasonal variations in thermal forcing. The poleward and downward shift of the jet axis in an individual year is usually abrupt and occurs in association with an enhancement of planetary wave activity. The wave driving of the mean flow in the <span class="hlt">stratosphere</span> generally has a dipolar structure with easterly accelerations near 40^circS and westerly accelerations in polar latitudes, which is consistent with the structure of the observed mean flow accelerations. In the three examples (1980, 1984 and 1985) of large early winter <span class="hlt">stratospheric</span> disturbances with a predominantly zonal wavenumber one pattern in the dataset, the high and low centers developed in the same geographical region. In all three cases, observations suggest, and simulations with the U. K. Meteorological Office <span class="hlt">stratosphere</span>-mesosphere model confirm, that the growth of the <span class="hlt">stratospheric</span> disturbances is due to the amplification of the zonal wavenumber 1 component of the flow at 100 mb. The behavior of wave 1 at 500 mb bears no obvious relation to its counterpart at 100 mb.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012Icar..221..560F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012Icar..221..560F"><span id="translatedtitle">The origin and evolution of Saturns 2011-2012 <span class="hlt">stratospheric</span> vortex</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fletcher, Leigh N.; Hesman, B. E.; Achterberg, R. K.; Irwin, P. G. J.; Bjoraker, G.; Gorius, N.; Hurley, J.; Sinclair, J.; Orton, G. S.; Legarreta, J.; Garca-Melendo, E.; Snchez-Lavega, A.; Read, P. L.; Simon-Miller, A. A.; Flasar, F. M.</p> <p>2012-11-01</p> <p>The planet-encircling springtime storm in Saturns troposphere (December 2010-July 2011, Fletcher, L.N. et al. [2011]. Science 332, 1413-1414; Snchez-Lavega, A. et al. [2011]. Nature 475, 71-74; Fischer, G. et al. [2011]. Nature 475, 75-77) produced dramatic perturbations to <span class="hlt">stratospheric</span> temperatures, winds and composition at mbar pressures that persisted long after the tropospheric disturbance had abated. Thermal infrared (IR) spectroscopy from the Cassini Composite Infrared Spectrometer (CIRS), supported by ground-based IR imaging from the VISIR instrument on the Very Large Telescope and the MIRSI instrument on NASAs IRTF, is used to track the evolution of a large, hot <span class="hlt">stratospheric</span> anticyclone between January 2011 and March 2012. The evolutionary sequence can be divided into three phases: (I) the formation and intensification of two distinct <span class="hlt">warm</span> airmasses near 0.5 mbar between 25 and 35N (B1 and B2) between January-April 2011, moving westward with different zonal velocities, B1 residing directly above the convective tropospheric storm head; (II) the merging of the <span class="hlt">warm</span> airmasses to form the large single <span class="hlt">stratospheric</span> beacon near 40N (B0) between April and June 2011, disassociated from the storm head and at a higher pressure (2 mbar) than the original beacons, a downward shift of 1.4 scale heights (approximately 85 km) post-merger; and (III) the mature phase characterised by slow cooling (0.11 0.01 K/day) and longitudinal shrinkage of the anticyclone since July 2011. Peak temperatures of 221.6 1.4 K at 2 mbar were measured on May 5th 2011 immediately after the merger, some 80 K warmer than the quiescent surroundings. From July 2011 to the time of writing, B0 remained as a long-lived stable <span class="hlt">stratospheric</span> phenomenon at 2 mbar, moving west with a near-constant velocity of 2.70 0.04 deg/day (-24.5 0.4 m/s at 40N relative to System III longitudes). No perturbations to visible clouds and hazes were detected during this period. With no direct tracers of motion in the <span class="hlt">stratosphere</span>, we use thermal windshear calculations to estimate clockwise peripheral velocities of 200-400 m/s at 2 mbar around B0. The peripheral velocities of the two original airmasses were smaller (70-140 m/s). In August 2011, the size of the vortex as defined by the peripheral collar was 65 longitude (50,000 km in diameter) and 25 latitude. <span class="hlt">Stratospheric</span> acetylene (C2H2) was uniformly enhanced by a factor of three within the vortex, whereas ethane (C2H6) remained unaffected. The passage of B0 generated a new band of <span class="hlt">warm</span> <span class="hlt">stratospheric</span> emission at 0.5 mbar at its northern edge, and there are hints of <span class="hlt">warm</span> <span class="hlt">stratospheric</span> structures associated with the beacons at higher altitudes (p < 0.1 mbar) than can be reliably observed by CIRS nadir spectroscopy. Analysis of the zonal windshear suggests that Rossby wave perturbations from the convective storm could have propagated vertically into the <span class="hlt">stratosphere</span> at this point in Saturns seasonal cycle, one possible source of energy for the formation of these <span class="hlt">stratospheric</span> anticyclones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920065078&hterms=Polar+Stratospheric+Cloud&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DPolar%2BStratospheric%2BCloud','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920065078&hterms=Polar+Stratospheric+Cloud&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DPolar%2BStratospheric%2BCloud"><span id="translatedtitle">Background <span class="hlt">stratospheric</span> aerosol and polar <span class="hlt">stratospheric</span> cloud reference models</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mccormick, M. P.; Wang, P.-H.; Pitts, M. C.</p> <p>1993-01-01</p> <p>A global aerosol climatology is evolving from the NASA satellite experiments SAM II, SAGE I, and SAGE II. In addition, polar <span class="hlt">stratospheric</span> cloud (PSC) data have been obtained from these experiments over the last decade. An undated reference model of the optical characteristics of the background aerosol is described and a new aerosol reference model derived from the latest available data is proposed. The aerosol models are referenced to the height above the tropopause. The impact of a number of volcanic eruptions is described. In addition, a model describing the seasonal, longitudinal, and interannual variations in PSCs is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120013522','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120013522"><span id="translatedtitle">The Evolution and Fate of Saturn's <span class="hlt">Stratospheric</span> Vortex: Infrared Spectroscopy from Cassini</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fletcher, Leigh N.; Hesman, B. E.; Arhterberg, R. K.; Bjoraker, G.; Irwin, P. G. J.; Hurley, J.; Sinclair, J.; Gorius, N.; Orton, G. S.; Read, P. L.; Simon-Miller, A. A.; Flasar, F. M.</p> <p>2012-01-01</p> <p>The planet-encircling springtime storm in Saturn's troposphere (December 2010-July 2011) produced dramatic perturbations to <span class="hlt">stratospheric</span> temperatures, winds and composition at mbar pressures that persisted long after the tropospheric disturbance had abated. Observations from the Cassini Composite Infrared Spectrometer (CIRS), supported by ground-based imaging from the VISIR instrument on the Very Large Telescope,is used to track the evolution of a large, hot <span class="hlt">stratospheric</span> anticyclone between January 2011 and the present day. The evolutionary sequence can be divided into three phases: (I) the formation and intensification of two distinct <span class="hlt">warm</span> airmasses near 0.5 mbar between 25 and 35N (one residing directly above the convective storm head) between January-April 2011, moving westward with different zonal velocities; (II) the merging of the <span class="hlt">warm</span> airmasses to form the large single '<span class="hlt">stratospheric</span> beacon' near 40N between April and June 2011, dissociated from the storm head and at a higher pressure (2 mbar) than the original beacons; and (III) the mature phase characterized by slow cooling and longitudinal shrinkage of the anticyclone since July 2011, moving west with a near-constant velocity of 2.70+/-0.04 deg/day (-24.5+/-0.4 m/s at 40N). Peak temperatures of 220 K at 2 mbar were measured on May 5th 2011 immediately after the merger, some 80 K warmer than the quiescent surroundings. Thermal winds hear calculations in August 2011 suggest clockwise peripheral velocities of 200400 mls at 2 mbar, defining a peripheral collar with a width of 65 degrees longitude (50,000 km in diameter) and 25 degrees latitude. <span class="hlt">Stratospheric</span> acetylene (C2H2) was uniformly enhanced by a factor of three within the vortex, whereas ethane (C2H6) remained unaffected. We will discuss the thermal and chemical characteristics of Saturn's beacon in its mature phase, and implications for <span class="hlt">stratospheric</span> vortices on other giant planets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012DPS....4440301F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012DPS....4440301F"><span id="translatedtitle">The Evolution and Fate of Saturns <span class="hlt">Stratospheric</span> Vortex: Infrared Spectroscopy from Cassini</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fletcher, Leigh N.; Hesman, B. E.; Achterberg, R. K.; Bjoraker, G.; Irwin, P. G. J.; Hurley, J.; Sinclair, J.; Gorius, N.; Orton, G. S.; Read, P. L.; Simon-Miller, A. A.; Flasar, F. M.</p> <p>2012-10-01</p> <p>The planet-encircling springtime storm in Saturn's troposphere (December 2010-July 2011) produced dramatic perturbations to <span class="hlt">stratospheric</span> temperatures, winds and composition at mbar pressures that persisted long after the tropospheric disturbance had abated. Observations from the Cassini Composite Infrared Spectrometer (CIRS), supported by ground-based imaging from the VISIR instrument on the Very Large Telescope, is used to track the evolution of a large, hot <span class="hlt">stratospheric</span> anticyclone between January 2011 and the present day. The evolutionary sequence can be divided into three phases: (I) the formation and intensification of two distinct <span class="hlt">warm</span> airmasses near 0.5 mbar between 25 and 35N (one residing directly above the convective storm head) between January-April 2011, moving westward with different zonal velocities; (II) the merging of the <span class="hlt">warm</span> airmasses to form the large single `<span class="hlt">stratospheric</span> beacon' near 40N between April and June 2011, dissociated from the storm head and at a higher pressure (2 mbar) than the original beacons; and (III) the mature phase characterised by slow cooling and longitudinal shrinkage of the anticyclone since July 2011, moving west with a near-constant velocity of 2.700.04 deg/day (-24.50.4 m/s at 40N). Peak temperatures of 220 K at 2 mbar were measured on May 5th 2011 immediately after the merger, some 80 K warmer than the quiescent surroundings. Thermal windshear calculations in August 2011 suggest clockwise peripheral velocities of 200-400 m/s at 2 mbar, defining a peripheral collar with a width of 65 degrees longitude (50,000 km in diameter) and 25 degrees latitude. <span class="hlt">Stratospheric</span> acetylene (C2H2) was uniformly enhanced by a factor of three within the vortex, whereas ethane (C2H6) remained unaffected. We will discuss the thermal and chemical characteristics of Saturns beacon in its mature phase, and implications for <span class="hlt">stratospheric</span> vortices on other giant planets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGC13I0788L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGC13I0788L"><span id="translatedtitle">Arctic <span class="hlt">stratospheric</span> sulphur injections: radiative forcings and cloud responses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lohmann, U.; Gasparini, B.; Miriam, K.; Kravitz, B.; Rasch, P. J.</p> <p>2014-12-01</p> <p>Observations and climate projections show a high sensitivity of the Arctic climate to the increase in greenhouse gas emissions, known as the polar amplification. This study evaluates the options of counteracting the rising polar temperatures by <span class="hlt">stratospheric</span> sulphur injections in the Northern Hemisphere high latitudes.10 Mt of sulphur dioxide are emitted in a point emission source setup centred at the 100 hPa pressure level over Svalbard island (80N,15E). We perform simulations with the general circulation models ECHAM5, ECHAM6, and GISS ModelE. We study pulsed emission simulations that differ among themselves by the injection starting date (March-September), injection length (1, 30, or 90 day emission period), and the vertical resolution of the model (for ECHAM6). We find injections in April to be the most efficient in terms of the shortwave radiative forcing at the top-of-the atmosphere over the Arctic region. The distribution of sulphate aerosol spreads out beyond the injection region, with a significant share reaching the Southern Hemisphere. Results from ModelE show high latitude injections could counteract the spring and summer temperature increase due to higher atmospheric CO2 concentrations. Preliminary results with a more realistic description of clouds in ECHAM-HAM reveal a complex pattern of responses, most notably: a decrease in Northern Hemisphere cirrus clouds strengthening the effect of <span class="hlt">stratospheric</span> aerosols in ECHAM5 a decrease in low-level clouds over the Arctic increasing the incoming solar radiation and causing a net positive radiative balance cirrus clouds are resilient to <span class="hlt">stratospheric</span> sulphur injections in the absence of sulphate <span class="hlt">warming</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=ozone&pg=7&id=EJ391165','ERIC'); return false;" href="http://eric.ed.gov/?q=ozone&pg=7&id=EJ391165"><span id="translatedtitle">Changing Composition of the Global <span class="hlt">Stratosphere</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>McElroy, Michael B.; Salawitch, Ross J.</p> <p>1989-01-01</p> <p>Discusses the chemistry of the <span class="hlt">stratosphere</span> at mid-latitudes, the Antarctic phenomenon, and temporal trends in ozone levels. Includes equations, diagrams of the global distribution of ozone, and halogen growth projections. Concludes that studies of <span class="hlt">stratospheric</span> ozone demonstrate that the global environment is fragile and is impacted by human</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920005296','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920005296"><span id="translatedtitle">Radiative flux measurements 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>Valero, Francisco P. J.</p> <p>1990-01-01</p> <p>The objective is to determine how the <span class="hlt">stratospheric</span> tropospheric exchange of water vapor is affected by the interaction of solar (visible) and planetary (infrared) radiation with tropical cumulonimbus anvils. This research involves field measurements from the ER-2 aircraft as well as radiative transfer modelling to determine heating and cooling rates and profiles that directly affect the exchange between the troposphere and the <span class="hlt">stratosphere</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997PhDT........17N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997PhDT........17N"><span id="translatedtitle">Chaotic advection 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>Ngan, Keith</p> <p></p> <p>The relevance of chaotic advection to <span class="hlt">stratospheric</span> mixing and transport is addressed in the context of (i) a simple Hamiltonian model (referred to as the two-wave model); and (ii) a numerical model of forced shallow- water flow on the sphere. As chaotic advection has traditionally been associated with time-periodic kinematic models, its relevance to the dynamically- evolving flows of geophysical fluid dynamics, and to the <span class="hlt">stratosphere</span> in particular, is unclear. In the first half of this thesis chaotic advection in the two-wave model is analysed in great detail. A large number of diagnostics are considered-transport fluxes, dispersion statistics, tracer spectra, Liapunov exponents, and correlation times. The main objective is to delineate the characteristics of chaotic advection in a physically plausible model of <span class="hlt">stratospheric</span> mixing and transport; the two-wave model, which is obtained from Rossby-wave critical-layer theory, is dynamically consistent to leading order in the wave amplitude, thus partially circumventing the dynamical consistency problem that has vexed previous geophysical applications of chaotic advection. A secondary objective is to describe the parameter dependence of mixing and transport, notably with respect to stochasticity (multiplicative and additive). In the second half of this thesis a similar analysis is undertaken for the shallow-water model, a system of a type which has been used to successfully simulate the dynamics of a perturbed polar vortex. By comparison with the two-wave results (and with predictions for random- strain turbulence), it is shown that chaotic advection occurs in the shallow-water system if there is sufficient spatial structure in the velocity field-namely the formation of cat's eyes in the surf zone, such as are commonly seen in numerical simulations of Rossby-wave critical layers. The cat's eyes may be thought of as an 'organizing structure' which acts in a manner akin to the heteroclinic structure of a chaotic system. These results appear to be in agreement with the central result of contour advection calculations, that the development of small-scale tracer structure in the lower <span class="hlt">stratosphere</span> is determined by the large-scale flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/188464','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/188464"><span id="translatedtitle">The influence of volcanic <span class="hlt">stratospheric</span> aerosols on interannual global climate variations. Ph.D. Thesis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Andsager, K.M.</p> <p>1992-12-31</p> <p>A qualitative physical mechanism has been proposed to explain the forcing of the EI Nino/Southern Oscillation (ENSO) by low-latitude volcanic <span class="hlt">stratospheric</span> aerosols. This mechanism is based on the normal global annual cycle resulting from the normal annual cycle in the distribution of incoming solar radiation. The presence of a volcanic <span class="hlt">stratospheric</span> aerosol, which backscatters incoming solar radiation, is hypothesized to trigger the ENSO through an amplification of the normal annual decrease in wind strength and corresponding increase in sea surface temperatures (SST) in the eastern tropical Pacific Ocean. The observational evidence for an association between the record of volcanic eruptions and SST and the Southern Oscillation Index (SOI, Tahiti SLP minus Darwin SLP) over the last 120 years is examined using superposed epoch analysis. Composites using as key dates low-latitude volcanic eruptions suggest that these eruptions are followed by statistically significantly <span class="hlt">warm</span> sea surface temperatures at least at the 1 percent level, if not higher, with the greatest <span class="hlt">warming</span> generally occurring in the first three seasons after the eruption. Satellite data on the distribution of recent volcanic aerosols suggests that an aerosol must only be present over the tropics (about 20 deg S to 20 deg N) to trigger an ENSO event. For the physical mechanism by which an ENSO event may be triggered by a volcanic <span class="hlt">stratospheric</span> aerosol, these results and the results of recent computer modeling studies imply the need for a shift away from past emphasis on surface cooling and SLP anomalies and toward consideration of <span class="hlt">stratospheric</span> <span class="hlt">warming</span> and changes in energy storage and transport.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990025891','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990025891"><span id="translatedtitle">Heterogeneous Chemistry Related to <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>Tolbert, Margaret A.</p> <p>1995-01-01</p> <p>Emissions from <span class="hlt">stratospheric</span> aircraft that may directly or indirectly affect ozone include NO(y), H2O, soot and sulfuric acid. To fully assess the impact of such emissions, it is necessary to have a full understanding of both the homogeneous and heterogeneous transformations that may occur in the <span class="hlt">stratosphere</span>. Heterogeneous reactions on <span class="hlt">stratospheric</span> particles play a key role in partitioning ozone-destroying species between their active and reservoir forms. In particular, heterogeneous reactions tend to activate odd chlorine while deactivating odd nitrogen. Accurate modeling of the net atmospheric effects of <span class="hlt">stratospheric</span> aircraft requires a thorough understanding of the competing effects of this activation/deactivation. In addition, a full understanding of the potential aircraft impacts requires that the abundance, composition and formation mechanisms of the particles themselves be established. Over the last three years with support from the High Speed Research Program, we have performed laboratory experiments to determine the chemical composition, formation mechanism, and reactivity of <span class="hlt">stratospheric</span> aerosols.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoRL..42.6852S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoRL..42.6852S"><span id="translatedtitle">Injection of iodine to 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>Saiz-Lopez, A.; Baidar, S.; Cuevas, C. A.; Koenig, T. K.; Fernandez, R. P.; Dix, B.; Kinnison, D. E.; Lamarque, J.-F.; Rodriguez-Lloveras, X.; Campos, T. L.; Volkamer, R.</p> <p>2015-08-01</p> <p>We report a new estimation of the injection of iodine into the <span class="hlt">stratosphere</span> based on novel daytime (solar zenith angle < 45°) aircraft observations in the tropical tropopause layer and a global atmospheric model with the most recent knowledge about iodine photochemistry. The results indicate that significant levels of total reactive iodine (0.25-0.7 parts per trillion by volume), between 2 and 5 times larger than the accepted upper limits, can be injected into the <span class="hlt">stratosphere</span> via tropical convective outflow. At these iodine levels, modeled iodine catalytic cycles account for up to 30% of the contemporary ozone loss in the tropical lower <span class="hlt">stratosphere</span> and can exert a <span class="hlt">stratospheric</span> ozone depletion potential equivalent to, or even larger than, that of very short-lived bromocarbons. Therefore, we suggest that iodine sources and chemistry need to be considered in assessments of the historical and future evolution of the <span class="hlt">stratospheric</span> ozone layer.</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_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" 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_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990014075&hterms=Montreal+protocol&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2528Montreal%2Bprotocol%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990014075&hterms=Montreal+protocol&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2528Montreal%2Bprotocol%2529"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Cooling and Arctic Ozone Recovery</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Danilin, Michael Y.; Sze, Nien-Dak; Ko, Malcolm K. W.; Rodriquez, Jose M.</p> <p>1998-01-01</p> <p>We present sensitivity studies using the AER( box model for an idealized parcel in the lower <span class="hlt">stratosphere</span> at 70 N during winter/spring with different assumed <span class="hlt">stratospheric</span> coolings and chlorine loadings. Our calculations show that <span class="hlt">stratospheric</span> cooling could further deplete ozone via increased polar <span class="hlt">stratospheric</span> cloud (PSC) formation and retard its expected recovery even with the projected chlorine loading decrease. We introduce the concept of chlorine-cooling equivalent and show that a 1 K cooling could provide the same local ozone depletion as an increase of chlorine by 0.4-0.7 ppbv for the scenarios considered. Thus, sustained <span class="hlt">stratospheric</span> cooling could further reduce Arctic ozone content and delay the anticipated ozone recovery in the Northern Hemisphere even with the realization of the Montreal Protocol and its Amendments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990039174&hterms=Montreal+protocol&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2528Montreal%2Bprotocol%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990039174&hterms=Montreal+protocol&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2528Montreal%2Bprotocol%2529"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Cooling and Arctic Ozone Recovery</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Danilin, Michael Y.; Sze, Nien-Dak; Ko, Malcolm K. W.; Rodriquez, Jose M.</p> <p>1998-01-01</p> <p>We present sensitivity studies using the AER box model for an idealized parcel in the lower <span class="hlt">stratosphere</span> at 70 deg N during winter/spring with different assumed <span class="hlt">stratospheric</span> cooling and chlorine loadings. Our calculations show that <span class="hlt">stratospheric</span> cooling could further deplete ozone via increased polar <span class="hlt">stratospheric</span> cloud (PSC) formation and retard its expected recovery even with the projected chlorine loading decrease. We introduce the concept of chlorine-cooling equivalent and show that a 1 K Cooling could provide the same local ozone depletion as an increase of chlorine by 0.4-0.7 ppbv for the scenarios considered. Thus, sustained <span class="hlt">stratospheric</span> cooling could further reduce Arctic ozone content and delay the anticipated ozone recovery in the Northern Hemisphere even with the realization of the Montreal Protocol and its Amendments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990063764&hterms=coagulation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dcoagulation','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990063764&hterms=coagulation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dcoagulation"><span id="translatedtitle">The Life Cycle of <span class="hlt">Stratospheric</span> Aerosol Particles</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamill, Patrick; Jensen, Eric J.; Russell, P. B.; Bauman, Jill J.</p> <p>1997-01-01</p> <p>This paper describes the life cycle of the background (nonvolcanic) <span class="hlt">stratospheric</span> sulfate aerosol. The authors assume the particles are formed by homogeneous nucleation near the tropical tropopause and are carried aloft into the <span class="hlt">stratosphere</span>. The particles remain in the Tropics for most of their life, and during this period of time a size distribution is developed by a combination of coagulation, growth by heteromolecular condensation, and mixing with air parcels containing preexisting sulfate particles. The aerosol eventually migrates to higher latitudes and descends across isentropic surfaces to the lower <span class="hlt">stratosphere</span>. The aerosol is removed from the <span class="hlt">stratosphere</span> primarily at mid- and high latitudes through various processes, mainly by isentropic transport across the tropopause from the <span class="hlt">stratosphere</span> into the troposphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910071867&hterms=freezing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dfreezing','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910071867&hterms=freezing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dfreezing"><span id="translatedtitle">Homogeneous freezing nucleation of <span class="hlt">stratospheric</span> solution droplets</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jensen, Eric J.; Toon, Owen B.; Hamill, Patrick</p> <p>1991-01-01</p> <p>The classical theory of homogeneous nucleation was used to calculate the freezing rate of sulfuric acid solution aerosols under <span class="hlt">stratospheric</span> conditions. The freezing of <span class="hlt">stratospheric</span> aerosols would be important for the nucleation of nitric acid trihydrate particles in the Arctic and Antarctic <span class="hlt">stratospheres</span>. In addition, the rate of heterogeneous chemical reactions on <span class="hlt">stratospheric</span> aerosols may be very sensitive to their state. The calculations indicate that homogeneous freezing nucleation of pure water ice in the <span class="hlt">stratospheric</span> solution droplets would occur at temperatures below about 192 K. However, the physical properties of H2SO4 solution at such low temperatures are not well known, and it is possible that sulfuric acid aerosols will freeze out at temperatures ranging from about 180 to 195 K. It is also shown that the temperature at which the aerosols freeze is nearly independent of their size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ERL.....7c4021L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ERL.....7c4021L"><span id="translatedtitle"><span class="hlt">Stratospheric</span> passenger flights are likely an inefficient geoengineering strategy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laakso, Anton; Partanen, Antti-Ilari; Kokkola, Harri; Laaksonen, Ari; Lehtinen, Kari E. J.; Korhonen, Hannele</p> <p>2012-09-01</p> <p>Solar radiation management with <span class="hlt">stratospheric</span> sulfur aerosols has been proposed as a potential geoengineering strategy to reduce global <span class="hlt">warming</span>. However, there has been very little investigation on the efficiency of specific injection methods suggested. Here, we show that using <span class="hlt">stratospheric</span> passenger flights to inject sulfate aerosols would not cause significant forcing under realistic injection scenarios: even if all present-day intercontinental flights were lifted above the tropopause, we simulate global surface shortwave radiative forcings of - 0.05 W m-2 and - 0.10 W m-2 with current and five times enhanced fuel sulfur concentrations, respectively. In the highly unlikely scenario that fuel sulfur content is enhanced by a factor of 50 (i.e. ten times the current legal limit) the radiative forcing is - 0.85 W m-2. This is significantly lower than if the same amount of sulfur were injected over the tropics ( - 1.32 W m-2, for 3 Tg (S) yr-1) due to a faster loss rate and lower intensity of solar radiation in the northern midlatitudes where current flight paths are concentrated. We also predict lower global forcing in northern hemisphere winter than in summer due to the seasonalities of the solar radiation intensity at midlatitudes, the related OH chemistry that produces sulfate aerosol, and removal of particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5456909','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5456909"><span id="translatedtitle">Global <span class="hlt">warming</span> implications of replacing CFCs</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fischer, S.K.; Fairchild, P.D.; Hughes, P.J. )</p> <p>1992-04-01</p> <p>The late 1980s were a challenging time for the HVAC and R industries because of the demands being made for increased energy efficiency, the development of alternative refrigerants that do not destroy <span class="hlt">stratospheric</span> ozone, and the intense pressures of international competition. The 1990s will not be any less demanding, with further requirements to improve efficiency and changing understandings of environmental acceptability. Dealing with the global <span class="hlt">warming</span> issue creates further difficulties in adapting the refrigeration and insulation technologies for future needs as chlorofluorocarbons are phased out of production and use in accordance with the Montreal Protocol. The study reported in this article was conducted to help industry, government and international policymakers reach sound decisions during the change-over from the CFCs to alternative compounds and technologies. Information developed in this effort complements ongoing studies to assess safety, toxicology, cost and other factors influencing these decisions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910016145','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910016145"><span id="translatedtitle">The Cl-36 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>Deck, Bruce; Wahlen, Martin; Weyer, Harley; Kubik, Peter; Sharma, Pankaj; Gove, Harry</p> <p>1991-01-01</p> <p>Initial measurements of the cosmogenic radionuclide, Cl-36, in the lower <span class="hlt">stratosphere</span> were made by accelerator mass spectrometry. Samples were obtained using the large volume LASL air sampling pods on a NASA WB-57F aircraft. Untreated (for collection of particulates only) and tetrabutyl ammonium hydroxide treated (for collection of particulates and HCl) IPC-1478 filters were flown on three flights in the lower <span class="hlt">stratosphere</span>. Chlorine (Cl) and Cl compounds are important trace constituents for <span class="hlt">stratospheric</span> chemistry, in particular with respect to O3 destruction. <span class="hlt">Stratospheric</span> Cl chemistry has recently received increased attention with the observation of strong O3 depletion in the Antarctic winter vortex and in the weaker and more complex Arctic winter vortices. Cosmogenic (Cl-36) is produced by spallation reactions from Ar mainly in the <span class="hlt">stratosphere</span>, and has had several applications as a geochemical tracer. The large amounts of Cl-36 introduced by nuclear weapon testing have been removed from the <span class="hlt">stratosphere</span> by now, and measurements in the <span class="hlt">stratosphere</span> to obtain cosmogenic production rates and concentration distributions is now possible. The use of cosmogenic Cl-36 as a tracer for <span class="hlt">stratospheric</span> Cl chemistry and for <span class="hlt">stratospheric</span>/tropospheric exchange processes is investigated. A first attempt to determine <span class="hlt">stratospheric</span> and tropospheric production rates, the partitioning of Cl-36 among particulate and gaseous Cl compounds, and the respective inventories and removal rates is being made. Results from a flight at 13.7 km, 30-33 degrees N, 97-107 degrees W, and from a second flight at 17.7 km, 43-45-36 degrees N, 92-94 degrees W, for the untreated and treated filters respectively are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000021112&hterms=freezing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfreezing','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000021112&hterms=freezing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfreezing"><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>Temperature histories based on 10-day back growth trajectories for six ER-2 flights during AASE I (1989) and AAOE (1987) are presented. These trajectories along with the properties of the observed PSC (polar <span class="hlt">stratospheric</span> cloud) particles are used here to infer the physical state of the pre-existing sulfuric acid aerosols. Of all the ER-2 flights described here, only the PSCs observed on the flights of January 24 and 25, 1989 are consistent with the thermodynamics of liquid ternary solutions of H2SO4/HNO3/H2O Ib PSCs). For these two days, back trajectories indicate that the air mass was exposed to SAT (sulfuric acid tetrahydrate) melting temperatures about 24 hours prior to being sampled by the ER-2. For the remaining ER-2 flights (January, 16, 19, and 20 for the AASE I campaign and August 17 for the AAOE campaign), the observed PSCs were probably composed of amorphous solid solutions of HNO3 and H2O (Type Ic PSCs). Formation of such Type Ic PSCs requires the presence of solid H2SO4 aerosols since liquid aerosols yield ternary solutions. The 10-day back trajectories of these flights indicate that the air mass was not exposed to SAT melting temperatures during the past week and had experienced cooling/<span class="hlt">warming</span> cycles prior to being sampled by the ER-2. These 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://www.osti.gov/scitech/biblio/250025','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/250025"><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://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tabazadeh, A.; Toon, O.B.; Hamill, P.</p> <p>1995-07-01</p> <p>Temperature histories based on 10-day back trajectories for six ER-2 flights during AASE I and AAOE are presented. These trajectories along with the properties of the observed PSC (polar <span class="hlt">stratospheric</span> cloud) particles are used here to infer the physical state of the pre-existing sulfuric acid aerosols. Of all the ER-2 flights described here, only the PSCs observed on the flights of January 24 and 25, 1989 are consistent with the thermo-dynamics of liquid ternary solutions of H{sub 2}SO{sub 4}/HNO{sub 3}/H{sub 2}O (Type Ib PSCs). For these two days, back trajectories indicate that the air mass was exposed to SAT (sulfuric acid tetrahydrate) melting temperatures about 24 hours prior to being sampled by the ER-2. For the remaining ER-2 flights (January, 16, 19, and 20 for the AASE I campaign and August 17 for the AAOE campaign), the observed PSCs were probably composed of amorphous solid solutions of HNO{sub 3} and H{sub 2}O (Type Ic PSCs). Formation of such Type Ic PSCs requires the presence of solid H{sub 2}SO{sub 4} aerosols since liquid aerosols yield ternary solutions. The 10-day back trajectories of these flights indicate that the air mass was not exposed to SAT melting temperatures during the past week and had experienced cooling/<span class="hlt">warming</span> cycles prior to being sampled by the ER-2. These temperature histories, recent laboratory measurements and the properties of glassy solids suggest that <span class="hlt">stratospheric</span> H{sub 2}SO{sub 4} 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. 23 refs., 2 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007ACPD....7.8933P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007ACPD....7.8933P"><span id="translatedtitle">Is there a <span class="hlt">stratospheric</span> fountain?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pommereau, J.-P.; Held, G.</p> <p>2007-06-01</p> <p>The impact of convection on the thermal structure of the Tropical Tropopause Layer (TTL) was investigated from a series of four daily radiosonde ascents and weather S-band radar observations carried out during the HIBISCUS campaign in the South Atlantic Convergence Zone in Southeast Brazil in February 2004. The temperature profiles display a large impact of convective activity on the thermal structure of the TTL. Compared to non-active periods, convection is observed to result in a cooling of 4.5C to 7.5C at the Lapse Rate Tropopause at 16 km, propagating up to 19 km or 440 K potential temperature levels in the <span class="hlt">stratosphere</span> in most intense convective cases. Consistent with the diurnal cycle of echo top heights seen by a S-band weather radar, a systematic temperature diurnal cycle is observed in the layer, displaying a rapid cooling of 3.5C on average (-9, -2C extremes) during the development phase of convection in the early afternoon during the most active period. Since the cooling occurs during daytime within a timescale of 6-h, its maximum amplitude is at the altitude of the Cold Point Tropopause at 390 K and temperature fluctuations associated to gravity waves do not display significant diurnal change, the afternoon cooling of the TTL cannot be attributed to radiation, advection, gravity waves or adiabatic lofting. It implies a fast insertion of adiabatically cooled air parcels by overshooting turrets followed by mixing with the warmer environment. During most intense convective days, the overshoot is shown to penetrate the <span class="hlt">stratosphere</span> up to 450 K potential temperature level. Such fast updraft offers an explanation for the presence of ice crystals, and enhanced water vapour layers observed up to 18-19 km (410-430 K) in the same area by the HIBISCUS balloons and the TROCCINOX Geophysica aircraft, as well as high tropospheric chemical species concentrations in the TTL over land observed from space. Overall, injection of cold air by irreversible mixing of convective overshoots as proposed by Danielsen (1982) do not appear as episodic isolated features, but common and systematic events over a land convective area, that is a <span class="hlt">Stratospheric</span> Fountain. Though the two-stages process proposed by Sherwood (2000) may also be operative, it offers a mechanism for producing the chemical, moisture and thermal properties observed in the <span class="hlt">stratosphere</span>. The consistency between convective cooling of the TTL and weather radar echoes heights observed during the summer over South-East Brazil and the TRMM radar OPFs and LIS lightning events maximum frequencies, the latter showing also maximum events over Africa, South-East Asia, the Indonesian Islands and Northern Australia depending on the season (Liu and Zipser, 2005), suggests the existence of several "<span class="hlt">Stratospheric</span> Fountains" over continents instead of the oceanic area of Micronesia as proposed by Newell and Gould-Stewart (1982), which appears a region of little overshoot.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=climate+AND+marine&pg=2&id=EJ412301','ERIC'); return false;" href="http://eric.ed.gov/?q=climate+AND+marine&pg=2&id=EJ412301"><span id="translatedtitle">Global <span class="hlt">Warming</span> Trends.</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>Jones, Philip D.; Wigley, Tom M. L.</p> <p>1990-01-01</p> <p>Results from the analysis of land and marine records from the past century are presented. It is indicated that the planet earth has <span class="hlt">warmed</span> about one-half of a degree celsius. The uncertainty of these measurements and future <span class="hlt">warming</span> trends are discussed. (CW)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=11242&keyword=social+AND+web&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=50206637&CFTOKEN=38183703','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=11242&keyword=social+AND+web&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=50206637&CFTOKEN=38183703"><span id="translatedtitle">EPA GLOBAL <span class="hlt">WARMING</span> WEBSITE</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>The U.S. EPA Global <span class="hlt">Warming</span> Site strives to present or direct viewers to the most timely social, scientific, and logistic information available on the global <span class="hlt">warming</span> issue. The site offers links to related sites as well as its own selection of material, which is expected to grow ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ACP....13.8787I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ACP....13.8787I"><span id="translatedtitle">Gravitational separation in the <span class="hlt">stratosphere</span> - a new indicator of atmospheric circulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ishidoya, S.; Sugawara, S.; Morimoto, S.; Aoki, S.; Nakazawa, T.; Honda, H.; Murayama, S.</p> <p>2013-09-01</p> <p>As a basic understanding of the dynamics of the atmospheric circulation, it has been believed that gravitational separation of atmospheric components is observable only in the atmosphere above the turbopause. However, we found, from our high-precision measurements of not only the isotopic ratios of N2, O2 and Ar but also the mole fraction of Ar, that gravitational separation occurs even in the <span class="hlt">stratosphere</span> below the turbopause; their observed vertical profiles are in good agreement with those expected theoretically from molecular mass differences. The O2/N2 ratio observed in the middle <span class="hlt">stratosphere</span>, corrected for gravitational separation, showed the same mean air age as estimated from the CO2 mole fraction. Simulations with a 2-dimensional model of the middle atmosphere indicated that a relationship between gravitational separation and the age of air in the <span class="hlt">stratosphere</span> would be significantly affected if the Brewer-Dobson circulation was enhanced due to global <span class="hlt">warming</span>. Therefore, gravitational separation is usable as a new indicator of changes in the atmospheric circulation in the <span class="hlt">stratosphere</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22086224','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22086224"><span id="translatedtitle">THERMAL AND CHEMICAL STRUCTURE VARIATIONS IN TITAN'S <span class="hlt">STRATOSPHERE</span> DURING THE CASSINI MISSION</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bampasidis, Georgios; Coustenis, A.; Vinatier, S.; Achterberg, R. K.; Lavvas, P.; Nixon, C. A.; Jennings, D. E.; Flasar, F. M.; Carlson, R. C.; Romani, P. N.; Guandique, E. A.; Teanby, N. A.; Moussas, X.; Preka-Papadema, P.; Stamogiorgos, S.</p> <p>2012-12-01</p> <p>We have developed a line-by-line Atmospheric Radiative Transfer for Titan code that includes the most recent laboratory spectroscopic data and haze descriptions relative to Titan's <span class="hlt">stratosphere</span>. We use this code to model Cassini Composite Infrared Spectrometer data taken during the numerous Titan flybys from 2006 to 2012 at surface-intercepting geometry in the 600-1500 cm{sup -1} range for latitudes from 50 Degree-Sign S to 50 Degree-Sign N. We report variations in temperature and chemical composition in the <span class="hlt">stratosphere</span> during the Cassini mission, before and after the Northern Spring Equinox (NSE). We find indication for a weakening of the temperature gradient with <span class="hlt">warming</span> of the <span class="hlt">stratosphere</span> and cooling of the lower mesosphere. In addition, we infer precise concentrations for the trace gases and their main isotopologues and find that the chemical composition in Titan's <span class="hlt">stratosphere</span> varies significantly with latitude during the 6 years investigated here, with increased mixing ratios toward the northern latitudes. In particular, we monitor and quantify the amplitude of a maximum enhancement of several gases observed at northern latitudes up to 50 Degree-Sign N around mid-2009, at the time of the NSE. We find that this rise is followed by a rapid decrease in chemical inventory in 2010 probably due to a weakening north polar vortex with reduced lateral mixing across the vortex boundary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.9146L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.9146L"><span id="translatedtitle">Global scale <span class="hlt">stratospheric</span> processes as measured by the infrasound IMS network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Pichon, A.; Ceranna, L.; Kechut, P.</p> <p>2012-04-01</p> <p>IMS infrasound array data are routinely processed at the International Data Center (IDC). The wave parameters of the detected signals are estimated with the Progressive Multi-Channel Correlation method (PMCC). This new implementation of the PMCC algorithm allows the full frequency range of interest (0.01-5 Hz) to be processed efficiently in a single computational run. We have processed continuous recordings from 41 certified IMS stations from 2005 to 2010. We show that microbaroms are the dominant source of signals and are near-continuously globally detected. The observed azimuthal seasonal trend correlates well with the variation of the effective sound speed ratio which is a proxy for the combined effects of refraction due to sound speed gradients and advection due to along-path wind on infrasound propagation. A general trend in signal backazimuth is observed between winter and summer, driven by the seasonal reversal of the <span class="hlt">stratospheric</span> winds. Combined with propagation modeling, we show that such an analysis enables a characterization of the wind and temperature structure above the <span class="hlt">stratosphere</span> and may provide detailed information on upper atmospheric processes (e.g., large-scale planetary waves, <span class="hlt">stratospheric</span> <span class="hlt">warming</span> effects). We correlate perturbations and deviations from the seasonal trend to short time-scale variability of the atmosphere. We discuss the potential benefit of long-term infrasound monitoring to infer <span class="hlt">stratospheric</span> processes for the first time on a global scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/14712270','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/14712270"><span id="translatedtitle">An intense <span class="hlt">stratospheric</span> jet on Jupiter.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Flasar, F M; Kunde, V G; Achterberg, R K; Conrath, B J; Simon-Miller, A A; Nixon, C A; Gierasch, P J; Romani, P N; Bézard, B; Irwin, P; Bjoraker, G L; Brasunas, J C; Jennings, D E; Pearl, J C; Smith, M D; Orton, G S; Spilker, L J; Carlson, R; Calcutt, S B; Read, P L; Taylor, F W; Parrish, P; Barucci, A; Courtin, R; Coustenis, A; Gautier, D; Lellouch, E; Marten, A; Prangé, R; Biraud, Y; Fouchet, T; Ferrari, C; Owen, T C; Abbas, M M; Samuelson, R E; Raulin, F; Ade, P; Césarsky, C J; Grossman, K U; Coradini, A</p> <p>2004-01-01</p> <p>The Earth's equatorial <span class="hlt">stratosphere</span> shows oscillations in which the east-west winds reverse direction and the temperatures change cyclically with a period of about two years. This phenomenon, called the quasi-biennial oscillation, also affects the dynamics of the mid- and high-latitude <span class="hlt">stratosphere</span> and weather in the lower atmosphere. Ground-based observations have suggested that similar temperature oscillations (with a 4-5-yr cycle) occur on Jupiter, but these data suffer from poor vertical resolution and Jupiter's <span class="hlt">stratospheric</span> wind velocities have not yet been determined. Here we report maps of temperatures and winds with high spatial resolution, obtained from spacecraft measurements of infrared spectra of Jupiter's <span class="hlt">stratosphere</span>. We find an intense, high-altitude equatorial jet with a speed of approximately 140 m s(-1), whose spatial structure resembles that of a quasi-quadrennial oscillation. Wave activity in the <span class="hlt">stratosphere</span> also appears analogous to that occurring on Earth. A strong interaction between Jupiter and its plasma environment produces hot spots in its upper atmosphere and <span class="hlt">stratosphere</span> near its poles, and the temperature maps define the penetration of the hot spots into the <span class="hlt">stratosphere</span>. PMID:14712270</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMGC53D..02B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMGC53D..02B"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Geoengineering: Sensitivity of the Global Hydrological Cycle to the Meridional Distribution of Aerosols</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bala, G.; Modak, A.</p> <p>2012-12-01</p> <p>Injection of sulfate aerosols into the <span class="hlt">stratosphere</span> is one of the promising geoengineering methods proposed to counteract global <span class="hlt">warming</span>. Both tropical and polar <span class="hlt">stratospheric</span> injections have been proposed. However, a systematic investigation of the hydrological implications of these vastly differing injections is lacking. In this study, for a fixed amount of total sulfate aerosols, we study the sensitivity of the global hydrological cycle to the meridional distribution of aerosols in a geoengineered world using a global climate model. We find that for a fixed total mass of aerosols the temperature mitigation is efficient when aerosols are weighted more in the tropical regions relative to a uniform distribution but the hydrological cycle would become less intense. If the same amount is distributed with more polar weighting, it is likely that changes in global hydrological cycle are mitigated but there would be residual <span class="hlt">warming</span>. For the fixed amount of aerosols and the many meridional distributions considered in our modeling study, a range of 1 K in global mean temperature and 3% in global mean precipitation changes are obtained. This indicates that a range of climate states are possible for a constant amount of aerosols and highlights the need for a careful evaluation of <span class="hlt">stratospheric</span> geoengineering proposals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150000795','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150000795"><span id="translatedtitle">Why Does the <span class="hlt">Stratosphere</span> Get Moister During the 21st Century?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dessler, A.E.; Schoberl, M. R.; Ye, H.; Wang, T.; Oman, L.; Douglass, A. R.</p> <p>2014-01-01</p> <p>All chemistry-climate models predict that 1) the TTL <span class="hlt">warms</span> during the 21st century and 2) that the humidity of air entering the <span class="hlt">stratosphere</span> increases over this same period. It seems reasonable to conclude that the former causes the latter, but to our knowledge no one has actually tested that. We do so here by analyzing one chemistry-climate model in detail (the Goddard Earth Observing System Chemistry Climate Model, GEOSCCM) and find that the <span class="hlt">warming</span> of the TTL explains only a fraction of the increase in humidity of air entering the <span class="hlt">stratosphere</span>. We do this by using meteorological fields from the model to drive a trajectory model, which estimates the water vapor variations in response to the large-scale temperature field. Water vapor simulated by the trajectory model increases by about one quarter of the amount it increases in the GEOSCCM. We conclude that, over the 21st century, an increase in the flux of ice through the TTL is responsible for most of the increase in the humidity of air entering the <span class="hlt">stratosphere</span> in this model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009NatGe...2...32I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009NatGe...2...32I"><span id="translatedtitle">The role of the <span class="hlt">stratosphere</span> in the European climate response to El Nio</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ineson, S.; Scaife, A. A.</p> <p>2009-01-01</p> <p>El Nio/Southern Oscillation (ENSO) is the largest natural interannual climate signal in the tropics; oscillations between <span class="hlt">warm</span> El Nio and cold La Nia phases occur every few years. The effects are felt not only in the centre of action, the tropical Pacific region, but around the globe. Observational studies show a clear response in European climate to ENSO in late winter. However, the underlying mechanisms of the link are not yet understood. Here we use a general circulation model of the atmosphere, that has been extended into the upper atmospheric layers, to provide end-to-end evidence for a global teleconnection pathway from the Pacific region to Europe via the <span class="hlt">stratosphere</span>. We present evidence for an active <span class="hlt">stratospheric</span> role in the transition to cold conditions in northern Europe and mild conditions in southern Europe in late winter during El Nio years. In our experiments, this mechanism is restricted to years when <span class="hlt">stratospheric</span> sudden <span class="hlt">warmings</span> occur. The response in European surface climate to the El Nio signal is large enough to be useful for seasonal forecasting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040082134','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040082134"><span id="translatedtitle">Extratropical <span class="hlt">Stratosphere</span>-Troposphere Mass Exchange</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schoeberl, Mark R.</p> <p>2004-01-01</p> <p>Understanding the exchange of gases between the <span class="hlt">stratosphere</span> and the troposphere is important for determining how pollutants enter the <span class="hlt">stratosphere</span> and how they leave. This study does a global analysis of that the exchange of mass between the <span class="hlt">stratosphere</span> and the troposphere. While the exchange of mass is not the same as the exchange of constituents, you can t get the constituent exchange right if you have the mass exchange wrong. Thus this kind of calculation is an important test for models which also compute trace gas transport. In this study I computed the mass exchange for two assimilated data sets and a GCM. The models all agree that amount of mass descending from the <span class="hlt">stratosphere</span> to the troposphere in the Northern Hemisphere extra tropics is approx. 10(exp 10) kg/s averaged over a year. The value for the Southern Hemisphere by about a factor of two. ( 10(exp 10) kg of air is the amount of air in 100 km x 100 km area with a depth of 100 m - roughly the size of the D.C. metro area to a depth of 300 feet.) Most people have the idea that most of the mass enters the <span class="hlt">stratosphere</span> through the tropics. But this study shows that almost 5 times more mass enters the <span class="hlt">stratosphere</span> through the extra-tropics. This mass, however, is quickly recycled out again. Thus the lower most <span class="hlt">stratosphere</span> is a mixture of upper <span class="hlt">stratospheric</span> air and tropospheric air. This is an important result for understanding the chemistry of the lower <span class="hlt">stratosphere</span>.</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_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" 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_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19970023225&hterms=atmos&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Datmos','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19970023225&hterms=atmos&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Datmos"><span id="translatedtitle">ATMOS <span class="hlt">Stratospheric</span> Deuterated Water and Implications for Tropospheric-<span class="hlt">Stratospheric</span> Transport</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moyer, Elisabeth J.; Irion, Fredrick W.; Yung, Yuk L.; Gunson, Michael R.</p> <p>1996-01-01</p> <p>Measurements of the isotopic composition of <span class="hlt">stratospheric</span> water by the ATMOS instrument are used to infer the convective history of <span class="hlt">stratospheric</span> air. The average water vapor entering the <span class="hlt">stratosphere</span> is found to be highly depleted of deuterium, with delta-D(sub w) of -670 +/- 80 (67% deuterium loss). Model calculations predict, however, that under conditions of thermodynamic equilibrium, dehydration to <span class="hlt">stratospheric</span> mixing ratios should produce stronger depletion to delta-D(sub w) of -800 to 900 (80-90% deuterium loss). Deuterium enrichment of water vapor in ascending parcels can occur only in conditions of rapid convection; enrichments persisting into the <span class="hlt">stratosphere</span> require that those conditions continue to near-tropopause altitudes. We conclude that either the predominant source of water vapor to the uppermost troposphere is enriched convective water, most likely evaporated cloud ice, or troposphere-<span class="hlt">stratosphere</span> transport occurs closely associated with tropical deep convection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19810054093&hterms=aerosol+compounds&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Daerosol%2Bcompounds','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810054093&hterms=aerosol+compounds&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Daerosol%2Bcompounds"><span id="translatedtitle">Nucleation and growth of <span class="hlt">stratospheric</span> aerosols</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Castleman, A. W., Jr.; Keesee, R. G.</p> <p>1981-01-01</p> <p>Formation mechanisms and nucleation processes are examined, and nucleation in the <span class="hlt">stratosphere</span> is considered, taking into account binary nucleation, ternary nucleation, binary heterogeneous nucleation, and heteromolecular nucleation. Attention is also given to the growth of aerosol particles, nucleation and growth in models, and the role of aerosols in the upper atmosphere. It is pointed out that various sampling studies and numerical models have provided evidence that the in situ oxidation of sulfur-bearing gases is responsible for the sulfate mass of the <span class="hlt">stratospheric</span> aerosol. Data obtained by Castleman et al. (1974) suggest that there is a common source of sulfur compounds for the <span class="hlt">stratosphere</span> of both the northern and southern hemispheres.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980015254','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980015254"><span id="translatedtitle">Laboratory Investigations of <span class="hlt">Stratospheric</span> Halogen Chemistry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wine, Paul H.; Nicovich, J. Michael; Stickel, Robert E.; Hynes, Anthony J.</p> <p>1997-01-01</p> <p>A final report for the NASA-supported project on laboratory investigations of <span class="hlt">stratospheric</span> halogen chemistry is presented. In recent years, this project has focused on three areas of research: (1) kinetic, mechanistic, and thermochemical studies of reactions which produce weakly bound chemical species of atmospheric interest; (2) development of flash photolysis schemes for studying radical-radical reactions of <span class="hlt">stratospheric</span> interest; and (3) photochemistry studies of interest for understanding <span class="hlt">stratospheric</span> chemistry. The first section of this paper contains a discussion of work which has not yet been published. All subsequent chapters contain reprints of published papers that acknowledge support from this grant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/150489','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/150489"><span id="translatedtitle">Observed <span class="hlt">stratospheric</span> profiles and <span class="hlt">stratospheric</span> lifetimes of HCFC-141b and HCFC-142b</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lee, J.M.; Sturges, W.T.; Penkett, S.A.</p> <p>1995-06-01</p> <p>The authors present profile measurements of HCFC-141b and HCFC-142b in the <span class="hlt">stratosphere</span>. The measurements show that these chemicals are not in equilibrium in the <span class="hlt">stratosphere</span> at present, and allow inferences of <span class="hlt">stratospheric</span> lifetimes. The lifetimes are strongly dependent upon the actual N{sub 2}O lifetime, and for an N{sub 2}O lifetime of 110y, are 68 {+-} 11y for HCFC-141b and a minimum of 138y for HCFC-142b.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ACP....15.2203K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ACP....15.2203K"><span id="translatedtitle">Northern Hemisphere <span class="hlt">stratospheric</span> winds in higher midlatitudes: longitudinal distribution and long-term trends</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kozubek, M.; Krizan, P.; Lastovicka, J.</p> <p>2015-02-01</p> <p>The Brewer-Dobson circulation (mainly meridional circulation) is very important for <span class="hlt">stratospheric</span> ozone dynamics and thus for the overall state of the <span class="hlt">stratosphere</span>. There are some indications that the meridional circulation in the <span class="hlt">stratosphere</span> could be longitudinally dependent, which would have an impact on the ozone distribution. Therefore, we analyse here the meridional component of the <span class="hlt">stratospheric</span> wind at northern middle latitudes to study its longitudinal dependence. The analysis is based on the NCEP/NCAR-1 (National Centers for Environmental Prediction and the National Center for Atmospheric Research), MERRA (Modern Era-Retrospective Analysis) and ERA-Interim (European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis Interim) reanalysis data. The well-developed two-core structure of strong but opposite meridional winds, one in each hemisphere at 10 hPa at higher northern middle latitudes, and a less pronounced five-core structure at 100 hPa are identified. In the central areas of the two-core structure the meridional and zonal wind magnitudes are comparable. The two-core structure at 10 hPa is almost identical for all three different reanalysis data sets in spite of the different time periods covered. The two-core structure is not associated with tides. However, the two-core structure at the 10 hPa level is related to the Aleutian pressure high at 10 hPa. Zonal wind, temperature and the ozone mixing ratio at 10 hPa also exhibit the effect of the Aleutian high, which thus affects all parameters of the Northern Hemisphere middle <span class="hlt">stratosphere</span>. Long-term trends in the meridional wind in the "core" areas are significant at the 99% level. Trends of meridional winds are negative during the period of ozone depletion development (1970-1995), while they are positive after the ozone trend turnaround (1996-2012). Meridional wind trends are independent of the sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) occurrence and the quasi-biennial oscillation (QBO) phase. The influence of the 11-year solar cycle on <span class="hlt">stratospheric</span> winds has been identified only during the west phase of QBO. The well-developed two-core structure in the meridional wind illustrates the limitations of application of the zonal mean concept in studying <span class="hlt">stratospheric</span> circulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ACP....14.1679B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ACP....14.1679B"><span id="translatedtitle">Radiative and dynamical contributions to past and future Arctic <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>Bohlinger, P.; Sinnhuber, B.-M.; Ruhnke, R.; Kirner, O.</p> <p>2014-02-01</p> <p>Arctic <span class="hlt">stratospheric</span> ozone depletion is closely linked to the occurrence of low <span class="hlt">stratospheric</span> temperatures. There are indications that cold winters in the Arctic <span class="hlt">stratosphere</span> have been getting colder, raising the question if and to what extent a cooling of the Arctic <span class="hlt">stratosphere</span> may continue into the future. We use meteorological reanalyses from the European Centre for Medium Range Weather Forecasts (ECMWF) ERA-Interim and NASA's Modern-Era Retrospective-Analysis for Research and Applications (MERRA) for the past 32 yr together with calculations of the chemistry-climate model (CCM) ECHAM/MESSy Atmospheric Chemistry (EMAC) and models from the Chemistry-Climate Model Validation (CCMVal) project to infer radiative and dynamical contributions to long-term Arctic <span class="hlt">stratospheric</span> temperature changes. For the past three decades the reanalyses show a <span class="hlt">warming</span> trend in winter and cooling trend in spring and summer, which agree well with trends from the Radiosonde Innovation Composite Homogenization (RICH) adjusted radiosonde data set. Changes in winter and spring are caused by a corresponding change of planetary wave activity with increases in winter and decreases in spring. During winter the increase of planetary wave activity is counteracted by a residual radiatively induced cooling. <span class="hlt">Stratospheric</span> radiatively induced cooling is detected throughout all seasons, being highly significant in spring and summer. This means that for a given dynamical situation, according to ERA-Interim the annual mean temperature of the Arctic lower <span class="hlt">stratosphere</span> has been cooling by -0.41 0.11 K decade-1 at 50 hPa over the past 32 yr. Calculations with state-of-the-art models from CCMVal and the EMAC model qualitatively reproduce the radiatively induced cooling for the past decades, but underestimate the amount of radiatively induced cooling deduced from reanalyses. There are indications that this discrepancy could be partly related to a possible underestimation of past Arctic ozone trends in the models. The models project a continued cooling of the Arctic <span class="hlt">stratosphere</span> over the coming decades (2001-2049) that is for the annual mean about 40% less than the modeled cooling for the past, due to the reduction of ozone depleting substances and the resulting ozone recovery. This projected cooling in turn could offset between 15 and 40% of the Arctic ozone recovery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/121739','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/121739"><span id="translatedtitle">Modeling the effects of UV variability and the QBO on the troposphere-<span class="hlt">stratosphere</span> system. Part I: The middle atmosphere</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Balachandran, N.K.; Rind, D.</p> <p>1995-08-01</p> <p>Results of experiments with a GCM involving changes in UV input ({plus_minus}25%, {plus_minus}10%, {plus_minus}5% at wavelengths below 0.3 {mu}m) and simulated equatorial QBO are presented, with emphasis on the middle atmosphere response. The UV forcing employed is larger than observed during the last solar cycle and does not vary with wavelength, hence the relationship of these results to those from actual solar UV forcing should be treated with caution. The QBO alters the location of the zero wind line and the horizontal shear of the zonal wind in the low to middle <span class="hlt">stratosphere</span>, while the UV change alters the magnitude of the polar jet and the vertical shear of the zonal wind. Both mechanisms thus affect planetary wave propagation. The east phase of the QBO leads to tropical cooling and high-latitude <span class="hlt">warming</span> in the lower <span class="hlt">stratosphere</span>, with opposite effects in the upper <span class="hlt">stratosphere</span>. This quadrupole pattern is also seen in the observations. The high-latitude responses are due to altered planetary wave effects, while the model`s tropical response in the upper <span class="hlt">stratosphere</span> is due to gravity wave drag. Increased UV forcing <span class="hlt">warms</span> tropical latitudes in the middle atmosphere, resulting in stronger extratropical west winds, an effect which peaks in the upper <span class="hlt">stratosphere</span>/lower mesosphere with the more extreme UV forcing but at lower altitudes and smaller wind variations with the more realistic forcing. The increased vertical gradient of the zonal wind leads to increased vertical propagation of planetary waves, altering energy convergences and temperatures. The exact altitudes affected depend upon the UV forcing applied. Results with combined QBO and UV forcing show that in the Northern Hemisphere, polar <span class="hlt">warming</span> for the east QBO is stronger when the UV input is reduced by 25% and 5% as increased wave propagation to high latitudes (east QBO effect) is prevented from then propagating vertically (reduced UV effect). 30 refs., 14 figs., 6 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990077343&hterms=tide&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dtide','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990077343&hterms=tide&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dtide"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Tides and Data Assimilation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Swinbank, R.; Orris, R. L.; Wu, D. L.</p> <p>1999-01-01</p> <p>In the upper <span class="hlt">stratosphere</span>, the atmosphere exhibits significant diurnal and semi-diurnal tidal variations, with typical amplitude of about 2K in mid-latitudes. In this paper we examine how well the tidal variations in temperature are represented by the Goddard Geodesic Earth Orbiting Satellite (GEOS-2) data assimilation system. We show that the GEOS-2 atmospheric model is quite successful at simulating the tidal temperature variations. However, the assimilation of satellite temperature soundings significantly damps the simulated tides. The reason is because the tides are not well represented by the satellite retrievals used by the assimilation system (which have a typical tidal amplitude of around 1K). As a result of this study, we suggest improvements that should be made to the treatment of satellite soundings by the assimilation system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870050668&hterms=Hydrogen+peroxide&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2528Hydrogen%2Bperoxide%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870050668&hterms=Hydrogen+peroxide&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2528Hydrogen%2Bperoxide%2529"><span id="translatedtitle">Evidence for <span class="hlt">stratospheric</span> hydrogen peroxide</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chance, K. V.; Traub, W. A.</p> <p>1987-01-01</p> <p>A statistically significant measurement of H2O2 in the <span class="hlt">stratosphere</span> has been obtained. The results were obtained from the 112.19/cm RQ5 branch of the torsional-rotational spectrum with a remote-sensing far-infrared Fourier transform spectrometer during the Balloon Intercomparison Campaign (BIC-2), on June 20, 1983. The concentration above the balloon gondola is unexpectedly large, corresponding to 0.68 + or - 0.21 parts per billion by volume (ppbv) at an effective altitude of 38.3 km. Below the gondola altitude the concentration of H2O2 is slightly less than expected from the model predictions at 33.2 km (0.19 + or - 0.05 ppbv) and significantly less than expected at 29.3 km (0.08 + or - 0.03 ppbv).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ACP....12.3659D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ACP....12.3659D"><span id="translatedtitle">The 2009-2010 Arctic <span class="hlt">stratospheric</span> winter - general evolution, mountain waves and predictability of an operational weather forecast model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drnbrack, A.; Pitts, M. C.; Poole, L. R.; Orsolini, Y. J.; Nishii, K.; Nakamura, H.</p> <p>2012-04-01</p> <p>The relatively <span class="hlt">warm</span> 2009-2010 Arctic winter was an exceptional one as the North Atlantic Oscillation index attained persistent extreme negative values. Here, selected aspects of the Arctic <span class="hlt">stratosphere</span> during this winter inspired by the analysis of the international field experiment RECONCILE are presented. First of all, and as a kind of reference, the evolution of the polar vortex in its different phases is documented. Special emphasis is put on explaining the formation of the exceptionally cold vortex in mid winter after a sequence of <span class="hlt">stratospheric</span> disturbances which were caused by upward propagating planetary waves. A major sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) occurring near the end of January 2010 concluded the anomalous cold vortex period. Wave ice polar <span class="hlt">stratospheric</span> clouds were frequently observed by spaceborne remote-sensing instruments over the Arctic during the cold period in January 2010. Here, one such case observed over Greenland is analysed in more detail and an attempt is made to correlate flow information of an operational numerical weather prediction model to the magnitude of the mountain-wave induced temperature fluctuations. Finally, it is shown that the forecasts of the ECMWF ensemble prediction system for the onset of the major SSW were very skilful and the ensemble spread was very small. However, the ensemble spread increased dramatically after the major SSW, displaying the strong non-linearity and internal variability involved in the SSW event.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ACPD...1132535D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ACPD...1132535D"><span id="translatedtitle">The 2009-2010 arctic <span class="hlt">stratospheric</span> winter - general evolution, mountain waves and predictability of an operational weather forecast model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drnbrack, A.; Pitts, M. C.; Poole, L. R.; Orsolini, Y. J.; Nishii, K.; Nakamura, H.</p> <p>2011-12-01</p> <p>The relatively <span class="hlt">warm</span> 2009-2010 Arctic winter was an exceptional one as the North Atlantic Oscillation index attained persistent extreme negative values. Here, selected aspects of the Arctic <span class="hlt">stratosphere</span> during this winter inspired by the analysis of the international field experiment RECONCILE are presented. First of all, and as a kind of reference, the evolution of the polar vortex in its different phases is documented. Special emphasis is put on explaining the formation of the exceptionally cold vortex in mid winter after a sequence of <span class="hlt">stratospheric</span> disturbances which were caused by upward propagating planetary waves. A major sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> (SSW) occurring near the end of January 2010 concluded the anomalous cold vortex period. Wave ice polar <span class="hlt">stratospheric</span> clouds were frequently observed by spaceborne remote-sensing instruments over the Arctic during the cold period in January 2010. Here, one such case observed over Greenland is analysed in more detail and an attempt is made to correlate flow information of an operational numerical weather prediction model to the magnitude of the mountain-wave induced temperature fluctuations. Finally, it is shown that the forecasts of the ECMWF ensemble prediction system for the onset of the major SSW were very skilful and the ensemble spread was very small. However, the ensemble spread increased dramatically after the major SSW, displaying the strong non-linearity and internal variability involved in the SSW event.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008GeoRL..3510812B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008GeoRL..3510812B"><span id="translatedtitle">Impact of geo-engineering on the ion composition of 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>Beig, Gufran</p> <p>2008-05-01</p> <p>A remedy called ``geo-engineering solution'' has been recently proposed by some scientists to handle the global <span class="hlt">warming</span> problem through injection of sulfates high aloft into the <span class="hlt">stratosphere</span>. However, this idea may have some other side impacts. We have investigated the perturbation caused by geo-engineering solution on the <span class="hlt">stratospheric</span> charged species using a coupled neutral-ion photochemical model. Model calculations indicate additional production of sulfuric acid immediately after the injection which further leads to increased abundance of heavy negative ion family by several orders of magnitude over the ambient. After 2 months, most of the H2SO4 vapor condensed to H2SO4 aerosols and the density of charged aerosol increases several folds and the effect spread further in the tropics. The perturbation in ionic species spread globally after about 1 year but became weaker in magnitude. The ion perturbation has implications on the electrical properties of the atmospheric medium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19840056658&hterms=Observation+solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DObservation%2Bsolar','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19840056658&hterms=Observation+solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DObservation%2Bsolar"><span id="translatedtitle"><span class="hlt">Stratospheric</span> ozone changes during the first year of SBUV observations. [Solar Backscatter UltraViolet</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nagatani, R. M.; Miller, A. J.</p> <p>1984-01-01</p> <p>Synoptic analyses of solar backscattered ultraviolet (SBUV) ozone data have been performed on a daily basis for the first year of Nimbus 7 operation, November 1978 through October 1979, at the standard pressure levels: 30, 10, 5, 2, 1, and 0.4 mbar. By combining these data with the daily NMC meteorological analyses of temperature and geostrophic wind at the same levels, elements of the ozone-temperature relationship as well as the horizontal eddy transports are examined. In particular, the existence of an upper <span class="hlt">stratospheric</span> high-latitude ozone minimum in winter is discussed, and the eddy fluxes are found to play a significant role in this feature, mainly associated with <span class="hlt">stratospheric</span> <span class="hlt">warming</span> pulses. At the same time, monthly average quantities are examined, and standing eddy components are related.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930064893&hterms=temperature+Monitoring&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dtemperature%2BMonitoring','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930064893&hterms=temperature+Monitoring&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dtemperature%2BMonitoring"><span id="translatedtitle">Precision lower <span class="hlt">stratospheric</span> temperature monitoring with the MSU - Technique, validation, and results 1979-1991</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Spencer, Roy W.; Christy, John R.</p> <p>1993-01-01</p> <p>The stability of TIROS-N Microwave Sounding Unit (MSU) channel 4, which monitors the deep-layer averaged temperature of the lower <span class="hlt">stratosphere</span>, is tested by intercalibrating MSU channel 4 data from the NIROS-N series of NOAA satellites during 1979-1991. The monthly gridpoint anomalies are validated with 10 years of radiosonde data during 1979-1988. The results demonstrated that the satellite sensors are very stable in their calibration and that the previously reported uncertainties in the <span class="hlt">stratospheric</span> temperature information produced by NOAA are not the result of calibration changes in the MSUs. It was found that the largest globally averaged temperature variations during 1979-1991 occur after the El Chichon (1982) and Pinatubo (1991) volcanic eruptions. These <span class="hlt">warm</span> events are superimposed upon a net downward trend in temperatures during the period. The cooling trend is strongest in polar regions and the Northern Hemisphere middle latitudes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740020775','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740020775"><span id="translatedtitle">Lidar measurements of <span class="hlt">stratospheric</span> aerosols over Menlo Park, California, October 1972 - March 1974</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, P. B.; Viezee, W.; Hake, R. D.</p> <p>1974-01-01</p> <p>During an 18-month period, 30 nighttime observations of <span class="hlt">stratospheric</span> aerosols were made using a ground based ruby lidar located near the Pacific coast of central California (37.5 deg. N, 122.2 deg. W). Vertical profiles of the lidar scattering ratio and the particulate backscattering coefficient were obtained by reference to a layer of assumed negligible particulate content. An aerosol layer centered near 21 km was clearly evident in all observations, but its magnitude and vertical distribution varied considerably throughout the observation period. A reduction of particulate backscattering in the 23- to 30-km layer during late January 1973 appears to have been associated with the sudden <span class="hlt">stratospheric</span> <span class="hlt">warming</span> which occurred at that time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7119836','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7119836"><span id="translatedtitle"><span class="hlt">Stratospheric</span> ozone depletion: Implications for marine ecosystems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hardy, J.; Gucinski, H.</p> <p>1989-01-01</p> <p>The <span class="hlt">stratospheric</span> ozone layer shields the earth from biologically damaging solar ultraviolet radiation. Chlorofluorocarbons (CFCs), used in refrigerants, etc. and halons, used in fire extinguishers, escape into the lower atmosphere and migrate to the <span class="hlt">stratosphere</span>, destroying the ozone layer by photochemically catalyzing the conversion of ozone to oxygen. Global decreases in <span class="hlt">stratospheric</span> ozone have been observed in recent years. As a result, UV-B radiation is likely to increase over the next few decades, having a very real potential for significant impacts on marine ecosystems. It would take decades to complete all the research necessary for a definitive assessment of the overall long-term effects of <span class="hlt">stratospheric</span> ozone depletion. However, a research program focusing on the major uncertainties could provide an assessment adequate for informed decision-making within five years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19790035058&hterms=aerosol+compounds&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Daerosol%2Bcompounds','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19790035058&hterms=aerosol+compounds&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Daerosol%2Bcompounds"><span id="translatedtitle">Nitrogen-sulfur compounds in <span class="hlt">stratospheric</span> aerosols</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Farlow, N. H.; Snetsinger, K. G.; Hayes, D. M.; Lem, H. Y.; Tooper, B. M.</p> <p>1978-01-01</p> <p>Two forms of nitrosyl sulfuric acid (NOHSO4 and NOHS2O7) have been tentatively identified in <span class="hlt">stratospheric</span> aerosols. The first of these can be formed either directly from gas reactions of NO2 with SO2 or by gas-particle interactions between NO2 and H2SO4. The second product may form when SO3 is involved. Estimates based on these reactions suggest that the maximum quantity of NO that might be absorbed in <span class="hlt">stratospheric</span> aerosols could vary from one-third to twice the amount of NO in the surrounding air. If these reactions occur in the <span class="hlt">stratosphere</span>, then a mechanism exists for removing nitrogen oxides from that region by aerosol particle fallout. This process may typify another natural means that helps cleanse the lower <span class="hlt">stratosphere</span> of excessive pollutants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780012748','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780012748"><span id="translatedtitle"><span class="hlt">Stratospheric</span> sounding by infrared heterodyne spectroscopy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Abbas, M. M.; Kunde, V. G.; Mumma, M. J.; Kostiuk, T.; Buhl, D.; Frerking, M. A.</p> <p>1978-01-01</p> <p>Intensity profiles of infrared spectral lines of <span class="hlt">stratospheric</span> constituents can be fully resolved with a heterodyne spectrometer of sufficiently high resolution. The constituents' vertical distributions can then be evaluated accurately by analytic inversion of the measured line profiles. Estimates of the detection sensitivity of a heterodyne receiver are given in terms of minimum detectable volume mixing ratios of <span class="hlt">stratospheric</span> constituents, indicating a large number of minor constituents which can be studied. <span class="hlt">Stratospheric</span> spectral line shapes, and the resolution required to measure them are discussed in light of calculated synthetic line profiles for some <span class="hlt">stratospheric</span> molecules in a model atmosphere. The inversion technique for evaluation of gas concentration profiles is briefly described and applications to synthetic lines of O3, CO2, CH4 and N2O are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000GeoRL..27.2081S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000GeoRL..27.2081S"><span id="translatedtitle">Bromoform as a source of <span class="hlt">stratospheric</span> bromine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sturges, William T.; Oram, David E.; Carpenter, Lucy J.; Penkett, Stuart A.; Engel, Andreas</p> <p>2000-08-01</p> <p>We have measured bromoform (CHBr3) in the troposphere and lower <span class="hlt">stratosphere</span> (sea level to 17 km) from balloons, aircraft and ground stations. The concentrations ranged from 2 to 20 ppt at sea level, and 0.1 to 1 ppt in the upper troposphere. Above the tropopause the concentrations declined sharply to less than 0.01 ppt above 14 km. CHBr3 accounted for 3% of total measured organic bromine (Bro) at the extratropical tropopause, and appeared to potentially contribute at least 9% of reactive bromine (Bry) in <span class="hlt">stratospheric</span> air of mean age less than 1 year. Inclusion of dibromomethane and the mixed bromochloromethanes increased these figures to about 10% of Bro and 20% of Bry respectively. Observations of CHBr3 in both Arctic and mid-latitudinal <span class="hlt">stratospheric</span> air, and in air masses with mean ages of more than 1.5 years, suggests that the CHBr3 in these locations originates predominantly from extratropical <span class="hlt">stratosphere</span>-troposphere exchange.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008Natur.453..163D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008Natur.453..163D"><span id="translatedtitle">Planetary science: Music of the <span class="hlt">stratospheres</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dowling, Timothy E.</p> <p>2008-05-01</p> <p>Fifteen-year oscillations in Saturn's equatorial <span class="hlt">stratosphere</span> bear a striking resemblance to the shorter-term oscillations seen on Earth and Jupiter - akin to notes played on a cello, a violin and a viola.</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_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" 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_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070035963','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070035963"><span id="translatedtitle">SOFIA: <span class="hlt">Stratospheric</span> Observatory for Infrared Astronomy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Becker, Eric; Kunz, Nans; Bowers, Al</p> <p>2007-01-01</p> <p>This viewgraph presentation reviews the <span class="hlt">Stratospheric</span> Observatory for Infrared Astronomy (SOFIA). The contents include: 1) Heritage & History; 2) Level 1 Requirements; 3) Top Level Overview of the Observatory; 4) Development Challenges; and 5) Highlight Photos.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070035890','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070035890"><span id="translatedtitle">SOFIA - <span class="hlt">Stratospheric</span> Observatory for Infrared Astronomy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kunz, Nans; Bowers, Al</p> <p>2007-01-01</p> <p>This viewgraph presentation reviews the <span class="hlt">Stratospheric</span> Observatory for Infrared Astronomy (SOFIA). The contents include: 1) Heritage & History; 2) Level 1 Requirements; 3) Top Level Overview of the Observatory; 4) Development Challenges; and 5) Highlight Photos.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007SPIE.6694E..0TW','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007SPIE.6694E..0TW"><span id="translatedtitle">How do bacteria reach 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>Wainwright, M.</p> <p>2007-09-01</p> <p>Culturable bacteria have recently been found in the <span class="hlt">stratosphere</span> (at heights up to 41km). How do such bacteria cross the tropopause to reach such heights? Although possible mechanisms are suggested here, such transfer remains difficult to explain. It is however, likely to more easily achieved by sub-micron bacteria. Such small forms have been found in terrestrial environments and have the potential to seed the <span class="hlt">stratosphere</span>. Large, ten micron clumps of bacteria have also been found in the <span class="hlt">stratosphere</span> and it is suggested that these are incoming to Earth from space. Finally, the possibility will be discussed that the presence of bacteria in the <span class="hlt">stratosphere</span> has led to an increase in the rate of evolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800014436','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800014436"><span id="translatedtitle">The stratcom 8 effort. [<span class="hlt">stratospheric</span> photochemistry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reed, E. I. (Editor)</p> <p>1980-01-01</p> <p>The ozone-nitrogen oxides ultraviolent flux interactions were investigated to obtain data on <span class="hlt">stratospheric</span> photochemistry. The balloon, rocket, and aircraft operations are described along with the instruments, parameter measurements, and payloads.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/445371','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/445371"><span id="translatedtitle">The chemistry of <span class="hlt">stratospheric</span> ozone depletion</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tuck, A.</p> <p>1997-01-01</p> <p>In the early 1980`s the Antarctic ozone hole was discovered. The ozone loss was 50 percent in the lower <span class="hlt">stratosphere</span> during springtime, which is made possible by the conditions over Antarctica in winter. The absence of sunlight in the <span class="hlt">stratosphere</span> during polar winter causes the <span class="hlt">stratospheric</span> air column there to cool and sink, drawing air from lower latitudes into the upper <span class="hlt">stratosphere</span>. This lower-latitude air gets closer to the Earth`s axis of rotation as it moves poleward and is accelerated by the need to conserve angular momentum to greater and greater westerly wind speeds forming a vortex bounded by the polar night jet stream. The air entering the vortex contains reactive ozone-destroying species. The observed ozone losses occurred concurrently with increases of chlorofluorocarbon increases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/900173','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/900173"><span id="translatedtitle"><span class="hlt">Stratospheric</span> Relaxation in IMPACT's Radiation Code</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Edis, T; Grant, K; Cameron-Smith, P</p> <p>2006-11-13</p> <p>While Impact incorporates diagnostic radiation routines from our work in previous years, it has not previously included the <span class="hlt">stratospheric</span> relaxation required for forcing calculations. We have now implemented the necessary changes for <span class="hlt">stratospheric</span> relaxation, tested its stability, and compared the results with <span class="hlt">stratosphere</span> temperatures obtained from CAM3 met data. The relaxation results in stable temperature profiles in the <span class="hlt">stratosphere</span>, which is encouraging for use in forcing calculations. It does, however, produce a cooling bias when compared to CAM3, which appears to be due to differences in radiation calculations rather than the interactive treatment of ozone. The cause of this bias is unclear as yet, but seems to be systematic and hence cancels out when differences are taken relative to a control simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960027887','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960027887"><span id="translatedtitle">Laboratory studies of <span class="hlt">stratospheric</span> aerosol chemistry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Molina, Mario J.</p> <p>1996-01-01</p> <p>In this report we summarize the results of the two sets of projects funded by the NASA grant NAG2-632, namely investigations of various thermodynamic and nucleation properties of the aqueous acid system which makes up <span class="hlt">stratospheric</span> aerosols, and measurements of reaction probabilities directly on ice aerosols with sizes corresponding to those of polar <span class="hlt">stratospheric</span> cloud particles. The results of these investigations are of importance for the assessment of the potential <span class="hlt">stratospheric</span> effects of future fleets of supersonic aircraft. In particular, the results permit to better estimate the effects of increased amounts of water vapor and nitric acid (which forms from nitrogen oxides) on polar <span class="hlt">stratospheric</span> clouds and on the chemistry induced by these clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870036267&hterms=cloud+computing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dcloud%2Bcomputing','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870036267&hterms=cloud+computing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dcloud%2Bcomputing"><span id="translatedtitle">Polar <span class="hlt">stratospheric</span> clouds inferred from satellite data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Austin, J.; Jones, R. L.; Remsberg, E. E.; Tuck, A. F.</p> <p>1986-01-01</p> <p>Anomalously high radiances from the ozone channel of the Limb Infrared Monitor of the <span class="hlt">Stratosphere</span> (LIMS) sounding instrument have been observed in the Northern Hemisphere winter lower <span class="hlt">stratosphere</span>. Such events, thought to be due to polar <span class="hlt">stratospheric</span> clouds (PSCs), are examined further by computing relative humidities using <span class="hlt">Stratospheric</span> Sounding Unit temperatures and water vapor measurements from the LIMS Map Archive Tape analyses. Regions identified as PSCs are found to correspond closely to regions of high humidity. While instances of saturation were found, the average humidity at the centers of 39 PSCs was calculated to be 58 percent. Possible reasons for this apparent discrepancy are discussed. Applying a similar approach to the Southern Hemisphere, in 1979, virtually no PSCs are found in the vortex after September 10 at 20 km. This result has important implications for a number of proposed explanations for the Antarctic ozone hole.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900041415&hterms=lait&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dlait','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900041415&hterms=lait&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dlait"><span id="translatedtitle"><span class="hlt">Stratospheric</span> temperatures during AASE - Results from 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.; Newman, Paul A.; Lait, Leslie R.; Lamich, David J.; Chan, K. Roland</p> <p>1990-01-01</p> <p>Comparisons of temperatures from the research analysis STRATAN to radiosonde data, Meteorological Measurement System (MMS) data, and the National Meteorological Center (NMC) analyses are presented for the Airborne Arctic <span class="hlt">Stratospheric</span> Expedition (AASE). The STRATAN analyses show consistent quality throughout AASE. The comparisons to MMS show that STRATAN more accurately represented low temperatures than NMC. This, coupled with forecast quality, show that STRATAN temperature fields are a valuable tool for diagnosing and forecasting polar <span class="hlt">stratospheric</span> clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.3260H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.3260H"><span id="translatedtitle">Decadal Trends in the Background <span class="hlt">Stratospheric</span> Aerosol</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hofmann, D. J.; Barnes, J. E.</p> <p>2009-04-01</p> <p><span class="hlt">Stratospheric</span> aerosol measurements are made with Nd(YAG) lidars at Boulder, Colorado and at Mauna Loa Observatory, Hawaii. Since the eruption of the volcano Pinatubo in June 1991, minor eruptions having brief, local <span class="hlt">stratospheric</span> effects have been observed, but there have been no major eruptions capable of perturbing the global <span class="hlt">stratosphere</span> above 20 km. This has provided an unusual opportunity to study the background aerosol, free of volcanic effects. The period following the decay of the Pinatubo aerosol, from about 1996 to the present, is the longest period without a major volcanic <span class="hlt">stratospheric</span> aerosol perturbation since the sulfate layer was discovered by Junge in 1959. Both Boulder and Mauna Loa show a well-defined annual variation in the background aerosol with a maximum in winter believed to be associated with transport from the tropical source region. There appears to be a clear biennial variation in the amplitude of the aerosol backscatter growth rate during these annual cycles at both sites. At Boulder, where aerosol lidar measurements began about 2000, an increasing decadal trend of about 8-10% per year in the integrated <span class="hlt">stratospheric</span> lidar backscatter has been observed above 20 km. At Mauna Loa, where the lidar record extends back to the 1970's, a similar increase in aerosol backscatter, beginning in about 2000, has been observed. Under non-volcanic conditions, the background sulfate aerosol is sustained mainly by sulfur dioxide (predominantly from the burning of coal) and carbonyl sulfide emissions at the surface which enter the <span class="hlt">stratosphere</span> in the tropics. Increased emissions and/or enhanced tropical upwelling circulation in the lower <span class="hlt">stratosphere</span>, possibly related to climate change, could thus affect the decadal trend of the background <span class="hlt">stratospheric</span> aerosol. It is shown that recent (since 2000) increases in coal burning may account for a portion of the aerosol increase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820026810&hterms=hydrogen+cyanide&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dhydrogen%2Bcyanide','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820026810&hterms=hydrogen+cyanide&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dhydrogen%2Bcyanide"><span id="translatedtitle">Spectroscopic detection of <span class="hlt">stratospheric</span> hydrogen cyanide</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coffey, M. T.; Mankin, W. G.; Cicerone, R. J.</p> <p>1981-01-01</p> <p>A number of features have been identified as absorption lines of hydrogen cyanide in infrared spectra of <span class="hlt">stratospheric</span> absorption obtained from a high-altitude aircraft. Column amounts of <span class="hlt">stratospheric</span> hydrogen cyanide have been derived from spectra recorded on eight flights. The average vertical column amount above 12 kilometers is 7.1 + or - 0.8 x 10 to the 14th molecules per square centimeter, corresponding to an average mixing ratio of 170 parts per trillion by volume.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/11456472','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11456472"><span id="translatedtitle">Studies of polar <span class="hlt">stratospheric</span> cloud formation.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Prenni, A J; Tolbert, M A</p> <p>2001-07-01</p> <p><span class="hlt">Stratospheric</span> ozone depletion was first reported in 1985. Early on, researchers identified polar <span class="hlt">stratospheric</span> clouds (PSCs) as being important in chemistry related to ozone depletion. PSCs exist as crystalline water-ice particles (type II), and as crystalline (type Ia) or liquid (type Ib) particles stable above the water-ice frost point. Uncertainty remains concerning the composition and formation mechanism of the most common PSC, type Ia. Here, we consider likely formation mechanisms for type Ia PSCs. PMID:11456472</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7164487','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7164487"><span id="translatedtitle">Laboratory simulation of polar <span class="hlt">stratospheric</span> clouds</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Callaghan, R.; Lim, I.J.; Murdock, D.E.; Sloan, J.J. ); Donaldson, D.J. )</p> <p>1994-03-01</p> <p>The authors describe an apparatus they have constructed to simulate the type of small particles ([approx]1[mu]m) which are found in polar <span class="hlt">stratospheric</span> clouds. They form these particles from nitric acid solutions and distilled water. This paper describes the physical properties of the particles they are able to form in this flow cell. Their observations suggest these particles resemble those found in both type II and type I polar <span class="hlt">stratospheric</span> clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15496919','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15496919"><span id="translatedtitle">Extreme climate of the global troposphere and <span class="hlt">stratosphere</span> in 1940-42 related to El Niño.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brönnimann, S; Luterbacher, J; Staehelin, J; Svendby, T M; Hansen, G; Svenøe, T</p> <p>2004-10-21</p> <p>Although the El Niño/Southern Oscillation phenomenon is the most prominent mode of climate variability and affects weather and climate in large parts of the world, its effects on Europe and the high-latitude <span class="hlt">stratosphere</span> are controversial. Using historical observations and reconstruction techniques, we analyse the anomalous state of the troposphere and <span class="hlt">stratosphere</span> in the Northern Hemisphere from 1940 to 1942 that occurred during a strong and long-lasting El Niño event. Exceptionally low surface temperatures in Europe and the north Pacific Ocean coincided with high temperatures in Alaska. In the lower <span class="hlt">stratosphere</span>, our reconstructions show high temperatures over northern Eurasia and the north Pacific Ocean, and a weak polar vortex. In addition, there is observational evidence for frequent <span class="hlt">stratospheric</span> <span class="hlt">warmings</span> and high column ozone at Arctic and mid-latitude sites. We compare our historical data for the period 1940-42 with more recent data and a 650-year climate model simulation. We conclude that the observed anomalies constitute a recurring extreme state of the global troposphere-<span class="hlt">stratosphere</span> system in northern winter that is related to strong El Niño events. PMID:15496919</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ClDy...36..579O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ClDy...36..579O"><span id="translatedtitle">On the potential impact of the <span class="hlt">stratosphere</span> upon seasonal dynamical hindcasts of the North Atlantic Oscillation: a pilot study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Orsolini, Yvan Joseph; Kindem, I. T.; Kvamstø, N. G.</p> <p>2011-02-01</p> <p>We have investigated the importance of the <span class="hlt">stratosphere</span>-troposphere linkage on the seasonal predictability of the North Atlantic Oscillation in a pilot study using a high horizontal resolution atmospheric general circulation model, and covering the 14 winters from 1979/1980 to 1992/1993. We made an ensemble of simulations with the Meteo-France "Arpege Climat" model (V3.0) with a well-resolved <span class="hlt">stratosphere</span>, and a broad comparison is drawn with hindcasts from previously published experiments using low-top and lower horizontal resolution models, but covering the same winters with the same ensemble size and verification method. For the January-February-March North Atlantic Oscillation index, the deterministic hindcast skill score is 0.59, using re-analyses as verification. It is comparable to the reported multi-model skill score (0.57). The largest improvement originates from the winter 1986/1987 characterised by a major <span class="hlt">stratospheric</span> sudden <span class="hlt">warming</span>. We demonstrate that there is then a high-latitude zonal-mean zonal wind decrease in the <span class="hlt">stratosphere</span>-troposphere hindcasts over a broad pressure range. This is consistent with a composite analysis showing that model anomalous vortex events, either weak or strong, lead to a North Atlantic Oscillation index anomaly in the troposphere, which persists, on average, for 1 month after the anomaly peaked in the <span class="hlt">stratosphere</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/46040','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/46040"><span id="translatedtitle">Global <span class="hlt">warming</span> elucidated</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shen, S.</p> <p>1995-03-01</p> <p>The meaning of global <span class="hlt">warming</span> and its relevance to everyday life is explained. Simple thermodynamics is used to predict an oscillatory nature of the change in climate due to global <span class="hlt">warming</span>. Global <span class="hlt">warming</span> causes extreme events and bad weather in the near term. In the long term it may cause the earth to transition to another equilibrium state through many oscillation in climatic patterns. The magnitudes of these oscillations could easily exceed the difference between the end points. The author further explains why many no longer fully understands the nature and magnitudes of common phenomena such as storms and wind speeds because of these oscillations, and the absorptive properties of clouds. The author links the increase in duration of the El Nino to global <span class="hlt">warming</span>, and further predicts public health risks as the earth transitions to another equilibrium state in its young history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=dinosaurs&pg=4&id=EJ658270','ERIC'); return false;" href="http://eric.ed.gov/?q=dinosaurs&pg=4&id=EJ658270"><span id="translatedtitle"><span class="hlt">Warm</span> and Cool Dinosaurs.</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>Mannlein, Sally</p> <p>2001-01-01</p> <p>Presents an art activity in which first grade students draw dinosaurs in order to learn about the concept of <span class="hlt">warm</span> and cool colors. Explains how the activity also helped the students learn about the concept of distance when drawing. (CMK)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150000726','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150000726"><span id="translatedtitle">Reconciling <span class="hlt">Warming</span> Trends</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schmidt, Gavin A.; Shindell, Drew T.; Tsigaridis, Konstantinos</p> <p>2014-01-01</p> <p>Climate models projected stronger <span class="hlt">warming</span> over the past 15 years than has been seen in observations. Conspiring factors of errors in volcanic and solar inputs, representations of aerosols, and El NiNo evolution, may explain most of the discrepancy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000011670&hterms=Greenhouse+effect+Atmospheric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528%2528Greenhouse%2Beffect%2529%2BAtmospheric%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000011670&hterms=Greenhouse+effect+Atmospheric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528%2528Greenhouse%2Beffect%2529%2BAtmospheric%2529"><span id="translatedtitle">An Estimation of the Climatic Effects of <span class="hlt">Stratospheric</span> Ozone Losses during the 1980s. Appendix K</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>MacKay, Robert M.; Ko, Malcolm K. W.; Shia, Run-Lie; Yang, Yajaing; Zhou, Shuntai; Molnar, Gyula</p> <p>1997-01-01</p> <p>In order to study the potential climatic effects of the ozone hole more directly and to assess the validity of previous lower resolution model results, the latest high spatial resolution version of the Atmospheric and Environmental Research, Inc., seasonal radiative dynamical climate model is used to simulate the climatic effects of ozone changes relative to the other greenhouse gases. The steady-state climatic effect of a sustained decrease in lower <span class="hlt">stratospheric</span> ozone, similar in magnitude to the observed 1979-90 decrease, is estimated by comparing three steady-state climate simulations: 1) 1979 greenhouse gas concentrations and 1979 ozone, II) 1990 greenhouse gas concentrations with 1979 ozone, and III) 1990 greenhouse gas concentrations with 1990 ozone. The simulated increase in surface air temperature resulting from nonozone greenhouse gases is 0.272 K. When changes in lower <span class="hlt">stratospheric</span> ozone are included, the greenhouse <span class="hlt">warming</span> is 0.165 K, which is approximately 39% lower than when ozone is fixed at the 1979 concentrations. Ozone perturbations at high latitudes result in a cooling of the surface-troposphere system that is greater (by a factor of 2.8) than that estimated from the change in radiative forcing resulting from ozone depiction and the model's 2 x CO, climate sensitivity. The results suggest that changes in meridional heat transport from low to high latitudes combined with the decrease in the infrared opacity of the lower <span class="hlt">stratosphere</span> are very important in determining the steady-state response to high latitude ozone losses. The 39% compensation in greenhouse <span class="hlt">warming</span> resulting from lower <span class="hlt">stratospheric</span> ozone losses is also larger than the 28% compensation simulated previously by the lower resolution model. The higher resolution model is able to resolve the high latitude features of the assumed ozone perturbation, which are important in determining the overall climate sensitivity to these perturbations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRD..119.2092L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRD..119.2092L"><span id="translatedtitle">Future Arctic temperature and ozone: The role of <span class="hlt">stratospheric</span> composition changes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Langematz, Ulrike; Meul, Stefanie; Grunow, Katja; Romanowsky, Erik; Oberlnder, Sophie; Abalichin, Janna; Kubin, Anne</p> <p>2014-03-01</p> <p>Using multidecadal simulations with the European Centre/Hamburg-Modular Earth Submodel System Atmospheric Chemistry (EMAC) model, the role of changing concentrations of ozone-depleting substances (ODSs) and greenhouse gases (GHGs) on Arctic springtime ozone was examined. The focus is on potential changes in the meteorological conditions relevant for Arctic ozone depletion. It is found that with rising GHG levels the lower Arctic <span class="hlt">stratosphere</span> will cool significantly in early winter, while no significant temperature signal is identified later in winter or spring. A seasonal shift of the lowest polar minimum temperatures from late to early winter in the second part of the 21st century occurs. However, Arctic lower <span class="hlt">stratosphere</span> temperatures do not seem to decline to new record minima. The future Arctic lower <span class="hlt">stratosphere</span> vortex will have a longer lifetime, as a result of an earlier formation in autumn. No extended vortex persistence is found in spring due to enhanced dynamical <span class="hlt">warming</span> by tropospheric wave forcing. Because of the dominant early winter cooling, largest accumulated polar <span class="hlt">stratospheric</span> cloud (PSC) areas (APSC) are projected for the middle of the 21st century. A further increase of APSC toward the end of the 21st century is prevented by increased dynamical polar <span class="hlt">warming</span>. EMAC suggests that in the near future, there is a chance of low Arctic springtime ozone in individual years; however, there is no indication of a formation of regular Arctic ozone holes. Toward the end of the 21st century, when ODSs will be close to the 1960 levels, further rising GHG levels will cause increased Arctic springtime ozone.</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_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" 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_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/484371','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/484371"><span id="translatedtitle">As estimation of the climatic effects of <span class="hlt">stratospheric</span> ozone losses during the 1980s</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>MacKay, R.M.; Ko, M.K.W.; Yang, Yajaing</p> <p>1997-04-01</p> <p>In order to study the potential climatic effects of the ozone hole more directly and to assess the validity of previous lower resolution model results, the latest high spatial resolution version of the Atmospheric and Environmental Research, Inc., seasonal radiative dynamical climate model is used to simulate the climatic effects of ozone changes relative to the other greenhouse gases. The steady-state climatic effect of a sustained decrease in lower <span class="hlt">stratospheric</span> ozone, similar in magnitude to the observed 1979-90 decrease, is estimated by comparing three steady-state climate simulations: (I) 1979 greenhouse gas concentrations and 1979 ozone, (II) 1990 greenhouse gas concentrations with 1979 ozone, and (III) 1990 greenhouse gas concentrations with 1990 ozone. The simulated increase in surface air temperature resulting from nonozone greenhouse gases is 0.272 K. When changes in lower <span class="hlt">stratospheric</span> ozone are included, the greenhouse <span class="hlt">warming</span> is 0.165 K, which is approximately 39% lower than when ozone is fixed at the 1979 concentrations. Ozone perturbations at high latitudes result in a cooling of the surface-troposphere system that is greater (by a factor of 2.8) than that estimated from the change in radiative forcing resulting from ozone depletion and the model`s 2 X CO{sub 2} climate sensitivity. The results suggest that changes in meridional heat transport from low to high latitudes combined with the decrease in the infrared opacity of the lower <span class="hlt">stratosphere</span> are very important in determining the steady-state response to high latitude ozone losses. The 39% compensation in greenhouse <span class="hlt">warming</span> resulting from lower <span class="hlt">stratospheric</span> ozone losses is also larger than the 28% compensation simulated previously by the lower resolution model. The higher resolution model is able to resolve the high latitude features of the assumed ozone perturbation, which are important in determining the overall climate sensitivity to these perturbations. 39 refs., 11 figs., 4 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/146544','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/146544"><span id="translatedtitle">Review of the decadal oscillation in the <span class="hlt">stratosphere</span> of the northern hemisphere</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Loon, H. van; Labitzke, K.</p> <p>1993-11-01</p> <p>The decadal oscillation of the temperature and geopotential height in the lower <span class="hlt">stratosphere</span> of the northern hemisphere can be followed back to the early 1950s. During this time it was in phase with the 11-year sunspot cycle. The correlation with the solar cycle is positive and largest in the <span class="hlt">stratospheric</span> geopotential heights of the subtropics below 10 mbar ({approximately}31 km, which is as high as the grid point data reach), especially on the western, ocean-dominated side of the hemisphere. As expected from the hydrostatic equation, it is also evident in the temperatures of the upper troposphere in the same region. There is no large correlation at high latitudes. The correlation with the sunspot cycle is weakest in January-February, but if the data in these months are grouped according to the wind direction in the quasi-biennial oscillation (QBO) of the lower equatorial <span class="hlt">stratosphere</span>, the positive subtropical correlations in the east years are as high as in all other months. There are, in addition large negative correlations in the Arctic in agreement with the strong teleconnection (negative correlation) between lower and higher latitudes in winter. There is no consistent sign in the weak correlations at middle and lower latitudes in the west years, but in the Arctic the correlation with the solar cycle is highly positive, because those major midwinter <span class="hlt">warmings</span> that occur in west years of the QBO take place in solar maxima, whereas the years without major <span class="hlt">warmings</span> are found in solar minima. There is not yet an explanation of the 10-12 year oscillation in the <span class="hlt">stratosphere</span>. 8 refs., 6 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/215125','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/215125"><span id="translatedtitle">Laboratory studies of polar <span class="hlt">stratospheric</span> cloud formation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tolbert, M.A.; Anthony, S.E.; Disselkamp, R.; Iraci, L.T.</p> <p>1995-12-31</p> <p>Polar <span class="hlt">stratospheric</span> clouds (PSCs) are generally classified as type I or type II, depending on their formation temperature. Type II PSCs form at <span class="hlt">stratospheric</span> temperatures near 189 K and are composed of water ice. Type I PSCs are stable at warmer temperatures and contain both nitric acid and water. Because nitric acid trihydrate (NAT) is the thermodynamically stable form of HNO{sub 3}/H{sub 2}O under <span class="hlt">stratospheric</span> conditions, it has often been assumed that type I PSCs are composed of NAT. Recent measurements, however, suggest that NAT may not form readily in the <span class="hlt">stratosphere</span> due to a kinetic barrier. Type I PSCs are believed to nucleate on preexisting <span class="hlt">stratospheric</span> sulfate aerosols composed of sulfuric acid and water. We are performing laboratory experiments to measure the nucleation and growth of type I PSCs on sulfuric acid. We study both thin film samples modeling <span class="hlt">stratospheric</span> particles and actual aerosol samples generated in the laboratory. The results of these studies will be discussed in the context of current theories for type I PSC formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRD..118.4533C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRD..118.4533C"><span id="translatedtitle">Microphysical and radiative changes in cirrus clouds by geoengineering 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>Cirisan, A.; Spichtinger, P.; Luo, B. P.; Weisenstein, D. K.; Wernli, H.; Lohmann, U.; Peter, T.</p> <p>2013-05-01</p> <p>In the absence of tangible progress in reducing greenhouse gas emissions, the implementation of solar radiation management has been suggested as measure to stop global <span class="hlt">warming</span>. Here we investigate the impacts on northern midlatitude cirrus from continuous SO2emissions of 2-10 Mt/a in the tropical <span class="hlt">stratosphere</span>. Transport of geoengineering aerosols into the troposphere was calculated along trajectories based on ERA Interim reanalyses using ozone concentrations to quantify the degree of mixing of <span class="hlt">stratospheric</span> and tropospheric air termed "troposphericity". Modeled size distributions of the geoengineered H2SO4-H2O droplets have been fed into a cirrus box model with spectral microphysics. The geoengineering is predicted to cause changes in ice number density by up to 50%, depending on troposphericity and cooling rate. We estimate the resulting cloud radiative effects from a radiation transfer model. Complex interplay between the few large <span class="hlt">stratospheric</span> and many small tropospheric H2SO4-H2O droplets gives rise to partly counteracting radiative effects: local increases in cloud radiative forcing up to +2 W/m2for low troposphericities and slow cooling rates, and decreases up to -7.5 W/m2for high troposphericities and fast cooling rates. The resulting mean impact on the northern midlatitudes by changes in cirrus is predicted to be low, namely <1% of the intended radiative forcing by the <span class="hlt">stratospheric</span> aerosols. This suggests that <span class="hlt">stratospheric</span> sulphate geoengineering is unlikely to have large microphysical effects on the mean cirrus radiative forcing. However, this study disregards feedbacks, such as temperature and humidity changes in the upper troposphere, which must be examined separately.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994PhDT........71L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994PhDT........71L"><span id="translatedtitle">Issues in <span class="hlt">Stratospheric</span> 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>Lloyd, Steven Andrew</p> <p></p> <p>Following the announcement of the discovery of the Antarctic ozone hole in 1985 there have arisen a multitude of questions pertaining to the nature and consequences of polar ozone depletion. This thesis addresses several of these specific questions, using both computer models of chemical kinetics and the Earth's radiation field as well as laboratory kinetic experiments. A coupled chemical kinetic-radiative numerical model was developed to assist in the analysis of in situ field measurements of several radical and neutral species in the polar and mid-latitude lower <span class="hlt">stratosphere</span>. Modeling was used in the analysis of enhanced polar ClO, mid-latitude diurnal variation of ClO, and simultaneous measurements of OH, HO_2, H_2 O and O_3. Most importantly, such modeling was instrumental in establishing the link between the observed ClO and BrO concentrations in the Antarctic polar vortex and the observed rate of ozone depletion. The principal medical concern of <span class="hlt">stratospheric</span> ozone depletion is that ozone loss will lead to the enhancement of ground-level UV-B radiation. Global ozone climatology (40^circS to 50^ circN latitude) was incorporated into a radiation field model to calculate the biologically accumulated dosage (BAD) of UV-B radiation, integrated over days, months, and years. The slope of the annual BAD as a function of latitude was found to correspond to epidemiological data for non-melanoma skin cancers for 30^circ -50^circN. Various ozone loss scenarios were investigated. It was found that a small ozone loss in the tropics can provide as much additional biologically effective UV-B as a much larger ozone loss at higher latitudes. Also, for ozone depletions of > 5%, the BAD of UV-B increases exponentially with decreasing ozone levels. An important key player in determining whether polar ozone depletion can propagate into the populated mid-latitudes is chlorine nitrate, ClONO_2 . As yet this molecule is only indirectly accounted for in computer models and field measurements. Therefore a laboratory prototype of an instrument to measure ClONO _2 concentrations in situ was developed, adapting techniques recently developed in this research group to measure ClO concentrations at the part-per-trillion level. The detection scheme involves heating a flowing air sample to almost 500K, thermally dissociating ClONO _2 into ClO and NO_2 , and measuring the resulting ClO concentration by titrating with NO to produce Cl atoms, which are detected by resonance fluoresence. The calibration of this technique is very sensitive to flow parameters (temperature, pressure, flow velocity, added NO concentration, and homogeneity of flow). The issues developed in this thesis contribute to our understanding of the mechanisms of <span class="hlt">stratospheric</span> ozone depletion and its potential global impact. It is becoming increasingly apparent that our ability to predict the future course of global ozone depletion is critically dependent on our ability to reproduce in situ and remote measurements with numerical models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=PIA04365&hterms=alberta&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dalberta','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=PIA04365&hterms=alberta&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dalberta"><span id="translatedtitle">Smoke Soars to <span class="hlt">Stratospheric</span> Heights</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> A new look at smoke from the Chisholm forest fire, which ignited on May 23, 2001 about 160 kilometers north of Edmonton in Alberta, Canada, provides confirming evidence that dense smoke can reach the upper troposphere and lower <span class="hlt">stratosphere</span>. Scientists have postulated a link between fires in northern forests and the observed enhancements in <span class="hlt">stratospheric</span> aerosols, but it is difficult to measure smoke aerosol heights directly. Here, height information for the Chisholm fire was retrieved using stereoscopic processing of data from multiple Multi-angle Imaging SpectroRadiometer (MISR) cameras. These images were acquired on May 29, when the severity of the fire had begun to stabilize after a cold front and strong low-level winds caused rapid spread of flame and an eruption of large-scale convection on May 28. This dramatic event was studied in detail by M. Fromm and R. Servranckx, 'Transport of forest fire smoke above the tropopause by supercell convection,' <i>Geophys. Res. Lett</i>., vol. 30, no. 10 (2003). <p/> The two left-hand images are natural color views from MISR's nadir and 60o forward viewing cameras in which a pall of yellowish smoke is apparent both above the surface and above clouds in the top portion of the images. This area is near the junction of Canada's Keewatin region and Northwest Territory, and about 1200 km northward of the originalfire location. Lake Athabasca is at the lower left. The second panel from the right is MISR's standard stereo height product (derived from the nadir and the two 26o cameras), while the right-hand panel is a specially-generated product using MISR's 46o and 60o forward-pointing cameras. Because the smoke appears thicker at the oblique view angles, better areal coverage is obtained and the retrievals are less sensitive to the underlying cloud deck. The southern portion of the smoke cloud is at an altitude of about 3.5 km; however, the smoke further to the north has risen above the tropopause (which is at about 11 km altitude) and intruded into the lower <span class="hlt">stratosphere</span>. These measurements indicate that smoke reaches heights of about 12-13 kilometers above sea level. The height fields pictured here are uncorrected for wind effects; wind-corrected heights (which have higher accuracy but sparser spatial coverage) for this smoke pall are about 0.5 km higher. <p/> The Multiangle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire globe between 82o north and 82o south latitude. These data products were generated from a portion of the imagery acquired during Terra orbit 7695. The panels cover an area of 380 kilometers x 1137 kilometers, and utilize data from blocks 36 to 43 within World Reference System-2 path 40. <p/> MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920020064&hterms=Polar+Stratospheric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DPolar%2BStratospheric','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920020064&hterms=Polar+Stratospheric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DPolar%2BStratospheric"><span id="translatedtitle">Lidar Observations of Polar <span class="hlt">Stratospheric</span> Clouds and <span class="hlt">Stratospheric</span> Temperatures at the South Pole</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Collins, Richard L.; Bowman, Kenneth P.; Gardner, Chester S.</p> <p>1992-01-01</p> <p>Polar <span class="hlt">stratospheric</span> clouds (PSC's) play a crucial role in the ozone chemistry of the polar regions. Current chemical models rely on the presence of these clouds to explain the rapid destruction of ozone observed each spring in Antarctica. We present lidar observations of PCS's and <span class="hlt">stratospheric</span> temperatures at the South Pole throughout the Antarctic winter and spring of 1990.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6914531','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6914531"><span id="translatedtitle">Global <span class="hlt">warming</span> on trial</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Broeker, W.S.</p> <p>1992-04-01</p> <p>Jim Hansen, a climatologist at NASA's Goddard Space Institute, is convinced that the earth's temperature is rising and places the blame on the buildup of greenhouse gases in the atmosphere. Unconvinced, John Sununu, former White House chief of staff, doubts that the <span class="hlt">warming</span> will be great enough to produce serious threat and fears that measures to reduce the emissions would throw a wrench into the gears that drive the Unites States' troubled economy. During his three years at the White House, Sununu's view prevailed, and although his role in the debate has diminished, others continue to cast doubt on the reality of global <span class="hlt">warming</span>. A new lobbying group called the Climate Council has been created to do just this. Burning fossil fuels is not the only problem; a fifth of emissions of carbon dioxide now come from clearing and burning forests. Scientists are also tracking a host of other greenhouse gases that emanate from a variety of human activities; the <span class="hlt">warming</span> effect of methane, chlorofluorocarbons and nitrous oxide combined equals that of carbon dioxide. Although the current <span class="hlt">warming</span> from these gases may be difficult to detect against the background noise of natural climate variation, most climatologists are certain that as the gases continue to accumulate, increases in the earth's temperature will become evident even to skeptics. If the reality of global <span class="hlt">warming</span> were put on trial, each side would have trouble making its case. Jim Hansen's side could not prove beyond a reasonable doubt that carbon dioxide and other greenhouse gases have <span class="hlt">warmed</span> the planet. But neither could John Sununu's side prove beyond a reasonable doubt that the <span class="hlt">warming</span> expected from greenhouse gases has not occurred. To see why each side would have difficulty proving its case, this article reviews the arguments that might be presented in such a hearing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/153561','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/153561"><span id="translatedtitle">Long range global <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rolle, K.C.; Pulkrabek, W.W.; Fiedler, R.A.</p> <p>1995-12-31</p> <p>This paper explores one of the causes of global <span class="hlt">warming</span> that is often overlooked, the direct heating of the environment by engineering systems. Most research and studies of global <span class="hlt">warming</span> concentrate on the modification that is occurring to atmospheric air as a result of pollution gases being added by various systems; i.e., refrigerants, nitrogen oxides, ozone, hydrocarbons, halon, and others. This modification affects the thermal radiation balance between earth, sun and space, resulting in a decrease of radiation outflow and a slow rise in the earth`s steady state temperature. For this reason the solution to the problem is perceived as one of cleaning up the processes and effluents that are discharged into the environment. In this paper arguments are presented that suggest, that there is a far more serious cause for global <span class="hlt">warming</span> that will manifest itself in the next two or three centuries; direct heating from the exponential growth of energy usage by humankind. Because this is a minor contributor to the global <span class="hlt">warming</span> problem at present, it is overlooked or ignored. Energy use from the combustion of fuels and from the output of nuclear reactions eventually is manifest as <span class="hlt">warming</span> of the surroundings. Thus, as energy is used at an ever increasing rate the consequent global <span class="hlt">warming</span> also increases at an ever increasing rate. Eventually this rate will become equal to a few percent of solar radiation. When this happens the earth`s temperature will have risen by several degrees with catastrophic results. The trends in world energy use are reviewed and some mathematical models are presented to suggest future scenarios. These models can be used to predict when the global <span class="hlt">warming</span> problem will become undeniably apparent, when it will become critical, and when it will become catastrophic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/45767','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/45767"><span id="translatedtitle">Ozone depletion and global <span class="hlt">warming</span> potentials of CF3I</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Solomon, S.; Burkholder, J.B.; Ravishankara, A.R.; Garcia, R.R. |</p> <p>1994-10-01</p> <p>Laboratory measurements of the infrared and near-ultraviolet absorption characteristics of CF3I (a potentially useful substitute for halons) are presented. Using these data together with a detailed photochemical model, it is shown that the lifetime of this gas in the sunlit atmosphere is less than a day. The chemistry of iodine in the <span class="hlt">stratosphere</span> is evaluated, and it is shown that any iodine that reaches the <span class="hlt">stratosphere</span> will be very effective for ozone destruction there. However, the extremely short lifetime of CF3I greatly limits its transport to the <span class="hlt">stratosphere</span> when released at the surface, especially at midlatitudes, and the total anthropogenic surface release of CF3I is likely to be far less than that of natural iodocarbons such as CH3I on a global basis. It is highly probable that the steady-state ozone depletion potential (ODP) of CF3I for surface releases is less than 0.008 and more likely below 0.0001. Measured infrared absorption data are also combined with the lifetime to show that the 20-year global <span class="hlt">warming</span> potential (GWP) of this gas is likely to be very small, less than 5. Therefore, this study suggests that neither the ODP nor the GWP of this gas represent significant obstacles to its use as a replacement for halons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ACP....1413705K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ACP....1413705K"><span id="translatedtitle">The impact of polar <span class="hlt">stratospheric</span> ozone loss on Southern Hemisphere <span class="hlt">stratospheric</span> circulation and climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keeble, J.; Braesicke, P.; Abraham, N. L.; Roscoe, H. K.; Pyle, J. A.</p> <p>2014-12-01</p> <p>The impact of polar <span class="hlt">stratospheric</span> ozone loss resulting from chlorine activation on polar <span class="hlt">stratospheric</span> clouds is examined using a pair of model integrations run with the fully coupled chemistry climate model UM-UKCA. Suppressing chlorine activation through heterogeneous reactions is found to produce modelled ozone differences consistent with observed ozone differences between the present and pre-ozone hole period. Statistically significant high-latitude Southern Hemisphere (SH) ozone loss begins in August and peaks in October-November, with > 75% of ozone destroyed at 50 hPa. Associated with this ozone destruction is a > 12 K decrease of the lower polar <span class="hlt">stratospheric</span> temperatures and an increase of > 6 K in the upper <span class="hlt">stratosphere</span>. The heating components of this temperature change are diagnosed and it is found that the temperature dipole is the result of decreased short-wave heating in the lower <span class="hlt">stratosphere</span> and increased dynamical heating in the upper <span class="hlt">stratosphere</span>. The cooling of the polar lower <span class="hlt">stratosphere</span> leads, through thermal wind balance, to an acceleration of the polar vortex and delays its breakdown by ~ 2 weeks. A link between lower <span class="hlt">stratospheric</span> zonal wind speed, the vertical component of the Eliassen-Palm (EP) flux, Fz and the residual mean vertical circulation, <span style="border-top: 1px solid #000; color: #000;">w*, is identified. In November and December, increased westerly winds and a delay in the breakup of the polar vortex lead to increases in Fz, indicating increased wave activity entering the <span class="hlt">stratosphere</span> and propagating to higher altitudes. The resulting increase in wave breaking, diagnosed by decreases to the EP flux divergence, drives enhanced downwelling over the polar cap. Many of the <span class="hlt">stratospheric</span> signals modelled in this study propagate down to the troposphere, and lead to significant surface changes in December.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E1571K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E1571K"><span id="translatedtitle">Curing of epoxy matrix composite in <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>Kondyurin, Alexey; Kondyurina, Irina; Bilek, Marcela</p> <p></p> <p>Large structures for habitats, greenhouses, space bases, space factories are needed for next stage of space exploitation. A new approach enabling large-size constructions in space relies on the use of the polymerization technology of fiber-filled composites with a curable polymer matrix applied in the free space environment. The polymerisation process is proposed for the material exposed to high vacuum, dramatic temperature changes, space plasma, sun irradiation and atomic oxygen (in low Earth orbit), micrometeorite fluence, electric charging and microgravitation. The <span class="hlt">stratospheric</span> flight experiments are directed to an investigation of the curing polymer matrix under the <span class="hlt">stratospheric</span> conditions on. The unique combination of low atmospheric pressure, high intensity UV radiation including short wavelength UV and diurnal temperature variations associated with solar irradiation strongly influences the chemical processes in polymeric materials. The first flight experiment with uncured composites was a part of the NASA scientific balloon flight program realised at the NASA <span class="hlt">stratospheric</span> balloon station in Alice Springs, Australia. A flight cassette installed on payload was lifted with a zero-pressure <span class="hlt">stratospheric</span> balloon filled with Helium. Columbia Scientific Balloon Facility (CSBF) provided the launch, flight telemetry and landing of the balloon and payload. A cassette of uncured composite materials with an epoxy resin matrix was exposed 3 days in the <span class="hlt">stratosphere</span> (40 km altitude). The second flight experiment was realised in South Australia in 2012, when the cassette was exposed in 27 km altitude. An analysis of the chemical structure of the composites showed, that the space irradiations are responsible for crosslinking of the uncured polymers exposed in the <span class="hlt">stratosphere</span>. The first prepreg in the world was cured successfully in <span class="hlt">stratosphere</span>. The investigations were supported by Alexander von Humboldt Foundation, NASA and RFBR (12-08-00970) grants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19800035571&hterms=fossil+fuels+effect+climate&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dfossil%2Bfuels%2Beffect%2Bclimate','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19800035571&hterms=fossil+fuels+effect+climate&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dfossil%2Bfuels%2Beffect%2Bclimate"><span id="translatedtitle">OCS, <span class="hlt">stratospheric</span> aerosols and climate</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Turco, R. P.; Whitten, R. C.; Toon, O. B.; Pollack, J. B.; Hamill, P.</p> <p>1980-01-01</p> <p>The carbonyl sulfide budget in the atmosphere is examined, and the effects of <span class="hlt">stratospheric</span> sulfate aerosol particles, formed in part from atmospheric carbonyl sulfate, on global climate are considered. From tropospheric measurements of carbon disulfide and the rate constant for the conversion of carbon disulfide to carbonyl sulfide, it is estimated that five Tg of carbonyl sulfide/year could be generated from carbon disulfide in the atmosphere. Direct sources of OCS include the refining and combustion of fossil fuels (1 Tg/year), natural and agricultural fires (0.2 to 0.3 Tg/year), and soils (0.5 Tg/year), yielding a total influx of from 1 to 10 Tg/year, up to 50% of which may be anthropogenic. Considerations of carbonyl sulfide sinks and concentrations indicate an atmospheric lifetime of one year, with OCS the major atmospheric sulfur compound. It is estimated that a ten-fold increase in atmospheric carbonyl sulfide would cause an optical depth perturbation comparable to that of a modest volcanic eruption, leading to an average global surface temperature decrease of 0.1 K, in addition to a possible greenhouse effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19840054369&hterms=Ozone+1980&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DOzone%2B1980','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19840054369&hterms=Ozone+1980&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DOzone%2B1980"><span id="translatedtitle">Semiannual oscillation of <span class="hlt">stratospheric</span> ozone</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Maeda, K.</p> <p>1984-01-01</p> <p>By applying spherical harmonic analysis to the ozone data obtained from the Nimbus-7 solar backscattered UV-radiation measurements for the period from November 1978 to October 1980, the following features of the semi-annual oscillation (SAO) in <span class="hlt">stratospheric</span> ozone are revealed: (1) the equatorial ozone SAO has a broad maximum of the order of 0.5 (mixing ratio in micro-g/g) between the 10 mb and 3 mb levels, and the maximum shifts downward from 1 mb in June (and December) to 40 mb in November (and May); (2) amplitudes of polar ozone SAO's are larger than that of the equatorial SAO, with a major maximum at 2 mb which is 2 micro-g/g at 75 deg N and 0.8 micro-g/g at 75 deg S, respectively; (3) the inverse phase between the polar and tropical SAO which occurs around the 3 mb (about 40 km) level can be interpreted in terms of the temperature-dependent ozone chemistry and the poleward meridional transport of ozone by dynamical processes in the atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatCC...5..849C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatCC...5..849C"><span id="translatedtitle">ENSO and greenhouse <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>Cai, Wenju; Santoso, Agus; Wang, Guojian; Yeh, Sang-Wook; An, Soon-Il; Cobb, Kim M.; Collins, Mat; Guilyardi, Eric; Jin, Fei-Fei; Kug, Jong-Seong; Lengaigne, Matthieu; McPhaden, Michael J.; Takahashi, Ken; Timmermann, Axel; Vecchi, Gabriel; Watanabe, Masahiro; Wu, Lixin</p> <p>2015-09-01</p> <p>The El Nio/Southern Oscillation (ENSO) is the dominant climate phenomenon affecting extreme weather conditions worldwide. Its response to greenhouse <span class="hlt">warming</span> has challenged scientists for decades, despite model agreement on projected changes in mean state. Recent studies have provided new insights into the elusive links between changes in ENSO and in the mean state of the Pacific climate. The projected slow-down in Walker circulation is expected to weaken equatorial Pacific Ocean currents, boosting the occurrences of eastward-propagating <span class="hlt">warm</span> surface anomalies that characterize observed extreme El Nio events. Accelerated equatorial Pacific <span class="hlt">warming</span>, particularly in the east, is expected to induce extreme rainfall in the eastern equatorial Pacific and extreme equatorward swings of the Pacific convergence zones, both of which are features of extreme El Nio. The frequency of extreme La Nia is also expected to increase in response to more extreme El Nios, an accelerated maritime continent <span class="hlt">warming</span> and surface-intensified ocean <span class="hlt">warming</span>. ENSO-related catastrophic weather events are thus likely to occur more frequently with unabated greenhouse-gas emissions. But model biases and recent observed strengthening of the Walker circulation highlight the need for further testing as new models, observations and insights become available.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014DPS....4650809S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014DPS....4650809S"><span id="translatedtitle">An exploration of Saturn's <span class="hlt">stratospheric</span> dynamics through Global Climate Modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Spiga, Aymeric; Guerlet, Sandrine; Indurain, Mikel; Millour, Ehouarn; Sylvestre, Mlody; Thierry, Fouchet; Meurdesoif, Yann; Thomas, Dubos</p> <p>2014-11-01</p> <p>A decade of Cassini observations has yielded a new vision on the dynamical phenomena in Saturn's troposphere and <span class="hlt">stratosphere</span>. Several puzzling signatures (equatorial oscillations with a period of about half a Saturn year, interhemispheric circulations affecting the hydrocarbons distribution, including possible effects of rings shadowing, sudden <span class="hlt">warming</span> associated with the powerful 2010 Great White Spot) cannot be explained by current photochemical and radiative models, which do not include dynamics. We therefore suspect that 1. the observed anomalies arise from large-scale dynamical circulations and 2. those large-scale dynamical motions are driven by atmospheric waves, eddies, and convection, in other words fundamental mechanisms giving birth to, e.g., the Quasi-Biennal Oscillation and Brewer-Dobson circulation in the Earths middle atmosphere. We explore the plausibility of this scenario using our new Global Climate Modeling (GCM) for Saturn. To build this model, we firstly formulated dedicated physical parameterizations for Saturns atmosphere, with a particular emphasis on radiative computations (using a correlated-k radiative transfer model, with radiative species and spectral discretization tailored for Saturn) aimed at both efficiency and accuracy, and validated them against existing Cassini observations. A second step consisted in coupling this radiative model to an hydrodynamical solver to predict the three-dimensional evolution of Saturn's tropospheric and <span class="hlt">stratospheric</span> flow. We will provide an analysis of the first results of those dynamical simulations, with a focus on the development of baroclinic and barotropic instability, on eddy vs. mean flow interactions, and how this could relate to the enigmatic signatures observed by Cassini. Preliminary high-resolution simulations with a new icosahedral dynamical solver adapted to high-performance computing will also be analyzed. Perspectives are twofold: firstly, broadening our fundamental knowledge of atmospheric waves and instabilities; secondly, provide the community with a "gas giant GCM" capable to interpret past and future observations of gas giants inside and outside our Solar System.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ACPD...14.1073Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ACPD...14.1073Z"><span id="translatedtitle">Evidence for an earlier greenhouse cooling effect in the <span class="hlt">stratosphere</span> before the 1980s over the Northern Hemisphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zerefos, C. S.; Tourpali, K.; Zanis, P.; Eleftheratos, K.; Repapis, C.; Goodman, A.; Wuebbles, D.; Isaksen, I. S. A.; Luterbacher, J.</p> <p>2014-01-01</p> <p>This study provides a new look at the observed and calculated long-term temperature changes since 1958 for the region extending from the lower troposphere up to the lower <span class="hlt">stratosphere</span> of the Northern Hemisphere. The analysis is mainly based on monthly layer mean temperatures derived from geopotential height thicknesses between specific pressure levels. Layer mean temperatures from thickness improve homogeneity in both space and time and reduce uncertainties in the trend analysis. Datasets used include the NCEP/NCAR I reanalysis, the Free University of Berlin (FU-Berlin) and the RICH radiosonde datasets as well as historical simulations with the CESM1-WACCM global model participating in CMIP5. After removing the natural variability with an autoregressive multiple regression model our analysis shows that the time interval of our study 1958-2011 can be divided in two distinct sub-periods of long term temperature variability and trends; before and after 1980s. By calculating trends for the summer time to reduce interannual variability, the two periods are as follows. From 1958 until 1979, non-significant trends or slight cooling trends prevail in the lower troposphere (0.06 0.06 C decade-1 for NCEP and -0.12 0.06 C decade-1 for RICH). The second period from 1980 to the end of the records shows significant <span class="hlt">warming</span> trends (0.25 0.05 C decade-1 for both NCEP and RICH). Above the tropopause a persistent cooling trend is clearly seen in the lower <span class="hlt">stratosphere</span> both in the pre-1980s period (-0.58 0.17 C decade-1 for NCEP, -0.30 0.16 C decade-1 for RICH and -0.48 0.20 C decade-1 for FU-Berlin) and the post-1980s period (-0.79 0.18 C decade-1 for NCEP, -0.66 0.16 C decade-1 for RICH and -0.82 0.19 C decade-1 for FU-Berlin). The cooling in the lower <span class="hlt">stratosphere</span> is a persistent feature from the tropics up to 60 north for all months. At polar latitudes competing dynamical and radiative processes are reducing the statistical significance of these trends. Model results are in line with re-analysis and the observations, indicating a persistent cooling in the lower <span class="hlt">stratosphere</span> during summer before and after the 1980s by -0.33 C decade-1; a feature that is also seen throughout the year. However, the lower <span class="hlt">stratosphere</span> modelled trends are generally lower than re-analysis and the observations. The contrasting effects of ozone depletion at polar latitudes in winter/spring and the anticipated strengthening of the Brewer Dobson circulation from man-made global <span class="hlt">warming</span> at polar latitudes are discussed. Our results provide additional evidence for an early greenhouse cooling signal in the lower <span class="hlt">stratosphere</span> before the 1980s, which it appears well in advance relative to the tropospheric greenhouse <span class="hlt">warming</span> signal. Hence it may be postulated that the <span class="hlt">stratosphere</span> could have provided an early warning of man-made climate change. The suitability for early warning signals in the <span class="hlt">stratosphere</span> relative to the troposphere is supported by the fact that the <span class="hlt">stratosphere</span> is less sensitive to changes due to cloudiness, humidity and man-made aerosols. Our analysis also indicates that the relative contribution of the lower <span class="hlt">stratosphere</span> vs. the upper troposphere low frequency variability is important for understanding the added value of the long term tropopause variability related to human induced 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=26447','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=26447"><span id="translatedtitle">Can ozone depletion and global <span class="hlt">warming</span> interact to produce rapid climate change?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hartmann, Dennis L.; Wallace, John M.; Limpasuvan, Varavut; Thompson, David W. J.; Holton, James R.</p> <p>2000-01-01</p> <p>The atmosphere displays modes of variability whose structures exhibit a strong longitudinally symmetric (annular) component that extends from the surface to the <span class="hlt">stratosphere</span> in middle and high latitudes of both hemispheres. In the past 30 years, these modes have exhibited trends that seem larger than their natural background variability, and may be related to human influences on <span class="hlt">stratospheric</span> ozone and/or atmospheric greenhouse gas concentrations. The pattern of climate trends during the past few decades is marked by rapid cooling and ozone depletion in the polar lower <span class="hlt">stratosphere</span> of both hemispheres, coupled with an increasing strength of the wintertime westerly polar vortex and a poleward shift of the westerly wind belt at the earth's surface. Annular modes of variability are fundamentally a result of internal dynamical feedbacks within the climate system, and as such can show a large response to rather modest external forcing. The dynamics and thermodynamics of these modes are such that strong synergistic interactions between <span class="hlt">stratospheric</span> ozone depletion and greenhouse <span class="hlt">warming</span> are possible. These interactions may be responsible for the pronounced changes in tropospheric and <span class="hlt">stratospheric</span> climate observed during the past few decades. If these trends continue, they could have important implications for the climate of the 21st century. PMID:10677475</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988EOSTr..69..820W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988EOSTr..69..820W"><span id="translatedtitle">Model predicts 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>Wainger, Lisa A.</p> <p></p> <p>Global greenhouse <span class="hlt">warming</span> will be clearly identifiable by the 1990s, according to eight scientists who have been studying climate changes using computer models. Researchers at NASA's Goddard Space Flight Center, Goddard Institute for Space Studies, New York, and the Massachusetts Institute of Technology, Cambridge, say that by the 2010s, most of the globe will be experiencing substantial <span class="hlt">warming</span>. The level of <span class="hlt">warming</span> will depend on amounts of trace gases, or greenhouse gases, in the atmosphere.Predictions for the next 70 years are based on computer simulations of Earth's climate. In three runs of the model, James Hansen and his colleagues looked at the effects of changing amounts of atmospheric gases with time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990010757&hterms=Nanoparticles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DNanoparticles','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990010757&hterms=Nanoparticles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DNanoparticles"><span id="translatedtitle">Bismuth Oxide Nanoparticles 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>Rietmeijer, Frans J. M.; Mackinnon, Ian D. R.</p> <p>1997-01-01</p> <p>Platey grains of cubic Bi2O3, alpha-Bi2O3, and Bi2O(2.75), nanograins were associated with chondritic porous interplanetary dust particles W7029C1, W7029E5, and 2011C2 that were collected in the <span class="hlt">stratosphere</span> at 17-19 km altitude. Similar Bi oxide nanograins were present in the upper <span class="hlt">stratosphere</span> during May 1985. These grains are linked to the plumes of several major volcanic eruptions during the early 1980s that injected material into the <span class="hlt">stratosphere</span>. The mass of sulfur from these eruptions is a proxy for the mass of <span class="hlt">stratospheric</span> Bi from which we derive the particle number densities (p/cu m) for "average Bi2O3 nanograins" due to this volcanic activity and those necessary to contaminate the extraterrestrial chondritic porous interplanetary dust particles via collisional sticking. The match between both values supports the idea that Bi2O3 nanograins of volcanic origin could contaminate interplanetary dust particles in the Earth's <span class="hlt">stratosphere</span>.</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_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" 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_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920005300','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920005300"><span id="translatedtitle">Airborne lidar <span class="hlt">stratospheric</span> ozone and aerosol investigations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Browell, Edward V.</p> <p>1990-01-01</p> <p>The objectives are to study the distribution of ozone (O3) and aerosols across the polar regions during the winter and spring periods and to relate these observations to chemical and dynamical processes that can contribute to the chemical perturbation of the polar <span class="hlt">stratosphere</span> and the possible destruction of O3. The distribution and characteristics of <span class="hlt">stratospheric</span> aerosols and polar <span class="hlt">stratospheric</span> clouds (PSCs) are required to understand heterogeneous chemical processes that can lead to O3 depletion, and observation of O3 variations are important in the direct detection of O3 depletion and in tracing atmospheric dynamics. An airborne Differential Absorption Lidar (DIAL) system is operated in a zenith mode from the NASA DC-8 aircraft to obtain data on the large scale spatial variability of O3, and aerosol/PSC's in the lower <span class="hlt">stratosphere</span> from about 11 to 23 km for O3, and 11 to 28 km for aerosols. The variability of O3 and aerosols/PSCs is studied in relation to chemical processes that can produce O3 depletion and to dynamics in the lower <span class="hlt">stratosphere</span> that transport gases and aerosols inside the vortex and in some cases, across the edge of the vortex.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930013868','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930013868"><span id="translatedtitle">The atmospheric effects of <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>Stolarski, Richard S. (Editor); Wesoky, Howard L. (Editor)</p> <p>1993-01-01</p> <p>This document presents a second report from the Atmospheric Effects of <span class="hlt">Stratospheric</span> Aircraft (AESA) component of NASA's High-Speed Research Program (HSRP). This document presents a second report from the Atmospheric Effects of <span class="hlt">Stratospheric</span> Aircraft (AESA) component of NASA's High Speed Research Program (HSRP). Market and technology considerations continue to provide an impetus for high-speed civil transport research. A recent United Nations Environment Program scientific assessment has shown that considerable uncertainty still exists about the possible impact of aircraft on the atmosphere. The AESA was designed to develop the body of scientific knowledge necessary for the evaluation of the impact of <span class="hlt">stratospheric</span> aircraft on the atmosphere. The first Program report presented the basic objectives and plans for AESA. This second report presents the status of the ongoing research as reported by the principal investigators at the second annual AESA Program meeting in May 1992: Laboratory studies are probing the mechanism responsible for many of the heterogeneous reactions that occur on <span class="hlt">stratospheric</span> particles. Understanding how the atmosphere redistributes aircraft exhaust is critical to our knowing where the perturbed air will go and for how long it will remain in the <span class="hlt">stratosphere</span>. The assessment of fleet effects is dependent on the ability to develop scenarios which correctly simulate fleet operations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890020521','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890020521"><span id="translatedtitle">Large-scale dynamics of the <span class="hlt">stratosphere</span> and mesosphere during the MAP/WINE campaign winter 1983 to 1984 in comparison with other winters</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Petzoldt, K.</p> <p>1989-01-01</p> <p>For the MAP/WINE winter temperature and wind measurements of rockets were combined with SSU radiances (<span class="hlt">Stratospheric</span> Sounder Unit onboard the NOAA satellites) and stratopause heights from the Solar Mesosphere Explorer (SME) to get a retrieved data set including all available information. By means of this data set a hemispheric geopotential height, temperature and geostrophic wind fields eddy transports for wave mean flow interaction and potential vorticity for the interpretation of nonlinear wave breaking could be computed. Wave reflection at critical lines was investigated with respect of <span class="hlt">stratospheric</span> <span class="hlt">warmings</span>. The meridional gradient of the potential vorticity and focusing of wave activity is compared with derived data from satellite observations during other winters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006epsc.conf..426C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006epsc.conf..426C"><span id="translatedtitle">Nitrogen compounds in Titan's <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>Coustenis, A.; Cirs Investigation Team</p> <p></p> <p>Titan's atmosphere is essentially composed of molecular nitrogen (N2). The chemistry between the two mother molecules (N2 and CH4) leads to the formation of a certain number of nitriles observed in Titan's <span class="hlt">stratosphere</span> as early as at the time of the Voyager 1 encounter in 1980. In the spectra taken by the Infrared Radiometer Interferometer Spectrometer (IRIS) the signatures of HCN, HC3N, C2N2 and C4N2 (in solid form) were found and reported. Subsequent observations from the ground better described the vertical profiles of these constituents and allowed for the detection of CH3CN (acetonitrile) in the mm range [3,4]. Recent data recorded by the Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft during the Titan flybys (October 2004 - June 2006) give a handle on the temporal and latitudinal variations of these constituents. The nadir spectra characterize various regions on Titan from 85S to 75N with a variety of emission angles. We study the emission observed in the mid-infrared CIRS detector arrays (covering roughly the 600-1500 cm-1 spectral range with apodized resolutions of 2.54 or 0.53 cm-1 ). The composite spectrum shows several molecular signatures of nitriles. Information is retrieved on the meridional variations of the trace constituents and tied to predictions by dynamical-photochemical models [1,2,5]. The nitriles show a significant enhancement at high northern latitudes albeit not as marked as at the time of the Voyager encounter. We will give a review of our current understanding of the minor nitrile chemistry on Titan. References : [1] Coustenis et al., 2006. Icarus, in press. [2] Flasar et al., 2005. Science 308, 975. [3] Marten, A., et al., 2002, Icarus, 158, 532-544. [4] Marten, A. & Moreno, R., 2003. 35th Annual DPS Meeting, Monterey, Ca, BAAS, 35, 952. [5] Teanby et al., 2006. Icarus, 181, 243-255.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ACPD...1418049K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ACPD...1418049K"><span id="translatedtitle">The impact of polar <span class="hlt">stratospheric</span> ozone loss on Southern Hemisphere <span class="hlt">stratospheric</span> circulation and climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keeble, J.; Braesicke, P.; Abraham, N. L.; Roscoe, H. K.; Pyle, J. A.</p> <p>2014-07-01</p> <p>The impact of polar <span class="hlt">stratospheric</span> ozone loss resulting from chlorine activation on polar <span class="hlt">stratospheric</span> clouds is examined using a pair of model integrations run with the fully coupled chemistry climate model UM-UKCA. Suppressing chlorine activation through heterogeneous reactions is found to produce modelled ozone differences consistent with observed ozone differences between the present and pre-ozone hole period. Statistically significant high latitude Southern Hemisphere (SH) ozone loss begins in August and peaks in October-November, with >75% of ozone destroyed at 50 hPa. Associated with this ozone destruction is a >12 K decrease of the lower polar <span class="hlt">stratospheric</span> temperatures and an increase of >6 K in the upper <span class="hlt">stratosphere</span>. The heating components of this temperature change are diagnosed and it is found that the temperature dipole is the result of decreased shortwave heating in the lower <span class="hlt">stratosphere</span> and increased dynamical heating in the upper <span class="hlt">stratosphere</span>. The cooling of the polar lower <span class="hlt">stratosphere</span> leads, through thermal wind balance, to an acceleration of the polar vortex and delays its breakdown by ~2 weeks. A link between lower <span class="hlt">stratospheric</span> zonal wind speed, the vertical component of the EP flux, Fz, and the residual mean vertical circulation, <span style="text-decoration: overline">w*, is identified. In December and January, increased westerly winds lead to increases in Fz, associated with an increase in tropopause height. The resulting increase in wavebreaking leads to enhanced downwelling/reduced upwelling over the polar cap. Many of the <span class="hlt">stratospheric</span> signals modelled in this study propagate down to the troposphere, and lead to significant surface changes in December.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012GeoRL..39.2806Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GeoRL..39.2806Z"><span id="translatedtitle">Importance of the upper-level <span class="hlt">warm</span> core in the rapid intensification of a tropical cyclone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Da-Lin; Chen, Hua</p> <p>2012-01-01</p> <p>In this study, the rapid intensification (RI) of tropical cyclone is examined using a 72-h cloud-permitting prediction of Hurricane Wilma (2005) with a record-breaking intensity of 882 hPa. Results show the formation of an upper-level <span class="hlt">warm</span> core from the descending air of <span class="hlt">stratospheric</span> origin in the eye, which coincides with the onset of RI; it reaches the peak amplitude of more than 18C from its initial conditions at the time of peak intensity. The descending air is associated with the detrainment of convective bursts in the eyewall, and it appears as (perturbation) cyclonic radial inflows above the upper outflow layer and causes the subsidence <span class="hlt">warming</span> below. We hypothesize that the upper divergent outflow layer favors the generation of a <span class="hlt">warm</span> core by protecting it from ventilation by environmental flows. Use of the hydrostatic equation shows that the <span class="hlt">warm</span> core of <span class="hlt">stratospheric</span> origin contributes more than twice as much as the lower-level <span class="hlt">warm</span> column to the pressure change at the peak intensity of Wilma. Results suggest that more attention be paid to the magnitude of storm-relative flows and vertical wind shear in the upper troposphere, rather than just vertical shear in the typical 850-200 hPa layer, in order to reasonably predict the RI of tropical cyclones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JCos...16.6677B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JCos...16.6677B"><span id="translatedtitle">Sources of particulates in the upper <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>Bigg, E. Keith</p> <p>2011-10-01</p> <p>The dominant forms of particles collected at altitudes of 39, 42 and 45km during three balloon flights over Australia were aggregates having components with diameters typically 40 to 50nm. Their partial electron transparency suggested an organic composition and all were accompanied by a volatile liquid that could be stabilised by reaction with a thin copper film. They closely resembled particles called "fluffy micrometeorites" collected earlier in the mesosphere from rockets and their properties were consistent with those of particles collected from a comet by a recent spacecraft experiment. Particles in the upper <span class="hlt">stratosphere</span> included some that resembled viruses and cocci, the latter being one of the organisms cultured from upper <span class="hlt">stratospheric</span> air in a recent experiment. A plausible source of the <span class="hlt">stratospheric</span>, mesospheric and cometary aggregates is consistent with the "panspermia" theory, that microorganisms present in space at the birth of the solar system could have reproduced in water within comets and brought life to Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950043435&hterms=Richard+bernard&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DRichard%2Bbernard','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950043435&hterms=Richard+bernard&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DRichard%2Bbernard"><span id="translatedtitle">Observations of lightning 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>Boeck, William L.; Vaughan, Otha H., Jr.; Blakeslee, Richard J.; Vonnegut, Bernard; Brook, Marx; Mckune, John</p> <p>1995-01-01</p> <p>An examination and analysis of video images of lightning, captured by the payload bay TV cameras of the space shuttle, provided a variety of examples of lightning in the <span class="hlt">stratosphere</span> above thunderstorms. These images were obtained on several recent shuttle flights while conducting the Mesoscale Lightning Experiment (MLE). The images of <span class="hlt">stratospheric</span> lightning illustrate the variety of filamentary and broad vertical discharges in the <span class="hlt">stratosphere</span> that may accompany a lightning flash. A typical event is imaged as a single or multiple filament extending 30 to 40 km above a thunderstorm that is illuminated by a series of lightning strokes. Examples are found in temperate and tropical areas, over the oceans, and over the land.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920009885','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920009885"><span id="translatedtitle">Lower <span class="hlt">Stratospheric</span> Measurement Issues Workshop Report</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schmeltekopf, Arthur L.</p> <p>1992-01-01</p> <p>The Lower <span class="hlt">Stratospheric</span> Measurement Issues workshop was held on 17-19 Oct. 1990. The 3-day workshop was sponsored by the Atmospheric Effects of <span class="hlt">Stratospheric</span> Aircraft (AESA) component of the High Speed Research Program (HSRP). Its purpose was to provide a scientific forum for addressing specific issues regarding chemistry and transport in the lower <span class="hlt">stratosphere</span>, for which measurements are essential to an assessment of the environmental impact of a projected fleet of high speed civil transports (HSCTs). The objective of the workshop was to obtain vigorous and critical review of the following topics: (1) atmospheric measurements needed for the assessment; (2) present capability for making those measurements; and (3) areas in instrumentation or platform development essential to making the measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930040393&hterms=Polar+Stratospheric+Cloud&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DPolar%2BStratospheric%2BCloud','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930040393&hterms=Polar+Stratospheric+Cloud&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DPolar%2BStratospheric%2BCloud"><span id="translatedtitle">Formation of model polar <span class="hlt">stratospheric</span> cloud films</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Middlebrook, Ann M.; Koehler, Birgit G.; Mcneill, Laurie S.; Tolbert, Margaret A.</p> <p>1992-01-01</p> <p>Fourier transform infrared spectroscopy was used to examine the competitive growth of films representative of polar <span class="hlt">stratospheric</span> clouds. These experiments show that either crystalline nitric acid trihydrate (beta-NAT) or amorphous films with H2O:HNO3 ratios close to 3:1 formed at temperatures 3-7 K warmer than the ice frost point under <span class="hlt">stratospheric</span> pressure conditions. In addition, with higher HNO3 pressure, we observed nitric acid dihydrate (NAD) formation at temperatures warmer than ice formation. However, our experiments also show that NAD surfaces converted to beta-NAT upon exposure to <span class="hlt">stratospheric</span> water pressures. Finally, we determined that the net uptake coefficient for HNO3 on beta-NAT is close to unity, whereas the net uptake coefficient for H2O is much less.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7065982','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7065982"><span id="translatedtitle">Formation of model polar <span class="hlt">stratospheric</span> cloud films</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Middlebrook, A.M.; Koehler, B.G.; McNeill, L.S.; Tolbert, M.A. )</p> <p>1992-12-24</p> <p>Fourier transform infrared spectroscopy was used to examine the competitve growth of films representative of polar <span class="hlt">stratospheric</span> clouds. These experiments show that either crystalline nitric acid trihydrate ([beta]-NAT) or amorphous films with H[sub 2]O:HNO[sub 3] ratios close to 3:1 formed at temperatures 3-7 K warmer than the ice frost point under <span class="hlt">stratospheric</span> pressure conditions. In addition, with higher HNO[sub 3] pressures the authors observed nitric acid dihydrate (NAD) formation at temperatures warmer than ice formation. However, their experiments also show that NAD surfaces converted to [beta]-NAT upon exposure to <span class="hlt">stratospheric</span> water pressures. Finally, the authors determined that the net uptake coefficient for HNO[sub 3] on [beta]-NAT is close to unity, whereas the net uptake coefficient for H[sub 2]O is much less. 13 refs., 4 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20060033954&hterms=engel&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%25EF%25BF%25BDengel','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20060033954&hterms=engel&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%25EF%25BF%25BDengel"><span id="translatedtitle">Measurements of Chlorine Partitioning in the Winter Arctic <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>Stachnik, R.; Salawitch, R.; Engel, A.; Schmidt, U.</p> <p>1999-01-01</p> <p>Under the extremely cold conditions in the polar winter <span class="hlt">stratosphere</span>, heterogeneous reactions involving HCl and CIONO(sub 2) on the surfaces of polar <span class="hlt">stratospheric</span> cloud particles can release large amounts of reactive chlorine from these reservoirs leading to rapid chemical loss of ozone in the Arctic lower <span class="hlt">stratosphere</span> during late winter and early spring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/121740','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/121740"><span id="translatedtitle">Modeling the effects of UV variability and the QBO on the troposphere-<span class="hlt">stratosphere</span> system. Part II: The troposphere</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rind, D.; Balachandran, N.K.</p> <p>1995-08-01</p> <p>Results of experiments with a GCM involving changes in UV input ({plus_minus} 25%, {plus_minus}5% at wavelengths below 0.3 {mu}) and simulated equatorial QBO are presented, with emphasis on the tropospheric response. The QBO and UV changes alter the temperature in the lower <span class="hlt">stratosphere</span>/upper troposphere <span class="hlt">warms</span>, tropospheric eddy energy is reduced, leading to extratropical tropospheric cooling of some 0.5{degrees}C on the zonal average, and surface temperature changes up to {plus_minus}5{degrees}C locally. Opposite effects occur when the extratropical lower <span class="hlt">stratosphere</span>/upper troposphere cools. Cooling or <span class="hlt">warming</span> of the comparable region in the Tropics decreases/increases static stability, accelerating/decelerating the Hadley circulation. Tropospheric dynamical changes are on the order of 5%. The combined UV/QBO effect in the troposphere results from its impact on the middle atmosphere; in the QBO east phase, more energy is refracted to higher latitudes, due to the increased horizontal shear of the zonal wind, but with increased UV, this energy propagates preferentially out of the polar lower <span class="hlt">stratosphere</span>, in response to the increased vertical shear of the zonal winds; therefore, it is less effective in <span class="hlt">warming</span> the polar lower <span class="hlt">stratosphere</span>. Due to their impacts on planetary wave generation and propagation, all combinations of UV and QBO phases affect the longitudinal patterns of tropospheric temperatures and geopotential heights. The modeled perturbations often agree qualitatively with observations and are of generally similar orders of magnitude. The results are sensitive to the forcing employed. In particular, the nature of the tropospheric response depends upon the magnitude (and presumably wavelength) of the solar irradiance perturbation. The results of the smaller UV variations ({plus_minus}5%) are more in agreement with observations, showing clear differences between the UV impact in the east and west QBO phase. 34 refs., 15 figs., 3 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990097312&hterms=information+retrieval&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dinformation%2Bretrieval','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990097312&hterms=information+retrieval&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dinformation%2Bretrieval"><span id="translatedtitle">Improved <span class="hlt">Stratospheric</span> Temperature Retrievals for Climate Reanalysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rokke, L.; Joiner, J.</p> <p>1999-01-01</p> <p>The Data Assimilation Office (DAO) is embarking on plans to generate a twenty year reanalysis data set of climatic atmospheric variables. One of the focus points will be in the evaluation of the dynamics of the <span class="hlt">stratosphere</span>. The <span class="hlt">Stratospheric</span> Sounding Unit (SSU), flown as part of the TIROS Operational Vertical Sounder (TOVS), is one of the primary <span class="hlt">stratospheric</span> temperature sensors flown consistently throughout the reanalysis period. Seven unique sensors made the measurements over time, with individual instrument characteristics that need to be addressed. The <span class="hlt">stratospheric</span> temperatures being assimilated across satellite platforms will profoundly impact the reanalysis dynamical fields. To attempt to quantify aspects of instrument and retrieval bias we are carefully collecting and analyzing all available information on the sensors, their instrument anomalies, forward model errors and retrieval biases. For the retrieval of <span class="hlt">stratospheric</span> temperatures, we adapted the minimum variance approach of Jazwinski (1970) and Rodgers (1976) and applied it to the SSU soundings. In our algorithm, the state vector contains an initial guess of temperature from a model six hour forecast provided by the Goddard EOS Data Assimilation System (GEOS/DAS). This is combined with an a priori covariance matrix, a forward model parameterization, and specifications of instrument noise characteristics. A quasi-Newtonian iteration is used to obtain convergence of the retrieved state to the measurement vector. This algorithm also enables us to analyze and address the systematic errors associated with the unique characteristics of the cell pressures on the individual SSU instruments and the resolving power of the instruments to vertical gradients in the <span class="hlt">stratosphere</span>. The preliminary results of the improved retrievals and their assimilation as well as baseline calculations of bias and rms error between the NESDIS operational product and col-located ground measurements will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1612671M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1612671M"><span id="translatedtitle">Is <span class="hlt">stratospheric</span> air getting younger with time?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Monge-Sanz, Beatriz; Chipperfield, Martyn; Dee, Dick; Simmons, Adrian; Stiller, Gabriele</p> <p>2014-05-01</p> <p>Most climate models have predicted that with the increase in greenhouse gases concentrations, the <span class="hlt">stratospheric</span> circulation will intensify, showing younger age-of-air (AoA) values in this region (e.g. Butchart et al., 2010; WMO, 2011). However, balloon and satellite observations do not agree with the widespread modelled trend towards younger age-of-air (Engel et al., 2009; Stiller et al., 2012). To increase our confidence in climate-chemistry projections, the causes for the apparent age-of-air disagreement between observations and most models need to be identified. Here we have carried out <span class="hlt">stratospheric</span> simulations with a chemistry transport mod