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Xiao Liu - One of the best experts on this subject based on the ideXlab platform.

  • Gravity wave variations in the polar stratosphere and Mesosphere from SOFIE/AIM temperature observations
    Journal of Geophysical Research: Atmospheres, 2014
    Co-Authors: Xiao Liu, James-m. Russell, Jia Yue, Ling Wang, Wei Yuan, Mark E. Hervig
    Abstract:

    A 6 year (2007-2013) temperature data set from the Solar Occultation for Ice Experiment (SOFIE) onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite is used to extract gravity waves (GWs) in the polar stratosphere and Mesosphere of both hemispheres. These data are continuous in the polar regions. The monthly mean GW potential energy (PE) increases exponentially with a scale height of similar to 13 km in the upper stratosphere and Mesosphere. GWs are stronger in the winter than in the summer and exhibit strong annual variation. GWs are stronger in the southern polar region (SPR) than in the northern polar region (NPR) except in the summer months. This is likely because there are stronger and longer-lasting zonal wind jets in the SPR stratosphere, as revealed from Modern-Era Retrospective analysis for Research and Applications (MERRA) wind data. The longitudinal variations of PE in the winter polar stratosphere are consistent with the elevated regions. In the Mesosphere, the longitudinal variations of PE do not vary with height significantly. The correlations between GW PE and the column ice water content (IWC, an indicator of the polar Mesosphere cloud) exhibit longitudinal and annual variations.

  • gravity wave variations in the polar stratosphere and Mesosphere from sofie aim temperature observations
    Journal of Geophysical Research, 2014
    Co-Authors: James-m. Russell, Xiao Liu, Jia Yue, Ling Wang, Wei Yuan, Mark E. Hervig
    Abstract:

    A 6 year (2007-2013) temperature data set from the Solar Occultation for Ice Experiment (SOFIE) onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite is used to extract gravity waves (GWs) in the polar stratosphere and Mesosphere of both hemispheres. These data are continuous in the polar regions. The monthly mean GW potential energy (PE) increases exponentially with a scale height of similar to 13 km in the upper stratosphere and Mesosphere. GWs are stronger in the winter than in the summer and exhibit strong annual variation. GWs are stronger in the southern polar region (SPR) than in the northern polar region (NPR) except in the summer months. This is likely because there are stronger and longer-lasting zonal wind jets in the SPR stratosphere, as revealed from Modern-Era Retrospective analysis for Research and Applications (MERRA) wind data. The longitudinal variations of PE in the winter polar stratosphere are consistent with the elevated regions. In the Mesosphere, the longitudinal variations of PE do not vary with height significantly. The correlations between GW PE and the column ice water content (IWC, an indicator of the polar Mesosphere cloud) exhibit longitudinal and annual variations.

Mark E. Hervig - One of the best experts on this subject based on the ideXlab platform.

  • Gravity wave variations in the polar stratosphere and Mesosphere from SOFIE/AIM temperature observations
    Journal of Geophysical Research: Atmospheres, 2014
    Co-Authors: Xiao Liu, James-m. Russell, Jia Yue, Ling Wang, Wei Yuan, Mark E. Hervig
    Abstract:

    A 6 year (2007-2013) temperature data set from the Solar Occultation for Ice Experiment (SOFIE) onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite is used to extract gravity waves (GWs) in the polar stratosphere and Mesosphere of both hemispheres. These data are continuous in the polar regions. The monthly mean GW potential energy (PE) increases exponentially with a scale height of similar to 13 km in the upper stratosphere and Mesosphere. GWs are stronger in the winter than in the summer and exhibit strong annual variation. GWs are stronger in the southern polar region (SPR) than in the northern polar region (NPR) except in the summer months. This is likely because there are stronger and longer-lasting zonal wind jets in the SPR stratosphere, as revealed from Modern-Era Retrospective analysis for Research and Applications (MERRA) wind data. The longitudinal variations of PE in the winter polar stratosphere are consistent with the elevated regions. In the Mesosphere, the longitudinal variations of PE do not vary with height significantly. The correlations between GW PE and the column ice water content (IWC, an indicator of the polar Mesosphere cloud) exhibit longitudinal and annual variations.

  • gravity wave variations in the polar stratosphere and Mesosphere from sofie aim temperature observations
    Journal of Geophysical Research, 2014
    Co-Authors: James-m. Russell, Xiao Liu, Jia Yue, Ling Wang, Wei Yuan, Mark E. Hervig
    Abstract:

    A 6 year (2007-2013) temperature data set from the Solar Occultation for Ice Experiment (SOFIE) onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite is used to extract gravity waves (GWs) in the polar stratosphere and Mesosphere of both hemispheres. These data are continuous in the polar regions. The monthly mean GW potential energy (PE) increases exponentially with a scale height of similar to 13 km in the upper stratosphere and Mesosphere. GWs are stronger in the winter than in the summer and exhibit strong annual variation. GWs are stronger in the southern polar region (SPR) than in the northern polar region (NPR) except in the summer months. This is likely because there are stronger and longer-lasting zonal wind jets in the SPR stratosphere, as revealed from Modern-Era Retrospective analysis for Research and Applications (MERRA) wind data. The longitudinal variations of PE in the winter polar stratosphere are consistent with the elevated regions. In the Mesosphere, the longitudinal variations of PE do not vary with height significantly. The correlations between GW PE and the column ice water content (IWC, an indicator of the polar Mesosphere cloud) exhibit longitudinal and annual variations.

Franz-josef Lübken - One of the best experts on this subject based on the ideXlab platform.

  • Temperature trends in the midlatitude summer Mesosphere
    Journal of Geophysical Research, 2013
    Co-Authors: Franz-josef Lübken, U. Berger, Gerd Baumgarten
    Abstract:

    [1] We have performed trend studies in the Mesosphere in the period 1961–2009 with Leibniz-Institute Middle Atmosphere (LIMA) model driven by European Centre for Medium-Range Weather Forecasts reanalysis below approximately 40 km and adapts temporal variations of CO2 and O3 according to observations. Temperatures in the Mesosphere/lower thermosphere vary nonuniformly with time, mainly due to the influence of O3. Here we analyze the contribution of varying concentrations of CO2 and O3 to the temperature trend in the Mesosphere. It is important to distinguish between trends on pressure altitudes, zp, and geometrical altitudes, zgeo, where the latter includes the effect of shrinking due to cooling at lower heights. For the period 1961–2009, temperature trends on geometrical and pressure altitudes can differ by as much as −0.9 K/dec in the Mesosphere. Temperature trends reach approximately −1.3±0.11 K/dec at zp∼60 km and −1.8±0.18 K/dec at zgeo∼70 km, respectively. CO2 is the main driver of these trends in the Mesosphere, whereas O3 contributes approximately one third, both on geometrical and pressure heights. Depending on the time period chosen, linear temperature trends can vary substantially. Altitudes of pressure levels in the Mesosphere decrease by up to several hundred meters. We have performed long-term runs with LIMA applying twentieth century reanalysis dating back to 1871. Again, trends are nonuniform with time. Since the late nineteenth century, temperatures in the Mesosphere have dropped by approximately 5–7 K on pressure altitudes and up to 10–12 K on geometrical altitudes.

  • In situ measurements of mesospheric turbulence during spring transition of the Arctic Mesosphere
    Geophysical Research Letters, 2002
    Co-Authors: A. Müllemann, Franz-josef Lübken, Markus Rapp, Peter Hoffmann
    Abstract:

    [1] The first in situ measurements of turbulence in the upper Arctic Mesosphere during the transition period from winter to summer were performed during the MIDAS/SPRING campaign in May 2000 from the Andoya Rocket Range in northern Norway (69°N). The ionization gauge CONE on board two sounding rockets identified height ranges with turbulent neutral density fluctuations which were used to determine turbulent energy dissipation rates. Accompanying in situ temperature measurements with falling spheres and remote wind measurements with a MF radar revealed the rapid seasonal change of the Mesosphere's thermal structure and large scale dynamics just during the campaign. Our in situ measurements give evidence of an equally rapid change of the turbulent structure of the Mesosphere within only ∼10 days. Models that take into account upward propagating gravity waves which break in the Mesosphere show reasonable agreement with our findings.

  • Thermal structure of the Arctic summer Mesosphere
    Journal of Geophysical Research, 1999
    Co-Authors: Franz-josef Lübken
    Abstract:

    In the last 10 years a total of 89 falling spheres (FS) have been launched at high latitudes (∼70°N) in the summer season between late April and late September. From this experimental technique, densities and temperatures in the Mesosphere and upper stratosphere (∼95–35 km) are deduced which represent nearly the entire data set regarding the thermal structure in the high-latitude summer Mesosphere where optical methods have problems to give reliable results because of the large solar photon background. Some of the launches took place at times in the season where no measurements have been performed before. The seasonal variation of the mean temperatures and densities derived from the FS measurements deviates significantly from the latest empirical models, in particular, in the upper Mesosphere during summer. For example, at the summer mesopause (88 km) the FS temperatures are lower by more than 10 K compared to CIRA-1986 in the time period from the beginning of June until the end of August. The thermal structure in the upper Mesosphere is rather persistent throughout the core summer months and changes rapidly in the winter-summer transition at mid-May, and vice versa at mid-August. For example, at typical noctilucent cloud altitudes (82 km) the mean temperature is in the range 153±3 K from the beginning of June until mid-August but changes by, typically, 5–10 K per week before and after this period. A comparison of the FS temperatures with the occurrence probability of noctilucent clouds and polar Mesosphere summer echoes suggests that the thermal structure is the main controlling factor for these layers, whereas other ingredients required to form aerosol particles, such as water vapor or condensation nuclei, are of secondary importance.

R G Roble - One of the best experts on this subject based on the ideXlab platform.

  • dynamical coupling of the stratosphere and Mesosphere in the 2002 southern hemisphere major stratospheric sudden warming
    Geophysical Research Letters, 2005
    Co-Authors: R G Roble
    Abstract:

    [1] NCEP data and a NCAR TIME-GCM simulation are used to explore the dynamical coupling of the stratosphere and Mesosphere during the 2002 Southern Hemisphere major stratospheric sudden warming. The analyses suggest the possibility of feedback interactions between the planetary wave forcing and the mesospheric/stratospheric mean state changes. Multiple strong planetary waves before the warming penetrate into the Mesosphere and weaken the polar jet. They alter the wave transmission condition in favor of more upward-poleward propagation of the wave energy at progressively lower altitudes. The jet reversal and the planetary wave surf zone also descend from the Mesosphere down to the stratosphere, making wave breaking more likely at decreasing altitudes with each wave episode. These changes in the wave transmission and breaking conditions in the Mesosphere and stratosphere may be critical for the extensive major stratospheric warming.

  • Review of mesospheric temperature trends
    Reviews of Geophysics, 2003
    Co-Authors: G. Beig, R G Roble, M. G. Mlynczak, Philippe Keckhut, Robert P. Lowe, J. Scheer, V. I. Fomichev, D. Offermann, W. J. R. French, M. G. Shepherd
    Abstract:

    In recent times it has become increasingly clear that releases of trace gases from human activity have a potential for causing change in the upper atmosphere. However, our knowledge of systematic changes and trends in the temperature of the Mesosphere and lower thermosphere is relatively limited compared to the Earths lower atmosphere, and not much effort has been made to synthesize these results so far. In this article, a comprehensive review of long-term trends in the temperature of the region from 50 to 100 km is made on the basis of the available up-to-date understanding of measurements and model calculations. An objective evaluation of the available data sets is attempted, and important uncertainly factors are discussed. Some natural variability factors, which are likely to play a role in modulating temperature trends, are also briefly touched upon. There are a growing number of experimental results centered on, or consistent with, zero temperature trend in the mesopause region (80–100 km). The most reliable data sets show no significant trend but an uncertainty of at least 2 K/decade. On the other hand, a majority of studies indicate negative trends in the lower and middle Mesosphere with an amplitude of a few degrees (2–3 K) per decade. In tropical latitudes the cooling trend increases in the upper Mesosphere. The most recent general circulation models indicate increased cooling closer to both poles in the middle Mesosphere and a decrease in cooling toward the summer pole in the upper Mesosphere. Quantitatively, the simulated cooling trend in the middle Mesosphere produced only by CO2 increase is usually below the observed level. However, including other greenhouse gases and taking into account a “thermal shrinking” of the upper atmosphere result in a cooling of a few degrees per decade. This is close to the lower limit of the observed nonzero trends. In the mesopause region, recent model simulations produce trends, usually below 1 K/decade, that appear to be consistent with most observations in this region

  • a study of a self generated stratospheric sudden warming and its mesospheric lower thermospheric impacts using the coupled time gcm ccm3
    Journal of Geophysical Research, 2002
    Co-Authors: R G Roble
    Abstract:

    [1] A stratospheric sudden warming episode was self-consistently generated in the coupled National Center for Atmospheric Research Thermosphere, Ionosphere, Mesosphere, and Electrodynamics General Circulation Model/Climate Community Model version 3 (TIME-GCM/CCM3). Taking advantage of the unique vertical range of the coupled model (ground to 500 km), we were able to study the coupling of the lower and upper atmosphere in this warming episode. Planetary wave 1 is the dominant wave component in this warming event. Analysis of the wave phase structure and the wave amplitude indicates that the wave may experience resonant amplification prior to the peak warming. The mean wind in the high-latitude winter stratopause and Mesosphere decelerates and reverses to westward due to planetary wave forcing and forms a critical layer near the zero wind lines. The wind deceleration and reversal also change the filtering of gravity waves by allowing more eastward gravity waves to propagate into the Mesosphere and lower thermosphere (MLT), which causes eastward forcing and reverses the westward jet in the MLT. This also changes the meridional circulation in the upper Mesosphere from poleward/downward to equatorward/upward, causing a depletion of the peak atomic oxygen layer at 97 km and significant reduction of green line airglow emission at high latitudes and midlatitudes. Planetary waves forced in situ by filtered gravity waves in the MLT grow in the warming episode. Their growth and interaction with tides create diurnal and semidiurnal variabilities in the zonal mean zonal wind.

James-m. Russell - One of the best experts on this subject based on the ideXlab platform.

  • Gravity wave variations in the polar stratosphere and Mesosphere from SOFIE/AIM temperature observations
    Journal of Geophysical Research: Atmospheres, 2014
    Co-Authors: Xiao Liu, James-m. Russell, Jia Yue, Ling Wang, Wei Yuan, Mark E. Hervig
    Abstract:

    A 6 year (2007-2013) temperature data set from the Solar Occultation for Ice Experiment (SOFIE) onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite is used to extract gravity waves (GWs) in the polar stratosphere and Mesosphere of both hemispheres. These data are continuous in the polar regions. The monthly mean GW potential energy (PE) increases exponentially with a scale height of similar to 13 km in the upper stratosphere and Mesosphere. GWs are stronger in the winter than in the summer and exhibit strong annual variation. GWs are stronger in the southern polar region (SPR) than in the northern polar region (NPR) except in the summer months. This is likely because there are stronger and longer-lasting zonal wind jets in the SPR stratosphere, as revealed from Modern-Era Retrospective analysis for Research and Applications (MERRA) wind data. The longitudinal variations of PE in the winter polar stratosphere are consistent with the elevated regions. In the Mesosphere, the longitudinal variations of PE do not vary with height significantly. The correlations between GW PE and the column ice water content (IWC, an indicator of the polar Mesosphere cloud) exhibit longitudinal and annual variations.

  • gravity wave variations in the polar stratosphere and Mesosphere from sofie aim temperature observations
    Journal of Geophysical Research, 2014
    Co-Authors: James-m. Russell, Xiao Liu, Jia Yue, Ling Wang, Wei Yuan, Mark E. Hervig
    Abstract:

    A 6 year (2007-2013) temperature data set from the Solar Occultation for Ice Experiment (SOFIE) onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite is used to extract gravity waves (GWs) in the polar stratosphere and Mesosphere of both hemispheres. These data are continuous in the polar regions. The monthly mean GW potential energy (PE) increases exponentially with a scale height of similar to 13 km in the upper stratosphere and Mesosphere. GWs are stronger in the winter than in the summer and exhibit strong annual variation. GWs are stronger in the southern polar region (SPR) than in the northern polar region (NPR) except in the summer months. This is likely because there are stronger and longer-lasting zonal wind jets in the SPR stratosphere, as revealed from Modern-Era Retrospective analysis for Research and Applications (MERRA) wind data. The longitudinal variations of PE in the winter polar stratosphere are consistent with the elevated regions. In the Mesosphere, the longitudinal variations of PE do not vary with height significantly. The correlations between GW PE and the column ice water content (IWC, an indicator of the polar Mesosphere cloud) exhibit longitudinal and annual variations.

  • Influence of El Niño‐Southern Oscillation in the Mesosphere
    Geophysical Research Letters, 2013
    Co-Authors: Natalia Calvo, James-m. Russell, Jia Yue, Xiankang Dou, M. G. Mlynczak, Chiao-yao She, Xianghui Xue
    Abstract:

    [1] Using the middle atmosphere temperature data set observed by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite experiment between 2002 and 2012, and temperatures simulated by the Whole Atmospheric Community Climate Model version 3.5 (WACCM3.5) between 1953 and 2005, we studied the influence of El Nino-Southern Oscillation (ENSO) on middle atmosphere temperature during the Northern Hemisphere (NH) wintertime. For the first time, a significant winter temperature response to ENSO in the middle Mesosphere has been observed, with an anomalous warming of ~1.0 K/MEI (Multivariate ENSO Index) in the tropics and an anomalous cooling of ~ −2.0 K/MEI in the NH middle latitudes. The observed temperature responses to ENSO in the Mesosphere are opposite to those in the stratosphere, in agreement with previous modeling studies. Temperature responses to ENSO observed by SABER show similar patterns to those simulated by the WACCM3.5 model. Analysis of the WACCM3.5 residual mean meridional circulation response to ENSO reveals a significant downwelling in the tropical Mesosphere and upwelling in the NH middle and high latitudes during warm ENSO events, which is mostly driven by anomalous eastward gravity wave forcing in the NH Mesosphere.

  • Large increase of NO2 in the north polar Mesosphere in January–February 2004: Evidence of a dynamical origin from GOMOS/ENVISAT and SABER/TIMED data
    Geophysical Research Letters, 2007
    Co-Authors: Alain Hauchecorne, E Kyrola, Jean-loup Bertaux, Francis Dalaudier, James-m. Russell, Martin-g. Mlynczak, Didier Fussen
    Abstract:

    Odd nitrogen species play an important role in the stratospheric ozone balance through catalytic ozone destruction. A layer of strongly enhanced NO2 was detected in the north polar Mesosphere by the GOMOS/ENVISAT stellar spectrometer in mid-January 2004. Large NO2 enhancements in the polar winter Mesosphere have been previously reported by several authors and have been attributed to NO production by solar proton or by energetic electron precipitations. The simultaneous occurrence of an intense mesospheric warming observed by the SABER/ TIMED instrument indicates that a strong air descent occurred in the polar region, transporting a large quantity of NO from the upper Mesosphere-lower thermosphere to the lower Mesosphere. The proposed mechanism may have a significant contribution to the budget of polar stratospheric ozone.

  • large increase of no2 in the north polar Mesosphere in january february 2004 evidence of a dynamical origin from gomos envisat and saber timed data
    Geophysical Research Letters, 2007
    Co-Authors: Alain Hauchecorne, E Kyrola, Jean-loup Bertaux, Francis Dalaudier, James-m. Russell, Martin-g. Mlynczak, Didier Fussen
    Abstract:

    [1] Odd nitrogen species play an important role in the stratospheric ozone balance through catalytic ozone destruction. A layer of strongly enhanced NO2 was detected in the north polar Mesosphere by the GOMOS/ENVISAT stellar spectrometer in mid-January 2004. Large NO2 enhancements in the polar winter Mesosphere have been previously reported by several authors and have been attributed to NO production by solar proton or by energetic electron precipitations. The simultaneous occurrence of an intense mesospheric warming observed by the SABER/TIMED instrument indicates that a strong air descent occurred in the polar region, transporting a large quantity of NO from the upper Mesosphere-lower thermosphere to the lower Mesosphere. The proposed mechanism may have a significant contribution to the budget of polar stratospheric ozone.