scholarly journals Observations of gravity wave forcing of the mesopause region during the January 2013 major Sudden Stratospheric Warming

2014 ◽  
Vol 41 (13) ◽  
pp. 4745-4752 ◽  
Author(s):  
R. J. Wit ◽  
R. E. Hibbins ◽  
P. J. Espy ◽  
Y. J. Orsolini ◽  
V. Limpasuvan ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Mesopause Region ◽  
Wave Forcing

scholarly journals Coupling in the middle atmosphere related to the 2013 major sudden stratospheric warming

2015 ◽  
Vol 33 (3) ◽  
pp. 309-319 ◽  
Author(s):  
R. J. de Wit ◽  
R. E. Hibbins ◽  
P. J. Espy ◽  
E. A. Hennum
Keyword(s):  
Gravity Wave ◽  
Global Perspective ◽  
Coupling Mechanism ◽  
Temperature Structure ◽  
Stratospheric Warming ◽  
Mean Flow ◽  
Sudden Stratospheric Warming ◽  
High Northern Latitude ◽  
Wave Forcing ◽  
Summer Hemisphere

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

scholarly journals Optimizing the Definition of a Sudden Stratospheric Warming

2018 ◽  
Vol 31 (6) ◽  
pp. 2337-2344 ◽  
Author(s):  
Amy H. Butler ◽  
Edwin P. Gerber
Keyword(s):  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Systematic Analysis ◽  
Wave Forcing ◽  
Zonal Winds ◽  
Stratospheric Temperature ◽  
Stratospheric Wind ◽  
Definition Of ◽  
Access To Data ◽  
The Continuum

Various criteria exist for determining the occurrence of a major sudden stratospheric warming (SSW), but the most common is based on the reversal of the climatological westerly zonal-mean zonal winds at 60° latitude and 10 hPa in the winter stratosphere. This definition was established at a time when observations of the stratosphere were sparse. Given greater access to data in the satellite era, a systematic analysis of the optimal parameters of latitude, altitude, and threshold for the wind reversal is now possible. Here, the frequency of SSWs, the strength of the wave forcing associated with the events, changes in stratospheric temperature and zonal winds, and surface impacts are examined as a function of the stratospheric wind reversal parameters. The results provide a methodical assessment of how to best define a standard metric for major SSWs. While the continuum nature of stratospheric variability makes it difficult to identify a decisively optimal threshold, there is a relatively narrow envelope of thresholds that work well—and the original focus at 60° latitude and 10 hPa lies within this window.

scholarly journals Strengthening of the Tropopause Inversion Layer during the 2009 Sudden Stratospheric Warming: A MERRA-2 Study

2016 ◽  
Vol 73 (5) ◽  
pp. 1871-1887 ◽  
Author(s):  
Krzysztof Wargan ◽  
Lawrence Coy
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Inversion Layer ◽  
Vertical Component ◽  
Circulation Model ◽  
Static Stability ◽  
Stratospheric Warming ◽  
Residual Circulation ◽  
Sudden Stratospheric Warming ◽  
Wave Forcing

Abstract The behavior of the tropopause inversion layer (TIL) during the 2009 sudden stratospheric warming (SSW) is analyzed using NASA’s Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), and short-term simulations with the MERRA-2 general circulation model. Consistent with previous studies, it is found that static stability in a shallow layer above the polar tropopause sharply increases following the SSW, leading to a strengthening of the high-latitude TIL. Simultaneously, the height of the thermal tropopause decreases by around 1 km. Similar behavior is also detected during other major SSW events between the years 2004 and 2013. Using an ensemble of general circulation model forecasts initialized from MERRA-2, it is demonstrated that the primary cause of the strengthening of the TIL is an increased convergence of the vertical component of the stratospheric residual circulation in response to an SSW-induced acceleration of the mean downward motion between 75° and 90°N. In addition, ~6% of the strengthening in 2009 is attributed to an enhanced anticyclonic circulation at the tropopause. A preliminary analysis indicates that during other recent SSW events there was a significant increase in the convergence of the vertical residual wind velocity throughout the middle and lower stratosphere. The static stability increase simulated by the model during the 2009 SSW is 60%–80% of that seen in MERRA-2. The underestimate is traced back to a tendency for the forecasts to underestimate the resolved planetary wave forcing on the stratosphere compared to the reanalysis.

scholarly journals The Role of Eddy-Eddy Interactions in Sudden Stratospheric Warming Formation

2019 ◽  
Author(s):  
Erik Anders Lindgren ◽  
Aditi Sheshadri
Keyword(s):  
General Circulation ◽  
Lower Stratosphere ◽  
Circulation Model ◽  
Wave Number ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Wave Forcing ◽  
Wave Numbers ◽  
Tropospheric Heating ◽  
Wave Flux

Abstract. The effects of eddy-eddy interactions on sudden stratospheric warming formation are investigated using an idealized atmospheric general circulation model, in which tropospheric heating perturbations of zonal wave numbers 1 and 2 are used to produce planetary scale wave activity. Eddy-eddy interactions are removed at different vertical extents of the atmosphere in order to examine the sensitivity of stratospheric circulation to local changes in eddy-eddy interactions. We show that the effects of eddy-eddy interactions on sudden warming formation, including sudden warming frequencies, are strongly dependent on the wave number of the tropospheric forcing and the vertical levels where eddy-eddy interactions are removed. Significant changes in sudden warming frequencies are evident when eddy-eddy interactions are removed even when the lower stratospheric wave forcing does not change, highlighting the fact that the upper stratosphere is not a passive recipient of wave forcing from below. We find that while eddy-eddy interactions are required in the troposphere and lower stratosphere to produce displacements when wave number 2 heating is used, both splits and displacements can be produced without eddy-eddy interactions in the troposphere and lower stratosphere when the model is forced by wave number 1 heating. We suggest that the relative strengths of wave numbers 1 and 2 vertical wave flux entering the stratosphere largely determine the split and displacement ratios when wave number 2 forcing is used, but not wave number 1.

scholarly journals Mid-Latitude Mesospheric Zonal Wave 1 and Wave 2 in Winter 2020–2021

2021 ◽  
Author(s):  
Yu Shi ◽  
Oleksandr Evtushevsky ◽  
Valerii Shulga ◽  
Gennadi Milinevsky ◽  
Andrew Klekociuk ◽  
...  
Keyword(s):  
Wavelet Analysis ◽  
Confidence Level ◽  
Geopotential Height ◽  
Time Lag ◽  
Planetary Waves ◽  
Stratospheric Warming ◽  
Altitude Range ◽  
Sudden Stratospheric Warming ◽  
Mesopause Region ◽  
Wave Numbers

Planetary waves in the mesosphere are studied using observational data and models to establish their origin, as there are indications of their generation independently of waves in the stratosphere. The quantitative relationships between zonal wave numbers m = 1 (wave 1) and m = 2 (wave 2) were studied with a focus on the mid-latitude mesosphere at 50N latitude. Aura Microwave Limb Sounder measurements were used to estimate wave amplitudes in geopotential height during the 2020–2021 winter major sudden stratospheric warming. The moving correlation between the wave amplitudes shows that, in comparison with the anticorrelation in the stratosphere, wave 2 positively correlates with wave 1 and propagates ahead of it in the mesosphere. A positive correlation r = 0.5–0.6, statistically significant at the 95% confidence level, is observed at 1–5-day time lag and in the 75–91 km altitude range, which is the upper mesosphere–mesopause region. Wavelet analysis shows a clear 8-day period in waves 1 and 2 in the mesosphere at 0.01 hPa (80 km), while in the stratosphere–lower mesosphere the period is twice as long at 16-days; this is statistically significant only in wave 2. Possible sources of mesospheric planetary waves are discussed.

scholarly journals The role of wave–wave interactions in sudden stratospheric warming formation

2020 ◽  
Vol 1 (1) ◽  
pp. 93-109 ◽  
Author(s):  
Erik A. Lindgren ◽  
Aditi Sheshadri
Keyword(s):  
General Circulation ◽  
Lower Stratosphere ◽  
Circulation Model ◽  
Wave Number ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Wave Interactions ◽  
Wave Forcing ◽  
Tropospheric Heating ◽  
Wave Flux

Abstract. The effects of wave–wave interactions on sudden stratospheric warming formation are investigated using an idealized atmospheric general circulation model, in which tropospheric heating perturbations of zonal wave numbers 1 and 2 are used to produce planetary-scale wave activity. Zonal wave–wave interactions are removed at different vertical extents of the atmosphere in order to examine the sensitivity of stratospheric circulation to local changes in wave–wave interactions. We show that the effects of wave–wave interactions on sudden warming formation, including sudden warming frequencies, are strongly dependent on the wave number of the tropospheric forcing and the vertical levels where wave–wave interactions are removed. Significant changes in sudden warming frequencies are evident when wave–wave interactions are removed even when the lower-stratospheric wave forcing does not change, highlighting the fact that the upper stratosphere is not a passive recipient of wave forcing from below. We find that while wave–wave interactions are required in the troposphere and lower stratosphere to produce displacements when wave number 2 heating is used, both splits and displacements can be produced without wave–wave interactions in the troposphere and lower stratosphere when the model is forced by wave number 1 heating. We suggest that the relative strengths of wave number 1 and 2 vertical wave flux entering the stratosphere largely determine the split and displacement ratios when wave number 2 forcing is used but not wave number 1.

Wind and temperature response of midlatitude mesopause region to the 2009 Sudden Stratospheric Warming

2012 ◽  
Vol 117 (D9) ◽  
pp. n/a-n/a ◽  
Author(s):  
Tao Yuan ◽  
B. Thurairajah ◽  
C.-Y. She ◽  
A. Chandran ◽  
R. L. Collins ◽  
...  
Keyword(s):  
Temperature Response ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Mesopause Region
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