Rapid Convective Transport of Tropospheric Air into the Tropical Lower Stratosphere during the 2010 Sudden Stratospheric Warming

Abstract. During September 2019 there was a sudden stratospheric warming over Antarctica, which brought disruption to the usually stable winter vortex. The mesospheric winds reversed and temperatures in the stratosphere rose by over 50 K. Whilst this was only the second SSW in the Southern Hemisphere (SH), the other having occurred in 2002, its Northern counterpart experiences about six per decade. Currently, an amplification of atmospheric waves during winter is thought to trigger SSWs. However, our understanding remains incomplete, especially in regards to its occurrence in the SH. Here, we investigate the interaction of two equatorial atmospheric modes, the Quasi Biennial Oscillation (QBO) and the Semiannual Oscillation (SAO) during the SH winters of 2019 and 2002. Using MERRA-2 reanalysis data we find that the two modes interact at low latitudes during their easterly phases in the early winter, forming a zero wind line that stretches from the lower stratosphere into the mesosphere. This influences the meridional wave guide, resulting in easterly momentum being deposited in the mesosphere throughout the polar winter, reducing the magnitude of the westerly winds. As the winter progresses these features descend into the stratosphere, until SSW conditions are reached. We find similar behaviour in two other years leading to delayed dynamical disruptions later in the spring. The timing and magnitude of the SAO and the extent of the upper stratospheric easterly QBO signal, that results in the SAO-QBO interaction, was found to be unique in these years, when compared to the years with a similar QBO phase. We propose that this early winter behaviour may be a key physical process in decelerating the mesospheric winds which may precondition the Southern atmosphere for a SSW. Thus the early winter equatorial upper stratosphere-mesosphere together with the polar mesosphere may provide critical early clues to an imminent SH SSW.

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SAO-QBO Coupling before the 2019 and 2002 Southern Sudden Stratospheric Warmings

10.5194/egusphere-egu21-9318 ◽

2021 ◽

Author(s):

Viktoria Nordström ◽

Annika Seppälä

Keyword(s):

Lower Stratosphere ◽

Reanalysis Data ◽

Stratospheric Warming ◽

Early Winter ◽

Sudden Stratospheric Warming ◽

Quasi Biennial Oscillation ◽

Westerly Winds ◽

Low Latitudes ◽

Biennial Oscillation ◽

Semiannual Oscillation

During September 2019 there was a sudden stratospheric warming over Antarctica, which brought disruption to the usually stable winter vortex. The mesospheric winds reversed and temperatures in the stratosphere rose by over 50~K. Whilst this was only the second SSW in the Southern Hemisphere (SH), the other having occurred in 2002, its Northern counterpart experiences about six per decade. Currently, an amplification of atmospheric waves during winter is thought to trigger SSWs. Our understanding, however, remains incomplete, especially with regards to its occurrence in the SH.&#160;Here, we investigate the interaction of two equatorial atmospheric modes, the Quasi Biennial Oscillation (QBO) and the Semiannual Oscillation (SAO) during the SH winters of 2019 and 2002. Using MERRA-2 reanalysis data we find that the two modes interact at low latitudes during their easterly phases in the early winter, forming a zero wind line that stretches from the lower stratosphere into the mesosphere. This influences the meridional wave guide, resulting in easterly momentum being deposited in the mesosphere throughout the polar winter, reducing the magnitude of the westerly winds. As the winter progresses these features descend into the stratosphere, until SSW conditions are reached. We find similar behaviour in two other years leading to delayed dynamical disruptions later in the spring. The timing and magnitude of the SAO and the extent of the upper stratospheric easterly QBO signal, that results in the SAO-QBO interaction, was found to be unique in these years, when compared to the years with a similar QBO phase.&#160;We propose that this early winter behaviour may be a key physical process in decelerating the mesospheric winds which may precondition the Southern atmosphere for a SSW. Thus the early winter equatorial upper stratosphere-mesosphere together with the polar mesosphere may provide critical early clues to an imminent SH SSW.

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

10.5194/wcd-2019-7 ◽

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.

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A comparison of the momentum budget in reanalysis datasets during sudden stratospheric warming events

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-7169-2018 ◽

2018 ◽

Vol 18 (10) ◽

pp. 7169-7187 ◽

Cited By ~ 7

Author(s):

Patrick Martineau ◽

Seok-Woo Son ◽

Masakazu Taguchi ◽

Amy H. Butler

Keyword(s):

Zonal Wind ◽

Lower Stratosphere ◽

Momentum Equation ◽

Lower Atmosphere ◽

Stratospheric Warming ◽

Sudden Stratospheric Warming ◽

Planetary Scale ◽

Momentum Budget ◽

Stratospheric Circulation ◽

Good Agreement

Abstract. The agreement between reanalysis datasets, in terms of the zonal-mean momentum budget, is evaluated during sudden stratospheric warming (SSW) events. It is revealed that there is a good agreement among datasets in the lower stratosphere and troposphere concerning zonal-mean zonal wind, but less so in the upper stratosphere. Forcing terms of the momentum equation are also relatively similar in the lower atmosphere, but their uncertainties are typically larger than uncertainties of the zonal-wind tendency. Similar to zonal-wind tendency, the agreement among forcing terms is degraded in the upper stratosphere. Discrepancies among reanalyses increase during the onset of SSW events, a period characterized by unusually large fluxes of planetary-scale waves from the troposphere to the stratosphere, and decrease substantially after the onset. While the largest uncertainties in the resolved terms of the momentum budget are found in the Coriolis torque, momentum flux convergence also presents a non-negligible spread among the reanalyses. Such a spread is reduced in the latest reanalysis products, decreasing the uncertainty of the momentum budget. It is also found that the uncertainties in the Coriolis torque depend on the strength of SSW events: the SSW events that exhibit the most intense deceleration of zonal-mean zonal wind are subject to larger discrepancies among reanalyses. These uncertainties in stratospheric circulation, however, are not communicated to the troposphere.

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Middle atmospheric water vapor and ozone anomalies during the 2010 major sudden stratospheric warming

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-32391-2011 ◽

2011 ◽

Vol 11 (12) ◽

pp. 32391-32422 ◽

Cited By ~ 1

Author(s):

D. Scheiben ◽

C. Straub ◽

K. Hocke ◽

P. Forkman ◽

N. Kämpfer

Keyword(s):

Water Vapor ◽

Lower Stratosphere ◽

Stratospheric Ozone ◽

Polar Vortex ◽

Atmospheric Water Vapor ◽

High Latitudes ◽

Stratospheric Warming ◽

Atmospheric Water ◽

Sudden Stratospheric Warming ◽

Stratospheric Water Vapor

Abstract. A major sudden stratospheric warming (SSW) occurred in the Northern Hemisphere in January 2010. The warming started on 26 January 2010, was most pronounced by the end of January and was accompanied by a polar vortex shift towards Europe. After the warming, the polar vortex split into two weaker vortices. The zonal mean temperature in the polar upper stratosphere (35–45 km) increased by approximately 25 K in a few days, while there was a decrease in temperature in the lower stratosphere and mesosphere. Local temperature maxima were around 325 K in the upper stratosphere and minima around 175 and 155 K in the lower stratosphere and mesosphere, respectively. In this study, we present middle atmospheric water vapor and ozone measurements obtained by a meridional chain of European ground-based microwave radiometers in Bern (47° N), Onsala (57° N) and Sodankylä (67° N). The instruments in Bern and Onsala are part of the Network for the Detection of Atmospheric Composition Change (NDACC). Effects of the SSW were observed at all three locations and we perform a combined analysis in order to reveal transport processes in the middle atmosphere above Europe during the SSW event. Further we investigate the chemical and dynamical influences of the SSW event. We find that the anomalies during the warming in water vapor and ozone were different for each location. A few days before the beginning of the major SSW, we observed a decrease in mesospheric water vapor above Bern, which we attribute to movement of the mesospheric polar vortex towards Central Europe. The most prominent H2O anomaly observed in Bern was an increase in stratospheric water vapor during the warming. In Onsala and Sodankylä, mesospheric water vapor increased within a few days during the warming and slowly decreased afterwards. Upper stratospheric ozone decreased during the warming over Bern by approximately 30% and by approximately 20% over Onsala. Over Sodankylä, a decrease in ozone below 30 km altitude was observed. This decrease is assumed to be caused by heterogeneous chemistry on polar stratospheric clouds. After the SSW, stratospheric ozone increased to higher levels than before at all three locations. The observed anomalies are explained by a trajectory analysis with reanalysis data from the European Center for Medium-Range Weather Forecasts (ECMWF). Most of the observed anomalies in water vapor and ozone during the warming are attributed to the location of the polar vortex, depending on whether a measurement site was inside or outside the polar vortex. The observed increase in mesospheric water vapor at high latitudes is explained by advection of relatively moist air from lower latitudes, whereas the observed increase in stratospheric water vapor at midlatitudes is explained by advection from high latitudes, i.e. from the moist stratospheric polar vortex.

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Evaluation of Antarctic Ozone Profiles derived from OMPS-LP by using Balloon-borne Ozonesondes

Scientific Reports ◽

10.1038/s41598-021-81954-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Edgardo Sepúlveda ◽

Raul R. Cordero ◽

Alessandro Damiani ◽

Sarah Feron ◽

Jaime Pizarro ◽

...

Keyword(s):

Radiative Forcing ◽

Lower Stratosphere ◽

Stratospheric Ozone ◽

Mean Bias Error ◽

Bias Error ◽

Mean Square ◽

Stratospheric Warming ◽

Sudden Stratospheric Warming ◽

Antarctic Ozone ◽

The Mean

AbstractPredicting radiative forcing due to Antarctic stratospheric ozone recovery requires detecting changes in the ozone vertical distribution. In this endeavor, the Limb Profiler of the Ozone Mapping and Profiler Suite (OMPS-LP), aboard the Suomi NPP satellite, has played a key role providing ozone profiles over Antarctica since 2011. Here, we compare ozone profiles derived from OMPS-LP data (version 2.5 algorithm) with balloon-borne ozonesondes launched from 8 Antarctic stations over the period 2012–2020. Comparisons focus on the layer from 12.5 to 27.5 km and include ozone profiles retrieved during the Sudden Stratospheric Warming (SSW) event registered in Spring 2019. We found that, over the period December-January–February-March, the root mean square error (RMSE) tends to be larger (about 20%) in the lower stratosphere (12.5–17.5 km) and smaller (about 10%) within higher layers (17.5–27.5 km). During the ozone hole season (September–October–November), RMSE values rise up to 40% within the layer from 12.5 to 22 km. Nevertheless, relative to balloon-borne measurements, the mean bias error of OMPS-derived Antarctic ozone profiles is generally lower than 0.3 ppmv, regardless of the season.

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How turbulent mountain stress influences sudden stratospheric warming ocurrence in WACCM

10.5194/egusphere-egu2020-10766 ◽

2020 ◽

Author(s):

Froila M. Palmeiro ◽

Rolando R. Garcia ◽

Natalia Calvo ◽

David Barriopedro ◽

Bernat Jiménez-Esteve

Keyword(s):

Lower Stratosphere ◽

Climate Model ◽

Polar Vortex ◽

Wave Drag ◽

Late Winter ◽

Stratospheric Warming ◽

Sudden Stratospheric Warming ◽

Subtropical Jet ◽

Vertical Propagation ◽

Stress Influences

The implementation of the Turbulent Mountain Stress (TMS) parametrization in the Whole Atmospheric Community Climate Model (WACCM) is found to be critical to obtain a realistic Sudden Stratospheric Warming (SSW) frequency in the Northern Hemisphere. Comparing two 50-year simluations, one with TMS (TMS-on) and one without (TMS-o&#64256;) reveals lower than observed SSW frequency in TMS-o&#64256; from December to February, while in March both simulations show SSW frequencies comparable to reanalysis. Meridional eddy heat &#64258;uxes in the lower stratosphere are stronger in TMS-on than in TMS-o&#64256;, except in March. These di&#64256;erences are accompanied by increased orographic gravity wave drag (OGWD) in TMS-o&#64256; that comes mainly from the Himalayas and the Rocky Mountains in response to stronger surface winds. Two di&#64256;erent mechanisms of how planetary and GWs interact are identi&#64257;ed in the simulations. In the lower stratosphere, enhanced dissipation of GWs in TMS-o&#64256; modi&#64257;es the subtropical jet and thus the conditions for refraction of planetary waves. In early winter, wave geometry diagnostics shows waveguides formation from 55N to 75N in TMS-on, enhancing wave propagation to the polar vortex. On the contrary, vertical propagation in TMS-off is in inhibited above the lower stratosphere and confined to latitudes south of 50N. Compensation between resolved and parametrized GWs is also observed, leading to weaker Eliassen-Palm &#64258;ux divergence in response to stronger OGWD in TMS-o&#64256;. In late winter, conditions for propagation are similar in both simulations by late winter, which explains the reduced TMS-o&#64256; bias in the frequency of March SSWs.

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A comparison of the momentum budget in reanalysis datasets during sudden stratospheric warming events

10.5194/acp-2017-837 ◽

2017 ◽

Author(s):

Patrick Martineau ◽

Seok-Woo Son ◽

Masakazu Taguchi ◽

Amy H. Butler

Keyword(s):

Zonal Wind ◽

Lower Stratosphere ◽

Momentum Equation ◽

Lower Atmosphere ◽

Stratospheric Warming ◽

Sudden Stratospheric Warming ◽

Planetary Scale ◽

Momentum Budget ◽

Stratospheric Circulation ◽

Good Agreement

Abstract. The agreement between reanalysis datasets, in terms of the zonal-mean momentum budget, is evaluated during sudden stratospheric warming (SSW) events. It is revealed that there is a good agreement among datasets in the lower stratosphere and troposphere concerning zonal-mean zonal wind, but less so in the upper stratosphere. Forcing terms of the momentum equation are also relatively similar in the lower atmosphere, but their uncertainties are typically larger than uncertainties of the zonal wind tendency. Similar to zonal wind tendency, the agreement among forcing terms is degraded in the upper stratosphere. Discrepancies among reanalyses increase during the onset of SSW events, a period characterized by unusually large fluxes of planetary-scale waves from the troposphere to the stratosphere, and decrease substantially after the onset. While the largest uncertainties in the momentum budget originate from the Coriolis torque, momentum flux convergence also presents a non-negligible spread among the reanalyses. Such a spread is reduced in the latest reanalysis products, decreasing the uncertainty of the momentum budget. It is also found that the uncertainties of the momentum budget depend on the strength of SSW events: the strongest SSWs being subject to larger discrepancies among reanalyses. These uncertainties in stratospheric circulation, however, are not communicated to the troposphere.

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

Weather and Climate Dynamics ◽

10.5194/wcd-1-93-2020 ◽

2020 ◽

Vol 1 (1) ◽

pp. 93-109 ◽

Cited By ~ 1

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.

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Features of the stratospheric circulation dynamics due to the January 2009 sudden stratospheric warming

Оптика атмосферы и океана ◽

10.15372/aoo20170408 ◽

2017 ◽

Keyword(s):

Stratospheric Warming ◽

Sudden Stratospheric Warming ◽

Stratospheric Circulation ◽

Circulation Dynamics

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