scholarly journals Wind variations in the mesosphere and lower thermosphere near 60°S latitude during the 2019 Antarctic sudden stratospheric warming

2021 ◽  
Author(s):  
Guiping Liu ◽  
Diego Janches ◽  
Ruth S. Lieberman ◽  
Tracy Moffat‐Griffin ◽  
Nicholas J. Mitchell ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Mesosphere And Lower Thermosphere

Effect of Semidiurnal Lunar Tides Modulated by Quasi-2-Day Wave on Equatorial Electrojet during Three Sudden Stratospheric Warming events

2021 ◽  
Author(s):  
Yaxian Li ◽  
Gang Chen
Keyword(s):  
Lower Thermosphere ◽  
Equatorial Electrojet ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Zonal Winds ◽  
Wave Characteristics ◽  
Lunar Tides ◽  
Time Period ◽  
Mesosphere And Lower Thermosphere ◽  
Good Agreement

<p>We present an analysis of the perturbations and wave characteristics in equatorial electrojet (EEJ) and equatorial zonal winds in the mesosphere and lower thermosphere region during three sudden stratospheric warming (SSW) events, based on the wind observations by two meteor radars in Indonesia and the geomagnetic field observations in India. During three SSWs, the shifting semidiurnal perturbations are consistently observed in the EEJ and accompanied with strong 2-day periodic perturbations simultaneously. The semidiurnal lunar (L2) tidal amplitudes in the EEJ and zonal winds show the prominent enhancements during the episodes of EEJ perturbations. The time-period spectra of the L2 tidal amplitudes in both the EEJ and zonal winds present the obvious quasi-2-day wave (QTDW) amplification with good agreement during these periods. Our results firstly reveal the important contributions of QTDW to EEJ perturbations during SSWs and the semidiurnal lunar tides modulated by QTDW serve as the main forcing agent therein</p>

scholarly journals Climatologies and long-term changes of mesospheric wind and wave measurements based on radar observations at high and mid-latitudes

2019 ◽  
Author(s):  
Sven Wilhelm ◽  
Gunter Stober ◽  
Peter Brown
Keyword(s):  
Kinetic Energy ◽  
Gravity Waves ◽  
Lower Thermosphere ◽  
Stratospheric Warming ◽  
Atmospheric Parameters ◽  
Sudden Stratospheric Warming ◽  
Wave Measurements ◽  
South West ◽  
Mesosphere And Lower Thermosphere

Abstract. We report long-term observations of atmospheric parameters in the mesosphere and lower thermosphere (MLT) made over the last two decades. Within this study, we show based on meteor wind measurement, the long-term variability of winds, tides, and kinetic energy of planetary and gravity waves. These measurements were done between the years 2002 and 2018 for the high latitude location of Andenes (69.3° N, 16° E) and the mid-latitude locations of Juliusruh (54.6° N, 13.4° E) and Tavistock (43.3° N, 80.8° W). While the climatologies for each location show a similar pattern, the locations differ strongly with respect to altitude and season of several parameters. Our results show annual wind tendencies for Andenes which are toward the south-west, with changes of up to 3 m/s per decade, while the mid-latitude locations showing smaller opposite tendencies to negligible changes. The diurnal and semidiurnal tides also show different results for each location. Furthermore, the kinetic energy for planetary waves showed strong peak values during winters which also featured the occurrence of sudden stratospheric warming. The influence of the 11-year solar cycle on the winds and tides is presented.

scholarly journals Identification of the mechanisms responsible for anomalies in the tropical lower thermosphere/ionosphere caused by the January 2009 sudden stratospheric warming

2019 ◽  
Vol 9 ◽  
pp. A39 ◽  
Author(s):  
Maxim V. Klimenko ◽  
Vladimir V. Klimenko ◽  
Fedor S. Bessarab ◽  
Timofei V. Sukhodolov ◽  
Pavel A. Vasilev ◽  
...  
Keyword(s):  
Electric Field ◽  
Phase Change ◽  
Lower Thermosphere ◽  
Upper Atmosphere ◽  
Electron Content ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Low Latitude ◽  
Plasma Drift ◽  
Solar Tide

We apply the Entire Atmosphere GLobal (EAGLE) model to investigate the upper atmosphere response to the January 2009 sudden stratospheric warming (SSW) event. The model successfully reproduces neutral temperature and total electron content (TEC) observations. Using both model and observational data, we identify a cooling in the tropical lower thermosphere caused by the SSW. This cooling affects the zonal electric field close to the equator, leading to an enhanced vertical plasma drift. We demonstrate that along with a SSW-related wind disturbance, which is the main source to form a dynamo electric field in the ionosphere, perturbations of the ionospheric conductivity also make a significant contribution to the formation of the electric field response to SSW. The post-sunset TEC enhancement and pre-sunrise electron content reduction are revealed as a response to the 2009 SSW. We show that at post-sunset hours the SSW affects low-latitude TEC via a disturbance of the meridional electric field. We also show that the phase change of the semidiurnal migrating solar tide (SW2) in the neutral wind caused by the 2009 SSW at the altitude of the dynamo electric field generation has a crucial importance for the SW2 phase change in the zonal electric field. Such changes lead to the appearance of anomalous diurnal variability of the equatorial electromagnetic plasma drift and subsequent low-latitudinal TEC disturbances in agreement with available observations. Plain Language Summary – Entire Atmosphere GLobal model (EAGLE) interactively calculates the troposphere, stratosphere, mesosphere, thermosphere, and plasmasphere–ionosphere system states and their response to various natural and anthropogenic forcing. In this paper, we study the upper atmosphere response to the major sudden stratospheric warming that occurred in January 2009. Our results agree well with the observed evolution of the neutral temperature in the upper atmosphere and with low-latitude ionospheric disturbances over America. For the first time, we identify an SSW-related cooling in the tropical lower thermosphere that, in turn, could provide additional information for understanding the mechanisms for the generation of electric field disturbances observed at low latitudes. We show that the SSW-related vertical electromagnetic drift due to electric field disturbances is a key mechanism for interpretation of an observed anomalous diurnal development of the equatorial ionization anomaly during the 2009 SSW event. We demonstrate that the link between thermospheric winds and the ionospheric dynamo electric field during the SSW is attained through the modulation of the semidiurnal migrating solar tide.

Whole Atmosphere Coupling during the September 2019 Antarctic Sudden Stratospheric Warming

2021 ◽  
Author(s):  
Yosuke Yamazaki ◽  
Yasunobu Miyoshi
Keyword(s):  
Large Scale ◽  
Lower Thermosphere ◽  
Upper Atmosphere ◽  
The Arctic ◽  
Electron Content ◽  
Stratospheric Warming ◽  
Sudden Stratospheric Warming ◽  
Total Electron ◽  
Total Electron Content Data ◽  
Zonal Wavenumber

<p>A sudden stratospheric warming (SSW) is a large-scale meteorological phenomenon, which is most commonly observed in the Arctic region during winter months. In September 2019, a rare SSW occurred in the Antarctic region, providing a unique opportunity to study its impact on the middle and upper atmosphere. Geopotential height measurements by the Microwave Limb Sounder aboard NASA's Aura satellite reveal a burst of westward-propagating quasi-6-day wave (Q6DW) with zonal wavenumber 1 in the mesosphere and lower thermosphere following the SSW. At this time, ionospheric data from ESA's Swarm satellite constellation mission show prominent 6-day variations in the daytime equatorial electrojet intensity and low-latitude plasma densities. The whole atmosphere model GAIA reproduces salient features of the middle and upper atmosphere response to the SSW. GAIA results suggest that the observed ionospheric 6-day variations are not directly driven by the Q6DW but driven indirectly through tidal modulations by the Q6DW. An analysis of global total electron content data reveals signatures of secondary waves arising from the nonlinear interaction between the Q6DW and tides.</p>

Study of temperature, wind speed and tides in the upper atmosphere from optical measurements during the 2017-2019 winter's

2020 ◽  
Author(s):  
Vasilyev Roman ◽  
Zorkaltseva Olga
Keyword(s):  
Wind Speed ◽  
Lower Thermosphere ◽  
Basic Research ◽  
Upper Atmosphere ◽  
Optical Measurements ◽  
Stratospheric Warming ◽  
East Siberia ◽  
Russian Science ◽  
Stratospheric Polar Vortex ◽  
Mesosphere And Lower Thermosphere

<p><strong>Abstract</strong>.The mesosphere and lower thermosphere are the least studied areas of the earth atmosphere. The reason for this is the lack of monitoring. We have the Fabry-Perot interferometer (FPI) installed in middle latitudes of East Siberia in the geophysical observatory of Institute of Solar-Terrestrial Physics SB RAS (51.8N, 103.1E).  The FPI is a unique instrument and has no analogues in Russia.The FPI with a temporal resolution of about 10–15 minutes observes the natural glow of the night atmosphere of 630.0, 557.7 nm and 843 nm, the characteristic heights of these lines are about 250, 100 and 90 km, respectively. In this study, we use data on the behavior of the zonal, meridional component of wind speed and temperature obtained with 557.7 nm line. We analyze the temperature regime and dynamics of the stratospheric polar vortex according to the data of climatic archive - ERA-interim to get the relationship of SSW and wind regime in MLT.  In this study, we consider winter atmosphere in 2017-2019 over East Siberia, namely the period of sudden stratospheric warming. We compared the evolution of stratospheric warming’s with temporary variations in background wind and temperature and tides in the mesosphere and lower thermosphere. It turned out that the sudden stratospheric warming's made a strong effect in upper layers of the atmosphere. During major stratospheric warming's, the zonal and meridional winds reversed and increase in the semidiurnal and thirdrdiurnal tides. Temperature in MLT dramatic drop followed by an increase during sudden stratospheric warming's. Minor sudden stratospheric warming's had a similar (but much lower in intensity) response in the upper atmosphere.</p><p>Acknowledgements. Analysis of stratosphere condition in this work was supported by the Russian Science Foundation, project No. 19-77-00009. Analysis of methosphere condition in ths work was supported by Rusian Foundation for Basic Research project No. 18-05-00594. The measurements were carried out on the instrument of Center for Common Use «Angara» [http://ckp-rf.ru/ckp/ 3056]. The authors gratefully acknowledge the access to the ECMWF ERA-Interim.</p>

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