Statistical Study Of The Middle And Upper Atmosphere Neutral Winds And Their Responses To SSWs

The detection of the atmospheric winds is the dominant method to study the atmosphere.Many wave dynamics in the atmospheric winds,such as the gravity waves,tides and planetary waves,can reveal the dynamic structure and process insight the atmospheres.Based on the atmospheric wind observations,we can investigate the distribution of the atmosphere,the propagation and coupled process under some special space weather events.Study the atmospheric winds would provide the theoretical and observational basic for building the model of atmospheres,which can also improve the ability to forecast and report the special space weather events.The present study,based on long-term observations and atmospheric dynamic theories,performed the statistical analysis of the mean winds and reported the responses of the atmospheric waves to stratospheric sudden warming(SSW)events.Results are mainly as follows,1.Based on the observations by a meteor radar chain located at Mohe,Beijing,Wuhan and Sanya along the 120°E meridian from 2009 to 2017,we statistical studied the long-term observations of the mean wind in the mesosphere and lower thermosphere(MLT)region.Results reveal that the mean winds are dominant by annual oscillation at the mid-latitudes,while the dominant modulations are the annual oscillation and the semiannual oscillation at low latitude.Two typical eastward acitivities of the mean zonal winds at the midlatitudes are from April to October above 85 km and from November to March below 90 km.We verified that the zonal mean wind reversals from eastward to westward around spring are consistent with the rapid changes of the gravity wave forcing,which reversals from westward to eastward.We compared the observation with the Horizontal Wind Model-07 and found that large discrepancies during winter time,at meridional component and low latitude.This study has been published on the top geophysical journal,Journal of Geophysical Research: Atmopsheres,and reviewed highly as: this paper shows a more rapid transition in the circulation in the Spring than the Fall.This is an important contribution coming from a more extensive data set than the earlier study,and indicates that this is a robust feature of the circulation.2.Stratospheric Sudden Warming(SSW)is a sudden varation occuring at the polar stratospheric region in the winter hemisphere.Large enhancement of the atmospheric temperature is typical occurred during SSWs.SSW has large influence on the redistribution of the global atmospheric energy and different atmospheric layers.It can change the local background winds,temperatures,chemical compositions and even the ionospheric parameter distrubulances.Based on the observation from December to January 2013 made by the four meteor radars located at Mohe(53.5°N,122.3°E),Beijing(40.3°N,116.2°E),Wuhan(30.5°N,114.6°E),and Sanya(18.3°N,109.6°E),we presented an analysis of the responses of the quasi 2 day waves to the 2013 SSW events.It is the first time that the enhancement of the quasi 2 day waves in the mid-latitudes in the Northern Hemisphere during a SSW has been reported.The consistent planetary waves observed at the four stations are very likely associated with the SSWs and the most prominent one is at the low latitude.These results are published on one of the top geophysical journals,Geophysical Research Letters,and has been cited many times.