亚暴期间等离子体对流速度及热层纬向风速度变化的统计学分析

本文利用2001年至2005年间CHAMP卫星及DMSP（F13,F15）卫星观测数据,对亚暴发生前后,亚暴初始位置所在磁地方时（Magnetic Local Time,MLT）东侧2h（＋2h,MLT）至西侧4h（-4h,MLT）范围内等离子体对流速度（Vy）及热层纬向风速度（Uy）的变化进行了统计学分析.研究发现在亚暴发生后的1.5h内,所有MLT区间的Vy均明显增大,且峰值位置的地磁纬度向赤道侧移动,1.5h后,Vy减小,峰值的纬度向极区移动,表明亚暴的发生能显著增强等离子体对流速度;在亚暴发生位置的西侧0-2h内,Vy增幅最大,这表明亚暴对热层的影响主要在西侧,影响最大的区域是西侧0-2hMLT区间;Uy在亚暴发生后3h持续增大,其对亚暴的响应相较于Vy有1.5h的延迟.

Responses of zonal wind at -40°N to stratospheric sudden warming events in the stratosphere, mesosphere and lower thermosphere

Based on the data at^40°N at different longitudes during different stratospheric sudden warming(SSW)events,the responses of zonal winds in the stratosphere,mesosphere and lower thermosphere to SSWs are studied in this paper.The variations of zonal wind over Langfang,China(39.4°N,116.7°E)by MF radar and the modern era retrospective-analysis for research and applications(MERRA)wind data during 2010 and 2013 SSW and over Fort Collins,USA(41°N,105°W)by lidar and MERRA wind data during 2009 SSW are compared.Results show that the zonal wind at^40°N indeed respond to the SSWs while different specifics are found in different SSW events or at different locations.The zonal wind has significant anomalies during the SSWs.Over Langfang,before the onset of 2010 and 2013 SSW,the zonal wind reverses from eastward to westward below about 60–70 km and accelerates above this region,while westward wind prevails from 30 to 100 km after the onset of2010 SSW,and westward wind prevails in 30–60 and 85–100 km and eastward wind prevails in 60–85 km after the onset of2013 SSW.Over Fort Collins during 2009 SSW,eastward wind reverses to westward in 20–30 km before the onset while westward wind prevails in 20–30 and 60–97 km and eastward wind prevails in 30–60 and in 97–100 km after the onset.Moreover,simulations by the specified dynamics version of the whole atmosphere community climate model(SD-WACCM)are taken to explain different responding specifics of zonal wind to SSW events.It is found that the modulation of planetary wave(PW)plays the main role.Different phases of PWs would lead to the different zonal wind along with longitudes and the different amplitudes and phases in different SSW events can lead to the different zonal wind responses.