The Wave-Like Auroral Structure around Auroral Expansion Onset  

作　　者：TANG Chao-Ling 汤朝灵(School of Space Science and Physics,Shandong University at Weihai,Weihai 264209)

机构地区：[1]School of Space Science and Physics,Shandong University at Weihai,Weihai 264209

出　　处：《Chinese Physics Letters》2011年第10期284-287,共4页中国物理快报（英文版）

基　　金：Supported by the National Natural Science Foundation of China under Grant Nos.41004075,40825014 and 40890162;the Shandong-Provincial Natural Science Foundation under Grant No.ZR2010DQ014.

摘　　要：We present the direct connection between the wave-like auroral structure around the time of auroral expansion onset and the ballooning mode waves in the near-Earth magnetotail.Based on the NASA mission time history of events and macroscale interactions during substorms(THEMIS)ground-based all-sky imagers,we show that around the time of auroral expansion onset,a wave-like auroral structure first has four luminosity peaks separated by 2–3°magnetic longitude(MLON).Subsequently,the wave-like structure propagates in the azimuthal direction and an overall bright arc spans approximately 1 h magnetic local time.The wavelength is estimated to be 120–180 km.Finally,a noticeable poleward auroral expansion is observed.The ballooning mode waves are identified by two THEMIS probes in the near-Earth magnetotail.The observed wavelength of the ballooning mode waves is approximately equal to the order of the ion Larmor radius.The wavelength of 1500–3000 km in the near-Earth magnetotail is comparable with the wave-like auroral structure estimate.This study suggests that the ballooning mode waves might play a crucial role in auroral expansion onset,corresponding to the wave-like auroral structure in this study.

关 键 词：EARTH STORM AURORA 

分 类 号：P35[天文地球—空间物理学]