Case study of an Equatorial Plasma Bubble Event investigated by multiple ground-based instruments at low latitudes over China  

作　　者：LongChang Sun JiYao Xu YaJun Zhu Wei Yuan XiuKuan Zhao 

机构地区：[1]State Key Laboratory of Space Weather,National Space Science Center,Chinese Academy of Sciences,Beijing 100190,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Key Laboratory of Earth and Planetary Physics,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China

出　　处：《Earth and Planetary Physics》2021年第5期435-449,共15页地球与行星物理（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grants No.41831073 and No.41804146);the Open Research Project of Large Research Infrastructures of Chinese Acadamy of Sciences—"Study on the interaction between low/midlatitude atmosphere and ionosphere based on the Chinese Meridian Project”;the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2020156);the Project of Stable Support for Youth Team in Basic Research Field,CAS(Grant No.YSBR-018);the International Partnership Program of the Chinese Academy of Sciences(Grant No.183311KYSB20200003)。

摘　　要：Observational evidence is insufficient to understand how equatorial plasma bubbles(EPBs)form over low latitudes.The mechanism of plasma-density enhancement(formation of"plasma blobs")at low latitudes is in dispute.In this paper,we use data from multiple ground-based instruments(one all-sky airglow imager,five digisondes,and one Fabry–Perot interferometer)to investigate the evolution of an EPB event that occurred at low latitudes over China on the night of 06 December 2015(06-Dec-2015).We provide observational evidence that an enhanced equatorward wind most likely induced by a substorm could have initiated the Rayleigh–Taylor instability(RTI)that destabilized several EPB depletions in an upwelling region of a large-scale wave-like structure(LSWS)in the bottomside ionosphere.Those EPB depletions were forced to surge poleward,from nearly 10°to 19°magnetic latitude,two hours before midnight.Smaller-scale bifurcations evolved rapidly from tips of airglow depletions by a secondary E×B instability when the aforementioned substorm-induced southwestward wind blew through.During the growth phase of the EPB depletions,a westward polarization electric field inside the LSWS is likely to have compressed plasma downward,inducing the two airglow-type blobs observed in the bottomside ionosphere,by a mechanism of LSWS-blob connection that we propose.We also provide observational evidence of brightness airglow depletions.We find that an enhanced poleward wind associated with a passing-by brightness wave(BW)is likely to have transported plasma to fill the airglow depletions,which finally evolved into brightness airglow structures.This study investigates the physical processes accompanied by the EPB event and those two-airglow blobs observed at low-latitudes over China.

关 键 词：Equatorial Plasma Bubble plasma blobs Rayleigh–Taylor instability secondary E×B instability nighttime brightness wave large-scale wave-like structure enhanced equatorward(poleward)wind 

分 类 号：P352.7[天文地球—空间物理学]