Spatially Quasi-periodic Finger-like Auroras during Substorms

Wang, Wenrui1,2; Yang, Jian2; Wang, Yong-Fu3; Shi, Quanqi4; Cui, Jun1

2020-07

10.3847/1538-4357/ab9645

ASTROPHYSICAL JOURNAL   影响因子和分区

0004-637X

1538-4357

North-south-aligned discrete auroras are common phenomena during substorms. A quasi-periodic form of such auroras distributed azimuthally in the nightside resembles a finger-like morphology. They were noticed in sawtooth-time substorms, but have not yet been paid much attention during other geomagnetic times. In this study, we investigate the longitudinal periodicity of those auroras for different types of substorms using IMAGE data from 2001 to 2003. Using an automated detection algorithm, we identified multiple north-south-aligned thin auroral structures in auroral images and found that their average center and length in latitude, and longitudinal wavelength (similar to 25 degrees) are essentially the same. However, the occurrent rates for finger-like auroras are substantially different, 83%, 64%, and 18% for sawtooth-time substorms, storm-time substorms and isolated substorms, respectively. Therefore, statistical results indicate that finger-like auroras occur in favor of geomagnetically more active times. Combining our data analysis and previous simulations, we suggest that interchange instability is a possible mechanism of spatially quasi-periodic finger-like auroras when a substorm injection happens in a very wide local time. It is particularly important to point out that the sawtooth events not only have a temporal periodicity as defined in particle injections, but also have a spatial periodicity as observed in auroral morphology for the majority of them.

Magnetic fields Magnetohydrodynamics Space plasmas

SCI

英语

通讯

Strategic Priority Research Program of the Chinese Academy of Sciences[XDB41000000] ; National Natural Science Foundation of China (NSFC)[41525015][41774186][41974187]

Astronomy & Astrophysics

Astronomy & Astrophysics

WOS:000552692200001

IOP PUBLISHING LTD

SPACE SCIENCE

Web of Science

1.Sun Yat Sen Univ, Sch Atmospher Sci, Zhuhai, Guangdong, Peoples R China
2.Southern Univ Sci & Technol, Dept Earth & Space Sci, Shenzhen, Guangdong, Peoples R China
3.Peking Univ, Inst Space Phys & Appl Technol, Beijing, Peoples R China
4.Shandong Univ, Sch Space Sci & Phys, Opt Astron & Solar Terr Environm, Weihai, Shandong, Peoples R China

Wang, Wenrui,Yang, Jian,Wang, Yong-Fu,et al. Spatially Quasi-periodic Finger-like Auroras during Substorms[J]. ASTROPHYSICAL JOURNAL,2020,897(2).

Wang, Wenrui,Yang, Jian,Wang, Yong-Fu,Shi, Quanqi,&Cui, Jun.(2020).Spatially Quasi-periodic Finger-like Auroras during Substorms.ASTROPHYSICAL JOURNAL,897(2).

Wang, Wenrui,et al."Spatially Quasi-periodic Finger-like Auroras during Substorms".ASTROPHYSICAL JOURNAL 897.2(2020).