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Investigation of Small‐Scale Electron Density Irregularities Observed by the Arase and Van Allen Probes Satellites Inside and Outside the Plasmasphere
Author(s) -
Thomas Neethal,
Shiokawa Kazuo,
Miyoshi Yoshizumi,
Kasahara Yoshiya,
Shinohara Iku,
Kumamoto Atsushi,
Tsuchiya Fuminori,
Matsuoka Ayako,
Kasahara Satoshi,
Yokota Shoichiro,
Keika Kunihiro,
Hori Tomoaki,
Asamura Kazushi,
Wang ShiangYu,
Kazama Yoichi,
Tam Sunny WingYee,
Chang TzuFang,
Wang BoJhou,
Wygant John,
Breneman Aaron,
Reeves Geoffrey
Publication year - 2021
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2020ja027917
Subject(s) - plasmasphere , van allen probes , electron density , van allen radiation belt , earth's magnetic field , physics , whistler , local time , quiet , geophysics , population , computational physics , geology , electron , magnetosphere , magnetic field , astronomy , statistics , mathematics , quantum mechanics , demography , sociology
In situ electron density profiles obtained from Arase in the night magnetic local time (MLT) sector and from RBSP‐B covering all MLTs are used to study the small‐scale density irregularities present in the plasmasphere and near the plasmapause. Electron density perturbations with amplitudes >10% from background density and with time‐scales less than 30‐min are investigated here as the small‐scale density irregularities. The statistical survey of the density irregularities is carried out using nearly 2 years of density data obtained from RBSP‐B and 4 months of data from Arase satellites. The results show that density irregularities are present globally at all MLT sectors and L ‐shells both inside and outside the plasmapause, with a higher occurrence at L > 4. The occurrence of density irregularities is found to be higher during disturbed geomagnetic and interplanetary conditions. The case studies presented here revealed: (1) The plasmaspheric density irregularities observed during both quiet and disturbed conditions are found to coexist with the hot plasma sheet population. (2) During quiet periods, the plasma waves in the whistler‐mode frequency range are found to be modulated by the small‐scale density irregularities, with density depletions coinciding well with the decrease in whistler intensity. Our observations suggest that different source mechanisms are responsible for the generation of density structures at different MLTs and geomagnetic conditions.