AUTHOR=Yan Rui , Xiong Chao , Zhima Zeren , Shen Xuhui , Liu Dapeng , Liu Chao , Guan Yibing , Zhu Keying , Zheng Lin , Lv Fangxian 

TITLE=Correlation Between Ne and Te Around 14:00 LT in the Topside Ionosphere Observed by CSES, Swarm and CHAMP Satellites

JOURNAL=Frontiers in Earth Science

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2022.860234

DOI=10.3389/feart.2022.860234

ISSN=2296-6463

ABSTRACT=<p>In this study, we have performed a detailed analysis for the correlation between electron density (<italic>Ne</italic>) and temperature (<italic>Te</italic>) at the topside ionosphere. <italic>In situ</italic> measurements from four satellites have been utilized, including the China Seismo-Electromagnetic Satellite (CSES), Swarm A and B, as well as the earlier Challenging Minisatellite Payload (CHAMP) satellite. To make a fair comparison, only simultaneous observations between CSES and Swarm A/B have been considered; while for CHAMP, as it doesn’t have overlaps with CSES period, the observations during similar low solar activity years are considered. Our study has been confined to the dayside around 14:00 local time (LT), due to the fixed LT coverage of CSES. Observations from the four satellites show generally consistent relationship between the <italic>Ne</italic> and <italic>Te</italic> at the topside ionosphere. When <italic>Ne</italic> is low, the <italic>Te</italic> is negative correlated with <italic>Ne</italic>, while the slop of negative relation becomes shallower or even reverses to a positive relation after <italic>Ne</italic> exceeds a certain threshold. The slope of <italic>Ne/Te</italic> relation shows also dependence on season and magnetic latitude (MLat), as the ionospheric <italic>Ne</italic> and <italic>Te</italic> themselves are seasonal and MLat dependent. Interestingly, we find two abnormal features of the Swarm <italic>Te</italic> measurements: 1) when <italic>Ne</italic> is lower than 1×10<sup>11</sup> m<sup>−3</sup>, <italic>Te</italic> sometimes becomes very scatter at low and middle latitudes; 2) when <italic>Ne</italic> is larger than 1×10<sup>11</sup> m<sup>−3</sup>, <italic>Te</italic> is grouped into two branches at the equatorial and low latitudes. Further analysis reveals that the flags used in the Swarm Level-1 B plasma density product cannot well distinguish the two abnormal features of <italic>Te</italic>, implying further efforts are needed for the Swarm <italic>Te</italic> data calibration.</p>