The Ionosphere at Middle and Low Latitudes Under Geomagnetic Quiet Time of December 2019

Abstract

The ionosphere acts as a terminal of solar-terrestrial system to display sophisticated processes when it is affected by external energy from the solar wind, magnetosphere, and the lower atmosphere in space weather events. The complicated features of ionospheric disturbance during space weather events are always a great subject of ionospheric physics and an important challenge for space weather predictions (e.g., Liu et al., 2018;Prölss, 2008). For instance, during geomagnetic storms the energy and energetic particles deposited in the polar upper atmosphere drive great changes in the chemical, electrodynamical, and thermodynamical processes in the whole ionosphere, and induce significant disturbances compared with the quiet time ionosphere (e.g.

Persistent Eastward EEJ Enhancement During the Geomagnetic Storm Recovery Phases

“…Figure 7 (a-b) presented that the Indian dTEC showed long-duration (9:00-18:00 LT) enhancements span 30°-50° latitudes with peak at 40°N latitude. While the band enhancement disappeared in the American sector (Figures 6 and 8), such band enhancements locate same latitude ranges with the nighttime midlatitude band structure during the quiet geomagnetic conditions (Kuai et al, 2021;Q.-H. Li et al, 2018;Zhong et al, 2019). Zhong et al (2019) found that the Ne in the F region ionosphere generally presented peaks near ±40° geomagnetic latitudes from 23:00 to 05:00 LT, similar results were also reported by Xiong et al (2019).…”

“…(2021) disclosed that the TEC at all local times presented similar band structure in the American sector on 6–8 December (the maximum Kp was 1.7). The formation of the nighttime band structure during the quiet time is tightly related with the uplift driven by the equatorward thermospheric winds and the plasma fill from plasmasphere (Kuai et al., 2021; Zhong et al., 2019). The storm‐induced equatorward winds could generally increase plasma density at midlatitudes by raising ionosphere to high altitudes where the recombination rate is low, and the effect is modulated by the geomagnetic configuration (Kohl & King, 1967; Rüster & King, 1976).…”

“…Thus, the similar occurrence climatology of two types of enhancement seems further support that the lower atmospheric forcing may modulate the ionospheric dynamo and cause the electric field eastward enhancement. The PEE seems belong to the "quiet-time disturbance" (Q-disturbance; David & Sojka, 2010;Kuai et al, 2021;L. Liu et al, 2020;Mikhailov et al, 2007;Zhao et al, 2008).…”

Anomalous Disturbance of the Ionosphere in the East Asia Region During the Geomagnetically Quiet Day on 1 November 2016

“…The maximum values of EEJ near 100°E and 120°E occurred at 04:02 UT and 01:43 UT, respectively, which are 2–3 hr earlier than the time of the maximum CODE‐TEC in the two longitude regions (06:00 UT and 05:00 UT). Figures 2–7 indicated that anomalous disturbances of ionospheric TEC and NmF2 in the East Asia region during 03:00–08:00 UT on 1 November 2016 are attributed to the enhancements of the eastward EEF (Kuai et al., 2021).…”

“…Kuai et al. (2021) explored ionospheric variations in the Asian‐Australian and American sectors during a period of geomagnetic quiet time in December 2019. The results showed that TEC has multiple prominent enhancements at middle and low latitudes in the two sectors, and TEC depletions occur repeatedly in the Asian‐Australian sector.…”