Comparison of seasonal and longitudinal variation of daytime MSTID activity using GPS observation and GAIA simulations

Earth, Planets and Space

Yasunobu Miyoshi¹  Yuichi Otsuka²  Atsuki Shinbori²  Mani Sivakandan³  Priyanka Ghosh³  Hiroyuki Shinagawa⁴ 

[1] Earth and Planetary Sciences, Kyushu University, 819-0395, Fukuoka, Japan;Institute for Space-Earth Environmental Research, Nagoya University, 464-8601, Nagoya, Japan;Institute for Space-Earth Environmental Research, Nagoya University, 464-8601, Nagoya, Japan;Leibniz Institute of Atmospheric Physics at the University of Rostock, Kühlungsborn, Germany;National Institute of Information and Communications Technology, 184-8795, Koganei, Tokyo, Japan;

关键词: Daytime MSTIDs;    GAIA model;    GPS;    Gravity waves;    Meridional wind;    TEC;   

DOI  :  10.1186/s40623-021-01369-5

来源: Springer

【 摘 要 】

The total electron content (TEC) data derived from the GAIA (Ground-to-topside model of Atmosphere Ionosphere for Aeronomy) is used to study the seasonal and longitudinal variation of occurrence of medium-scale traveling ionospheric disturbances (MSTIDs) during daytime (09:00–15:00 LT) for the year 2011 at eight locations in northern and southern hemispheres, and the results are compared with ground-based Global Positioning System (GPS)-TEC. To derive TEC variations caused by MSTIDs from the GAIA (GPS) data, we obtained detrended TEC by subtracting 2-h (1-h) running average from the TEC, and calculated standard deviation of the detrended TEC in 2 h (1 h). MSTID activity was defined as a ratio of the standard deviation to the averaged TEC. Both GAIA simulation and GPS observations data show that daytime MSTID activities in the northern and southern hemisphere (NH and SH) are higher in winter than in other seasons. From the GAIA simulation, the amplitude of the meridional wind variations, which could be representative of gravity waves (GWs), shows two peaks in winter and summer. The winter peak in the amplitude of the meridional wind variations coincides with the winter peak of the daytime MSTIDs, indicating that the high GW activity is responsible for the high MSTID activity. On the other hand, the MSTID activity does not increase in summer. This is because the GWs in the thermosphere propagate poleward in summer, and equatorward in winter, and the equatorward-propagating GWs cause large plasma density perturbations compared to the poleward-propagating GWs. Longitudinal variation of daytime MSTID activity in winter is seen in both hemispheres. The MSTID activity during winter in the NH is higher over Japan than USA, and the MSTID activity during winter in the SH is the highest in South America. In a nutshell, GAIA can successfully reproduce the seasonal and longitudinal variation of the daytime MSTIDs. This study confirms that GWs cause the daytime MSTIDs in GAIA and amplitude and propagation direction of the GWs control the noted seasonal variation. GW activities in the middle and lower atmosphere cause the longitudinal variation.

【 授权许可】

CC BY