Responses of Multiday Oscillations in the Nighttime Thermospheric Temperature to Solar and Geomagnetic Activities Measured by Fabry-Perot Interferometer in China

摘要

The nighttime thermospheric temperature (~250 km) measured by FPI (Fabry-Perot interferometer) at Xinglong (40.2°N, 117.4°E) station from 2010 to 2018 is used to investigate the responses of the multiday oscillations (periods of 27, 13.5, 9, and 7 days) in thermospheric temperature to oscillations in F_(10.7) and Ap index. The results show that (1) the 27-, 13.5-, 9-, and 7-day oscillations in the thermospheric temperature depend on solar phases. The 27-day oscillations are predominant during solar maximum, while the 13.5-, 9-, and 7-day oscillations are significant during solar ascending phase, and (2) the 27-day oscillations in the thermospheric temperature are highly correlated (correlation coefficient >0.8) with the F_(10.7) and Ap index. Especially during solar maximum phase, the high-correlation occurrence rate between the thermospheric temperature and F_(10.7) (Ap index) is up to 278.5 (191.0) days per year; (3) the 13.5-, 9-, and 7-day oscillations are highly correlated with Ap index during the solar descending phase; and (4) the phase lags corresponding to the largest high-correlation occurrence rates are mostly about 0.1π during specific solar phase.