Study of a Quasi‐27‐Day Wave in the MLT Region During Recurrent Geomagnetic Storms in Autumn 2018

Abstract

AbstractA quasi‐27‐day wave (Q27DW) caused by the rotational period of solar radiation is commonly observed in the atmospheric dynamics. In the present study, we report an enhancement of a Q27DW during recurrent geomagnetic storms in the autumn of 2018 based on the zonal wind observations in the mesosphere and lower thermosphere (MLT) region over Beijing (BJ, 40.3°N, 116.2°E). According to our analysis, the solar radiation and the seasonal variation are not important in exciting the observed Q27DW. A 27‐day oscillation exists in both solar wind data and Kp index during the recurrent geomagnetic storms. The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperature and ozone data also reveal a Q27DW signature at 97 km. Using the long‐term observation of BJ meteor radar, two more cases are found during springtime in 2010 and 2018 under the solar quiet condition. Our results indicate that the recurrent geomagnetic storms due to high‐speed solar winds can modulate the temperature and ozone in the MLT region, which is responsible for generating a Q27DW in the MLT zonal winds over BJ. This study suggests that the variation of planetary waves in the MLT neutral winds at mid‐latitude is likely associated with the recurrent geomagnetic storms and high‐speed solar winds.