Mid-Latitude Mesospheric Responses of the Solar Eclipse on 21 June 2020 Observed by the Wuhan MST Radar

An annular solar eclipse shifted across the earth from the middle of Africa to the Pacific on 21 June 2020. The Wuhan Mesosphere-Stratosphere-Troposphere (MST) radar was located on the eclipse path to provide us a rare opportunity to investigate the atmospheric responses to the rapid variation of solar radiations. The east, north, and vertical beams of the Wuhan MST radar were applied to record the echoes from mesosphere with 10 min sampling period. A Digisonde located near the MST radar was also used to investigate the variations of ionospheric Es layer during the solar eclipse. The mesosphere region between 70 and 80 km heights presented obvious responses to the eclipse. The echoes disappeared at around the eclipse maximum, indicating the dominant role of the solar radiation. The descending and ascending echo structures were recorded in the first and recovery phases of the eclipse, respectively. The Digisonde also found the evidence of the eclipse induced gravity waves in the Es layer that just above the mesosphere. The lunar shadow produced southward winds on the northside of the eclipse path is considered to induce the descending echo structure. The upward propagating gravity waves generated during the eclipse may be responsible for the ascending echo structure.