Response of Sporadic <i>E</i> Layer to Sudden Stratospheric Warming Events Observed at Low and Middle Latitudes
Qiong Tang, Chen Zhou, Yi Liu, Guanyi Chen
Abstract
Abstract This paper investigates the variations of middle‐ and low‐latitude sporadic E ( E s ) layers during 2011–2012 and 2012–2013 sudden stratospheric warming (SSW) events by using observations from six ionosondes in East Asia over China and Japan region. Observations of E s critical frequency ( f o E s ) at all these ionosondes present obvious enhancements around the days of new and full moon during SSW periods. Wavelet spectra of f o E s during two SSW events exhibit noticeable enhanced 14.5‐day modulation, which resembles the lunar semimonthly period. In addition, simultaneous wind measurements by meteor radar also show enhancement of 14.5‐day periodic oscillation after SSW onset. Tidal components extracted from meteor radar wind measurements in mesosphere and lower thermosphere region and from ionospheric F region critical frequency ( f o F 2 ) are noticeably modulated by the lunar phase. These observational evidences reveal that the semimonthly lunar period of 14.5 days can be a contributing factor to variations of E s layer during SSW event.