Local‐Time and Vertical Characteristics of Quasi‐6‐Day Oscillation in the Ionosphere During the 2019 Antarctic Sudden Stratospheric Warming
Jia‐Ting Lin, Chien‐Hung Lin, P. K. Rajesh, Jia Yue, C. Y. Lin, Tomoko Matsuo
Abstract
Abstract This study investigates new characteristics of ionospheric modulations driven by quasi‐6‐day wave (Q6DW) burst following a rare Antarctic sudden stratospheric warming (SSW) in September 2019. Local‐time and vertical variations of the amplitude and phase of quasi‐6‐day oscillation (Q6DO) in the ionosphere are examined by using data assimilation analysis of electron density from three‐dimensional Global Ionosphere Specification (GIS). The maximum amplitudes of Q6DO are located symmetrically ±20° off the magnetic equator at ~12 LT, with a secondary peak at 17 LT. The amplitude of Q6DO weakens at 15 LT, with a sudden phase shift, suggesting multiple dynamo processes driving the Q6DO‐related ionospheric variations. The altitude‐latitude structure of Q6DO shows that the ionospheric modulations extend beyond the equatorial ionization anomaly, indicating the wind dynamo source regions at higher latitudes. A likely physical mechanism is discussed based on possible interactions of Q6DW and semidiurnal migrating tides leading to the dynamo modulation and phase differences.