The Evolution of Solar Tide‐Like Signatures in the Ionospheric Total Electron Content During Major Sudden Stratospheric Warming Events.

By using total electron content (TEC) from the global ionospheric maps, the solar tide‐like signatures in the ionosphere are explored. We further study how the main components evolve during the 2009 and 2018 major stratospheric sudden warming events (SSWs). The method of a least‐square fit is applied for extracting the solar tide‐like components. The three predominant components are SW2, D0, and SW1, amplitude of which increase in the equatorial ionization anomaly region after the onset of both SSW events, especially in the northern hemisphere. During the SSW events, the solar tide‐like components vary significantly with latitude and their evolutions show hemispherical asymmetries. Each same component presents similar evolutionary trend during both events. The characteristics of ionospheric tide‐like signatures and related mechanisms are discussed. The SW2 tide‐like responses in TEC closely follow the changes in the tidal wind fields in the lower thermosphere, which provide evidences of the atmosphere‐ionosphere coupling during SSW events. In addition, the latitudinal asymmetric distributing of stratospheric ozone and ionospheric TEC background during the SSW may be influence factors for the hemispherical asymmetries in tide‐like signatures responses in TEC. Plain Language Summary: Stratosphere sudden warming (SSW) is a meteorological event in which the stratospheric atmospheric temperature will increase dramatically within a matter of days even in the northern polar winter. Although it is a stratospheric phenomenon, the tidal variations from the lower atmosphere can impose their influences even at the ionospheric height during SSW events. We present the evolutions of dominant tide‐like components in the total electron content data. In addition, the changes of the ionospheric migrating tide‐like components are like those in the mesospheric neutral winds. These similarities imply a strong atmosphere‐ionosphere coupling during a major SSW event. Key Points: The predominant ionospheric tide‐like components were SW2, D0, and SW1 during the 2009 and 2018 major stratospheric sudden warming (SSW) eventsAfter the SSWs onset, there were enhancements for the three tide‐like components in the equatorial ionization anomaly region, especially for the northern hemisphereThe SW2 tide‐like responses in total electron content had similar responses with the changes in the tidal winds in the lower thermosphere [ABSTRACT FROM AUTHOR]