Stratospheric sudden warming effects on the ionospheric migrating tides during 2008–2010 observed by FORMOSAT-3/COSMIC

• Variations of ionospheric tidal components during 2008–2010 SSW events are investigated.
• Decreases of zonal mean, DW1, and TW3 components occur during the temperature increase.
• Simultaneous enhancements of SW2 and SW1 are seen after the temperature increase.
• Phase shifts of migrating tides and stratospheric temperature increases occur simultaneously.

In this paper, ionospheric electron densities obtained from radio occultation soundings of FORMOSAT-3/COSMIC are decomposed into their various constituent tidal components for studying the stratospheric sudden warming (SSW) effects on the ionosphere during 2008–2010. The tidal analysis indicates that the amplitudes of the zonal mean and major migrating tidal components (DW1, SW2 and TW3) decrease around the time of the SSW, with phase/time shifts in the daily time of maximum around EIA and middle latitudes. Meanwhile consistent enhancements of the SW2 and nonmigrating SW1 tides are seen after the stratospheric temperature increase. In addition to the amplitude changes of the tidal components, well matched phase shifts of the ionospheric migrating tides and the stratospheric temperatures are found for the three SSW events, suggesting a better indicator of the ionospheric response. Although the conditions of the planetary waves and the mean winds in the middle atmosphere region during the 2008–2010 SSW events may be different, similar variations of the ionospheric tidal components and their associated phase shifts are found.