Quasi-5-Day Oscillations During Arctic Major Sudden Stratospheric Warmings From 2005 to 2021

Traveling quasi-5-day oscillations (Q5DOs) with different wavenumbers are independently observed in the mesosphere and the lower thermosphere during many recent sudden stratospheric warming (SSW) events, but their common activities during SSWs are still unclear. Based on the geopotential height data measured by the Aura/Microwave Limb Sounder (MLS) from August 2004 to March 2021, we statistically investigate the characteristics of the Q5DOs during eight Arctic major SSW events. The amplitudes of the Q5DOs are obtained by a new fitting method, which inhibits the effect of rapid changes in stationary planetary waves during SSWs. Our results reveal a robust feature that Q5DOs were enhanced during all interested SSW events. Our analysis indicates that eastward and westward propagating Q5DOs can be simultaneously enhanced during SSWs. Additionally, the wavenumbers of the enhanced Q5DOs are found to be associated with the geometry of polar vortices. Extremely strong westward Q5DOs with wavenumber 2 are consistently observed during split-type major SSWs. Quasi-5-day oscillations (Q5DOs) are commonly enhanced during eight major sudden stratospheric warming (SSW) events Westward and eastward propagating Q5DOs can be simultaneously enhanced during major SSWs The enhanced wave-2 Q5DOs are highly associated with the split-type SSWs