Investigation of the Anomalous Planetary Wave Activities During Sudden Stratospheric Warming Events in 2002/2003

Abstract During austral summer of 2002/2003, the TIMED/TIDI meridional wind observations show that after the attenuation of the climatological quasi‐2‐day wave (Q2DW) with westward zonal wavenumber 3 (W3) and a period of 47 hr (hrs) in January, a 53 hr abnormal W3 Q2DW event occurred in February with symmetric latitudinal structure about the equator. Our analysis indicates that this abnormal W3 Q2DW is generated by the nonlinear interaction between the climatological W3 Q2DW and a ∼ zonally symmetric oscillation associated with a sudden stratospheric warming (SSW). The SSW occurring in boreal winter modulated the meridional circulation through interhemispheric coupling, which influenced the background wind in the summer hemisphere and favored the amplification of a symmetric Q2DW mode in February consequently. The diagnostic analysis reveals that this February W3 Q2DW was mainly amplified near the stratopause at low latitudes of the Southern Hemisphere, where the background atmospheric conditions are suitable for the amplification of the W3 Q2DW. Thus, both the nonlinear interaction and favorable background atmospheric conditions contribute to the occurrence of the abnormal W3 Q2DW in February.