Abstract:Stratospheric Arctic vortex (SAV) anomalies can afford indications to extreme weather and Arctic ozone losses in winter and spring. The SAV in early spring is found to be related to the second mode of the interannual sea surface temperature (SST) in the Tropical Pacific in 1979-2020, the spatial pattern of SST anomalies in the western equatorial Pacific from the ERA-5 reanalysis data. The specific progress of the western equatorial Pacific SST anomalies affecting the SAV is revealed by the CAM5 numerical simulations. The SST warming in the western equatorial Pacific in winter and spring can intensify local deep convective precipitation. Then the anomalous latent heating induces a Rossby wave (high pressure anomalies in the upper troposphere) to its northwest side through the Matsuno-Gill atmospheric response. The Rossby wave adjusts the strength and position of the strongest trough-ridge system of the Northern Hemisphere in the North Pacific along the great circle path, leading to a decrease of the amplitude of wave 1 of the meridional wind and an increase of the phase difference of the wave 3 between the meridional wind and temperature, which results in less wave activity fluxes of the wave 1 and wave 3 propagating to the stratosphere. Finally, the less poleward transport of eddy heat flux enhances the SAV in spring.