Abstract:Based on NCEP/NCAR monthly mean reanalysis, CMAP and GPCP monthly mean precipitation datasets over the period of 1979-2014, the inter-annual characteristics of the stratospheric polar vortex breakdown and its relationship with the precipitation over the South Asia in May were studied. Results show that the Northern Hemisphere stratospheric polar vortex breakdown is characterized by inter-annual variations. In addition, as the stratospheric polar vortex breaks down early(late),abnormal signals propagate downward from the stratosphere in March and reaches upper troposphere in April, with high(low) temperature, weak(strong) polar vortex, weak(strong) polar jet above the upper troposphere. It is also found that inter-annual variations of the stratospheric polar vortex breakdown are closely related to the precipitation anomalies over the South Asia in May. As the stratospheric polar vortex breaks down late, in the stratosphere, the negative geopotential height anomalies dominate over the Arctic region while the positive geopotential height anomalies over the middle latitudes in April. These positive geopotential height anomalies over the middle latitudes propagate downward and even reach the upper troposphere above the North Arabian Sea in May, which act to form a favorable condition for precipitation over the South Asia, and vice versa.