Interannual sea-surface temperature oscillations and tropical cyclone activity over the North Pacific basin

Two different flavors of tropical Pacific Ocean warming events have been identified each with its distinctive impacts on tropical cyclone (TC) activity over the North Pacific basin. The eastern Pacific warming (EPW) is associated with the eastward displacement of genesis and track density activity of TCs in western Pacific. It is related with the eastward extension of the monsoon trough and the low-level westerly flow. In contrast, the central Pacific warming (CPW) is associated with TCs generated in the north-western part of the western Pacific. TCs tend to penetrate through the entire western Pacific with a higher probability of land-fall over the eastern China coast and the southern part of Korea and Japan. The TC activity in the eastern Pacific also shows westward shift in CPW summer compared to EPW both in the genesis location and track density. The differences of TC activity over the entire North Pacific between the EPW and CPW years are related to thermodynamics factors and large-scale circulation anomalies driven by the different location of boundary forcing over the equatorial Pacific Ocean.