Poleward migration of tropical cyclones in the western North Pacific and its regional impacts on rainfall in Asia

Abstract

The region of Asia, which is surrounded by the western North Pacific (WNP), is one of the areas most affected by tropical cyclones (TCs). Since the 20th century, the characteristics and regional impact of TCs in this area have changed significantly, possibly due to global warming. However, the relationships between changes in the translation speed of TCs, poleward migration and TC-induced rainfall in the WNPs have not been well investigated. Using daily precipitation and TC data from 1979 to 2020, this diagnostic study explored the poleward migration of TCs, changes in their TC translation speeds and the effects of TCs on countries along the Pacific Rim. Over the 42-year study period, TCs experienced a decrease in intensity, lifespan, frequency and translation speeds and a northwestward migration in the genesis position, recurving position and tracks. However, the intensity and lifespan of high-intensity TCs, which are defined as those with intensities exceeding 75% of all TCs, have increased significantly. Consequently, daily maximum precipitation of TCs decreased significantly with a τ value ranging from 0.294 to 0.442 for the M-K test on inland China, the Philippines and Myanmar, but increased significantly with a τ value ranging from −0.410 to −0.615 in coastal areas of East Asia, especially China and northern Kalimantan Island, as confirmed by the distribution of TC-induced precipitation. Our findings indicate that coastal East Asian countries are becoming increasingly vulnerable to high-intensity TCs. © 2023 Royal Meteorological Society.