Extent of High Winds and Heavy Rainfall Induced by Tropical Cyclones in South Korea

Abstract:

This study has investigated the spatial extent of high winds and heavy rainfall induced by tropical cyclone (TC) landfalls in South Korea over the period 1979–2014 by analyzing a high-resolution reanalysis data. By comparing weather station data with the reanalysis data, the lowest bounds of high winds and heavy rainfall are set at 11.2 m s^-1 and 1.38 mm hr^-1, respectively; these correspond to the 99^th percentiles of the observed daily maximums of winds and accumulated rainfall. The number of grids in which wind speed and rainfall exceed these threshold values is regarded as the high winds and heavy rainfall extent, respectively. Analysis results show that both of the high winds and heavy rainfall extent are positively correlated with the TC landfall intensity while the ratio of the high winds extent to the total TC-influence extent is negatively correlated with the ratio of the heavy rainfall extent to the total TC-influence extent. Accordingly, the heavy rainfall dominated TC generally shows weaker winds and heavier rainfall than high winds dominated TC. This negative relationship between the relative extent of high wind and heavy rainfall becomes more noticeable as TC weakens. A composite analysis on large-scale environments revealed that the presence of anomalous upper tropospheric trough and jet flow over the Korean peninsula appears to be responsible for heavy rainfall dominated TC, and vice versa for high winds dominated TC.