Influence of vertical wind shear on wind- and rainfall areas of tropical cyclones making landfall over South Korea.

Dasol Kim,Doo-Sun R Park,Jinwon Kim,Chang-Hoi Ho,Ji Nie

doi:10.1371/journal.pone.0209885

Abstract

The wind- and rainfall areas of tropical cyclones (TCs) making landfall over South Korea were examined for the period 1998–2013 by using the Modern Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) and Tropical Rainfall Measuring Mission (TRMM) 3B42 data. Here, the wind- and rainfall areas were defined as the regions where wind speeds and precipitation rates exceed 14 m s-1 and 80 mm day-1 within 1000 km from the TC center, respectively. In general, TCs show significantly asymmetric wind and rainfall structures, with strong vertical wind shear appearing over South Korea during the landfall period. The rainfall area significantly increases with environmental vertical wind shear while the wind area is not sensitive to it. Composite analyses of the cases of strong and weak vertical wind shear confirm that the increase of rainfall area is related to the asymmetric convection (rising/sinking motion in the downshear-left/upshear-right side) induced by the vertical wind shear. This work highlights the importance of local atmospheric environment in determining the area primarily affected by strong winds or heavy rainfall during TC landfalls.

Highlights

The extent of areas affected by a tropical cyclone (TC) at the time of its landfall is a critical factor in determining the damages caused by the tropical cyclones (TCs) [1,2,3]
The TC intensity of the MERRA-2 was calculated as the 10-m maximum wind speed and minimum central sea level pressure (SLP) within a radius of 300 km from the TC center
The daily maximum wind speeds over South Korea obtained from the 69 weather stations during TC landfall are significantly correlated (r = 0.67) with those from the MERRA-2, the absolute values in MERRA-2 are smaller than the observed

Summary

Introduction

The extent of areas affected by a tropical cyclone (TC) at the time of its landfall is a critical factor in determining the damages caused by the TC [1,2,3]. Areal extents of TCs, have received much less attention than other TC properties such as tracks and intensities (e.g., maximum wind speed or minimum central pressure). The National Hurricane Center of the United States, a leading agency in TC predictions, produced formal verifications of the wind radii forecasts only recently [6].

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