A case study of precipitation of an anti-S-type track tropical cyclone over the Arabian Sea

Abstract

A tropical cyclone (TC) is an extreme weather phenomenon that can bring heavy rainfall. In this study, the precipitation mechanism of TC ARB 06 is investigated over the Arabian Sea (AS) in December 1998. The results show that the water vapor was sourced primarily from the southern Indian ocean, and the precipitation intensity was primarily related to the water vapor and vertical movement. The precipitation tended to the right (left) side of the path when the TC moved westward (northward). Due to the influence of wind at 200 hPa in December 1998, the environmental vertical wind shear (VWS) rotated 90° clockwise from north during the passage of the TC. With the instability of the atmospheric stratification below 700 hPa, the potential convection caused by the TC also occurred below 700 hPa. The environmental VWS mainly affected the offset of vertical movement below 700 hPa, and the offset direction was consistent with the direction of the VWS. Combined with the counterclockwise entrainment effect of the TC, the precipitation was concentrated downshear and to the left of the shear vector.