Characteristics of Barotropic Energy Conversion in Rapid Intensifying and Decaying Tropical Cyclones Over the Western North Pacific

Abstract

Abstract The prediction of the tropical cyclone (TC) intensity remains a difficult issue. This study analyzes local instantaneous barotropic kinetic energy conversion in the lower troposphere in rapid intensifying (RI) and rapid decaying (RD) TCs over the western North Pacific (WNP) during June through November from 1979 to 2017. The kinetic energy conversion to the synoptic eddies is separated for climatological mean, interannual and intraseasonal flows. It is found that the intraseasonal cyclonic flows display a northwest‐southeast orientation in the RI TCs, but a circular feature in the RD TCs. Intraseasonal and climatological mean zonal flows contribute together to the positive kinetic energy conversion in the northwest quadrant of the RI TCs. Intraseasonal meridional flows induce positive (negative) kinetic energy conversion in the northeast (south) part of the RD TCs. The kinetic energy conversion associated with interannual flows is small for both the RI and RD TCs.

Keywords

• rapid intensifying and decaying TCs
• the barotropic kinetic energy conversion
• the background flows on different time scales
• the western North Pacific