Evolution of Thermodynamic Structures During Rapid Growth and Decay of Extremely Severe Cyclonic Storm Chapala (2015)

Abstract

ABSTRACT: The structure and evolution of inner-core convective bursts and their differences associated with rapid intensification (RI) and rapid decay (RD) of tropical cyclone CHAPALA are examined. The inception of RI was associated with substantial increase of convective heating and its vertical extent in the inner core. Increase in diabatic heating was of the order of 12-21 oC, particularly in the middle and upper troposphere. Latent heat release produced a diabatically generated potential vorticity (PV) in vertical column. The immediate cause of RI was a significant increase of moisture flux from surface to 500 hPa. This was accomplished primarily by updrafts of the order of 6-12 Pa s−1, representing the strong vertical motion distribution inside the warm core convective zone. The episode of deep convective bursts transpired during the period of RI. The evolving flow became highly symmetric and dominated by deep convective axisymmetric vortex structures. The RD coincided with the significant weakening in updraft of moisture flux consequently decrease of diabatic heating in the middle and upper troposphere and dissipation of upper and lower PV. Keywords: tropical cyclone, rapid intensification, rapid decay, potential vorticity, latent heat, diabatic heating, Arabian Sea