Entropy flow properties of a typhoon as simulated by a meso-scale model

¹  National Meteorological Center, CMA - 46 Zhongguancun S Avenue, CHN-100081, Beijing, China
²  State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences 46 Zhongguancun S Avenue, CHN-100081, Beijing, China

Corresponding author: cliu@cams.cma.gov.cn

Received: 21 March 2008
Accepted: 5 May 2008

Abstract

Typhoon Matsa (2005) is examined in terms of entropy flow through the entropy flow formula that is the organic component of the entropy balance equation derived from the Gibbs relation. The entropy flows in the various stages of their evolution are diagnosed based on the outputs of the Pennsylvania State University (PSU)/National Center for Atmospheric Research (NCAR) Mesoscale Model version 5 (MM5). The results show that: i) the vertical distribution of entropy flow for the typhoon is characterized by a predominant negative entropy flow (NEF) in a large portion of the troposphere with positive flow in the upper levels during its development; ii) the simulated centres of severe rainfall match well with the zones of large NEF, demonstrating that large NEF may be a significant indicator for severe weather events; and, iii) the typhoon, as a dissipative structure, develops only when the entropy flow from its surroundings is negative, and tends to decay when the NEF is weakened or replaced by positive entropy flow, suggesting that the self-organization of the typhoon is dependent on NEF.