An evaluation of cyclone genesis parameter over the Bay of Bengal using model analysis

Abstract

The thermodynamical condition necessary for tropical cyclogenesis are commonly satisfied over most of the oceans while the dynamical conditions have large day to day variations. Zehr (1992) designed a parameter known as Genesis Parameter (GP) which involves three dynamical conditions of the environment. In this paper an intercomparison of Genesis Parameter associated with some recent developing and non-developing low pressure systems is made with a view to get an idea of its threshold value for the Bay of Bengal. Model analysis field at the resolution      1°  ´ 1° lat./long. is used for derivation of GP.  The study reveals that GP value around 20 ´ 10 –12 sec-2 against T. No. 1.5 has the potential to develop into a severe cyclonic storm.  Both for the Orissa super cyclone of October 1999 and the Bangladesh very severe cyclonic storm with core of hurricane winds of May 1997, GP attained its peak intensity at        T. No. 3.5.  There was a time lag of about  24-36 hours between GP max. and highest intensity of the system. It appears to provide useful predictive signals for the operational cyclone warning work.