RELATION OF THERMODYNAMIC PARAMETERS OF THE ATMOSPHERE WITH CYCLOGENESIS IN THE TROPICAL NORTHWESTERN PACIFIC OCEAN

M. S. Permyakov, N. P. Malikova, E. Yu. Potalova, and T. I. Tarkhova

Cyclogenesis conditions in the tropical northwestern Pacific are studied using monthly mean data for every cyclone separately in different stages of its development. It is shown that tropical cyclones (TCs) originate and develop in regions with small background gradients of surface temperature and air pressure. A relation of a nondimensional thermodynamic parameter determined by static atmospheric stability and humidity in the boundary layer to TC development is found. Parameter values critical to TC development are close to 1, and its large values correspond to regions with a high frequency of TC formation and development. On seasonal and monthly scales, the major factors of TC genesis are the sea surface temperature and its gradients.