A new index for tropical cyclone development from sea surface temperature and evaporation fields

Abstract

In this study, we present a new index (called the H-index) which is the spatial mean gradient of the logarithm of the surface wind speed with respect to sea surface temperature (SST), and can be easily computed from large scale fields of evaporation and SST Two independent physically based arguments indicate that tropical cyclones would tend to be spun-up in regions of negative H of large magnitude (<-1). In these regions which only occur in the tropics, significant releases of kinetic energy (KE) into the atmosphere from the ocean mixed layer due to convective instability give rise to warm core systems which may develop into intense TCs. The monthly mean histograms of H evaluated from reana..