The occurrence of hurricanes is of great significance for many regions of the World. An important contemporary question is whether there are likely to be any changes in patterns due to global warming. In this paper we present a new, easily computed index for the development of hurricanes which is based on the spatial evaluation of the gradient of evaporation with respect to sea surface temperature over the ocean. The principle of the technique leading to the specification of the index (called the H-index), which was originally presented at the 8th International Conference on Southern Hemisphere Meteorology and Oceanography held at Foz do Iguacu, Brazil, April 24-28, 2006 (Bye and Keay 2006), is reviewed in The Global Relation Between Sea Surface Temperature and Evaporation, and is then applied spatially in Spatial Evaluation of the Temperature Gradient of Evaporation. The Physical Meaning of the Hurricane Index gives a detailed discussion of the physical meaning of the H-index in terms of the mixed layer dynamics and a simple cyclostrophic model of a hurricane, Results: (I) The Observed H Fields presents the results of the evaluation of the H-index, and Results: (II) Comparison Between Observed Tropical Cyclone Numbers and the Standard Deviation of the H-index applies the index to simulate TC occurrences in three generation regions (the West Pacific (WPAC), the Atlantic (ATL) and the East Pacific (EPAC)) using both reanalysis fields and climate model results. Discussion looks at the analysis in terms of the large scale dynamics and briefly compares the H-index with other hurricane indices, and also outlines possible future developments.
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