A Climatology of Intense Tropical Cyclones in the North Indian Ocean Over the Past Three Decades (1980-2008)

Abstract

The North Indian Ocean (NIO) is not considered as one of the more active tropical cyclone basins. On average each year, only five or six systems reach at least the tropical storm stage, 35 knots or more (Singh et al. 2001). In the current debate on global warming and the evolution of the intense cyclones number, studies have given different results for the NIO. Webster et al. (2005) found an extreme increase of the Cat 4 and 5 cyclones number (Saffir and Simpson 1974) from 1975 to 2004. Landsea et al. (2006) have shown that the databases were not reliable enough as reanalysed Cat 4 and 5 cyclones have been estimated at Cat 2 and/or 3 in the previous best track. And this could change the trend reported by Webster et al. (2005). Kossin et al. (2007) did not highlight any trend from 1983 to 2005 for the same intensities. In order to bring new features, this paper provides a climatology of intense tropical cyclones in the NIO from 1980 to 2008 based on the reanalyses of the satellite pictures. This study has been inspired from Landsea (1993) who published a paper on a climatology of intense Atlantic hurricanes. The intense cyclones are those with maximum sustained winds of 100 knots or more.