A collective list of historical El Niño and La Niña events has been developed, based on an examination of different indices describing the El Niño‐Southern Oscillation (ENSO) phenomenon. Based on this list, tropical cyclone (TC) data from a newly created TC archive for the Southern Hemisphere (SH) have been stratified accordingly and significant changes in TC occurrences depending on warm or cold phases of ENSO have been identified. TC trends in the SH (area south of the equator, 30°E to 120°W) have been examined. For the 1981/82 to 2005/06 TC seasons, there are no apparent trends in the total numbers and cyclone days of TCs, nor in numbers and cyclone days of severe TCs with minimum central pressure of 970 hPa or lower. However, significant positive trends in occurrences and cyclone days of severe TCs with minimum central pressure of 945 hPa or lower have been identified.

[1] The statistical significance of trends in tropical cyclones (TCs) in the South Indian Ocean (SIO) and the South Pacific Ocean (SPO) has been examined. Calculation of significance is based on nonparametric Monte Carlo methods, and in addition we explore whether a constant model, a linear model, or a simple breakpoint model represents a best fit to the data. For the 1981 -1982to 2006 are no apparent trends in the total numbers of TCs (by which, in this study, we mean those tropical systems attaining a minimum central pressure of 995 hPa or lower), nor in numbers of 970 hPa TCs in the SIO and the SPO (such TCs being called severe in the Southern Hemisphere). Positive trends in the numbers of 945 hPa and 950 hPa TCs in the SIO are significant but appear to be influenced to some extent by changes in data quality. In the Australian region, no significant trends in the total numbers of TCs, or in the proportion of the most intense TCs, have been found.

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