Long-term changes in Australian tropical cyclone numbers.

Tropical cyclone ( TC) observations are used to examine changes in the TC climatology of the Australian region. The ability to investigate long-term changes in TC numbers improves when the El Niño-Southern Oscillation ( ENSO) is considered. Removing variability in TC numbers associated with ENSO shows a significant decreasing trend in TC numbers at the 93-98% confidence level. Additionally, there is some indication of a temporal change in the relationship between ENSO and TC numbers, with ENSO accounting for about 35-50% of the variance in TC numbers during the first half of the study period, but only 10% during the second half. [ABSTRACT FROM AUTHOR]