"Climate Change and Southern Hemisphere Tropical Cyclones" International Initiative – Progress since the First International Conference on Indian Ocean Tropical Cyclones and Climate Change - Monitoring and Prediction of Tropical Cyclones in the Indian Ocean and Climate Change - page 22

linear trend from which the significance level has been determined. The linear
trend significances were calculated in the two-tailed form, and the overall
significance of the trend was (conservatively) taken to be the larger of the two
assessments. Secondly, the TC time series have also been subjected to a single
break-point testing procedure. This is a non-parametric procedure based on
the Mann-Whitney statistic (Pettitt, 1979).
For severe (970 hPa or lower) TCs (Fig. 2), there are no significant trends
in the SIO and the SH, although the declining trend (-0.096 TCs/yr) in the
SPO is border-line significant (11% two-tailed).
For the most intense (950 hPa or lower) TCs (Fig. 3), there is no significant
trend in the SPO, but the trends are significant in the SIO (+0.15 TCs/yr; 1%
two-tailed) and in the SH as a whole (+0.14 TCs/yr; 3% two-tailed). Similar
Fig. 2: As for Fig.1, but for TCs with LMCP of 970 hPa or lower.
Fig. 3: As for Fig.1, but for TCs with LMCP of 950 hPa or lower.