Murakami, Hiroyuki; Delworth, Thomas L.; Cooke, William F.; Zhao, Ming; Xiang, Baoqiang; Hsu, Pang-Ch, 2020, Detected climatic change in global distribution of tropical cyclones, PNAS 2020 117 (20) 10706-10714, https://doi.org/10.1073/pnas.1922500117

Historical trend in the frequency of occurrence of the most intense tropical cyclones (from 1980 to 2020) - An increase of 0.1 per year means one additional hurricane every 10 years. Here intense storms are defined as the same as major hurricanes (>=96 kt or >=111 mph in maximum wind speed).

In the netCDF file, "slope" is the TCF trend in the units of "number per day." So, please multiply it by 365 when you plot the trend in the units of "number per year" as shown in the figure in the paper. The variable "pval" is the p-value for the trend. When pval is less than or equal to 0.05, the trend on the grid cell is statistically significant at the 95% level.

The projected future change in frequency is shown in Fig. S3a for global and Fig. S3b for North Atlantic, respectively, in the Supplement of the paper. The model project decreasing number of storms in both global and North Atlantic toward the end of this century. Regarding storm intensity, although the results were not shown in the paper, the climate models project increasing storm intensity under a warmer climate.

Further information in Carbon Brief https://www.carbonbrief.org/global-warming-has-changed-spread-of-tropical-cyclones-around-the-world/

See also data in an interactive way at Perry World House Global Climate Security Atlas https://global.upenn.edu/perryworldhouse/global-climate-security-atlas