The Distribution and Evolution of Sea Surface Temperature at Tropical Cyclone Genesis across Ocean Basins

The mechanisms of tropical cyclone (TC) genesis are still not clear, however some environmental factors such as warm sea surface temperature (SST) are thought to be favorable to TC genesis. Recent studies have examined the distribution of SST at the time of TC genesis to revisit the threshold SST for TC genesis. They have confirmed a global threshold of about 26°C for TCs in the IBTrACS database in the era of global satellite observations.

Here, we perform a basin-by-basin analysis of the SST distributions at the time of TC genesis and their long-term trends in the five most active ocean basins. The probability distribution functions of genesis SST are very close to normal distributions, with different values of the mean and standard deviation for each basin. A consequence of these differences between basins is that an apparent global threshold SST for TC genesis arises from the climatological colder basins. The mean genesis SST shows a statistically significant warming trend over the last 30 years for each ocean basin. This trend generally reflects the corresponding basin-mean warming trend, which is suggestive of anthropogenic climate change.