Questioning whether seasonal advance of intense tropical cyclones since the 1980s truly exists

Abstract

Shan et al. (2023) recently reported significant seasonal advances of intense tropical cyclones (TCs) in both the Northern Hemisphere (NH) and Southern Hemisphere (SH) since the 1980s, and emphasized the data insensitivity of this conclusion, based on the Advanced Dvorak Technique-Hurricane Satellite (ADT-HURSAT) and the International Best Track Archive for Climate Stewardship (IBTrACS) datasets. However, this conclusion contradicts our recent findings. Following the procedures outlined in Shan et al., our analysis reveals that the seasonal advancing trend of intense TCs does not pass the significance test in the SH. Meanwhile, for the NH, the trend is statistically significant only when using the ADT-HURSAT, but not when using the IBTrACS. These discrepancies may be due to flaws in the calculations performed by Shan et al. The above findings raise doubts about the reproducibility and validity of Shan et al.'s conclusions regarding the global seasonal advance of intense TCs. We argue that the reported seasonal advance of intense TCs since the 1980s is inconclusive, and further investigations are needed.