An Updated Look at Tropical Cyclone Data/Statistics From A Global Perspective

In recent years, there has been a growing tendency by many in the meteorological community (media and scientist) to predict expected seasonal tropical cyclone frequency in the Atlantic Basins. Typically, the numbers are compared to seasonal averages. Although this is of most immediate concern to people in the eastern U.S., it focuses attention on the Atlantic Basin exclusively. Further, it drives climate change discussions to extrapolate global cyclone activity from that observed or predicted in one basin.

Given the increased tropical cyclone occurrence in the Atlantic in recent years, these predictions often show a large positive bias (i.e., there are more years in which the expected number of storms exceeds or far exceeds longer term climatological average).

In an attempt to determine if the Atlantic frequency increase is borne out globally, we set out to collect data from weather agencies around the world and present it in a way that was as unbiased as possible. While there were inconsistencies across the various datasets, especially in regard to wind data, we were still able to construct a realistic global cyclone database. Based on our analyses, we have concluded that high activity levels in one basin are often balanced low activity in others. The Atlantic – Eastern Pacific couplet is only one such example.

This paper will serve as an update to our previous 2011 paper, which introduced our efforts. At that time, we found, on average, 70 named tropical cyclones worldwide. In both this and our original study, we did not address the issue of naming short-lived tropical systems, which was found to be inconsistent across worldwide ocean basins.

Our results suggest, that from a global climate change perspective, there is NOT a growing NUMBER of tropical cyclones. In the current iteration of our study, we are examining, at least preliminarily, global Accumulated Cyclone Energy (ACE) values. As these values are computed more widely in the coming months, we also hope to include a breakdown of worldwide tropical systems by category and duration.