Is the recorded increase in short-duration North Atlantic tropical storms spurious?

The number of North Atlantic tropical storms lasting 2 days or less exhibits a large increase starting from the middle of the 20th century, driving the increase in recorded number of tropical storms over the past century. Here we present a set of quantitative analyses to assess whether this behavior is more likely associated with climate variability/change or with changes in observing systems. By using statistical methods combined with the current understanding of the physical processes, we are unable to find support for the hypothesis that the century-scale record of short-lived tropical cyclones in the Atlantic contains a detectable real climate signal. Therefore, we interpret the long-term secular increase in short-duration North Atlantic tropical storms as likely to be substantially inflated by observing system changes over time. These results strongly suggest that studies examining the frequency of North Atlantic tropical storms over the historical era (between the 19th century and present) should focus on storms of duration greater than about 2 days.