Towards a Homogenized Century-Scale Record of Atlantic Major Hurricanes

In order to understand the historical context of recent Atlantic hurricane seasons, and to explore the impact of climate variability and change on Atlantic major (Cat. 3-4-5) hurricane activity, we develop a probabilistic ship-track-based correction to account for likely undercounts recorded in Atlantic major hurricane activity due to changing observing practices. We explore the sensitivity of the estimate to parameters in the methodology, and find that a likeliest estimate of ~1 major hurricane per year missed in the late 19th century and early 20th century. The records are compared to estimates of environmental parameter changes, and to model-based estimates of the sensitivity of Atlantic hurricanes to modes of climate variability and radiatively-forced changes. After the ship-based adjustment, we find that the century-scale increasing trend in the number of major hurricanes is no longer statistically distinguishable from zero, though the impact of ENSO and Atlantic multi-decadal variations remains clear. The long-term evolution of the ratio of adjusted major hurricanes to total hurricanes is also examined, to assess potential century-scale increases in Atlantic hurricane intensity.