Prominent influence of salinity on hurricane rapid intensification

Hurricane rapid intensification (RI) is difficult to predict and poses a formidable threat to coastal populations. A warm upper-ocean is well-known to favor RI, but role of salinity is less clear. In this study, it is shown that the subsurface ocean's influence on Atlantic hurricane RI exhibits two regimes. In the western region, including the Gulf of Mexico and the western Caribbean, temperature stratification plays an important role in hurricane RI, with little impact from salinity. In the eastern region dominated by the Amazon-Orinoco plume, salinity stratification prominently impacts RI. While weak temperature stratification aids cold wake reduction for hurricanes in the western region, strong salinity stratification causes less surface cooling in the east. Thus, salinity may be a useful predictor of RI occurrence in the eastern region. In both regions, the importance of the cold wake, and consequently the subsurface ocean, is enhanced during RI compared to weaker intensification.