Characteristics and Impacts of Rossby Wave Breaking during the Atlantic Hurricane Season

This study investigates the characteristics and impacts of anticyclonic Rossby wave breaking (RWB) during the Atlantic hurricane seasons (July-Oct). Although RWB is detected near the tropopause, it perturbs the wind and moisture fields throughout the troposphere and modulates the sea-level pressure and precipitation. RWB plays an important role in the moisture and momentum exchange between the tropics and extratropics. When extratropical RWB occurs more frequently, the tropical Atlantic is subject to stronger VWS and reduced tropospheric moisture, which contributes to suppressed TC activity over the Atlantic. A significant negative correlation was found between the frequency of RWB occurrence and Atlantic TC activity (TC counts, hurricane counts and the accumulated cyclone energy) during 1979-2013, and the correlations are comparable to the correlations of Atlantic TC activity with sea surface temperature of the Atlantic Main Development Region, and stronger than the correlations with the Nino3.4 index. The implication of the findings for the predictability of Atlantic TC activity will also be discussed.