Evaluating changes in the moisture sources for tropical cyclones precipitation in the North Atlantic that underwent extratropical transition

Abstract

In this study, we investigated the changes in the origin of moisture for the precipitation associated with tropical cyclones (TCs) after extratropical transition (ET) over the North Atlantic Ocean basin from 1980 to 2018. We analyzed the 24 hr before and after the occurrence of ET events. By applying a TC-centric methodology we found that the moisture uptake (MU) occurred predominantly in the south and southwest sectors within ∼2,000 km of TC center before ET and from the southwest and west sectors after ET. In addition, the development of the cold front and the warm conveyor belt after ET induces changes in the moisture transport pattern. Overall, the secondary circulation of TCs favored the moisture flux inward for TCs precipitation, while the large-scale baroclinic environment controlled the MU after ET.