Projected changes in moisture sources and sinks affecting the US East Coast and the Caribbean Sea

Abstract

This study uses a combination of the FLEXPART Lagrangian dispersion model with the Weather Research and Forecasting (WRF) mesoscale Eulerian model (FLEXPART-WRF) to analyze the expected mid- to late-century changes in the moisture sources and sinks of the North American East Coast (ENA) and the Gulf of Mexico (GM), as well as their most relevant abrupt moisture transport events–atmospheric rivers (ARs) and low-level jets of the Great Plains (GPLLJ) and the Caribbean (CLLJ). Both the ENA and GM are expected to increase in importance as moisture source regions over the century, both overall and in their contributions to the ARs and both LLJs. A notable increase in the intensity of the GPLLJ and CLLJ moisture sources is also observed. All of these behaviors are neither spatially nor temporally homogeneous and need to be analyzed in a seasonal context. Likewise, the most relevant signs of change are practically all observed by the end of the century. Other noteworthy behaviors are also observed, including an increase in humidity associated with landfalling atmospheric river events in the winter months, or a notable latitudinal shift of the CLLJ's area of influence. These findings are best understood within the context of an observed increase in both continental precipitation and sea surface temperature.