Caribbean Low-Level Jet future projections using a multiparameter ensemble of RegCM4 configurations

A multiparameter ensemble generated by four configurations of the regional model RegCM4 using different cumulus parameterizations and driven by the HadGEM2-ES global model is used to project changes in the Caribbean wind field, with the focus on the Caribbean Low-Level Jet (CLLJ). Two scenarios are considered, the RCP4.5 and RCP8.5. The CLLJ shows a strengthening (weakening) during the summer (winter) months compared to present day conditions in both a near future (2020-2049) and far future (2070-2099) time slice, with an eastward and northward expansion (contraction) in the core region. The warmer conditions produce an increase in specific humidity and an intensified moisture flux from the lower to the middle atmosphere in correspondence of the jet intensification. This occurs as a result of an expansion (contraction) of the North Atlantic Subtropical High of about +2 hPa (-2 hPa) into the Caribbean. All the changes are statistically significant at the 95% confidence level with a consensus across all the ensemble members.