Role of Caribbean low-level jet and Choco jet in the transport of moisture patterns towards Central America

Central America (CAM) is a thin strip of land, whose climate is influenced by the presence of low-level jets, by transporting atmospheric moisture from the surrounding oceanic masses (Pacific and Atlantic Oceans). In this study, we analyzed the seasonal patterns of water vapor transport to this region and their interannual variability, with special emphasis on the role of the Caribbean low-level jet (CLLJ) and the Choco jet (CJ). The semi-lagrangian 2D model Dynamic Recycling Model (DRM) is implemented, using information from ERA-Interim reanalysis during the period 1980-2012. Our results suggest that approximately 72% of mean annual atmospheric moisture transported to Central America comes from the Atlantic Ocean, with a contribution of 35% from the Caribbean Sea, and 23 and 14% from the North Atlantic and the Tropical North Atlantic, respectively. This transport is closely related to the CLLJ, showing that a strong (weak) jet induces a greater (smaller) transport from the Atlantic to CAM. On the other hand, transport from the Pacific exhibits a very marked seasonality, responding to the intensity of the CJ, which during high intensity episodes stimulates an increase in transport of water vapor. Finally, at the interannual time scale, it is found that during the positive phase of the El Nino–Southern Oscillation (ENSO) more moisture from the Caribbean reaches CAM during boreal Spring and Autumn, in contrast to a marked decrease from the Pacific during Autumn. A comparison of our results with the work by Duran-Quesada et al. (2017) using the 3D FLEXPART model, suggests that the DRM has a bias in estimating the mean annual cycle of water vapor transport associated with the CLLJ wind shear. However, the DRM is able to capture the interannual variability of the moisture transport and its response to ENSO and anomalies in the low-level jets.