Seasonal and interannual variability of moisture fluxes over the Intra-Americas Sea and associations with rainfall

The seasonal and interannual variability of the moisture fluxes over the Intra-Americas Sea (IAS) is evaluated using the NCEP-NCAR global reanalysis. Our seasonal results are consistent with previous studies. The seasonal variability of the moisture fluxes consists of a winter and a summer regime. It is during the summer that the IAS is most effective in supplying the moisture to central US via the northern branch of the Caribbean low-level jet (CLLJ). Winter moisture is mainly delivered to the central US from the Pacific with some contribution from the Gulf of Mexico. The interannual changes of the summer and winter inflow of moisture from the IAS into central US are primarily associated with the flow from the Atlantic through the IAS eastern boundary and secondarily with the moisture divergence in the IAS. The source of the moisture is mainly the Gulf of Mexico and the area just east of the IAS and the sink is precipitation over central US. The main mechanism for these interannual variations appears to be the Pacific North American (PNA) teleconnection pattern. Associations with ENSO mainly involve the zonal moisture exchange between the Atlantic and Pacific.