Regional long-term climate change (1950-2000) in the midtropical Atlantic and its impacts on the hydrological cycle of Puerto Rico

Large-scale climate data for the north tropical Atlantic (NTA) region show that air temperatures have increased during the past 50 years (1955-1959 to 2000-2004) with moderate warming near the Caribbean islands to considerable heating in the northern region. This pattern may be driven by sea surface temperature anomalies in the same region of study that follow relatively small changes in the Caribbean basin to stronger anomalies in the northeast. These changes might be associated with changes in the long-term pattern of the NTA high-pressure system that drives climate in the region. A series of mesoscale numerical experiments were designed to study the regional impacts these large-scale changes have on the hydrological cycle of the island of Puerto Rico. Results indicate that increased easterly surface winds for the 1950-2000 time frame disrupts a pattern of inland moisture advection and convergence zone, increasing cloud base heights and reducing the total column liquid water content over high elevations. This combination of factors produces a reduction in precipitation over the central and eastern mountains of Puerto Rico.