Remote Sensing and In-Situ Investigation over Western Puerto Rico during Saharan Dust Season

The island of Puerto Rico is located in the northeastern Caribbean. Its climate is heavily influenced by the easterly trade winds and its topography. Due to an abundance of tropical moisture, convection, and orographic clouds, strong thunderstorms tend to develop over western Puerto Rico during the summer months. Also, during these months heavy dust episodes from the Saharan Air Layer (SAL) frequently cover the island inducing hazy skies and can suppress thunderstorm development. In order to determine the state of the atmosphere over western Puerto Rico, radiosonde data was taken over Mayagüez (18.21N, 66.13W) for comparison with National Weather Service (NWS) San Juan radiosonde data. Analysis of the data for both cities revealed that vertical profiles of dew-point temperature, air temperature, and wind differ significantly near both locations between the surface and the 500 mb level, indicating a higher moisture content over western Puerto Rico. In addition, investigation of accumulated precipitation totals attained from NWS radar show that higher totals are found on the western side of the island for the days studied. Data were taken during fifteen non-consecutive days, and an average of 40 mm of rain was the difference between both cities, even with the presence high dust concentrations over the island.