The EnviroAtlas project gathered Puerto Rico's climate data using the PRISM model. PRISM blends rainfall and temperature measurements with the island's topography. The result is a map showing the average annual precipitation and the minimum and maximum temperatures for 1963β1995. On average, the island receives about 2,500β―mm of rain per year, but the central mountains collect over 4,000β―mm, while coastal areas get less than 1,500β―mm. Minimum temperatures range from 15β―°C in the highest zones to 22β―°C at sea level. Maximum temperatures vary from 28β―°C to 32β―°C, depending on the season. These differences create unique microclimates: montane rainforests host species different from the sandy beaches. Farmers use these maps to pick suitable crops, like coffee in cooler areas and sugarcane in hot plains. Moreover, scientists compare these βnormalsβ with recent data to see how climate change is shifting rain and heat. If the future brings more drought, the maps will help plan water resources and protect the most vulnerable habitats.
The PRISM (Parameter-elevation Regressions on Independent Slopes Model) technique is a statistical interpolation method that estimates climate variables on a fine grid, typically 800β―m or 4β―km. It leverages the correlation between elevation, aspect, distance from the sea, and other topographic factors to correct point measurements from scattered weather stations. For the 1963β1995 period, PRISM calculated annual averages of precipitation (mm) and minimum and maximum temperatures (°C) across the island, generating 30βyear climate normals, a standard recognized by the IPCC for assessing climate deviations. The spatial resolution allows distinguishing local variations, such as orographic rainfall in the Luquillo mountain range, where moist air rises and condenses, producing heavier precipitation than in coastal plains. Model uncertainties stem from station density, historical data quality, and the model's ability to capture microβclimatic phenomena like sea breezes. Nevertheless, PRISM has been validated with independent data, showing RMSE (Root Mean Square Error) errors below 10β―% for rainfall and 1β―°C for temperatures. These maps are essential for hydrology studies, ecological modeling, and climate vulnerability assessments, providing a robust baseline against which recent warming and precipitation trends can be compared. Moreover, scientists can integrate PRISM data with climate change models (GCMs) to project future scenarios at a local scale, supporting adaptation planning for coastal and mountainous communities in Puerto Rico.
