May 23 - July 29
Factors Affecting Precipitation over Western Puerto Rico during the NASA 2021 CPEX-AW Project
Kevin Martinez-Lopez (University of Puerto Rico at Mayaguez), Dr. Naoko Sakaeda (OU/SoM), Dr. Shun-Nan Wu (OU/SoM), and Dr. Elinor Martin (OU/SoM)
What is already known:
- A mesoscale thermal low and a sea breeze pattern develop most days over Puerto Rico.
- The orography of Puerto Rico, combined with locally induced diurnal processes, are important for producing the diurnal rainfall normally received across the interior and western sections of Puerto Rico.
- Saharan dust plumes tend to reduce precipitation.
What this study adds:
- We looked at multiple factors to examine how these factors contributed to more or less diurnal precipitation over western Puerto Rico, and what is needed to get high amounts of rain.
- If just one of the factors were unfavorable, the chances of receiving large amounts of rainfall were reduced.
- A combination of multiple favorable factors resulted in higher rainfall.
- We have indications that lower concentrations of Saharan dust have three contributions to increased precipitation: higher precipitable water, lower convective inhibition, and a stronger convergence between the north and south coast of Puerto Rico.
Abstract:
Afternoon precipitation typically occurs over western Puerto Rico throughout the year, but its duration and intensity can vary significantly on a daily basis. Much research has been done to analyze the different local processes that lead to afternoon rainfall, such as the sea breeze, a thermal low and two counteracting gyres in the northwestern and southwestern parts of the island. However, it is not fully understood how the combination of these factors results in a higher or lower amount of precipitation. This study uses a set of 30 weather balloons that were launched during the NASA 2021 Convective Processes Experiment - Aerosols Winds project, two buoys and an Aerosol Robotic Network station to investigate the variations in the atmospheric conditions present during the late morning hours, right before convection develops in the early afternoon. We consider the role of sea breeze, the Saharan dust, the Convective Available Potential Energy, Convective Inhibition and the Precipitable Water obtained with the weather balloons as drivers for the diurnal precipitation. Results suggest that high rainfall was observed when most of the aforementioned factors were favorable for rainfall, but if only one factor was unfavorable, less rainfall was observed. We also find that the higher amount of Saharan dust increases the convective inhibition and reduces the convergence between the north and south coasts. This suggests that the lower amount of Saharan dust has three contributions to enhance rainfall over western Puerto Rico: higher precipitable water, lower convective inhibition, and a stronger north-south convergence. The convective inhibition had the highest correlation with afternoon rainfall.