Topographic–Thermal Circulations and GPS-Measured Moisture Variability around Mayaguez, Puerto Rico

Abstract

To investigate topographic-thermal circulations and the associated moisture variability over western Puerto Rico, field data were collected from 15 to 31 March 2011. Surface meteorological instruments and groundbased GPS receivers measured the circulation and precipitable water with high spatial and temporal resolution, and the Weather Research and Forecasting (WRF) Model was used to simulate the mesoscale flow at 1-km resolution. A westerly onshore flow of ;4 m s 21 over Mayaguez Bay was observed on many days, due to an interaction between thermally driven [38C (10 km) 21 ] seabreeze circulation and an island wake comprised of twin gyres. The thermally driven sea breeze occurred only when easterly synoptic winds favorably oriented the gyres with respect to the coast. Moisture associated with onshore flow was characterized by GPS measured precipitable water (PW). There is diurnal cycling of PW . 3 cm over the west coast during periods of onshore flow. The WRF Model tends to overestimate PW on the west side of the island, suggesting evapotranspiration as a process needing further attention. Fluctuations of PW affect local rainfall in times of convective instability.

Observing the Diurnal Cycle of Coastal Rainfall over Western Puerto Rico in Collaboration with University of Puerto Rico Students

“…Most of the forecast rainfall is located near a convergence zone and a cyclonic feature over northwestern Puerto Rico. This type of forecast is consistent with previous analyses of rainfall events associated with sea-breeze and orographic circulations over western Puerto Rico (Jury et al 2009;Villamil-Otero et al 2015). The global domain also ensured that large-scale synoptic features-including the North Atlantic subtropical high, upper-tropospheric troughs, and tropical cyclones-were captured within the model domain.…”

“…Western Puerto Rico is an example of such regions where the strong diurnal cycle of rainfall is observed but its prediction remains challenging. About two thirds of the daily rainfall happens around 2:00-5:00 pm local time (LT) (Jury 2022), but the precise location of the heaviest rainfall can vary from day to day (Jury et al 2009;Jury and Chiao 2013;Villamil-Otero et al 2015). To better understand the complex factors that modulate the diurnal cycle of precipitation in Puerto Rico, radiosondes were launched to collect needed observations as part of the National Aeronautics and Space Administration (NASA)'s Convective Processes Experiment-Aerosols and Winds (CPEX-AW) field campaign.…”

“…Those local effects include the complex island topography in combination with sea breeze circulations that form by late morning associated with temperature contrasts between the island and its surrounding water. This sea breeze is thought to contribute to the afternoon initiation of convection through its landward flux of moisture and near-surface convergence with topography and background southeasterly trade winds (Jury et al 2009;Jury and Chiao 2013;Villamil-Otero et al 2015).…”

Puerto Rico Grid Resilience and Transitions to 100% Renewable Energy Study (PR100): Final Report

“…The same study proposed that mechanisms that lead to precipitation in the complex topographical and atmospheric context of tropical islands like Puerto Rico were not fully understood, and simulation approaches have difficulty reflecting the real-world dynamics. More recent studies (Villamil-Otero et al 2015) have continued to try to refine the methods for modeling precipitation in these contexts. Consequently, simulation of precipitation is more challenging and should be considered more uncertain than other climate variables.…”

El Estudio de Resiliencia de la Red Electrica de Puerto Rico y Transiciones a Energia 100% Renovable (PR100): Informe Final [Puerto Rico Grid Resilience and Transitions to 100% Renewable Energy Study (PR100): Final Report]

“…El mismo estudio propuso que los mecanismos que conducen a la precipitación en el complejo contexto topográfico y atmosférico de islas tropicales como Puerto Rico no se entendían completamente, y los enfoques de simulación tienen dificultades para reflejar la dinámica del mundo real. Estudios más recientes (Villamil-Otero et al 2015) han seguido intentando perfeccionar los métodos para modelar la precipitación en estos contextos. En consecuencia, la simulación de la precipitación es más desafiante y debe considerarse más incierta que otras variables climáticas.…”