Numerical Simulations of Island-Induced Circulations and Windward Katabatic Flow over the Guadeloupe Archipelago

Abstract

Abstract This article deals with the first high-resolution numerical modeling of the weather over the small and high islands of the Guadeloupe archipelago. Its main goal is to analyze the mechanisms that drive local-scale airflow circulations over this archipelago, using the 1-km Weather Research and Forecasting Model (WRF). Three meteorological situations corresponding to weak trade winds (WTW), medium trade winds (MTW), and strong trade winds (STW) have been selected and are linked with local Froude number values of 0.21, 0.41, and 0.82, respectively. For these three weather types, simulated typical meteorological variables present a good agreement with observational data at several locations. The 48-h simulations allow the completion of the previous coarse observational descriptions that did not include a map of the wind, skin temperature, cloud cover, and sensible heat flux for the whole archipelago. The expected local wind regime areas (windward, inland, and leeward) are retrieved in the model outputs, including the predominance of thermal and orographic effects over Grande-Terre Island and Basse-Terre Island, respectively. Under STW, the convection is inhibited and the local circulations are driven by the orography. In the case of WTW, the model simulates well a katabatic wind, inducing cold nocturnal reversed flow on the windward coast of Basse-Terre. This circulation, opposing the trade winds, extends to the sea and Grande-Terre Island. This flow has a maximum wind speed of 4.7 m s−1. This particular flow occurring in the most densely populated area produces an important nocturnal pollution period due to industrial sources (the diesel power plants of the archipelago).