Climatology of aerosols over the Caribbean islands: aerosol types, synoptic patterns and transport

Abstract

We present a climatological study of aerosols in four representative Caribbean Sea islands that is based on daily mean values of aerosol optical properties for the period 2008¿16, using the aerosol optical depth (AOD) and Ångström exponent (AE) to classify the dominant aerosol type. A climatological assessment of the spatiotemporal distribution of the main aerosol types, their links with synoptic patterns, and the transport from different sources is provided. Maximum values of AOD occur in the rainy season, coinciding with the minimum in AE and an increased occurrence of dust, whereas the minimum of AOD occurs in the dry season, due to the predominance of marine aerosols. Marine and dust aerosol are more frequent in the easternmost islands and decrease westward because of an increase of continental and mixture dust aerosols. Therefore, the westernmost station displays the most heterogeneous composition of aerosols. Using a weather-type classification, we identify a quantifiable influence of the atmospheric circulation in the distribution of Caribbean aerosols. However, they can occur under relatively weak and/or diverse synoptic patterns, typically involving transient systems and specific configurations of the Azores high that depend on the considered station. Backward trajectories indicate that dry-season marine aerosols and rainy season dust are transported by air parcels traveling within the tropical easterly winds. The main source region for both types of aerosols is the subtropical eastern Atlantic Ocean, except for Cuba, where the largest contributor to dry-season marine aerosols is the subtropical western Atlantic. Different aerosol types follow similar pathways, suggesting a key role of emission sources in determining the spatiotemporal distribution of Caribbean aerosols.