The Role of Convection on the Decreasing Caribbean Precipitation during a Regional, Warming Sea Surface Temperature Period: 1982–2017

This study investigates the decreasing precipitation trends during the sea-surface temperature (SST) warming period (1982 – 2017) that has been detected in the Caribbean and surrounding region. Drying trends were observed for the annual, early rainfall (ERS), and dry season (DS) for regionally accumulated rainfall and an increasing trend for the late rainfall season (LRS). Results show a link between warming SSTs and rainfall on an annual mode, however, drivers of convection during individual seasons reduce the impact of warmer SST conditions. Long-term trends in convection were analyzed using the Galvez-Davison Index (GDI) for tropical convection. Results show higher, statistically significant correlations with precipitation across the region than with sea-surface temperatures. Additionally, the GDI highlights the atmospheric conditions that drive convection during individual seasons. The dominant processes are heat/moisture availability, cool/warm mid-levels, and subsidence inversion, which drive the LRS, ERS, and DS respectively. However, the drivers of these conditions need further investigation as SSTs continue to rise but the region continues to get drier.