Caribbean Precipitation and the Madden-Julian Oscillation

The regional climate of the Caribbean is influenced by remote events in the Pacific and Atlantic Oceans. The Madden-Julian Oscillation (MJO), which originates in the Indian Ocean, has been linked to tropical Atlantic climate and tropical cyclogenesis in the Gulf of Mexico but an explicit relationship between the MJO and Caribbean precipitation has not been investigated until now. This study uses 12 years (1997-2008) of Global Precipitation Climatology Project daily 1° gridded data to identify intraseasonal variability in precipitation across the Caribbean region that is connected to the MJO. During the early phases of the MJO, precipitation across the Caribbean is increased up to 50 % and decreases of a similar magnitude are observed in latter phases of the MJO life cycle. The influence of the MJO on Caribbean precipitation appears to be due to a combination of changes in the Caribbean low-level jet (CLLJ), upper-level divergence, vertical wind shear and sea surface temperature. Particularly large changes in low-level divergence associated with the CLLJ are postulated to play a major role in precipitation variability in the Southern Caribbean. This study also indicates a relationship between the MJO and extreme wet events in the Caribbean Sea, Puerto Rico and Cuba. This strong connection between the MJO and the regional climate of the Caribbean stresses the need to understand global-regional connections before we can adequately simulate precipitation variability in numerical models, which typically have difficulties in accurately capturing the MJO and precipitation variability.