Annual cycle of the SPI in Barbados and the ONI 1970 to 2016.
Annual cycle of (a) SPI (6-month timescale) (SPI-6) calculated using precipitation data from the CIMH synoptic weather station (elevation of 112 m) located in the western parish of St. James, Barbados. (b) ONI, defined as the 3-month running-mean sea surface temperature departures from average in the Niño 3.4 region (120–170°W, 5°S–5°N), from January 1970 to December 2016. Source: NOAA/NWS/CPC. Severe droughts (negative SPI-6 values; brown shading) tend to coincide with El Niño events (positive ONI values; red shading). CIMH, Caribbean Institute of Meteorology and Hydrology; ONI, Oceanic Niño Index; SPI, Standardised Precipitation Index.