Figure 4. Anomalies of observed and simulated July, August, September mean precipitation in the Sahel (10°W–30°E, 10°N–20°N) derived from the GPCC dataset (blue line) and computed from an ensemble of climate simulations with prescribed observed sea-surface temperature (black dashed line) (Park et al., 2016). Green line: standardized anomalies of the NDVI (Normalized Differential Vegetation Index), a measure of vegetation coverage and greenness, taken from Kaptué et al. (2015).