Figure 7.1. Rainfall, runoff and evapotranspiration derived from climate simulation results of Hahmann (H; 2004) and Wang and Eltahir (W; 2000). Hahmann’s results are for the Amazon centred on the equator, and Wang and Eltahir’s for Africa at the equator. Both studies examined the differences between ‘uniform’ precipitation over a model grid square and ‘variable’ precipitation (added to about 10% of the grid square). Large differences are seen between the two cases in the two studies: a large reduction in precipitation is seen in the Hahmann variable case relative to the uniform case, whereas an increase is seen for the Wang and Eltahir variable case. The differences are even greater for runoff: Hahmann’s uniform case runoff is three times as large as the variable case, whereas Wang and Eltahir have almost no runoff for their uniform case.