Macroscale estimation of evaporation from regional water balance

Annual evaporation (E) is often determined using the water balance approach, E = P—Q, because precipitation (P) and runoff (Q) are easily obtainable for most parts of the world. From a regional perspective, P and Q are point observations, containing information pertaining both to the regional trend and to the local environment. Trend surface analysis provides a simple method to filter out the local element, permitting a regional estimation of …