A rainfall–runoff scheme for use in the Hamburg climate model

Abstract With a view to increasing the realism of the description of land surface processes in the Hamburg climate model, a scheme is introduced that accounts for the partition of rainfall at the ground between infiltration into the soil and surface runoff. The scheme was adapted and calibrated for the catchment of the river Arno and takes the heterogeneity of the land surface within a grid area into account. For the use in the general circulation model it has been expanded to account for stronger runoff components in regions of mountainous terrain. The GCM simulated annual globally averaged runoff is found to be in good agreement with observations.