Timescales of land surface evapotranspiration response in the PILPS phase 2(c)

Present-day land surface schemes used in weather prediction and climate models include parameterizations of physical processes whose complex nonlinear interactions can lead to models of unknown spatial and temporal characteristics. This paper describes the timescales of the evapotranspiration response of 16 land surface schemes which participated in the Project for Intercomparison of Land-surface Parameterization Schemes (PILPS) Phase 2(c) Red-Arkansas River experiment. The basins were represented by 61, 1°×1° grid boxes. Ten years of hourly meteorological data were used to force 16 land surface schemes off line. The evapotranspiration responses of the models are characterized by an impulse response function (or unit kernel) which is described by a two-parameter model, representing the fast response of evaporation from the canopy surface or bare soil and a slower one due to transpiration. The analysis of the results shows significant differences among the various LSS in their characteristic timescales across the basins.