THE PROJECT FOR INTERCOMPARISON OF LAND-SURFACE PARAMETERIZATION SCHEMES (PILPS) PHASE 2(C) RED-ARKANSAS RIVER BASIN EXPERIMENT - 1 - EXPERIMENT DESCRIPTION AND SUMMARY INTERCOMPARISONS

0Sixteen land-surface schemes participating in the Project for the Int ercomparison of Land-surface Schemes (PILPS) Phase 2(c) were run using 10 years (1979-1988) of forcing data for the Red-Arkansas River basin s in the Southern Great Plains region of the United States. Forcing da ta (precipitation, incoming radiation and surface meteorology) and lan d-surface characteristics (soil and vegetation parameters) were provid ed to each of the participating schemes. Two groups of runs are presen ted. (1) Calibration-validation runs, using data from six small catchm ents distributed across the modeling domain. These runs were designed to test the ability of the schemes to transfer information about model parameters to other catchments and to the computational grid boxes. ( 2) Base-runs, using data for 1979-1988, designed to evaluate the abili ty of the schemes to reproduce measured energy and water fluxes over m ultiple seasonal cycles across a climatically diverse, continental-sca le basin. All schemes completed the base-runs but five schemes chose n ot to calibrate. Observational data (from 1980-1986) including daily r iver flows and monthly basin total evaporation estimated through an at mospheric budget analysis, were used to evaluate model performance. In general, the results are consistent with earlier PILPS experiments in terms of differences among models in predicted water and energy fluxe s. The mean annual net radiation varied between 80 and 105 W m(-2) (ex cluding one model). The mean annual Bowen ratio varied from 0.52 to 1. 73 (also excluding one model) as compared to the data-estimated value of 0.92. The run-off ratios varied from a low of 0.02 to a high of 0.4 1, as compared to an observed value of 0.15. In general, those schemes that did not calibrate performed worse, not only on the validation ca tchments, but also at the scale of the entire modeling domain. This su ggests that further PILPS experiments on the value of calibration need to be carried out. (C) 1998 Elsevier Science B.V. All rights reserved .