Objective quantitative spatial verification of distributed snow cover simulations - an experiment for the whole of Switzerland

Skill measures based on 2 x 2 contingency tables were adopted for the quantitative internal verification of snow cover simulations with the distributed hydrological model PREVAH, which provided a high resolution simulation of the hydrological cycle for Switzerland for the 1981-2000 period. Simulated snow cover has been compared to data monitored at 103 stations. The skill measures provide valuable quantitative indications on the correspondence of the modelled and observed values. The analysis with objective scores reveals better model estimates of snow cover presence and distribution in locations above 1000 m a.s.l., relative to lower areas. For explicit spatial verification, 20 NOAA-AVHRR snow cover scenes were compared to the model results. The spatial and temporal differences in the agreement between observed and simulated snow cover patterns were assessed. PREVAH provides reliable snow cover simulations. The results also reveal that scores from 2 x 2 contingency tables provide objective methodological support in the quantitative estimation of the agreement between observed and simulated spatial patterns.