Global daily precipitation estimates proved over the European Alps

This paper is a contribution to answer the question on how well do global p recipitation fields, often used for climate model verifications, represent reality. Here we focus on the experimental version of the GPCP-1DD product, the daily precipitation estimates based on satellite measurements from the Global Precipitation Climatology Projects (GPCP) and t+6 to t+30 hours mod el predictions from the European Centre for Medium. Range Weather Forecast (ECMWT). The spatial/temporal resolution of both data sets is 1 degree/dail y. The ground truth is represented by 3100 daily rain gauge measurements op erating during June/July 1997 in the region of The Mesoscale Alpine Program me (MAP). These observations have been analyzed within the MAP section of t he global grid by statistical interpolation. Verification results are given in terms of difference fields (mean error GPCP = -0.59 mm/day; ECMWF = -1. 13mm/day), rank-order correlation coefficients (mean monthly value,GPCP = 0 .52; ECMWF = 0.67) as well as accuracy scores (probability of detection GPC P = 0.62; ECMWF = 0.80 and false alarm ratio GPCP = 0.21; ECMWF = 0.18) and skill scores (true skill statistics GPCP = 0.36; ECMWF = 0.54). These scor es indicate that both global datasets have deficits in estimating realistic ally precipitation amounts. However, the ECMWF Predictions have a high perf ormance in forecasting the spatial distribution of the precipitating areas. A major result of this study is also that accuracy and skill of the GPCP-1 DD estimates have been shown to be significantly lower than those of the EC MWF forecasts. Only the mean error of the GPCP-1DD products is low, due to the calibration with monthly synoptic data.