Statistical Evaluation of Combined Daily Gauge Observations and Rainfall Satellite Estimates over Continental South America

Thispaperdescribesacomprehensiveassessmentofanewhigh-resolution,gauge‐satellite-basedanalysisof daily precipitation over continental South America during 2004. This methodology is based on a combination ofadditiveandmultiplicativebiascorrectionschemestogetthelowestbiaswhencomparedwiththeobserved values (rain gauges). Intercomparisons and cross-validation tests have been carried out between independent rain gauges and different merging techniques. This validation process was done for the control algorithm [TropicalRainfallMeasuringMission(TRMM)MultisatellitePrecipitationAnalysisreal-timealgorithm]and five different merging schemes: additive bias correction; ratio bias correction; TRMM Multisatellite PrecipitationAnalysis,researchversion;andthecombinedschemeproposedinthispaper.Thesemethodologieswere tested for different months belonging to different seasons and for different network densities. All compared, merging schemes produce better results than the control algorithm; however, when finer temporal (daily) and spatial scale (regional networks) gauge datasets are included in the analysis, the improvement is remarkable. The combined scheme consistently presents the best performance among the five techniques tested in this paper. This is also true when a degraded daily gauge network is used instead of a full dataset. This technique appearstobe a suitabletoolto producereal-time, high-resolution,gauge-and satellite-based analysesofdaily precipitation over land in regional domains.

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