Evaluation of the enhanced near realtime precipitation data for Land Data Assimilation System

The Climate Prediction Center (CPC) of National Center for Environmental Predictions (NCEP) has been producing near realtime daily precipitation data for the conterminous US. This daily product is then time-distributed into an hourly product using the WSR-88D (i.e., NEXRAD) Stage IV precipitation data. The CPC precipitation data set was originally produced at 1/4 degree spatial resolution using the Cressman scheme. The multi-agency/multi-university Land Data Assimilation System (LDAS) has been using this data set to drive its various land surface models. Recently, Hydrology Laboratory of National Weather Service has been collaborating with CPC and the Environmental Modeling Center (EMC), also of NCEP, to develop a higher spatial resolution precipitation product using a new analysis scheme. This new scheme utilizes the inverse distance weighting method to interpolate the precipitation field spatially. It also uses the PRISM precipitation climatology to adjust for orographic precipitation effect. This presentation will intercompare these two precipitation products. A statistical analysis will be conducted to examine the spatial difference between these two data sets. Cumulative differences over various analysis periods will also be analyzed. Finally the effect of different precipitation data on the performance of land surface models will be investigated.