Archival precipitation data set for the Mississippi River Basin: Evaluation

The goals of the Global Energy and Water Cycle Experiment Continental-Scale International Project (GCIP) point to the need fo high resolution data sets on all elements of the land surface and atmospheric hydrologic cycle. A high resolution precipitation data set has been derived from radar reflectivity observations taken from the National Weather Service WSR-88D radars in the continental U.S. To evaluate the product the authors provide several case studies of radar-rain gauge comparisons at locations throughout the Mississippi River Basin. They present bias, root mean square difference, fractional standard difference, and correlation coefficient statistics for radar-rain gauge comparisons for the hourly, daily, monthly, yearly and warm season temporal scale. These point (gauge) and pixel (radar) comparisons show large discrepancies at the hourly scale, on the order of 600-800%. An evaluation of the differences associated with temporally integrated estimates shows marked reduction in these discrepancies. At the long-term (warm season), these reduce to about 10%. An estimate of the difference in the comparison of the long term accumulation of gridded gauge based estimates and radar estimates at 0.25° × 0.25° shows values in the range of 20% but decrease to about 15% after applying filtering techniques in the basin-wide comparisons.