An Intercomparison of Precipitation Values from the OneRain Corporation Algorithm and the National Weather Service Procedure

Two widely used procedures for optimally combining radar- and gauge-derived rainfall are those by the OneRain Corporation and the National Weather Service (NWS). This paper statistically compares values from the two schemes. We consider the area of the South Honda Water Management District (SFWMD) during the 2005 calendar year. Comparisons are presented for yearly, monthly, and seasonal intervals and during Hurricane Wilma. In addition, differences between the two schemes based on hourly precipitation data are compared with those from 6 hourly and daily accumulations which often are used in hydrologic models. In summary, the paper describes the extent to which the OneRain and NWS products can be used interchangeably, i.e., those situations when differences are expected to be small or large.