Regional Evaluation Through Independent Precipitation Measurements: USA

This chapter concerns the validation of high resolution (mostly 0.25°, daily and three-hourly) precipitation products over the United States. A synthesis of relevant studies is followed by comparisons of high resolution estimates based on satellites and models, with in situ ground validation data over the US. All the comparisons use multiple satellite estimates as well as model data (from the NCEP GFS). First, daily results are shown from the ongoing, web-based, real-time International Precipitation Working Group validation activity over the US. Next, validation data from 15 sub-daily gauges over Kansas and Oklahoma are used to assess the performance of three-hourly precipitation estimates, with attention to the distribution of precipitation. Finally, results from the comparison of several products against data collected from the North American Monsoon Experiment are given. Results show that existing high resolution products have great skill over many areas of the US, even at the three-hourly time-scale. Significant issues still exist over orography and results are seasonally dependent.