A Comparison of High Resolution Precipitation Accumulation Estimates from the WSR-88D Precipitation Algorithm with Rain Gage Data

摘要

Rain gage measurements were compared with high-resolution, best match radar estimates for three different events in Oklahoma. Average G/R ratios were cmputed using two methods: (1) a method weighted towards the gage amounts and (2) a method having equal weight for all observations. Method (2) proved to be highly sensitive to low accumulations of radar and gage data that were not exactly the same. Best match radar estimates were in the same accumulation category as the gage amount for 60% of the comparisons in the June 1993 case, 12% of the comparisons in the December 1993 case, and 45% of the comparisons in the April 1994 case. Overall, 35% (140/398) of the gage-radar pairs were in the same accumulation category with a majority (61%) of pairs having gage amounts higher than radar estimates. Finally, two examples were shown how apparently poor gage-radar comparisons would have been considered matches in Manion and Klazura (1993) . This underscores the need for much finer data level resolution on WSR-88D precipitation products. Many more data cases from several different offices are needed to better understand the characteristics and judge the performance of the PPS. The author plans to continue this type of study and is eliciting participation and cooperative study with interested forecast offices.