Contact:


Project Plan:

Start Date: January 2003

Status: Completed.

End Date: May 2003

Abstract:

As part of the CBRFC's NWS Internal HCM message, we have added the NEXRAD radar precipitation "Mean Field Bias" as calculated by the MPE (Mulitsensor Precipitation Estimator) for radars in the CBRFC area.

"Each radar site has its own mean field bias value for "correcting" the precipitation. The application of the mean field bias value is an attempt to make the radar-estimated precipitation amounts more accurate and reliable. In effect, the mean field bias value is applied to unbias the radar estimated precipitation amounts."

"The bias values are arrived at by comparing ground truth precipitation observations (from gages) with the raw radar-estimated rainfall amounts over ten different spans of time (also known as memory spans) ranging from under an hour, daily, weekly, monthly, seasonal, to period of record (Hydroview/MPE User's Guide)."

We have made some local adjustments to the MPE software. In order for a "gage/radar" pair to be used in the mean field bias calculation, both must have a value of 0.25".

By using radar climatology and applying some local adjustments, we have chosen where we can "trust" radar precipitation estimates by season. Please see the radar masks below.



Here is an example of the Bias values from the internal