Static and dynamic calibration of radar data for hydrological use

The HYREX dense raingauge network over the Brue catchment in Somerset, Engl and is used to explore the accuracy of calibrated (raingauge-adjusted) weat her radar data. Calibration is restricted to the use of any single gauge wi thin the catchment so as to simulate the conditions in a typical rainfall m onitoring network. Combination of a single gauge and a radar estimate is us ed to obtain calibrated radar estimates, with the "calibration factor" vary ing dynamically from one time-frame to the next. Comparing this dynamic cal ibration with a static (long-term) calibration factor indicates the distanc e from a gauge over which the dynamic calibration is useful. A tapered cali bration factor is implemented which behaves in the same way as the raw dyna mic calibration at short distances, tending towards the static calibration factor at larger distances. This hybrid approach outperforms raingauge, unc alibrated radar, and statically-calibrated radar estimates of rainfall for the majority of raingauges in the catchment. The results provide valuable g uidance on the density of raingauge network to employ in combination with a weather radar for flood estimation and forecasting.