Application of Radar-Raingauge Co-Kriging to Improve QPE and Quality Control of Real-time Rainfall Data

Quantitative precipitation estimation (QPE) often serves as an important input to hydrological and weather warning operations. Automatic raingauge (RG) data are not only fundamental in QPE but also act as the ground truth in warning operation and forecast validation. Quality control (QC) is required before the data can be used quantitatively due to systematic and random errors. Extremely large random errors and unreasonably small/zero values can hamper effective monitoring of heavy rain. Yet, both are difficult to be detected correctly. A recently proposed QC procedure based on localized radar-raingauge co-Kriging QPE and RG-QPE residuals was enhanced and described in this paper. Improved QPE performance in Hong Kong, a coastal city surrounded by waters and lacking raingauges on three sides, were demonstrated through selected cases and controlled tests.