Improved Qpe by Utilizing Multi Angle Ppis Measurements

Abstract:

Hybrid surface rainfall (HSR) studies have been conducted using the lowest elevation angle avoiding the effects of non-meteorological echoes (Fulton et al. 1998; Kwon et al. 2012). Since the HSR technique needs complete radar volume scan, time resolution depends on the radar schedule. In addition, the time lag due to difference between radar height and the ground can be corrected by the best cross-correlation (BCC) (Kneifel et al. 2015). The random error can be minimized by applying different area average (DAA) according to the radar beam height (Chiang et al. 2006). In this study, new QPE techniques using multi-angle PPIs measurements are proposed and are then evaluated by comparing ground disdrometer data. We also try to reduce effects of the time lag and beam broadening by applying BCC and DAA techniques. The Mt. Bisl S-band dual-polarization radar data is used. We compare three different types of rainfall products: SWEEP, HSR1.0 and HSR2.5. The SWEEP used all PPIs with individual time information. The HSR1.0 and HSR2.5 produced HSR maps every 1 minute and 2.5 minutes, respectively with fixed a time window of 2.5 times. We applied 2 options to SWEEP, HSR1.0, and HSR2.5 products to analyze rainfall estimation errors. The one option applied the BCC method to reduce error from the time lag. The other option applied the DAA according to beam heights.The results of QPE verification using three methods are summarized as follows: 1) Accurate QPE is possible with finer resolution. 2) The accuracy of HSR1.0 is increased because the variability of precipitation is well represented as the reflectivity increases. 3) Results of HSR1.0 are shows a good score regardless of BCC and DAA

Acknowledgements

This study was funded by the Korea Environmental Industry & Technology Institute (KEITI) of the Korea Ministry of Environment (MOE) as “Advanced Water Management Research Program”. (79615)