Advancements in 0-6 Hour Blended Quantitative Precipitation Forecasting Technique for South China
CHEN Chao
WANG Min
ZHOU Xinyu
LIU Duanling
ZHANG Asi
Abstract：To further improve the accuracy of 0-6 quantitative precipitation forecast(QPF),this study applied phase and intensity corrections to hourly precipitation data from the CMA-GD(R3)model and the CMA-GD(R1)model,followed by blending achieved based on an adaptive blending equation.Secondly,extrapolation was performed on two dual-polarization radar parameters:horizontal reflectivity(ZH)and specific differential propagation phase shift(KDP).Based on the spatiotemporal classification of precipitation in Guangdong using multi-year disdrometer data and the fitting of precipitation retrieval relationships,precipitation retrieval was realized.Finally,dynamic weighting blending technique was used to blend dual-polarization radar extrapolation with model forecasts.Key factors affecting forecast accuracy,such as different model blending schemes and extrapolation schemes based on different constant-altitude plan-position-indicator(CAPPI)parameters at varying heights,were analyzed.The results show that:(1)For weak precipitation(rainfall intensity＜5 mm·h-1),the three model blending schemes exhibited varying performance across different regions and forecast times.However,for rainfall intensities ≥ 5 mm·h-1,the dual-polarization radar extrapolation combined with two model blending products(QPF_Blending)outperformed single-model blending products(QPF_R1 and QPF_R3)by at least 15％,with greater improvements observed for higher rainfall intensities.(2)In inland areas(beyond 130 km from the coastline),the use of CAPPI parameters at excessively low or high altitudes significantly impacted the accuracy of 1-hour QPF.Overall,CAPPI extrapolation at a height of 3 km yielded the highest QPF accuracy.(3)The improved 0-6 hour QPF products showed significant improvements in equitable threat score or threat score(TS)at various forecast lead times and precipitation levels,with a TS score improvement rate of 20.4％when the rainfall intensity was higher than 1 mm·h-1,and the improvement rate increased with increasing rainfall intensity.These findings effectively support the operational forecasting and warning of heavy rainfall within 0-6 hours in South China,which is of great significance for disaster prevention and mitigation.
Keywords：dual-polarization radarmesoscale modelquantitative precipitation forecasting(QPF)
Publication Date：2025-02-28
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：15( 26-40 )