The Adaptive Algorithm Research Based On The Echo Structure For Quantitative Precipitation Estimate

There is a huge challenge in the area of quantitative precipitation estimation of convective Short time floods caused by local heavy rain. In order to improve the accuracy of nowcasting convective precipitation estimation, summarizing the various methods of quantitative measurement of precipitation and analyzing the limitations of statistical method of rainfall estimating. Precipitation difference affects the accuracy of precipitation estimates because there are differences in power, heat and water vapor in different types of precipitation, which make different micro-physical mechanisms and internal structures. Based on the physical mechanism of precipitation and precipitation echo structure, coefficient A and exponent b in Z-I relationship are the spatial function rather than simply a constant, so that providing a theoretical basis for the adaptive method to quantitative estimate precipitation.The article research precipitation mechanism of convective precipitation, mixed precipitation and stratiform precipitation and analyzes their echo structural features, precipitation micro-physical characteristics and extinction law of echo. Multiple parameters have impact on precipitation such as center height, composite reflectivity factor (CR) and vertical liquid water content(VIL), so the first is to distinguish between three different types of precipitation from the structure, and then use statistical methods to fit. Respectively using 1gCR-1gI and CR-I data pairs to fit. Depending on the type of raindrop and corresponding Z-I relationship, reducing precipitation measurement error due to the unstable Z-I relationship caused by raindrop change to solve the problem that seriously underestimating heavy rainfall. The results show that 1gCR-1gI data pairs better when fitting by order and CR-I data pairs are better when fitting by high order, which means that the adaptive method to quantitative estimate precipitation is reasonable, the instability of Z-I relationship caused by physical properties and structural characteristics of precipitation.This article also research binary function relationship between CR, VIL and precipitation of convective precipitation and mixed precipitation and there is a good correlation between fitting results. The result shows that taking into account of CR and VIL can solve the problem that seriously underestimating heavy rainfall.