Raindrop Size Distribution Parameters Retrieved from Xinfeng C-Band Polarimetric Radar Observations

Abstract

The objective of this research was to acquire a raindrop size distribution (DSDs) retrieved from C-band polarimetric radar observations scheme for the first time in south China. An observation period of the precipitation process was selected, and the shape-slope (μ-Λ) relationship of this region was statistically analyzed using the raindrop sample observations from the two-dimensional video disdrometer (2DVD) at Xinfeng Station, Guangdong Province. Simulated data of the C-band polarimetric radar reflectivity ZHH and differential reflectivity ZDR were obtained through scattering simulation. The simulation data were combined with DSD fitting to determine the ZDR-Λ and log10(ZHH/N0)-Λ relationships. Using Xinfeng C-band polarimetric radar observations ZDR and ZHH, the raindrop Gamma size distribution parameters μ, Λ, and N0 were retrieved. A scheme for using C-band polarimetric radar to retrieve the DSDs was developed. This research revealed that during precipitation process, the DSDs obtained using the C-band polarimetric radar retrieval scheme are similar to the 2DVD observations, the precipitation characteristics of rainfall intensity (R), mass-weighted mean diameter (Dm) and intercept parameter (Nw) with time obtained by radar retrieval are basically consistent with the observational results of the 2DVD. This scheme establishes the relationship between the observations of the C-band polarimetric radar and the physical quantities of the numerical model. This method not only can test the prediction of the model data assimilation system on the convective scale and determine error sources, but also can improve the microphysical precipitation processes analysis and radar quantitative precipitation estimation. The present research will facilitate radar data assimilation in the future.