Comparative evaluation of micro rain radar with ground precipitation observation instruments and its application study

The micro rain radar (MRR) inversion results can be influenced by various factors. In this study, the rain gauge (RG) observations are used as the benchmark to evaluate the precipitation detection capability and application effect of MRR. The raindrop size distributions (DSD) and the corresponding inversed characteristic parameters obtained by MRR and the co-located DSG5 present weather sensor during the precipitation events from March 2022 to May 2023 at the Xiangyang National Basic Meteorological Station are implied, to evaluate the precipitation detection capability of MRR from the prospect of different heights and different rainfall types. The application effect of MRR was also analyzed by using observations during a typical rain event on May 4, 2023, in Xiangyang. The results are as follows. (1) The observed hourly rainfalls of MRR and rain gauge are most consistent with each other at the height of 100 m. (2) MRR shows the best performance at stratiform rain detection compared with convective precipitation and light rain. (3) Compared to DSG5, the contributions of medium and large raindrops to the rain rates observed by MRR are smaller during the convective rain, while the concentrations of small raindrops and their contributions to rain rates are greater. (4) Compared to MRR, the average DSD for small and medium raindrops during convective and stratiform rain observed by DSG5 are smaller. During light rain, the average DSD observed by DSG5 are also smaller for small raindrops, but larger for large raindrops. (5) During the typical rain event in Xiangyang, the bright band heights at the melting layer of stratiform and light rain remain relatively stable at around 3.8 km. For the stratiform rain, the particles undergo complex phase transitions in the bright band and eventually melt into raindrops. These raindrops mainly experienced collision and evaporation of small raindrops during their descent to the ground, and medium raindrops make the greatest contribution to the surface rain rate.