ZJU-AERO V0.5: An Accurate and Efficient Radar Operator designed for CMA-GFS/MESO with the capability to simulate non-spherical hydrometeors

Abstract

In this study, we present a new forward polarimetric radar operator called the Accurate and Efficient Radar Operator designed by ZheJiang University (ZJU-AERO). This operator was designed to interface with the numerical weather prediction (NWP) model of the global forecast system/regional mesoscale model of the China Meteorological Administration (CMA-GFS/MESO). The main objective of developing this observation operator was to assimilate observations from the precipitation measurement radar (PMR). It is also capable of simulating the ground-based radar's polarimetric radar variables, excluding the Doppler variables such as radial velocity and spectrum width. To calculate the hydrometeor optical properties of ZJU-AERO, we utilize the invariant-imbedding T-matrix (IITM) method, which can handle non-spherical and inhomogeneous hydrometeor particles in the atmosphere. The optical database of ZJU-AERO was designed with a multi-layered architecture to ensure the flexibility in hydrometeor morphology and orientation specifications while maintaining operational efficiency. Specifically, three levels of databases are created that store the single-scattering properties for different shapes at discrete sizes for various fixed orientations, integrated single-scattering properties over shapes and orientations, and bulk-scattering properties incorporating the size average, respectively. In this work, we elaborate on the design concepts, physical basis, and hydrometeor specifications of ZJU-AERO. Additionally, we present a case study demonstrating the application of ZJU-AERO in simulating the radar observations of Typhoon Haishen.