Efficient Forward Radar Operator Simulations in Melting Layer Scenarios and Evaluations of Melting Layer Scheme in ZJU-AERO Based on Ground-Based and Spaceborne Radar Observations

In this study, we proposed a novel method for improving the computational efficiency of forward radar operator in melting layer (ML) scenarios for ground-based radar. This method is based on the insights that the vertical gradients of scattering properties of stratiform cloud/precipitation systems far outweigh their horizontal gradients. Based on this new volume-sampling approach, significant performance improvements (up to 85% savings in CPU core-time with minimal loss in simulation details) were observed when simulating low fixed-elevation-angle Plan Position Indicator scans in ZJU-AERO. This study also validates the capability of the forward radar operator ZJU-AERO (Accurate and Efficient Radar Operator designed by ZheJiang University) to simulate the ML through case studies and observation verifications using both ground-based and spaceborne radar observations. The ML polarimetric signatures (Z_H, Z_DR, K_DP, and ρ_hv) in volume scan observations of a ground-based radar (S-band) from CINRAD-98DP (China's new generation Doppler weather radars with polarimetric capacity) were compared with their counterparts simulated by ZJU-AERO. Path-integrated attenuation observations obtained from Dual-frequency Precipitation Radar on board the Global Precipitation Measurements satellite were used to verify the simulated ML attenuation effects in the Ku- and Ka-bands. Results showed that the polarimetric signatures and attenuation effects of the ML generally matched up well with measurements, except for the correlation coefficients ρ_hv. Overall, these findings demonstrate the effectiveness of ZJU-AERO in modeling the ML across different platforms and radar types.