Statistical Analysis of the Doppler Velocity Correction of Ka-band Cloud Radar and Microrain Radar Measurements

This study is trying to address that the uncertainty may be caused by the cloud radar Doppler velocity aliasing issue with the aid of Microrain radar and distrometer measurements. The Mesoscale Heavy Rain Observing System (MHROS) located at Xianning, Hubei province of China, provides a comprehensive measurement during Integrative Monsoon Frontal Rainfall Experiment (IMFRE) in the summer of 2018. Eight precipitation events during IMFRE are selected under either convective or stratiform clouds except one event that includes both convective and stratiform rain periods. The data collected during this field champion allow us to investigate (1) the effectively of the existing dealiasing algorithm for cloud radar Doppler velocity; (2) the relationship between the Doppler velocities measured by cloud radar and the precipitation rate measured by the disdrometer. The algorithm is simplified and then applied to seven events of convective clouds and/or stratiform clouds in the campaign. MRR measured velocities are used as a criterion to validate the dealiasing velocities of cloud radar measured Doppler velocities under four different rain rate ranges. The multi-instrument measurements provide a verification for the dealiasing processing. Comparisons reveal cloud radar velocities agree well with MRR velocities under rain rate between 0 and 1mm/h with correlation coefficient of 0.98 and bias less than -0.3 m/s . For other three rain rate ranges, the agreements are also acceptable, therefore four linear fitting relationships between the dealiasing Doppler velocities and the rain rate are proposed, respectively. Velocity vertical profiles of convective and stratiform clouds are also analyzed, and melting band is consistent with zero degree isotherm for stratiform clouds. At convective regions, the Doppler velocities are positively correlated with the precipitation rate, and the values increases while approaching the ground. At stratiform regions, very strong variation of Doppler velocities within the melting band, and the values are slightly deceasing with height except when the precipitation rate is greater than 10 mm h^-1. In further work, we will extract the particles’ falling velocities out of the Doppler velocities, which can be used to retrieve particle diameter and more microphysical information by particles diameter transformation will be inferred.