Radar refractivity retrievals provide insight on high-resolution near-surface moisture distribution, which are considered important to study convective and boundary layer processes. Accurate refractivity retrievals are critical for further quantitative application, such as assimilating refractivity into numerical models or radar network implementation. The concept of the retrieval technique is that the radar-received phase of a fixed ground target varies with the refractivity along its beam path. However, the technique as originally developed makes some crude assumptions about the heights of ground targets and constant vertical gradient of refractivity (dN/dH). In this study, we collect dual-polarization data at lower elevations to estimate one of the main biases of refractivity retrieval associated with these simple assumptions. Therefore, a more accurate horizontal refractivity map at a given height and a more reliable dN/dH field will be obtained.
A map of near-surface moisture from radar refractivity retrieval