Tracking a Warm Rain Cell and Retrieving the Lower Order Moments and DSD: A Case Study Using 2 X-Band Polarimetric Radars

Recently a technique was developed to retrieve moments of rain drop size distributions from X-band polarimetric radar measurements (Bringi et al., 2020, https://doi.org/10.5194/amt-13-4727-2020) . The technique involves estimating two reference moments from reflectivity and differential reflectivity as well as specific attenuation, followed by the estimation of other moments utilizing a suitable/optimal function to represent the underlying shape, the function being based on the generalized gamma model.

In this paper we apply the same technique to data from two high resolution X-band radars whose scan sequence was PPIs from one radar which covered the rain cell over a larger area topping the storm while the second radar scans were RHIs with good vertical resolution and a much narrower azimuth sector. The cell was tracked with an operational S-band radar and its scan sequence was fast surveillance scans to track rain cells using an internally developed software. The [azimuth, elevation] from the S-band radar was transmitted to the two X-band radars which started the PPI and RHI scans in coordination with a cycle time 3 minutes or less. This enabled the study of the evolution of warm rain and the process rates in a Lagrangian sense.