Retrieval of the rain drop size distribution using telecommunication dual-polarization microwave links

The possibility to estimate the path-averaged rain rate using commercial telecommunication microwave links has been recently demonstrated, taking advantage of the near-linearity between the specific attenuation affecting the link signal and the rain rate. In the present work, measurements from commercial telecommunication dual-polarization microwave links are used to retrieve the effective drop size distribution (DSD) along the link path. Assuming a deterministic relationship between the scale and shape parameters, the three parameter values of the Gamma DSD model can be estimated from the rain-induced attenuation affecting the horizontally and vertically polarized signals. Once the effective DSD along the path of the link is obtained, it is easy to derive the corresponding rain variables. In particular, the derived path-averaged rain rate, radar reflectivity in the horizontal polarization and the differential reflectivity are compared with independent estimates from a nearby polarimetric weather radar, for different types of rain events. The good agreement between these series shows that reliable DSD estimates can be retrieved from commercial telecommunication dual-polarization microwave link data.