The melting layer of precipitation has a major impact on remote sensing and telecommunications. However, there is a shortage of observational studies to validate and constrain the melting layer models especially for high-frequency radar bands. In this paper, we report how multifrequency radar Doppler spectra can be used to retrieve the melting layer attenuation at Ka- and W-bands. The presented analysis is based on identifying Rayleigh scattering regions in radar Doppler spectra measurements where dual-wavelength spectral ratios can be related to differential attenuation. We show that the estimated attenuation at Ka- and W-bands agrees reasonably well with previously reported studies, but there are indications of differences at higher rain rates. We advocate that this technique can be applied to long-term observations to advance our knowledge of the melting process. The parameterizations of melting layer attenuation as a function of rain rate and radar reflectivity are also presented. Plain Language Summary While the melting layer is a relatively narrow layer in precipitation systems, it has a significant impact on telecommunication and remote sensing applications. For spaceborne and ground-based radar measurements, unaccounted attenuation in the melting layer may cause significant errors in retrievals of rainfall rate and ice cloud properties, respectively. There are two approaches to quantify attenuation in the melting layer, namely, through modeling or observations. Modeling studies have been carried out and are reported in the scientific literature; however, it is acknowledged that there is a shortage of observational studies that could help us to constrain the models. In this paper, we present a study that utilizes radar Doppler spectra recorded at X-, Ka-, and W-bands to retrieve melting layer attenuation. We show that the estimated attenuation at Ka- and W-bands agrees reasonably well with previous studies, but there are indications of differences at higher rain rates. With the utilization of this technique, long-term observations are expected to advance our knowledge of the melting process, as well as modeling of the melting layer attenuation for applications in millimeter-wavelength radars, passive microwave remote sensing, 5G/6G commercial links, and space-Earth telecommunications.
