Multi-Frequency Radar Measurements of Rain at K/Ka/W Bands

Abstract

This paper presents experimental multi-frequency radar measurements of rain obtained simultaneously at K -, Ka -, and W -band frequencies using colocated vertically pointing radars operating at 24,35, and 94 GHz. The analysis focuses on frequency-dependent behavior of radar reflectivity and mean Doppler velocity during an hour precipitation event. Systematic differences in reflectivity are observed across the three frequency bands, with increasing impact of non-Rayleigh scattering and rain-induced attenuation toward higher frequencies. Doppler velocity measurements reveal consistent reduction of mean fall velocity at Ka- and W-band due to enhanced sensitivity to small-drop populations. Surface rain-gauge observations indicate intermittent precipitation reaching the ground, highlighting the importance of vertical context and sub-cloud evaporation for interpretation of radar measurements. The results demonstrate the complementary nature of multi-frequency radar observations and their potential for improved characterization of precipitation processes.