Snow measurement using a dual Ka-band radar system for GPM/DPR algorithm development

Both equivalent radar reflectivity factor (Z_e) and specific attenuation (k) in several snow events are measured using a dual Ka-band radar system. Different k-Z_e relations are obtained depending on surface air temperature. When surface air temperature is just above 0 °C, k-Z_e relations scatter and larger k values than those of rain appear. On the other hand, when surface air temperature is below 0 °C, both k and Z_e are small and a slight positive trend appears in the k-Z_e relations. The difference of k-Z_e relations can be attributed to the difference of the backscattering and attenuation characteristics between wet and dry snow. To confirm wet/dry snow existences, 2D-video-disdrometer data are analyzed. Velocity-size distributions of wet snow events are different from those of dry snow events. Graupels also show different velocity-size distributions from wet and dry snow particles with different k-Z_e relations.