Solid precipitation 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 were measured using a dual Ka-band radar system, which consists of two identical Ka-band radars. Because ground measurements of snow at Ka-band are limited, measured k-Z_e relations of snow can improve the GPM/DPR algorithm performance.

Different k-Z_e relations were obtained depending on surface air temperature. When surface air temperature was just above 0 ºC, k-Z_e relations were scattered and larger k values than those of rain. On the other hand, when surface air temperature was below 0 ºC, both of k and Z_e were small and the slight positive trend was found in the k-Z_e relations. The difference of k-Z_e relations of snow 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 were analyzed. Velocity-size distributions of wet snow events were clearly different from those of dry snow events. Graupels also showed different velocity-size distributions from wet and dry snow particles, and k-Z_e relations of graupel were also presented.