A dual-frequency (W-band and G-band) radar optimal estimation framework to retrieve drizzle properties more accurately

Abstract. High-resolution cloud radar observations are generated from a large eddy simulation of drizzling marine stratocumulus. These observations are then used to investigate dual-frequency measurements combining W-band (94 GHz) and G-band (239 GHz), a pairing that offers unique sensitivity to early-stage drizzle and small liquid water paths by exploiting the differential backscatter and extinction signatures of hydrometeors. An optimal estimation framework is implemented to retrieve key drizzle microphysical properties from the simulated observations. We demonstrate that the synergies of a nadir-looking W-band and G-band radar system can result in more than one order of magnitude reduction in the uncertainty of the estimated drizzle mass mixing ratio, number concentration, and mass-weighted mean diameter compared to W-band only observations. The methodology can be applied to W-band and G-band airborne observations to improve drizzle estimation. Furthermore, we show that these reductions in uncertainty can be attainable from a spaceborne platform with mission architecture and radar parameters realizable with current technology.