95-GHz Doppler radar and lidar synergy for simultaneous ice microphysics and in-cloud vertical air motion retrieval

We introduce a combined 95-GHz radar multi-parameter (radar reflectivity Ze, Doppler velocity VD, and/or linear depolarization ratio LDR) and lidar backscatter coefficient b bk algorithm for the simultaneous retrieval of ice cloud microphysics and in-cloud vertical air motion Vair within a single radar volume. Unlike earlier methods, our new approach is not limited to a specific temporal or spatial scale of Vair, which makes it applicable to the interaction between cloud dynamics and ice cloud microphysics on various scales. Full one-to-one validation of the retrieved Vair was performed, for the first time, by collocated VHF Doppler radar measurement (Equatorial Atmospheric Radar) every 3 min for a cloud observed on 14 November 2005, at Kototabang, West Sumatra, Indonesia. The spatial structure of the retrieved up-/downward Vair in cloud agreed closely with direct measurements, with an average difference of -0.009 ± 0.119 ms-1. The frequency distributions for the retrieved and measured Vair also agreed closely, with peaks of similar width observed around 0 ms-1. A large improvement in the microphysical retrieval was achieved due to the accurate estimation of the Ze-weighted particle fall velocity Vtz from VD. The correlation coefficient between ice water content retrieved with the estimated Vair and that retrieved with the Vair measured by the EAR improved to 0.70 from values as low as 0.28 without the Vair retrieval.