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

Abstract

We introduce a combined 95-GHz radar multi-parameter (radar reflectivity Z e, Doppler velocity V D, and/or linear depolarization ratio LDR) and lidar backscatter coefficient β bk algorithm for the simultaneous retrieval of ice cloud microphysics and in-cloud vertical air motion V air within a single radar volume. Unlike earlier methods, our new approach is not limited to a specific temporal or spatial scale of V air, 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 V air 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 V air 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 V air 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 Z e -weighted particle fall velocity V tz from V D. The correlation coefficient between ice water content retrieved with the estimated V air and that retrieved with the V air measured by the EAR improved to 0.70 from values as low as 0.28 without the V air retrieval. Copyright 2009 by the American Geophysical Union.