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High resolution retrieval of liquid water vertical distributions using collocated Ka‐band and W‐band cloud radars
Author(s) -
Huang Dong,
Johnson Karen,
Liu Yangang,
Wiscombe Warren
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2009gl041364
Subject(s) - remote sensing , radar , environmental science , microwave radiometer , lidar , attenuation , microwave , ka band , radiometer , liquid water path , cloud base , geology , meteorology , optics , cloud computing , physics , computer science , precipitation , telecommunications , quantum mechanics , operating system
The retrieval of cloud water content using dual‐frequency radar attenuation is very sensitive to error in radar reflectivity. Either a long radar dwell time or an average over many range gates is needed to reduce random noise in radar data and thus to obtain accurate retrievals – but at the cost of poorer temporal and spatial resolution. In this letter we have shown that, by using advanced mathematical inversion techniques like total variation regularization, vertically resolved liquid water content can be retrieved at an accuracy of about 0.15 gm −3 at 40 m resolution. This is demonstrated using the co‐located Ka‐band and W‐band cloud radars operated by the Atmospheric Radiation Measurement program. The liquid water path calculated from the radars agrees closely with that from a microwave radiometer, with a mean difference of 70 gm −2 . Comparison with lidar observations reveals that the dual‐frequency retrieval also reasonably captures the cloud base height of drizzling clouds – something that is very difficult to determine from radar reflectivity alone.