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- Title
Studying Altocumulus with Ice Virga Using Ground-Based Active and Passive Remote Sensors.
- Authors
Zhien Wang; Sassen, Kenneth; Whiteman, David N.; Demoz, Belay B.
- Abstract
Mixed-phase clouds are still poorly understood, though studies have indicated that their parameterization in general circulation models is critical for climate studies. Most of the knowledge of mixed-phase clouds has been gained from in situ measurements, but reliable remote sensing algorithms to study mixed-phase clouds extensively are lacking. A combined active and passive remote sensing approach for studying supercooled altocumulus with ice virga, using multiple remote sensor observations, is presented. Precipitating altocumulus clouds are a common type of mixed-phase clouds, and their easily identifiable structure provides a simple scenario to study mixed-phase clouds. First, ice virga is treated as an independent ice cloud, and an existing lidar–radar algorithm to retrieve ice water content and general effective size profiles is applied. Then, a new iterative approach is used to retrieve supercooled water cloud properties by minimizing the difference between atmospheric emitted radiance interferometer (AERI)–observed radiances and radiances, calculated using the discrete-ordinate radiative transfer model at 12 selected wavelengths. Case studies demonstrate the capabilities of this approach in retrieving radiatively important microphysical properties to characterize this type of mixed-phase cloud. The good agreement between visible optical depths derived from lidar measurement and those estimated from retrieved liquid water path and effective radius provides a closure test for the accuracy of mainly AERI-based supercooled water cloud retrieval.
- Subjects
CUMULUS clouds; CLOUDS; METEOROLOGY; REMOTE sensing; OPTICAL radar; INTERFEROMETERS; SUPERCOOLED liquids; ALTOCUMULUS
- Publication
Journal of Applied Meteorology (1988), 2004, Vol 43, Issue 3, p449
- ISSN
0894-8763
- Publication type
Article
- DOI
10.1175/1520-0450(2004)043<0449:SAWIVU>2.0.CO;2