Representation of Arctic Mixed-Phase Clouds and the Wegener-Bergeron- Findeisen Process in Climate Models: Perspectives from a Cloud-Resolving Study

• Published in: Journal of Geophysical Research
• Main Authors: Fan, J., Ghan, S., Ovchinnikov, M., Liu, Xiaohong, Rasch, P. J., Korolev, A.
• Format: Other Non-Article Part of Journal/Newspaper
• Language: English
• Published: University of Wyoming. Libraries 2011
• Subjects: 3-dimensional; Aircraft measurement; Arctic clouds; Cloud microphysics; Cloud particles; Cloud properties; Cloud resolving model; Cloud-resolving; Depositional growth; Field campaign; Fixed variance; Gain insight; Gamma function; Gaussian functions; General circulation model; Ice particles; Ice water content; Large deviations; Liquid saturation; Mixed-phase cloud; Probability density function (pdf); Stratiform clouds; Sub-grids; Surface-based; Vertical velocity; Water distributions; Capacitance; Climate models; Clouds; Computer simulation; Liquids; Probability density function; Water supply systems; Water vapor; Ice; aircraft; climate modeling; Gaussian method; probability; stratiform cloud; three-dimensional modeling; Arctic; Engineering
• Online Access: https://hdl.handle.net/20.500.11919/713; https://doi.org/10.1029/2010JD015375

©2011 by the American Geophysical Union. Two types of Arctic mixed-phase clouds observed during the ISDAC and M-PACE field campaigns are simulated using a 3-dimensional cloud-resolving model (CRM) with size-resolved cloud microphysics. The modeled cloud properties agree reasonably well with aircraft measurements and surface-based retrievals. Cloud properties such as the probability density function (PDF) of vertical velocity (w), cloud liquid and ice, regimes of cloud particle growth, including the Wegener-Bergeron-Findeisen (WBF) process, and the relationships among properties/processes in mixed-phase clouds are examined to gain insights for improving their representation in General Circulation Models (GCMs). The PDF of the simulated w is well represented by a Gaussian function, validating, at least for arctic clouds, the subgrid treatment used in GCMs. The PDFs of liquid and ice water contents can be approximated by Gamma functions, and a Gaussian function can describe the total water distribution, but a fixed variance assumption should be avoided in both cases. The CRM results support the assumption frequently used in GCMs that mixed phase clouds maintain water vapor near liquid saturation. Thus, ice continues to grow throughout the stratiform cloud but the WBF process occurs in about 50% of cloud volume where liquid and ice co-exist, predominantly in downdrafts. In updrafts, liquid and ice particles grow simultaneously. The relationship between the ice depositional growth rate and cloud ice strongly depends on the capacitance of ice particles. The simplified size-independent capacitance of ice particles used in GCMs could lead to large deviations in ice depositional growth.