5B.4
Resolution dependence of parameterized physics inferred from nonhydrostatic model experiments
Joon-Hee Jung, University of California, Los Angeles, CA; and A. Arakawa
A two-dimensional cloud-resolving model (CRM) covering a horizontal domain of 512 km is used to examine the dependence of model physics on horizontal resolution in the meso-scale range. For this purpose the CRM is integrated with 2-, 8-, and 32-km resolutions under a variety of large-scale and surface conditions. The results show that when a cumulus parameterization is not included while individual clouds are not resolved, spurious meso-scale circulations develop as a substitute to cumulus convection. Consequently, systematic errors appear on large-scale thermodynamic fields although the domain averaged vertical profiles of the source and sink terms in the thermodynamic and water budget equations (Òreal physicsÓ) hardly change with resolutions. We then explore the resolution dependence of Òapparent physicsÓ needed by a model that does not resolve individual clouds. We diagnose the Òapparent physicsÓ from the difference between the result of the CRM and that of a dynamics model that is consistent with the CRM but without physics. It is found that the Òapparent physicsÓ is considerably different from the Òreal physicsÓ even in the averages over the entire domain and it is resolution dependent. In the middle and upper troposphere, transports associated with microphysical processes are mainly responsible for this difference.
Session 5B, Convection IV (Parallel with Sessions 5A, 5C, & 5D)
Tuesday, 30 April 2002, 11:00 AM-12:30 PM
Previous paper Next paper