CAQIMS - Components, Illinois State Water Survey

Climate and Atmospheric Science

Climate, Air Quality and Impact Modeling System (CAQIMS)

A Basis for Achieving Economic, Societal and Environmental Goals in Illinois

Xin-Zhong Liang
Department of Atmospheric Sciences and Illinois State Water Survey, Institute of Natural Resource Sustainability, University of Illinois
Regional Climate Model (RCM)

The CWRF is the Climate Extension of the Weather Research and Forecast model (WRF), incorporating all its functionalities for numerical weather predictions while enhancing the capability for climate applications (see Liang et al. 2004b for an introductory description). The WRF was originally designed mainly for numerical weather prediction (NWP) and not expressly for climate studies. To extend its capability for applications on regional climate scales, we have developed the CWRF with four crucial characteristics to improve: [1] planetary-mesoscale interaction by including an optimal buffer zone treatment that integrates realistic energy and mass fluxes across the lateral boundaries of the regional climate model (RCM) domains (Liang et al. 2001); [2] surface-atmosphere interaction by incorporating new physics modules for planetary boundary layer, land surface and terrestrial hydrology as well as observed variations or dynamic predictions of vegetation, ocean and sea ice; [3] convection-cloud-radiation interaction by implementing fully-coupled, new physical parameterizations for cumulus, cloud microphysics, cloud formation, and radiative transfer; and [4] system consistency throughout all process modules by utilizing unified water vapor saturation and solar zenith angle functions, common physical constants and coherent tunable parameters. These improvements have been accomplished through iterative, extensive model refinements, sensitivity experiments, and rigorous validations over the past 3 years. As a result, the CWRF has demonstrated greater capability and better performance in simulating the U.S. regional climate than the CMM5 (Liang et al. 2001, 2004a).

A series of papers are being prepared to document details of the CWRF formulations and skills in weather forecasts and climate predictions. The first of the series depicts the construction and implementation of surface boundary conditions, where the CWRF concept and its major modules representing surface-atmosphere interactions are briefly described (Liang et al. 2004b). The latest updates are being currently carried out to further improve surface-atmosphere [2] and convection-cloud-radiation [3] interactions, and will be completed before the proposed project starts. Most relevant to this proposed research is the land surface representation, which is described in more detail below.

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