Illinois State Water Survey - CAQIMS - Components, University of Illinois at Urbana-Champaign

A Basis for Achieving Economic, Societal and Environmental Goals in Illinois
Xin-Zhong Liang

General Circulation Model (GCM)
An RCM requires data from a GCM to specify the conditions at the lateral boundaries of the RCM domain. There are a number of groups world-wide that have developed sophisticated GCMs. In principal, it would be desirable to use all of them for driving the RCM. However, at the present time, the computer resources required to run an RCM are very large and this cannot be done. We have initially decided to use two GCMs. The criteria used to choose these include the representation of the range of future climate outcomes, the quality of the GCM, and availability and accessibility of the needed data.

We have examined the characteristics of 9 coupled GCMs in terms of their representation of the central U.S. climate. All of the models reproduce basic features of the large-scale circulation but none are perfect. None are clearly superior. Thus, any of these GCMs are possible candidates and the ultimate choice was based on representation of the range of future climate outcomes and availability of data. Based on these criteria, the PCM and HadCM3 were chosen.

The Parallel Climate Model (PCM) is a joint effort of the National Center for Atmospheric Research and the U.S. Department of Energy. The warming exhibited by this model is among the smallest. The data are also readily available. Thus, it is chosen to represent the low end of the potential future warming.

The Hadley Centre's third generation coupled model (HadCM3) is one of the warmest models. The data are also readily accessible. This model is chosen to represent the high end of potential future warming.

 
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