regional forcings on climate as summarized by Kabat et al. (2004). However, despite the plausible scientific basis as to why teleconnections should be expected and the analog to ENSO events, the global teleconnections associated with these regional forcings are not as widely accepted. The argument against the robustness of the long-range connectivity involves possible oversensitivity of the climate models that have been used in the studies and the statistical significance of the results.

To address these comments, climate models with appropriate sensitivity and resolution should be used to perform experiments with observed regional anomalies of diabatic forcing, as well as with realistic perturbation simulations (such as between natural and current landscapes). The results should be tested statistically to assess the robustness of any differences. Van den Hurk et al. (2003), for example, conducted three ensembles of five runs each: the control ensemble used constant global leaf area index (LAI) values; the second ensemble used seasonally varying LAI fields; and a third ensemble used the same seasonally varying LAI fields but with a noise term added. This methodology should be adopted for each of the regional diabatic forcings. Sufficient computer resources are required for these computationally expensive integrations.

Simulating Regional Climate

A summary of the current state of regional climate modeling is reported in Kabat et al. (2004). A major new direction is the dynamic coupling between the regional atmosphere and land surface and between the atmosphere and oceans (e.g., Eastman et al., 2001a,b). Coupled atmosphere-sea ice simulations are also being performed. The incorporation of atmospheric chemistry, including aerosol effects, also needs to be included in this dynamic coupling. Matsui et al. (2004), for example, show the sensitivity of the aerosol effects on cloud and precipitation processes due to environmental thermodynamic structure. These modeling tools will permit the investigation of the role of regional radiative forcing in altering regional climate as well as high-spatial-resolution estimates of the ability of regional climate change and variability to teleconnect to other regions and globally.

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