8.2.1.2 Horizontal and Vertical Resolution

The horizontal and vertical resolutions of AOGCMs have increased relative to the TAR. For example, HadGEM1 has eight times as many grid cells as HadCM3 (the number of cells has doubled in all three dimensions). At the National Center for Atmospheric Research (NCAR), a T85 version of the Climate System Model (CSM) is now routinely used, while a T42 version was standard at the time of the TAR. The Center for Climate System Research (CCSR), National Institute for Environmental Studies (NIES) and Frontier Research Center for Global Change (FRCGC) have developed a high-resolution climate model (MIROC-hi, which consists of a T106 L56 Atmospheric GCM (AGCM) and a 1/4° by 1/6° L48 Ocean GCM (OGCM)), and The Meteorological Research Institute (MRI) of the Japan Meteorological Agency (JMA) has developed a TL959 L60 spectral AGCM (Oouchi et al., 2006), which is being used in time-slice mode. The projections made with these models are presented in Chapter 10.

Due to the increased horizontal and vertical resolution, both regional- and global-scale climate features are better simulated. For example, a far-reaching effect of the Hawaiian Islands in the Pacific Ocean (Xie et al., 2001) has been well simulated (Sakamoto et al., 2004) and the frequency distribution of precipitation associated with the Baiu front has been improved (Kimoto et al., 2005).