Idealized tropical cyclone-like vortices (TCLVs) are inserted into regional climate model simulations of current and enhanced greenhouse climates and the subsequent behaviour of the vortices is analysed. This technique is similar to that of Knutson et al. (1998), but was developed independently and focusses on the Australian region. The TCLVs are simulated using multiply-nested domains at a finest horizontal resolution of 30 km, with 18 vertical levels. Forty-six TCLVs are simulated under the current climate, and fifty under enhanced greenhouse conditions. Under enhanced greenhouse conditions, modest increases in mean storm intensities are simulated, although generally these are not statistically significant. Similar results were found for the North Pacific by Knutson et al. (1998). Unlike the North Pacific, the Australian region tends to be more geographically constricted, and storms often hit land soon after they have been initialized. If land-falling storms are excluded from the analysis, the increases in intensity under enhanced greenhouse conditions are greater. This suggests that the strongest effects of climate change may occur in large, open ocean basins where storms are more likely to reach their potential intensities. An analysis is also made of the thermodynamic and dynamical constraints on the idealized TCLVs under the different climates.
Reference
Knutson, T.R., R.E. Tuleya and Y. Kurihara, 1998: Simulated increase of hurricane intensities in a CO2-warmed climate. Science 279, 1018-1020.