The Future Responses of Tropical Extreme Convection to Climate Change based on GCRM simulation

The tropics are the most active regions of convective activity on earth, which plays a crucial role in global atmospheric energy and water cycle. Climate change due to increases of greenhouse gas concentrations has led to a substantial increase in intense convection and extreme precipitation.  We use simulations from a global cloud-system resolving model, Nonhydrostatic Icosahedral Atmosphere Model (NICAM), to study the future changes of extreme convection include overshooting deep convection (ODCs) and the most intense convection (MICs) at the end of the 21st century. Combining TRMM satellite observations with ERA5 reanalysis data, we find that the NICAM well reproduces the spatio-temporal distributions of TRMM observed extreme convection and atmospheric environment. The results show that future extreme convection will show a globally increasing trend with climate warming. However, the trends vary either between different convective property thresholds or between different regions. For example, the future occurrences of ODCs with cloud top height above 15.5 km, 16.9 km and 18.3 km scaled by the global temperature increase will increase by 7%/K, 27%/K and 90%/K, respectively, over ocean where the atmosphere becomes warmer and wetter in a warming world. The corresponding changes are -1%/K, 10%/K and 37%/K over land where the atmosphere is hotter but drier. In the other hand, the frequency of MICs will increase significantly in the Atlantic and central Pacific, while decrease slightly in central and northern Africa. Specifically, the frequency of MICs in the Northern Hemisphere will increase significantly in boreal summer and decrease in boreal winter. Nevertheless, the GCRM simulations also show some discrepancies compare to the observations, i.e., the simulated convection over northeast of the South America was significantly less, which still need a further improvement. However, GCRM will be a crucial tool for studying global climate change and will undoubtedly provide important assistance for us to better address future climate change.