The impact of enhanced carbon dioxide concentrations on deep tropical convection (DTC) is explored using (he National Center for Atmospheric Research (NCAR) Climate System Model (CSM1) model. A 134-year simulation in which CO2 concentrations increase 1 % year-1 is analyzed. With approximately present-day CO2 concentrations (367 ppmv) the CSM1 simulation captures the observed relationship between outgoing longwave radiation (OLR) and sea-surface temperature (SST) in the tropics. The temperature threshold for deep convection in the model is approximately 24.75° C. As CO2 concentrations increase, the simulated threshold temperature for tropical convection progressively increases to -25.55° C and 26.55° C at 2×CO2 (year 80) and 3.4×CO2 (year 133). The fully coupled climate model response to increased CO2 concentrations implies that the expansion of the 26° C isotherm, the present-day observed threshold, will not yield an expansion of the regions of DTC.
All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)