Sensitivity of Water and Energy Cycle to SST Increase and Doubling CO2 as Simulated with a Multiscale Modeling Framework

Abstract:

This study examines the sensitivity of water and energy cycle simulated by a super-parameterized Community Atmosphere Model (SPCAM) with an intermediately-prognostic higher-order turbulence closure (IPHOC) to climate perturbations. Sensitivity experiments with doubling CO₂ and uniform 2K increase of sea surface temperature (SST) are performed and compared with the control experiment with present-day SST and sea ice distributions. In most respects, the climate sensitivity of SPCAM-IPHOC lie within the typical range of conventionally general circulation models and are comparable to SPCAM without IPHOC except that SPCAM-IPHOC does not simulate strong reductions in the boundary layer cloud over land as SPCAM. The global hydrological cycle is weakened in the doubling CO₂  experiment – there is a 2.2% reduction in tropical rainfall and a similar reduction in surface evaporation and liquid water path. On the other hand, the global hydrological cycle is strengthened in the 2K SST increase experiment – there is a 8% increase in tropical rainfall and a similar increase in surface evaporation and liquid water path. A detailed analysis of various aspects of the global water and energy cycle will be presented at meeting.