[U-02] Projection and detection of global environmental change

[U02-P02] Impacts of Precipitation Modeling on cloud response to grobal warming in MIROC6

*Nagio Hirota¹, Takuro Michibata², Hideo Shiogama¹, Tomoo Ogura¹, Kentaro Suzuki³ (1.National Institute for Environmental Studies, 2.Okayama University, 3.The University of Tokyo)

Keywords:Global warming, precipitation process, MIROC6, cloud feedback

Uncertainties in global mean temperature projections are primarily associated with the spread in cloud feedback across models, which accelerate or decelerate global warming through cloud sunshade and/or greenhouse effects. A possible reason for the spread in cloud response is the overly simplified treatment of precipitation in models, where rain and snow particles immediately fall from the atmosphere down to the surface within a single model time interval of about 10 min. Here, we introduced a more sophisticated precipitation scheme that explicitly calculates the physical processes of falling rain and snow particles, thus preserving their “memory” in the atmosphere with their sunshade and greenhouse effects incorporated. As a result, the representation of clouds is significantly improved in this model, and greenhouse effects by clouds in warming climates are significantly enhanced. This study lends credence to higher cloud feedback and climate sensitivity if models incorporate the missing feedback processes in line with observational constraints.