[A-AS05] Weather, Climate, and Environmental Science Studies using High-Performance Computing

[AAS05-P04] Projection of high clouds and its link to ice hydrometeors: An approach by using long-term global cloud-system resolving simulations

*Ying-Wen Chen¹, Masaki Satoh^1,2, Chihiro Kodama², Akira Noda², Yohei Yamada² (1.Atmospheric and Ocean Research Institute, The University of Tokyo , 2.Japan Agency for Marine-Earth Science and Technology)

Keywords:Cloud-System Resolving Model, Global Warming Experiment

This study examines projections of high clouds related to sea surface temperature (SST) change using 14-km simulation output of NICAM, a global cloud-system resolving model. This study focuses on how the vertical and horizontal structure of high cloud response to the SST pattern and how these cloud responses linked to the ice hydrometeors, such as cloud ice, snow and graupel, which are not resolved by conventional GCMs. Under the present climate, the vertical and horizontal structure of the simulated tropical high cloud amount increase against positive tropical mean SST anomalies have similar behaviors to GOCCP cloud fraction against to HadISST. We furthermore showed that the simulated high cloud amount is mainly attributed to the cloud ice. Under a warming climate, the composite vertical and horizontal structure of the tropical high cloud response to the SST shows similar behavior to that under the present climate, while the amplitude of the variation is greater than that under the present climate with a factor of 1.5 and spread wider than that under the present climate; this amplification contributes to the high cloud increase under the warming climate, which is directly linked to the wider spatial spread of cloud ice in the eastern Pacific region. This study specifically reveals the similarity of the patterns of the responses of the high cloud fraction and cloud ice to global warming, indicating that an appropriate treatment of ice hydrometeors in global climate models is a key to simulating high clouds and their response to global warming.