[A-AS02] High performance computing of next generation weather, climate, and environmental sciences using K

[AAS02-05] Vertical grid spacing necessary for simulating tropical cirrus clouds

*清木 達也¹、小玉 知央¹、佐藤 正樹²、端野 典平³、萩原 雄一朗⁴、岡本 創³ (1.国立研究開発法人海洋研究開発機構、2.東京大学　大気海洋研究所、3.九州大学　応用力学研究所、4.宇宙航空研究開発機構　地球観測研究センター)

キーワード：General Circulation Model, Climate, Cirrus

The distribution of simulated cirrus clouds over the tropics is affected by the particular model’s vertical grid spacing. To examine this effect, we use a high-resolution atmospheric general circulation model NICAM with 28-km and 14-km horizontal meshes. We show that a vertical grid spacing of at least 400 m is necessary to resolve the bulk structure of cirrus clouds. As one reduces the vertical grid spacing below about 1000 m, the visible cirrus cloud fraction decreases, the cloud thins (optically and geometrically), the cloud-top height lowers, and consequently, the OLR increases. These effects are stronger over the tropics. When using a vertical grid spacing of 400 m or less, the vertical profiles of effective radii and ice water content converge toward measurements (CloudSat satellite and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation).