[A-AS08] [EE] 雲降水過程の統合的理解に向けて

[AAS08-08] MIROC6におけるMJO東方伝播の改善

*廣田 渚郎¹、小倉 知夫¹、建部 洋晶²、塩竈 秀夫¹、渡部 雅浩³、木本 昌秀³ (1.国立環境研究所、2.海洋開発研究機構、3.東京大学)

キーワード：MJO, climate model MIROC6, convection

A new version of the atmosphere–ocean general circulation model cooperatively produced by the Japanese research community, known as the Model for Interdisciplinary Research on Climate (MIROC6), has recently been developed. Many aspects of the Madden Julian Oscillation (MJO) simulations are improved compared with its previous version MIROC5. For example, MJO amplitudes underestimated in MIROC5 are enhanced; the MJO convective envelopes over the Indian Ocean, which often decays too early around the Maritime Continent in MIROC5, propagate farther to the Central Pacific; the vertical structure of the MJO related humidity shows more realistic stepwise moistening associated with the transition from shallow convection to deep convection. Our preliminary analyses indicate that these improvements are associated with a newly implemented shallow convection scheme. The shallow convection in MIROC6 transports the boundary layer moisture to the lower free troposphere, mitigating dry biases around 800hPa over the Western Pacific. MIROC6 also shows improvements in climatological mean precipitation and shallow cloud distribution.