[A-CG45] [EE] Multi-scale ocean-atmosphere interaction in the tropical Indo-Pacific region

[ACG45-P10] Large ensemble high-resolution climate simulations – Application to Event Attribution study

*Yukiko Imada¹, Shuhei Maeda¹, Masahiro Watanabe², Hideo Shiogama³, Ryo Mizuta¹, Masayoshi Ishii¹, Masahide Kimoto² (1.Meteorological Research Institute, Japan Meteorological Agency, 2.Atmosphere and Ocean Research Institute, 3.National Institute for Environmental Studies)

Keywords:Large ensemble climate simulation, AGCM, Extreme event, Heatwaves, Pacific decadal variability, Global warming

Recently, an unprecedentedly large ensemble of climate simulations with a 60 km atmospheric general circulation model and dynamical downscaling with a 20 km regional climate model have been released in Japan (the “Database for Policy Decision making for Future climate change [d4PDF]”) to assess probabilistic change in localized severe events that have large uncertainty from internal variability. Internal variability includes decadal variations in the ocean, inter-annual variability in the extratropical atmosphere, intra-seasonal variation in the tropics, and so on. Two sets of ensemble for past climate with and without historical trends associated with the anthropogenic effect, respectively, and an ensemble for 4 K warmer future climate are simulated more than 5000 years in d4PDF. Here, we will introduce our recent works using large ensemble simulations focusing on how much the inter-annual and decadal variability in the Pacific Ocean contributed to increased occurrence of heatwaves around the globe when compared to anthropogenic global warming.