Does the Reduction in the Southern Ocean Radiation Bias Alleviate the
The radiation bias over the Southern Ocean was terribly bad in MRI-CGCM3
that was used for CMIP5 simulations. However, the bias is significantly
reduced in MRI-ESM2 (Yukimoto et al. 2019) that is used for CMIP6
simulations by various modifications related to clouds (Kawai et al.
2019). On the other hand, the double-ITCZ problem is also alleviated in
the MRI-ESM2 (Tian and Dong, 2020). Is the reduction in the Southern
Ocean radiation bias the cause of alleviation of the double-ITCZ
problem? Each modification that contributed to the reduction of the
Southern Ocean radiation bias in the MRI-ESM2 was progressively reverted
to the corresponding older treatment in order to examine their
individual impacts on the ITCZ problem. Results show the double-ITCZ
problem worsens almost monotonically when the excessive shortwave
insolation over the Southern Ocean increases (Kawai et al. 2020, 2021).