a. Dynamical downscaling method
A high-resolution version of the Max Planck Institute Earth System Model
(MPI-ESM), MPI-ESM-1-2-HR, which corresponds to a 1.0° × 1.0° grid
spacing and has an output interval of 6-hour, was used to set the
initial and lateral boundary conditions to perform dynamical downscaling
over the PRD due to its good representation of large-scale forcing and
high spatial resolution. The model’s horizontal resolution of 100 km for
the atmospheric component and 40 km for the ocean component rank high
among CMIP6 models and can provide more accurate initial and boundary
conditions for the regional model and better capture small-scale
physical processes (Adachi and Tomita 2020). In the evaluation of the
multi-models in CMIP5, MPI-ESM-MR, the antecedent version of
MPI-ESM-1-2-HR, outperformed the other models in simulating the East
Asian monsoon regions (Camargo 2013). MPI-ESM-1-2-HR in CMIP6 has higher
resolution and complexity than its lower-resolution versions and has
shown to have a well-balanced radiation budget and a better performance
in atmospheric dynamic, such as mid-latitude storm track dynamics and
atmospheric blocking (Müller et al. 2018; Xu et al. 2021; Han et al.
2022). Moreover, MPI-ESM-1-2-HR can effectively reproduce the
temperature signals of the 20th century and has
projected that the global warming level from 1850 to 2080–2100 will
range from 1.5 °C in RCP2.6 to 4.4 °C in RCP8.5. The Weather Research
and Forecasting (WRF) model was used as a nested regional model, driven
by MPI-ESM-1-2-HR, to generate fine-resolution regional climate
information pertaining to the PRD.