Nonhydrostatic Icosahedral Atmospheric Model (NICAM) studies on the
supercomputer Fugaku: Challenges and next directions
NICAM (Nonhydrostatic Icosahedral Atmospheric Modeling) has been used to
conduct global storm resolving simulations with a mesh size of O(km)
over the globe (Satoh, M. et al. 2017). Using the supercomputer
“Fugaku”, we explore studies in the following directions: 1.
Large-ensemble simulations (1000 members), 2. longer-duration
simulations (100 years: HighResMIP; Kodama, C. et al. 2021), 3.
higher-resolution simulations (less than a kilometer dx; Miyamoto et al.
2013), 4. high-resolution atmosphere-ocean coupled model simulations
(atmosphere 3.5 km × ocean 0.1 deg: NICOCO; Miyakawa, T. et al. 2017),
and 5. large ensemble data assimilations with NICAM-LETKF (Yashiro, H.
et al. 2020). In this talk, we first review the current activities of
NICAM on Fugaku. As the most uncertain component of atmospheric models
in general, we intercompared the cloud properties of the DYAMOND
simulation data (Stevens, B. et al. 2019; Roh, W. et al. 2021). We found
that the domain averaged outgoing long-wave radiation is relatively
similar across the models, but the net shortwave radiation at the top of
the atmosphere shows significant differences among the models (Figure).
The vertical profiles of cloud concentration are widely divergent among
models, and cloud water content exhibits larger intermodel differences
than cloud ice. This result implies more focused evaluations of clouds
are required for improving the global storm resolving models. The
forthcoming satellite “EarthCARE” (Illingworth, A. et al. 2015)
provides a comprehensive dataset for cloud evaluations of atmospheric
models, particularly by the first cloud Doppler radar from space. We
present possible strategies for the new era of satellite collaboration
studies with global storm resolving models.