As the availability of computer resources increases, various directions of research can
be pursued with global atmospheric models. The non-hydrostatic icosahedral atmospheric
model (NICAM) was originally developed approximately 10 years ago to run high-resolution
simulations (3.5km) using a high-end supercomputer (the Earth Simulator, JAMSTEC). Now,
on the K computer at RIKEN Advanced Institute for Computational Science (AICS), while the
horizontal mesh size has decreased to less than one kilometer (870 m) over the global domain,
other types of computationally intensive simulations using NICAM have also emerged. Multi
decadal simulations (30 years) with Atmospheric Model Intercomparison Project (AMIP) type
conditions have been performed and counterpart simulations under future conditions were also
conducted to investigate the impacts of global warming on clouds and atmospheric circulation.
Ensemble simulations to predict intra-seasonal variability have also been conducted to
investigate Madden–Julian oscillations (MJO) and the boreal summer intra-seasonal oscillations
(BSISO). Ensemble sizes have been further increased to 10,240 for assimilation via NICAM
and local ensemble transform Kalman filter (NICAM–LETKF). NICAM has also been coupled
with the ocean model COCO to study atmosphere–ocean interactions. Various options for
clouds and other physical schemes have been implemented and tested with Earth observation
data from satellites in particular.
In this talk, we review the development and scientific outcomes of NICAM in its 10-
year history and show the results of the convective properties simulated by the 870 m mesh
simulations and their resolution dependency. We find that an essential change in the simulated
convection properties occurs at a grid spacing of approximately 2 km as a global mean. The
differences in the convective properties of various types of disturbances and diurnal cycles of
convection are also examined.
Reference:
Satoh, M., Tomita, H., Yashiro, H., Miura, H., Kodama, C., Seiki, T., Noda, A. T., Yamada, Y.,
Goto, D., Sawada, M., Miyoshi, T., Niwa, Y., Hara, M., Ohno, Y., Iga, S., Arakawa, T., Inoue, T.,
Kubokawa, H. (2014) The Non-hydrostatic Icosahedral Atmospheric Model: Description and
development. Progress in Earth and Planetary Science. 1, 18.
doi.org/10.1186/s40645-014-0018-1
24.02.2016
13:30 Uhr