NICAM (Nonhydrostatic ICosahedral Atmospheric Model) is a global cloud resolv-ing model (GCRM) for very high resolution simulation and is designed to be run with high computational efficient and accuracy. NICAM was first developed by cooperation of RIGC/JAMSTEC and AORI/the University of Tokyo. Several new numerical tech-niques are employed on the dynamical part, e.g., modified icosahedral grid (Tomita et al. 2001) and for the new non-hydrostatic scheme with total energy conservation (Satoh 2003), a simple but accurate horizontal advection scheme (Miura 2007). The physical schemes are also developed and tested dedicatedly: the 6 categories single moment bulk microphysics (NSW6; Tomita 2008), the new PBL scheme (MYNN; Noda et al. 2009), the radiation scheme (MSTRNX; Sekiguchi and Nakajima 2008). Recent model de-scription is found in Satoh et al. (2008). In this presentation, we give an overview for our recent activities and future directions.
2. Highlighted recent results
NICAM was run with 3.5km horizontal grid interval for the highest resolution. The first simulation was conducted for the aqua planet experiments and showed multi-scale structure of tropical cloud systems (Tomita et al. 2005; Nasuno et al. 2009). Cloud properties were realistically simulated by comparing satellite observations (Masunaga et al., 2008; Inoue et al. 2010). Successful simulation of Madden-Julian Oscillation was performed by NICAM (Miura et al. 2007). Since then, we have been intensively pro-moting the research of reproducibility and mechanism of intra seasonal variation, tropi-cal cyclones, and monsoon circulations (Fudeyasu et al. 2008; Oouchi et al. 2009, Ta-niguchi et al. 2010). Recently, we have conducted a time-slice experiment under a future warmed climate to investigate the change of tropical cyclones (Yamada et al. 2010). Although the integration period was relatively short (five months for each run), the ten-dency of less number and stronger intensity of TCs under the warmed climate was ob-tained. These results are consistent with the previous studies by cloud-parameterized GCM (e.g. Oouchi et al. 2006).
3. Ongoing projects and future directions
In order to examine the impact of global high resolution run, we are now collaborating with COLA, ECMWF, NICS, and Cray under the Athena project (http://wxmaps.org/athena/home/). In this project, the model intercomparison is per-formed between NICAM (7 km horizontal grid interval) and IFS (16 km horizontal grid interval) which is hydrostatic operational model in ECMWF. From the first quick anal-ysis, we found that the diurnal cycle in the cloud resolving model is better represented than the cloud-parameterized hydrostatic model. On the other hand, NICAM has still a large precipitation bias over the tropics, especially over the Indian ocean. The reduction of this bias is one of main subjects. In 2012, the K-computer, which is a high-performance super-computer with 10 PFLOPS speed and 1PB memory, will be operated in Japan. NICAM will be fully used in the strategic program of theme preventing disaster. By using this machine, we will investigate the extended predictability of tropical weather and the change of TCs under the future climate with statistical approach.
-Fudeyasu, H., Wang, Y., Satoh, M., Nasuno, T., Miura, H., Yanase, W., 2008: The global cloud-resolving model nicam successfully simulated the lifecycles of two real tropical cyclones. Geophys. Res. Lett., 35, L22808, doi:10.1029/2008GL036003.
-Inoue, T., Satoh, M., Hagihara, Y., Miura, H., Schmetz, J., 2010: Comparison of high-level clouds represented in a global cloud-system resolving model with CALIP-SO/CloudSat and geostationary satellite observations. J. Geophys. Res., 115, D00H22, doi:10.1029/2009JD012371.
-Masunaga, H., Satoh, M., Miura, H., 2008: A Joint Satellite and Global CRM Analysis of an MJO event: Model Diagnosis. J. Geophys. Res., Atmosphere, 113, D17210, doi:10.1029/2008JD009986.
-Miura, H., 2007: An upwind-baiased conservative advection scheme for spherical hex-agonal-pentagonal grids. Mon. Wea. Rev., 135, 4038-4044.
-Miura, H., Satoh, M., Nasuno, T., Noda, A.T., Oouchi, K., 2007: A Madden-Julian Os-cillation event realistically simulated by a global cloud-resolving model. Science, 318, 1763-1765.
-Nasuno, T., Miura, H., Satoh, M., Noda, A. T., Oouchi, K., 2009: Multi-scale organiza-tion of convection in a global numerical simulation of the December 2006 MJO event using explicit moist processes. J. Meteor. Soc. Japan, 87, 335-345.
-Noda, A.T., Oouchi, K., Satoh, M., Tomita, H., Iga, S.-I., Tsushima, Y., 2009: Impor-tance of the subgrid-scale turbulent moist process: cloud distribution in global cloud-resolving simulations. Atmospheric Research, Atmos. Res., 96, 208-217.
-Oouchi,K., Yoshimura,J., Yoshimura,H., Mizuta,R., Kusunoki,S., Noda,A., 2006: Tropical cyclone climatology in a global-warming climate as simulated in a 20km-mesh global atmospheric model. J. Meteoro. Soc. Japan, 84, 259-276.
-Oouchi, K., Noda, A. T., Satoh, M., Wang, B., Xie, S.-P., Takahashi, H., Yasunari, T., 2009: Asian summer monsoon simulated by a global cloud-system resolving model: Diurnal to intra-seasonal variability. Geophys. Res. Lett., 36, L11815, doi:10.1029/2009GL038271.
-Satoh,M., 2003: Conservative scheme for a compressible nonhydrostatic model with moist processes. Mon. Wea. Rev., 131, 1033-1050.
-Satoh, M., T. Matsuno,T., H. Tomita, H. Miura, T. Nasuno, S. Iga, 2008: Nonhydros-tatic Icosahedral Atmospheric Model (NICAM) for global cloud resolving simulations. J. Comp. Phys., 227, 3486-3514.
-Sekiguchi, M., Nakajima, T., 2008: A k-distribution-based radiation code and its com-putational optimization for an atmospheric general circulation model. Journal of Quan-titative Spectroscopy and Radiative Transfer, 109, Issues 17-18, 2779-2793.
-Taniguchi, H., Yanase, W., Satoh, M., 2010: Ensemble simulation of cyclone Nargis by a Global Cloud-system-resolving Model. -- Modulation of cyclogenesis by the Mad-den-Julian Oscillation. J. Meteor. Soc. Japan, 88, 571-591.
-Tomita,H., Tsugawa,M., Satoh,M., Goto, K., 2001: Shallow water model on a modified icosahedral geodesic grid by using spring dynamics. J. Comp. Phys., 174, 579-613.
-Tomita, H., Miura, H, Iga, S. Nasuno, T., and Satoh, M., 2005: A global cloud-resolving simulation: preliminary results from an aqua planet experiment. Geophys. Res. Lett., 32, L08805, doi:10.1029/2005GL022459.
-Tomita, H., 2008: New microphysics with five and six categories with diagnostic gen-eration of cloud ice. J. Meteor. Soc. Japan, 86A, 121-142.
-Yamada, Y., Oouchi, K., Satoh, M., Tomita, H., Yanase, W., 2010: Projection of changes in tropical cyclone activity and cloud height due to greenhouse warming: global cloud-system-resolving approach. Geophys. Res. Lett., 37, L07709, doi:10.1029/2010GL042518.