1. Ocean modelling activities in Japan (some of activities in China and Korea are included in the report) report to the CLIVAR Working Group for Ocean Model Development 7 th session, August 2007 by Hiroyuki Tsujino (MRI-JMA)

2. 1.Updates on oceanic components of global climate models for the next IPCC future climate projections FRCGC and CCSR: Centennial time-scale climate projection with Earth System Model, NPZD ocean eco-system, 1-deg. resolution CCSR, FRCGC, and NIES: Decadal time-scale climate projection (prediction) with high-resolution CGCM (60 km AGCM, 20 km OGCM) updates on some schemes and physics (advection, ice-thermodynamics) MRI-JMA: Centennial time-scale climate projection with Earth System Model, ocean bio-geochemical model, 1-deg. resolution Emphases on assessment of regional impacts using “time-slice” runs (regional climate model with 10 km ocean model) common coupler (atmosphere, ocean, chemicals) designed for ES to facilitate comparison

3. 1.Updating oceanic components of global climate models for the next IPCC future climate projections 2.Developing systems for seasonal to inter-annual (or longer) climate predictions 3.Updating regional ocean models for use in regional marine environment forecasts Activities are Focused on... Two research centers in China (LASG, BCC) are preparing for IPCC AR5. They are managing their own OGCM (eta-coordinate). FIO couples wave model with existing OGCMs to obtain vertical diffusion There does not seem to be major institutional effort in Korea right now. The APEC computer center will be build in Korea.

4. 3.Updating regional ocean models for use in regional marine environment forecasts FRCGC (POM), MRI-JMA(MRI.COM), RIAM (RIAMOM), Kyoto Univ. Efforts to include additional processes (biogeochemistry) to achieve higher resolution... Currently about 10 km grid spacing for relatively large region, physics only 2.Systems for seasonal to inter-annual (or longer) climate predictions MRI-JMA... ENSO (seasonal) forecast TL95L50 and 1 degree Ocean, 3D-VAR ocean data assimilation CGCM with on-line 3D-VAR data assimilated ocean FRCGC and CCSR... Decadal projection 60 km AGCM and 20 km OGCM, Ensemble Kalman Filter data assimilation for ocean and surface wind

5. 4. CORE Inter-annual forcing run: FRCGC, CCSR long-term variablity is reproduced well, mostly driven by wind stress anomalies Normal year forcing: MRI-JMA some would prefer using another re-analysis (e.g., ERA, JRA (by JMA’s AGCM)) complaining about… Equatorial thermocline (wind stress), Hawaiian lee precipitation (FRCGC-CCSR, per. comm.) radiation in the Arctic region

6. Quasi-global ocean only model with 1/8º x 1/12º (10 km) => recently globalized hierarchy of the North Pacific models differing in horizontal resolution Need for the tracer advection scheme suitable to eddying simulations … new advection scheme SOM, and/or tuning of the anisotropic GM … SOM is recently introduced and implemented in Japan community 1/4x1/61/12x1/181/36x1/54 GrADS software option PDEF to quicklook on regular grid

7. Two-way nesting ocean in CGCM (CCSR and MRI-JMA) data assimilation : robust diagnostic / semi prognostic Low resolution model : predictor – corrector ? conservation of volume, tracer, … in both models? sustainable (not ad hoc) software (or run on separated CPUs) Sharing of program codes recently turned out to be too difficult to be united or shared … Next generation code C-grid, unstructured mesh, adaptive mesh, which should we choose?