J-ARGO/index_e.html). Until the present (April 2007), a total of about 400 Argo floats have been deployed in the Pacific, Indian and Southern Oceans.
4. Research on Tropical Pacific and Indian Ocean
FRCGC of JAMSTEC started experimental prediction of ENSO in the Pacific and IOD in the Indian Ocean (http://www.jamstec.go.jp/frsgc/research/d1/iod/). The 2006 IOD was correctly predicted well ahead in November, 2005 (http://www.jamstec.go.jp/jamstec-e/PR/0610/1016/index.html). More intensive real-time acquisition of subsurface ocean data will lead to better forecasting skill and thus greater contribution to the society. To achieve this, in close collaboration with NOAA and other agencies under the auspices of EOS/GEOSS, JAMSTEC has extended the TRITON surface buoy and ADCP mooring array from the western Pacific to the eastern Indian Ocean (http://www.jamstec.go.jp/iorgc/eng/list/p1c.html). Those activities will also contribute to better description and understanding of the oceanic and atmospheric processes involved in the air-sea interaction in the tropical climate system. We particularly note that the 2006 positive IOD event was captured for the first time by the in situ buoy array in the Indian Ocean.
5. Data Assimilation Studies
Following the development of the earth-observing systems and high-speed computers, ocean data assimilation studies in Japan have markedly progressed, in both research and operational modes, during the last decade. Research activities have primarily been conducted in association with the Japan GODAE (Global Ocean Data Assimilation Experiment) consortium. Thanks to the great efforts of members, a variety of oceanographic products (e.g., sea surface and sub-surface temperature and salinity, ocean current, sea surface height and sea ice distributions), mainly in the western North Pacific Ocean and the Sea of Japan, are now distributed operationally on web site and by radio facsimile. These products are also available on the NEAR-GOOS Regional Real Time Data Base (http://goos.kishou.go.jp). Another remarkable achievement in terms of data assimilation studies is the construction of a leading-edge 4-dimensional variational coupled ocean-atmosphere data assimilation system. This system demonstrates a one-year-lead prediction capability of El Niño events and has the advantage of providing greater information content and forecast potential than do models or data alone. The reanalysis dataset is now accessible (http://www.jamstec.go.jp/frcgc /k7-dbase2/). Major groups within Japan GODAE are now in proceeding not only with ocean prediction and reanalysis but also with OSE/OSSE conducted by the international GODAE.
6. Ecosystem Modeling Studies
The Kuroshio area is major spawning area for pelagic fish, and Northern Pacific is well known as a productive area for these fish. Ecosystem modeling, coupled with physical modeling, has been conducted by Japanese Fisheries Agency and the PICES MODEL Task Team (http://www.pices.int/members/task_teams /MODEL.aspx) since 2000. Numerical models appropriate to the marginal seas, such as the Japan Sea, have also developed to reconstruct findings derived from observations, helping to clarify the underlying mechanisms. This has also included ecosystem model. A part of ecosystem modeling in the Sea of Okhotsk is supported by the Research Institute for Humanity and Nature (RIHN) (http://www. chikyu.ac.jp/AMORE/en/index-enf.htm).
7. Activity of Marine Biogeochemical Studies
As a new international project of marine chemistry, GEOTRACES (an international study of the marine biogeochemical cycles of trace elements and their isotopes) was set up in 2004; a Japanese marine geochemistry group has taken part in its establishment and advancement since 2003. GEOTRACES SSC and its Science Plan (published in September 2006) have been approved by SCOR. The project has three phases: (1) the preparation phase (planning, preparation and distribution of standards, inter-calibration, etc.), (2) the main phase (series of 12-15 sections to cover all major ocean basins, using compatible sampling and measurement protocols), and (3) the parallel and follow-up process studies phase. Several of the preceding cruises were conducted in the Pacific Ocean between 2003 and 2005 using R/V Hakuho Maru (JAMSTEC). (http://www.geotraces.org/)