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Japan Seas

P8 - Japan Coastal Ocean Predictability Experiment (JCOPE)

P8-domain description JCOPE2 - Model domain and SST

A high-resolution forecast system of the Northwest Pacific Ocean has been developed to investigate predictability of the Kuroshio path variation south of Japan (Miyazawa and Yamagata, 2003). This project has begun October 1997 under the initiative of the Frontier Research Center for Global Change (FRCGC), which is supported Japan Agency for Marine-Earth Science and Technology (JAMSTEC).

Domain
Our ocean model is based on the Princeton Ocean Model with generalized coordinate of sigma (POMgcs). A high-resolution regional model with spatial grid of 1/12° and 45 vertical levels is embedded in a low-resolution model covering the North Pacific region (30°S-62°N, 100°E-90°W) with a spatial grid of about ¼° and 21 sigma levels. The inner model domain covers the northwest Pacific (12°-62°N, 117°-180°E) and its lateral boundary conditions are determined from the basin-wide model using the one-way nesting method (Guo et al., 2003).

Modelling strategy & forcings
The model is driven by wind stresses, and heat and salt fluxes. The wind stress and heat flux field are calculated from the 6-hourly NCEP/NCAR reanalysis data and the QuikSCAT Near-Realtime (NRT) data product using the bulk formula. The salinity at the surface is restored to the monthly mean climatology with a time scale of 30 days. Synoptic variations in the Northwest Pacific Ocean are well simulated using the high-resolution model (Miyazawa et al., 2004).

Using an optimum interpolation (OI) method, weekly mean various data are created from sea surface height anomaly (Jason-1 and Geosat Follow On), sea surface temperature (NOAA/AVHRR), and subsurface temperature/salinity profiles including the ARGO data (GTSPP). To consistently assimilate those data into the model, the multivariate optimum interpolation method is adopted to estimate the analysis data of temperature/salinity in vertical column. The analysis data are smoothly introduced into the model using the Incremental Analysis Update (IAU).

Since our preliminary study suggests the model has a forecasting skill of two months for the Kuroshio path variation south of Japan (Miyazawa et al., 2005), two months forecast run driven by the monthly mean climatological surface forcing is weekly updated.
Visualized forecast results are weekly uploaded to the JCOPE web site .

Since the beginning of the forecast operation in December 2001, the JCOPE system has shown passable forecast skill of the Kuroshio path south of Japan. In particular, both the formation in summer 2004 and decline in summer 2005 of the Kuroshio large meander have been successfully predicted two months before the events. Detail of the JCOPE forecast system is described in Kagimoto et al. (2006).

The present JCOPE forecast system with the horizontal resolution of approximately 10 km has potential to predict path variations of the Kuroshio. Hence by releasing the output to the public we may contribute to people who are engaged particularly in open-ocean fishery and shippings as well as scientists who study on the Kuroshio. The resolution is, however, still too coarse for the public to utilize the output (e.g. for coastal fishery and coastal leisure).

Hence we have been developing a further fine resolution (1/108°) forecast model for the coastal region including the Tokyo-bay, Sagami-Bays and Suruga-Bay. Since in such areas tidal currents are as important as the geostrophic currents, we are now developing a tidal simulation model (Kagimoto et al., 2006).


Project status
Outputs of the current JCOPE ocean forecast system can be utilized as pseudo-data for many purposes. We have distributed the JCOPE data products to many users including scientists, governmental organizations, and private companies since November 2003. Because of the fineness of the horizontal resolution, the JCOPE data have been used for the lateral boundary condition of a regional ocean model and for the bottom boundary condition of a regional atmospheric model. Recently JAMSTEC and the Fisheries Research Agency of Japan (FRA) have started a collaboration study, FRA-JCOPE, to establish the ocean fishery forecast in Japan coastal ocean through inclusion of additional observations obtained by the FRA into the modified JCOPE system.

 

 

References
Guo, X., H. Hukuda, Y. Miyazawa, and T. Yamagata, 2003: A triply nested ocean model for simulating the Kuroshio - Roles of horizontal resolution on JEBAR. J. Phys. Oceanogr., 33, 146-169.

Kagimoto, T., Y. Miyazawa, X. Guo, and H. Kawajiri, 2006: High resolution Kuroshio forecast system - Description and its applications, in High Resolution Numerical Modeling of the Atmosphere and Ocean, W. Ohfuchi and K. Hamilton (eds), Springer, New York, submitted.

Miyazawa, Y. and T. Yamagata, 2003: The JCOPE ocean forecast system: First ARGO Science Workshop, November 12-14, 2003, Tokyo, Japan.

Miyazawa, Y., X. Guo, and T. Yamagata, 2004: Roles of meso-scale eddies in the Kuroshio paths, J. Phys. Oceanogr., 34, 2203-2222.

 

(Last Updated: 17-01-2008)