Updated: June 1, 2004

Eddy-Resolving Simulation of the World Ocean

A continuing effort of pushing the frontier of the global eddy-resolving simulation: one of the center's core projects cooperatively designed by oceanographic research teams in Frontier Research System for Global Change.

Objective

The world ocean plays an important role in climate variability and its reliable modeling with less parameterization is a growing concern for not only the oceanographic but also climate research community as a whole. Accumulated knowledge through modeling studies shows that high-resolution simulations are quite informative and hence useful for data-sparse climate researches since their outputs are expected to provide comprehensive three dimensional datasets that aid us in interpreting the extensive observations made during the last decade [Smith et al., 2000].

Recent numerical studies suggest that a grid spacing on the order of 0.1° is a threshold for a good representation of the western boundary currents and of the mesoscale eddy kinetic energy [Chassignet et al., 2002]. The usefulness of such high-resolution simulations are demonstrated here focusing on the enhanced regional features of surface circulations manifested in our eddy-resolving global ocean simulation carried out on the Earth Simulator.

OGCM

Based on MOM3, we have developed an OGCM code (OFES: OGCM for the Earth Simulator) optimized for massively-parallel computations on the ES.

Overview of the selected outputs

  1. Sea surface height variability
    Figure 1. The rms variability of sea surface height. (Left) Observation from satellite altimetry. (Right) Simulation result.

  2. Tropical instability waves
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    Figure 2. A snapshot of sea surface temperature in the Tropical Pacific.

  3. Sea surface temperature field and the western boundary currents reflected in it
    Figure 3. (a) A snapshot of sea surface temperature in the Kuroshio region and (b) that in the Gulf Stream region.

  4. Thermocline structure in the equatorial Pacific ocean
    Figure 4. (Left) Mean zonal geostrophic flow [cm s-1], temperature [°C], and salinity [psu] between Hawaii and Tahiti and from 0–400 m, for the period April 1979–March 1980. Adapted from Wyrtki and Kilonsky [1984]. (Right) Annual mean fields calculated from the model results along 155°W in the year 50.