The eastward currents at 200–450 m

The eastward currents at 200–450 m selleck screening library depths and 3–5° from the equator are the northern and southern Tsuchiya jets (TJs; Tsuchiya, 1972, Tsuchiya, 1975, Tsuchiya, 1981, McCreary et al., 2002, Furue et al., 2007 and Furue et al., 2009). The structures

of the model TJs agree fairly well with observations, except that the model has westward currents on the equatorward sides of the TJs. The observed field shows another eastward current just south of the primary one, often termed the secondary Tsuchiya Jet, which is much weaker in the model. Note also that the model has other, vertically-coherent, narrow zonal flows at depths farther from the equator. Eddy-resolving models usually have similar, but stronger, flows, sometimes called “striations” or “zonal jets” (Maximenko et al., 2008),

which are thought to be at least partly driven by eddies (e.g., Nakano and Hasumi, 2005 and Richards et al., 2006). These flows are much weaker in our model than in typical eddy-resolving models, likely because our mesoscale eddies are much weaker. There are large-scale bands of high sea-surface salinity between hypoxia-inducible factor cancer 20 °S°S and 10 °S°S and between 20 °N°N and 30 °N°N (not shown). Waters subducted in these regions flow equatorward in the main pycnocline, forming the tongues of high salinity visible in Fig. 2. Much of this water flows eastward in the EUC, upwells into the mixed layer in the eastern equatorial Pacific, and returns to subtropics near the surface, thereby forming the Pacific’s shallow overturning circulation cells, the Subtropical Cells (STCs; McCreary and Lu, 1994). The tongue from the southern hemisphere is more pronounced partly because surface salinity is higher in the southern hemisphere and partly because the subducted water reaches the equator by a more direct path than

in the northern hemisphere (Lu and McCreary, 1995). As a result, there is a sharp front of salinity in the pycnocline across the equator. The vertical structure of salinity is complicated near the equator because of this feature especially on the northern side. Overall, the model salinity field agrees well with the Argo climatology. The most conspicuous difference is that maximum values Sulfite dehydrogenase of salinity are considerably higher than their observed counterparts both in the northern and southern hemispheres. Indeed, the surface salinity is much higher in our model than in the Argo climatology (not shown), and it is the subduction of this water that leads to the model’s larger subsurface salinities. All solutions follow similar adjustment processes. They include a very fast, initial response due to interactions of gravity and barotropic waves with eddies (Section 3.2.1), a more gradual diffusive, local response (Section 3.2.2), and slower remote adjustments due to wave propagation and advection (Section 3.2.3). Fig. 3 shows δTSEδTSE at z=150z=150 m and t=300t=300 days as an example.

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