**3. Results**

When the GLOM is forced with the temperature restoring and wind stress functions described in the previous section (Figure 5), it generates large-scale circulation patterns and stratification that are similar to those in the world ocean in nature. In this section, we examine these structures, and compare results for the simulation with interior mixing to the one without, as well as both simulations to observations. The results generally support the main conclusion of HF12—that a model with zero tracer diffusivity can produce most of the large-scale circulation and stratification structure seen in nature (i.e., the zero-order solution), with interior mixing contributing first-order perturbations.

#### *3.1. Horizontal Stream Function*

The horizontal circulation in the simulation with interior mixing (Figure 6a) is qualitatively consistent with that predicted by theory [30] for a forcing like that shown in Figure 5. Anticyclonic (cyclonic) gyres are present where the curl in the wind stress is negative (positive) with Sverdrup flow in the eastern portion of ocean basins, and more intense return flow in the form of western boundary currents to the east of continents. The model also produces an Antarctic Circumpolar Current (ACC), with gyres in the Ross and Weddell Seas. While the ACC is somewhat weaker than in nature [31], this is probably attributable to the low resolution of the model. In the simulation without mixing (Figure 6b), the overall flow structure is similar, but the amplitude of most gyres is slightly weaker, and the ACC is also weaker.

**Figure 6.** Horizontal streamfunction (10 Sv contour interval). (**a**) Simulation with interior mixing. (**b**) Simulation without interior mixing. Positive (negative) contours are drawn with solid (dashed) lines, with contour values ranging from −45 to 105 Sv.

#### *3.2. Surface Temperature Field*

Despite the idealized nature of the GLOM and the forcing, it qualitatively captures many of the departures from zonal symmetry seen in the observed sea surface temperature (SST) field, including warm tongues protruding poleward at mid-latitudes along the eastern boundaries of North America, Asia, Africa, and South America, an equatorial cold tongue in the eastern Pacific, and isotherms that slope northward from west to east across the North Atlantic (Figure 7).

Of course, the low model resolution leads to western boundary currents that are broader and weaker than those observed in nature. Moreover, other features whose forcing is not included in the model are not well represented. For example, in nature, marine stratocumulus clouds are prevalent to the west of South America. They reflect a significant portion of the solar heating, reducing the SST there [32]. This forcing is not included in the GLOM simulations, and consequently SSTs are higher to the west of South America in the model (Figure 7a,b) than they are in nature (Figure 7c).
