Ocean Model

Ocean Model

Processes Simulated by the Parallel Ocean Program

In order to adequately simulate climate, models must include the ocean. After all, most of the heat in the climate system is stored in the ocean. Furthermore, much of the natural variability in the climate system is controlled by oscillations in the ocean that are closely coupled to the atmosphere.

In contrast, NWP models use set ocean conditions, typically using satellite observations of sea surface temperatures, which are held constant through the course of a model run.

There are several important differences between the ocean and atmosphere that affect climate modeling:

  • Ocean processes operate over much longer time scales when compared to atmospheric processes. Complete mixing of the ocean takes centuries, and thus changes in forcing can take decades to appear in the ocean.
  • Ocean observations are sparse, which makes verification of model results more difficult. While satellites provide many observations of the surface, deep profiles come largely from drifting buoys that yield only about 300 profiles per day from the top 750 meters.

In many respects, ocean models are quite similar to atmospheric models; the equations of motion are largely the same. There are, however, some notable exceptions:

  • Ocean models are forced entirely at the surface
  • Ocean models need to account for salinity, which plays a large role in determining density
  • Surface currents are largely wind driven

Current climate models may now include an ocean ecosystem model. This model can be used as a component of the global carbon cycle model. It also enables a feedback from biogeochemistry to the ocean physics whereby the calculated chlorophyll content impacts the absorption of solar radiation in the ocean.

To learn more, see the COMET module Introduction to Ocean Models.