1.2.7. Global state estimation of the ocean

An important application of MITgcm is in state estimation of the global ocean circulation. An appropriately defined ‘cost function’, which measures the departure of the model from observations (both remotely sensed and in-situ) over an interval of time, is minimized by adjusting ‘control parameters’ such as air-sea fluxes, the wind field, the initial conditions etc. Figure 1.12 and Figure 1.13 show the large scale planetary circulation and a Hopf-Muller plot of Equatorial sea-surface height. Both are obtained from assimilation bringing the model in to consistency with altimetric and in-situ observations over the period 1992-1997.

Figure 1.12 Circulation patterns from a multi-year, global circulation simulation constrained by Topex altimeter data and WOCE cruise observations. This output is from a higher resolution, shorter duration experiment with equatorially enhanced grid spacing.

Figure 1.13 Equatorial sea-surface height in unconstrained (left), constrained (middle) simulations and in observations (right).