Idealized Models

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Idealized ocean models are useful tools which can be used to investigate processes in the ocean.  One such tool is the Process Study Ocean Model (PSOM), which I adapted with Amala Mahadevan for use in the coastal ocean for my dissertation work. The model was designed with idealized shelf-slope geometry to examine exchange mechanisms for biogeochemically important tracers between the coastal ocean and the open ocean. I designed a series of biogeochemical tracers to trace the bottom boundary layer waters and to mimic the behavior of nitrate (dissolved and particulate), methane, and iron.

In an idealized east coast system, I examined mechanisms for cross-shelf exchange and ventilation along the shelf break front. The shelf break pump mechanism brought methane released from slope sediments and deep slope nutrients onto the shelf through an oscillation of the shelf break front caused by the winds. The front would flatten in response to upwelling favorable winds and straighten in response to downwelling favorable winds. Material from the slope was entrained in the bottom boundary layer around the foot of the front and brought to the surface via the oscillation in the front.  The sensitivity of the mechanism to wind forcing and shelf geometry was examined in the model.

The model described above was adapted for use in an upwelling regime, like the west coast of the US. I designed an iron-like tracer based released from the sediments using observed dissolved iron fluxes. In the model, iron originating from the sediments on the shelf is exported offshore in the bottom boundary layer during downwelling events. If this mechanism exists in all upwelling dominated regimes, then the upwelling regimes would export iron to the open ocean equivalent to the estimated dissolved flux from aerosols.