The Sub-Mesoscale Ocean Dynamics Experiment (S-MODE) mission is testing the hypothesis that submesoscale ocean dynamics, i.e. processes with scales of 1-10 km, make important contributions to vertical exchange of physical, chemical and biological variables in the upper ocean. This requires coordinated application of newly-developed in situ and remote sensing techniques, and will provide an unprecedented view of the physics of submesoscale eddies and fronts and their effects on vertical transport in the upper ocean. S-MODE is using measurements from a novel combination of platforms and instruments, along with data analysis and modeling, to test the hypothesis.
A major difficulty in simulating Earth’s climate system is that there are interactions across scales, so that the large time and space scales can be sensitive to processes on small scales. As the computational resolution of global ocean models has improved, scientists have begun to suspect that kilometer-scale eddies and fronts, called “submesoscale” variability, have a net effect on ocean-atmosphere heat exchange that is larger than the heating from the greenhouse effect. State-of-the-art computer models agree in predicting that these eddies have important long-term effects on the upper-ocean, but their predictions are sensitive to relatively small details in model physics and implementation. The resolution and detail of these simulations has surpassed our ability to ‘ground truth’ them with spaceborne or in situ sensors. There is thus a pressing need for a comprehensive benchmark data set on these submesoscale motions to address this important source of uncertainty in simulating the global ocean.
The S-MODE study domain is off the west coast of northern California, USA, marked by the green polygon in the image below.