“Submesoscale” eddies and fronts on scales of less than a few kilometers seem to play an important role in the global ocean energy budget and seem to interact strongly with biogeochemical and biological processes, such as phytoplankton production.
Recently, they gain a lot of attention due to the development of high-resolution coastal models that are now starting to resolve these features. Observations that resolve submesoscale eddies and fronts with sufficient resolution are, however, very sparse, as they are very hard to locate and follow with traditional research vessels and satellites: their life-time is on the order of a several hours and frontal gradients need to be resolved on the meter scale.
The University of California at Los Angeles (UCLA) has initiated a series of Submesoscale Experiments (SubEx) off California that are now led by the Helmholtz-Zentrum Hereon in partnership with UCLA, the Jet Propulsion Laboratory (JPL), the University of California at Santa Barbara (UCSB), the Naval Research Laboratory (NRL), the University of Victoria (UVic), the University of Oldenburg, and the University of Twente.
Several planes equipped with highly-sensitive infrared cameras, hyperspectral cameras, and SAR deliver information about sea surface temperature, ocean color, and surface roughness with a resolution of 1 to 25 m. The planes are used to locate the eddies and fronts, deliver spatial information and guide the in situ measurements from multiple fast vessels quickly deploying a towed instrument array for subsurface temperature, salinity and oxygen, as well as current meters, drifters, surfactant samplers, and optical instruments. An additional vessel is equipped with SuFMos and RDCP current measurements to deliver surface current and roughness.
Future experiments are planned in the Baltic Sea in order to observe submesoscale eddies and fronts, determine their role in the local ocean energy cascade and for phytoplankton growth.