Exploring the Ocean Mesoscale.

A rainy morning here in New Jersey, perfect for fine tuning our steering on the Trans-Atlantic Gliders.  First Rutger’s Scarlet Knight is trying to cross a series of three alternating warm and cold filaments.  The warm filaments are moving north, the cold ones south, and we are trying to fly east.  We are in a warm filament and are 35 km from the edge of the front where we cross into the cold.

According to the altimeter, we just flew across the center of the eddy and have entered the southward flowing side. We need to fly east quickly now, so we can jump into the southward flowing current of the eddy just to our east.  As we are advected south, if we don’t get far enough east, we continue spinning around in the eddy we are now in.  If we do get far enough east, we get whipped around the next eddy towards Spain & Portugal.

Back to the tropics, Teledyne’s Drake is doing the exact same thing.  We are flying eddy to eddy.  In this case we just left the eddy to our south and are now entrained in the eddy to out north.  We are using the glider speed to choose an exit point the puts us as close as we can get to our next eddy of interest.  We are often amazed how a surface current measured from an altimeter in space can be so well correlated with a depth averaged current measured by a glider that is undulating between the surface and 1200 m, but this highlights the dominating influence of the ocean mesoscale.

In oceanography, the eddy fields we are navigating the gliders through in the above images are known as the energtic ocean mesoscale.  http://en.wikipedia.org/wiki/Eddy_(fluid_dynamics) . When we look at our ocean from satellites in space, we see the mesoscale eddies are everywhere.  They dominate any image of the ocean, just as the weather patterns dominate any image of the atmoshpere.  http://www.gfdl.noaa.gov/ocean_mesoscale_eddies . One of the challenges of climate prediction is that most climate models that include the ocean do not yet resolve this energetic mesoscale.  http://www.clivar.org/organization/wgomd/meso/MESO_summary.pdf . This short executive summary of a recent meeting of the world’s experts on this topic indicates it may take a generation of researchers to fully understand the impact of the ocean mesoscale on climate.  That generation of researchers will be made up of the students currently sitting in our classrooms. This is why government agencies, universities, and companies are working together on projects like this. It is why the COOLroom is on a university main campus, why these two gliders are crossing the Atlantic, and why there are over 100 school districts with letters on board.