Weathering the Strom, Riding the Rings

Gulf Stream forecasters love storms.  The storms mix up the surface layers, and instead of looking at a uniformly warm but thin surface layer, you get to see the horizontal gradients associated with the deeper flows.  In the case below, the eddy structure is clearly visible in the sea surface temperature image.  When you get images like this, they are very valuable, because they are instantaneous.  They show the actual shape of the features.  Our eventual goal is that strong cold eddy near 42 N between 40 W and 43 W.  We want to ride its southern side.  You also can see some of the warmer eddy to the northwest of the cold eddy.  RU17 is in clouds (the black regions in this enhancement).

Below the altimetry is in excellent agreement with the satellite sea surface temperature The cold eddy (low in blue) we are going for is clearly outlined, and we see the warm eddy (high in red to the northwest).  The problem here is that the cold eddy RU17 is trying to use today is located under the clouds near 39 N,47 W.  According to the altimetry, RU17 is crossing through the strongest nortward currents associated with that eddy.  We know that is not the case.  RU17's currents remain below 20 cm/sec, very week.  So the altimetry, a several day composite, is smearing this feature and we need to wait for another overpass to refine our current estimates in this region.

Once refinement is to use a dynamical model, in this case the Navy's NLOM model that does the dynamic interpolation of the altimetric field to try to eliminate the smearing in time and space you get from raw altimetry.  The dynamic constraint is the the interpolation requires F=m*a, a significant constraint since the apple hit Newton on the head. In this dynamically constrained interpolation (current speed contoured below), the eddy we are looking to ride is still to our east.

Below is the countours of north/south velocity, and we still want to steer into those strong currents to the north. 

And find those strong currents to the east (bright red) we see here associated with that eddy.

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