Archive for November 1st, 2009

Some mighty fine piloting

Sunday, November 1st, 2009

Scarlet's noon surfacing returned much more favorable currents.  Down to 15 cm/sec, mostly south and a very little bit east.  With Scarlet pointed due east, and running 15 cm/sec relative to the water, our resultant direction over the ground was more like southeast.   And we used all of Scarlet's velocity to move us from a strong unfavorable current to a weaker and more favorable place.  We'll continue on this path for another segment or two.  Pretty nice piloting on a weekend.

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More surprises from the eastern North Atlantic

Sunday, November 1st, 2009

Scarlet sent us home some surprising news that currents had increased to 28 cm/sec to the SSW.   We have not seen currents this strong for weeks.  Yesterday's guidance from the altimeter had us in a region with virtually no currents.  Today's altimetry is different again, currents to southeast are back, but not in the form of an eddy.  Some of what we are seeing is the actual evolution of the ocean eddy field.  Some of it is caused by the sampling pattern of the altimeter.  Sometimes you have to wait several days for a satellite to pass near you to update your estimated current fields.  Regardless of why (actual evolution or undersampling) the roadmap is changing every couple days. Antonio's waypoint change to straight east yesterday turned out to be a very good decision. With this morning's reported current stronger than Scarlet's own velocity, the best we can do is fly perpendicular to this current until we break free.  Thats exactly what Scarlet did last night, and its what we'll continue to do today.  Distance to the Spanish EEZ is down to about 240 kilometers.

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Drake's reported currents also increased overnight.  He is riding a tail-current, making 30 km in the last 13 hour segment.  Time to shift his waypoint further east.

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