Sunday, March 23, 2008

A new route home

Above Satellite image of Sea Surfact Temperature shows the Warm Core ring we are targeting to be centered near 39 30N, 63 30 W. We'll have to adjust our target waypoint to be a bit farther west once we get into the ring. But right now we want to fly to the north, so we are ok for the night. Once we are in the ring, the currents will spin us clockwise around it, and it will be a natural adjustment to fly toward 63 45 W. it looks like the southern side of the targeted warm core ring is at about 39 N, and RU15 is just south of that location. We should begin to see the temperatures warm and the currents spin around to flow to the west. Once that current switches direction, we switch the waypoint.

Once RU15 is in the ring, we see the new exit point now on the northwest side. The idea is to leave the ring where you see the warm (yellow) water heading towards the shelf break. This region will have favorable currents. The cold (blue) water is shelf water, and unfavorable currents for our northward journey.

Above is the temperature section. Most recent data on the right. You can see the warming as we head north out of the Stream into the ring.

Above are the current vectors for the last 2 days. You can see the sharp decrease as we leave the Stream, and now the currents are starting to turn. The present waypoint if perfect for now, perpendicular to the currents, pulling us northward into the ring. As soon as the currents switch direction and flow to the west, likely sometime tomorrow during the day, we will switch to a waypoint on the west side of the ring. The current waypoint is on the east side. The new waypoint will be somethin like 39 30 N, 63 45 W. The idea is to put this point on directly west of the ring center, and more than 2/3 of a ring radius out. Because the ring is moving west, subsequent imagery may make that new waypoint as far as 39 30 N, 64 00 W.

Here are the current speeds and directions. Still above 0.5 m/sec, about twice the speed of the glider. So there is no way to fly against this current. We have to use the currents to our advantage to advect us in the directions we want to go, and use the glider speed to move us from one favorable current to another. It is a different way of flying.

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