Figure 1. Was happy to see today’s update of the altimetry from Colorado. As usual, the large scale circulation patterns are well represented, with the partially separated Loop Current Eddy. Most of the Loop Current entering the Gulf then quickly turning east and out, with a smaller amount of that water making the full loop around the eddy. At first I was interested in the northwest corner of this eddy, since the altimetry has a large bulge in this direction. And the bulge and other circulation features (indicated with red arrows) in this region do appear to line up well with the NOAA forecast location of the oil spill shown as the thin black line. Especially that strong jet to the southeast. Also note the clockwise circulation feature observed in the altimetry between 89.5 W and 90 W. Thats where the Navy gliders are operating (see figures below).
Figure 2. But when I copy those red arrows drawn from the altimetry over Matt’s 3 day composite SST, it looks like the pure altimetry product is not correct in the region with the strong southeast jet. The SST product has the loop current eddy further south. There also is a Horizon Marine drifter exactly in the path of the strong southeastward jet in the altimetry, and the drifter is barely moving. Clearly a track by track assimilation into a model is going to give a better result than a pure statistical interpolation of altimeter tracks, and this is one example where it appears to make a difference. It also highlights the need for additional assimilation data in this region, since altimetry carries a very strong weight in many assimilation schemes. In other highlights, it looks like RU21 is pulling out of the warmest water of the Loop Current Eddy and, looking downstream, pulling off to the left, while the Horizon Marine drifter is staying with the eddy and pulling off to the right. We hope the separation between these two continues to grow as we loop RU21 back onto the shelf. The USF Glider Sam is finding 15 cm/sec currents to the southeast on the midshelf inshore of the warm filament. Seaglider remains surveying the region near the Deepwater Horizon site. More gliders are scheduled for tomorrow.