DeepWater Horizon Oil Spill

Figure 1: Today’s oil spill forecast from NOAA.  First impression is that it looks like good news for the Florida panhandle.  The main part of the slick has moved away from the coast.  But all the news in New Jersey last night and today has been about the tar balls washing up in Panama City.  The farthest east reported so far. So we labeled Panama City in red, and took a look at the data.

Figure 2: We zoom into the northern, higher concentration, slick and turn on the 25-hour average HF Radar currents (the green arrows) in the northeast. Many of the current vectors are heading alongshore to the east or offshore to the south.  The offshore components is where the good news comes from, they appear to be pushing the main part of the slick away from the Florida panhandle.  It looks like the alongshore components bring news that is not as good.  There is that small patch of the oil slick that is separated from the main body and is sitting just offshore Panama City.  Since the HF Radar network is not complete in the Gulf, we don’t have coverage for that small separated piece of the slick.

Figure 3.  Ok, so if we can’t figure out where it is going, maybe we can at least figure out where that slick is at.  That means we turn to the satellite radar imagery from CSTARS.  This overlay shows it perfectly.  Right at the southern edge of the HF Radar coverage, where the data on the southeast flowing currents end, we see the dark lines of the oil slicks associated with this separated region.  The lines trend southwest to northeast, right offshore Panama City and nearly up onto the beach.  This must be what we are hearing all the news reports about today.

Figure 4: Now lets turn on another image radar image from CSTARS.  This one crosses over the main slick.  That dark band of the slick that extends to the south of the Deepwater Horizon site is reflected in the NOAA spill forecast.  Three Gliders are in or near this band, the Scripps/WHOI spray and the two NAVO Seagliders.  Looks like they are well lined up to sample this part of the slick.  The iRobot Seaglider remains near the drill site itself.

Figure 5: Now over to the southern, less concentrated slick.  Here we zoom into the Florida shelf. The band of slicks is right along the outer Florida shelf, moving up onto the shelf in the north and back out again on the south.  Where to from there? Another lap around the Loop Current Eddy?  The Horizon Marine buoy says maybe not.  It made the same trip off the Florida shelf and into the Loop Current.  Looks like it will pass to the south of Key West in the net day or so.  If the slicks follow this route, that means it found an exit route out of the Gulf.  Looks like we will be broadening our region of data coverage over the next week.

Figure 6.  Here is the HyCOM forecast that gives us an idea of what it takes for the oil slick to make the jump from the Loop Current Eddy into the Loop Current like the Horizon Marine drifter.  Yesterday we saw from a comparison of the HyCOM surface currents with the Satellite ocean color from UDel that the HyCOM model is doing extremely well. As water leaves the Florida shelf on the southeast side of the Loop Current Eddy, it enters a long (over 200 km) and narrow (about 20 km) shear zone between the Loop Current Eddy and the Loop Current itself.  If the slick stays in the Loop Current Eddy, it goes around for another lap.  If it crosses the narrow shear zone and enters the Loop Current, it exits the Gulf.

The glider fleet is doing a solid job, with expected gliders to reinforce the effort in the coming week.  The two groups are coordinating their sampling in the northern Gulf spill zone and the second group flying along the Florida shelf.

For the spill zone glider group.  The 2 NAVO and Scripps/WHOI gliders are flying three parallel cross shore lines.  The NAVO are showing enhanced backscatter near the seafloor. Surface waters are complex showing low salinity plumes with enhanced CDOM.  The chlorophyll maximum also shoals near in the area of the low salinity plume.

The iRobot/APL glider continues to show very interesting data.  There is complex surface features most associated with the presence or absence of a low salinity plume. The mid-water zone continues to be a unique CDOM feature that has not been observed by any other glider during this whole time.  A key need in the next week is get some calibration data to better explore that CDOM signals.  The mid-water CDOM maximum is not associated with enhanced chlorophyll or particles.

For the Florida gliders, the Mote/Rutgers/UDel gliders are continuing to survey the Florida shelf.  The features between all the gliders are consistent. Enhanced CDOM, backscatter and chlorophyll at depth.  The coming week will likely have us joined by USF which had a glider hit by a pesky remora last week.  The plans laid out by the team currently are:  RU23 is looking good after also shaking off a Remora and the glider should be ready for recovery by Monday. For RU21 we want to check the onboard pressure sensor  for any  any corrosion or biofouling that is causing some erratic signals.  We should be a in a recovery zone in 3-4 days.   Since we are near the 30 meter isobath, we are  going to turn off optics.  Waldo can cover the 30 meter inward over the next couple days.  UDel is flying well and we have about a week  to get back to the Keys or Sanibel, or 8-9+ days back to Sarasota.  We have about 9 days of battery left at the current sampling regime.