Figure 1. Summary of data sources contributing to the IOOS assets in the water and on the shore. Over on the left we have a cluster of 3 gliders, the Scripps-WHOI spray (orange) and the two Navy Seagliders (red & yellow). In the immediate vicinity of the Deepwater Horizon site is the iRobot/APL Seaglider (green). On the right on the Florida shelf , running north to south we have the Slocum gliders, including USF glider Bass, Rutgers RU21 & Ru23, and U. Delaware’s UD134. USM & USF HF Radar networks are up, with the USM network covering the area where the highest oil concentration is heading towards shore.
Figure 2. Flipping on the satellite Sea Surface Temperature (SST), the general shape of the Loop Current eddy is visible, but surface temperature differences are getting washed out. One good bet for SST imagery at times like these is Mitch Roffer. Mitch spends a lot of time getting the best enhancements.
igure 3. Before going much further, I wanted to zoom into the oil spill and the surface currents from the National HF Radar network. HF Radar gives us a convergence zone right along 87.75 W. Nearshore currents are northeast as the oil spreads eastward along the Florida panhandle coast until the current toward toward shore between 86.75 and 86.5 W.
Figure 4. A quick check of the altimetry clearly shows an interaction with the Loop Current eddy and the Florida shelf between 26 N and 27 N. One should always be cautious interpreting altimeter data in shelf seas, but this one does indicate something is going on. A good place to go from here is the model.
Figure 5. On to HyCOM. Plotted here as sea surface height (color fill) and surface currents (black arrows). Now the interaction between Loop Current Eddy and Florida shelf looks much more reasonable. From that location between 26 N and 27 N, currents are leaving the Loop Current Eddy and turning left to head back up to the northwest, flowing along the shelf break on the shallow side. A Horizon Marine drifter confirms the presence of this filament. The NOAA Oil Spill forecast has this piece of the slick confined to the recirculation zone between the Loop Current eddy and the countercurrents in this filament.
Due to popular demand we are providing this update today.
See enclosed PDF analysis as the graphic is enclosed. Overall we continue to monitor the distribution and movements of the oil and oil-water-dispersant mixture from infrared, RGB, visible and synthetic aperture radar (SAR). Today we were able to use the RGB data to visualize the surface oil which augmented the SAR from yesterday. However, we mostly used the infrared and ocean color imagery (enclosed) today as it was very clear and we were able to see the details of the currents that we have not been able to see since last week. We have outlined in olive green surface oil that we have been able to see in the last 48 hours from SAR and RGB imagery. Due to the angle of the satellite passes we were unable to visualize the oil west of the Mississippi Delta that we observed last week.
We were able to see the oil either touching the shore or very close to the shore at Gulf Shores, Alabama. We also observed some indications that the oil has spread all the way west to the Santa Rosa Island area (offshore of the coastline), but the imagery is not conclusive. We would expect the oil to continue moving eastward based on the flow of the water along the Florida Panhandle that we observed during the last 24 hours. However, the good news is that the winds today (from the northwest and northeast) support holding the oil- water mixture offshore for the time being.
Southwest of Tampa we were able to see many water mass boundaries, but we need a longer time period with clear skies to locate the center of circulation of the cyclonic eddy (counter-clockwise circulation) located southwest of Tampa, Florida. Our best estimate is that the center of circulation is near 85°15′W & 27°00′N. This eddy appears to be moving southward slowly and seems to be “flattening ” the large Loop Current eddy “Franklin” which now seems to have an irregular shape suggesting that the eddy circulation is unstable. We have not colored the areas with oil in grey as we have lost continuity with the exact water masses that we were following last week due to the three days of cloud interference. We will not guess on their location. However, on-site reports along with SAR data last week indicate to us that all the areas shown with “oil” contains petroleum from the Deepwater Horizon spill. We have been able to outline the tendrils of the oil-water mixture that originated from the Deepwater Horizon spill site. These tendrils are shown in gray. Note that they are following the eastern boundary of the eddy Franklin between 84°00′W – 84°30′N from 27°30′N to the elongated egg-shaped eddy centered near 85°00′W & 24°15′N. It seems important to us that you sample these tendrils for oil at the surface and at depth. We observed oil at the surface in a similar situation last week along the eastern boundary of the Eddy Franklin and now that oil is circulating in a counter-clockwise dir ection in the elongated egg-shaped eddy. The key to understanding if the oil is headed to the Florida Keys rests in the area near 84°30 ‘W & 24°45′N to 84°30′W & 24°30′N and west to 85°00′W & 24°30′N. We would like to have someone confirm the presence of oil and to see if the oil is moving toward the Florida Keys using drifting buoys in the oil. We do not know if the area near 84°15′W & 24° 50′N has oil yet. We do not believe there is oil there, but in-situ verification at the surface and at depth is needed. Any petroleum based sheen, oil on Sargasso weed, smell of petroleum would indicate t o us that there is oil there. The tendril of the oil-water mixture n ear 86°00′W & 23°45′N seems to have bifurcated flow with some of the oil-water moving westward with the flow of eddy Franklin, while som e is moving northeastward around the elongated egg-shaped eddy. Of note it appears that the large Loop Current eddy Franklin is not separated from the Loop Current at least at the surface as evidenced by the cooler Yucatan Current water is now providing a buffer between the Loop Current and the large eddy. The large Loop Current eddy Franklin remains unstable due to the many counter-clockwise rotating eddy flowing around the outside, the southward motion and forces of the eddy west of Tampa, FL, and the friction by the west Florida continental shelf. However, the apparent separation from the Loop Current is good news for the ecosystem and people living in the Florida Keys and southeast Florida for the time being. We still are concerned about the path of the oil that resides in the eddy southwest of Tampa, FL and its ultimate fate as it approaches the area near 85°00′W & 24°30′N.
If you decide to use this analysis or the images contained within, please give credit to ROFFS. We still need funding support for this work. We suggest that you contact your emergency managers, Coast Guard, etc. and tell them you want an independent analysis of the oil situation. If nothing else as an independent confirmation of the information they are receiving now from others. Remember that every fishing trip is important to use ROFFS to help you find fish.
Today we are also providing an ocean color image derived from the NASA Aqua satellite’s MODIS sensor. We have provided a color palette that we feel reflects the color the water. While we will not discuss this image in detail for the non-experienced image viewer, note the “ocean color” from the area of the surface oil plume centered near 8 7°45′W & 29°15′N. With careful analysis one can see the very blue Yucatan Current, the Loop Current and the separation between the Eddy Nelson and the Loop Current.
If you want to learn about ocean color from satellites, see the NASA website http://oceancolor.gsfc.nasa.gov/ and you will see more than perhaps you wanted. Of course you can al ways ask us when you see us at scientific meetings, boat and fishing shows, or simply around town in West Melbourne Florida where our headquarters are located.