BP / Gulf Oil Spill – MODIS Images, June 18 and 19

MODIS Terra and Aqua images on June 18 and June 19 have some cloud-cover problems but still show oil slick and sheen spanning areas of 11,278 square miles and 18,473 square miles respectively, with oil apaprently coming ashore from Gulf Shores, Alabama to points as far east as Seacrest and Rosemary Beach, Florida. Oil is also apparent in Pensacola Bay on the 18th:

MODIS/Terra satellite image, June 18, 2010

Strong thunderstorms form large, dense masses of bright white cloud in this image — one area of cloud obscures the location of the leaking Macondo well, source of the ongoing BP / Deepwater Horizon oil spill. Oil slicks and sheen viewed through breaks in the cloud cover at least 11,278 square miles (29,210 km2). Oil appears to be making landfall along the beaches of Perdido Key, Alabama, and east along the coast to Destin, Florida. Oil slicks also seem to occur within Pensacola Bay itself. Compare with the MODIS/Aqua image taken the next day, on June 19:

MODIS/Aqua satellite image, June 19, 2010

Not as many thunderstorms and cloudy patches on this image, revealing the continuing upwelling of fresh oil around the location of BP’s leaking well. Slicks and sheen span 18,473 square miles (47,847 km2) on this image. Thin patches appear to be making landfall from Gulf Shores, Alabama to Perdido Key in Florida, and from Grayton Beach State Park to the Seacrest / Rosemary Beach area along the Florida coast.

Leaking Well at Platform 23051 Location – Rate?

Just a quick followup to our last post. The Ocean Saratoga rig is working to plug 26 wells that had been connected to an oil platform damaged (and destroyed, or removed) by Hurricane Ivan in 2004:

The Taylor wells are leaking an average of less than one- third of a barrel of oil each day, the Interior Department said. The leaks have been “substantially reduced” over the years by containment domes and other interventions, Taylor said in a statement yesterday.

1/3 of a barrel is 14 gallons. The slick we measured on June 18 satellite imagery holds an estimated 3,157 gallons of oil, assuming the slick is only 1 micron thick. It would take 225 days, at a rate of 14 gallons per day, to make an oil slick that large. Oil on the surface of the ocean can’t survive that long — especially a slick that’s only 1/1000th of a millimeter thick.

The leakage rate from these wells in recent days must be significantly higher, probably in the range of 100-400 gallons per day. If they’ve been leaking at that rate since Hurricane Ivan, that’s a total of 210,000-840,000 gallons of oil. To put it in perspective, less than one day’s worth of leakage from BP’s Macondo well.

BP / Gulf Oil Spill – June 12 MODIS/Aqua Image

This MODIS/Aqua satellite image, taken on June 12, has a broad sunglint pattern centered on the eastern Gulf that effectively illuminates the main oil slick as well as areas of what we interpret as much thinner sheen. The bright band of sunglint spanning this image reveals fine structure (squiggly bright lines) in areas to the east of what we interpret as the main area of oil slick; this structure can be caused by natural surfactants, or it may indicate very thin layers of residual sheen related to the ongoing spill. As on June 9, there is some ambiguity in our delineation of the area of slicks and sheen (orange line), which extends across an area of 23,140 square miles (59,932 km2) — as big as our home state of West Virginia:

MODIS/Aqua satellite image taken June 12, 2010

Oil appears to be making landfall across 40 miles of coast east of Mobile Bay, from Gulf Shores, Alabama to Perdido Key, Florida. Tendrils of oil, possibly thin sheen, reach toward the Florida coast from Pensacola almost as far east as Panama City. Some news accounts support this analysis.

And the government just revised the estimated leak rate from the well – they now say it’s leaking anywhere between 1.5-2.5 million gallons per day, with the containment device currently capturing about 500-600 thousand gallons of that flow. That means that since BP cut the riser and installed the latest containment cap, at least 900 thousand gallons – and possibly as much as 2 million gallons – have entered the Gulf daily. At the high end that’s nearly twice as much as the 1.1 million gallon estimate SkyTruth and Dr. Ian MacDonald of Florida State University made back on May 1.

BP / Gulf Oil Spill – Memo Shows BP’s Spill Rate Calculations

Dr. Ian MacDonald at Florida State University just provided us with this BP memo detailing the spill-rate calculations performed by BP. Click it to see the full-sized version. We guess this is how BP came up with their very low estimated leak rates of 42,000 gallons (1,000 barrels) and 210,000 gallons (5,000 barrels) per day. The official estimated leak rate now stands at 20,000-30,000 barrels per day (and possibly much higher).

Read more about the varying spill-rate estimates, and this memo, in a Washington Post article by Joel Achenbach.

BP / Gulf Oil Spill – June 7 and June 9, 2010

Playing some catch-up from Capital Hill Ocean Week. We served on a panel yesterday and gave a presentation on the spill (starting at 36:10 in this video). Thanks for your patience, we’re stretched pretty thin!

Here are MODIS/Terra satellite images of the Gulf from June 7 and June 9. The image taken June 7 shows slick and sheen across an area of 9,075 square miles (23,504 km 2). A large dark area west of the slick may be a low-wind area within the generally bright belt of sunglint west of the Mississippi Delta. There may be slicks or sheen obscured by this low-wind region:

MODIS/Terra satellite image taken June 7, 2010

Compare this with the MODIS/Terra taken on June 9, which has a broad sunglint pattern centered on the eastern Gulf that effectively illuminates the main oil slick as well as areas of what we interpret as much thinner sheen. The bright band of sunglint spanning this image reveals fine structure (squiggly bright lines) in areas to the north, south and west of what we interpret as the main area of oil slick; this structure can be caused by natural surfactants, or it may indicate very thin layers of residual sheen related to the ongoing spill. Lots of judgment calls made when encircling the area of slicks and sheen (orange line), but we come up with a total area of 16,434 square miles (42,565 km2):

MODIS/Terra satellite image taken June 9, 2010

We don’t think the actual area of ocean affected by slicks and sheen nearly doubled in just two days; instead, we think the MODIS image from June 9 was just much more effective at showing those areas than many of the images we’ve been collecting throughout this incident. And it is possible that some of the area we’ve delineated contains natural surfactant rather than spilled oil. Again, a difficult image to interpret in some areas.