Well, guess what? The latest weekly dump of NRC reports was just made available by the Coast Guard, and our faithful little report-scraping robot just pushed them out through our SkyTruth Alerts incident mapping and email-alerting system. And once again, what Taylor reported on May 7th doesn't jive with what we observed in the Gulf that same day.
Taylor reported a slick 9.7 miles long and half a mile wide, covering a total area of 4.85 square miles (12.56 sq km), based on an aerial overflight that took place at 9:15am local time on May 7. They estimate the total volume of oil in this slick amounts to 14.6 gallons.
We observed a slick more than 16 miles long and covering a total area of 5.95 square miles (15.4 sq km) on a Landsat-8 satellite image that was taken just two hours after Taylor's overflight, at 11:25am. Based on a conservative thickness estimate of 1 micron for the slick, we calculate the slick holds 4,066 gallons of oil.
Satellite image analysts with the federal government, at NOAA's National Environmental Satellite, Data and Information Services division (NESDIS), have also been using satellite images to monitor the Gulf. They reported to the NRC a slick over 17 miles long, but didn't give an area or volume estimate. Based on their description of the slick, we're certain they were looking at the same Landsat-8 image that we analyzed. Our measurements of the slick length are comparable.
So, SkyTruth and government analysts documented a slick almost twice as long as the slick Taylor reported. And our conservatively estimated volume is 278 times greater than Taylor's report. Even if we take Taylor's slick-length report at face value, applying a 1 micron thickness value to a slick covering 4.85 square miles yields a volume estimate of 3,316 gallons. To take that down to their total reported volume of only 14.6 gallons, you'd have to assume the oil only covered 0.4% of the 4.85 square mile area they reported as being an oil slick observable from the air. Seems unrealistic, doesn't it?