Gulf of Mexico – Time To Get Serious About Routine Satellite Monitoring

The ongoing Deepwater Horizon oil spill has provided a rare scientific opportunity: for the first time, multiple satellite remote-sensing systems, from visible to infrared to radar, are providing daily images of a large area in the Gulf of Mexico. This systematic imaging is proving useful for measuring the size and location of oil slicks and sheen, and for estimating the rate of leakage from BP’s failed Macondo well.

It’s also demonstrating another important ability — here at SkyTruth we think we’ve discovered a small but possibly chronic leak from an oil platform located a few miles off the Mississippi Delta, unrelated to but not far from BP’s leaking well:

Time-series of images showing possible small leak from Platform 23051

We first mentioned this back on May 15. According to GIS data from the Minerals Management Service showing the locations of all fixed oil and gas platforms in the Gulf, the platform that appears to be leaking is identified by Complex ID # 23051. You can look up more info at the MMS website. According to MMS this platform was installed in 1984, and it is manned 24/7 (most platforms in the Gulf are unmanned). The sequence of satellite images above shows what appears to be a small oily slick emanating from the platform location on multiple dates, captured by several different satellite imaging systems. We’ve observed the slick on Envisat MERIS and ASAR images taken on April 25 and 26, and May 12, 18 and 31; on RADARSAT images taken May 8 and 11; and on COSMO-SkyMed images taken May 11, 14 and 15. (Pet Peeve Alert: These are all foreign satellites, operated by Germany, Italy, Canada. Radar imagery is the go-to tool for detecting and monitoring oil slicks, yet the U.S. does not operate a single civilian radar satellite. Instead, we’ve been buying radar images of this disaster from other nations. This is nuts.)

On May 27 a scientist from the University of West Florida was flying over the Gulf to investigate the BP oil spill, and noticed an obvious discharge plume coming from a rig – here is one of the pictures she took during that flight:

Discharge plume from rig in Gulf of Mexico, May 27, 2010. Photo by Dr. Enid Sisskin and Southern Alliance for Clean Energy.

This appears to be a small jackup drill rig actively drilling in relatively shallow water. The brown plume looks like it could be drilling mud. But along with the apparent oily leak from 23051 this discharge raises a few questions:

  • How much chronic, day-to-day pollution is associated with offshore drilling?
  • Who is doing the necessary oversight to minimize this pollution?
  • How effective is this oversight?
  • As our vast offshore infrastructure of platforms and pipelines ages, can we effectively identify small chronic problems before they turn into big problems?

All of these questions point to a readily available technical tool that can contribute, right now, to providing some answers: regular monitoring of the Gulf using satellite images from a variety of remote-sensing systems. If the U.S. had such a program we could systematically assess how common smaller pollution events are, and immediately respond in the event of sudden pollution emergencies like the ongoing BP spill, recent pipeline leaks, the offshore and coastal spills that resulted from hurricanes Katrina, Rita and Ike, and other time-critical incidents.

Much of the hardware and trained personnel that could implement a Gulf-wide monitoring system already exists, at the CSTARS facility housed at the University of Miami. CSTARS has their own satellite dishes and image-processing capability. They’ve been producing gigabytes of satellite imagery since the BP spill began on April 20. But CSTARS only gets activated for this work during emergencies. Maybe it’s time to extend that mission and conduct regular, routine, continuous monitoring so we can get a more complete picture of how well our nation’s publicly owned waters and offshore resources are being managed.

BP / Gulf Oil Spill – Moving Toward Florida Straits (??)

We just finished analyzing the MODIS / Aqua satellite image shot the afternoon of May 27. It again clearly shows the main body of the oil slick (solid orange line) around the site of the leaking Macondo well, and also shows deep entrainment in the Loop Current. Disturbingly, we see signs of thin surfactant – possibly oil from this spill – in the Loop Current where it moves past the Dry Tortugas and toward the Florida Straits (dashed orange line):

MODIS / Aqua satellite image, May 27, 2010

There are natural processes that generate thin layers of oily surfactant, so this does not necessarily show that oil from the spill is moving into the Straits yet. But the spill has clearly been interacting with the Loop current since May 17, and at a speed of 1 to 2 knots (see below), ten days is enough time for some of that oil to have moved 240 to 480 nautical miles (276-552 miles). Although it’s 510 miles as the crow flies from the leaking well site to Florida Straits, the convoluted path taken by the Loop Current adds up to a total distance of about 900 miles, so we may not be there yet. Consider this a possibility, not a definitive conclusion.

Systematic water sampling in the eastern Gulf sure would be helpful to pin this down – is anyone doing that?

Sea-Surface Velocity (SSV) map derived from satellite radar altimeter data, May 27, 2010. Location of the Loop Current is indicated by green to red band of relatively high velocity at the ocean surface. Source: Colorado Center for Astrodynamics Research.

BP is currently trying out the “top kill” procedure to plug the leaking well. The success of this attempt is still uncertain, but at least the blowout preventer appears to be hanging together under the increased strain. Live video feed shows what appears to be a strong plume of oil and drilling mud coming from one of the leaks in the busted-up riser pipe. Keep your fingers crossed – this really needs to work.

BP / Gulf Oil Spill – 39 Million Gallons And Growing

The MODIS / Terra satellite image of the Gulf taken yesterday (May 24, 2010) is a relatively cloud-free look at the ongoing oil spill in the eastern Gulf of Mexico. Areas covered by oil slick and sheen are marked with a solid orange line. Areas where we think there may be slicks and sheen, but our analysis is of lower confidence, are shown by dashed orange lines. All together, slicks and sheen are possibly covering as much as 28,958 square miles (75,000 km2). That’s an area as big as the state of South Carolina:

MODIS / Terra image, May 24, 2010, with SkyTruth analysis

We also though it would be interesting to produce a matching version of this image with none of our annoying annotation:

MODIS / Terra image, May 24, 2010, with no analysis or annotation

It’s Day 35 of this fatal incident. Our estimated spill rate of 1.1 million gallons (26,500 barrels) per day, now on the conservative end of the scientific estimates, leads us to conclude that almost 39 million gallons of oil have spilled into the Gulf so far. BP and the federal government had said that they would announce a new official estimate of the daily spill rate on May 22, but we’ve heard nothing more about that. As far as we can tell, they are still claiming the spill rate is 210,000 gallons (5,000 barrels) per day. At that much lower rate, the total amount spilled would be 7.35 million gallons.

BP / Gulf Oil Spill – Satellite Images Show Spreading Slick

The MODIS / Terra image taken on Saturday, May 22 shows oil slick and sheen covering 16,538 square miles (42,833 km2):

MODIS / Terra satellite image, May 22, 2010.

Clouds and haze obscure the southeastern Gulf, but a small patch of what might be oil entrained in the Loop Current is visible. As we’ve said before, it is possible the Loop Current has a distinct color even without the presence of oil, so this is a low-confidence analysis and therefore is shown with a dashed orange line. Sure wish they’d send a vessel out there to do some sampling transects. Note the very broad area of sunglint covering the western half of this image. Look closely and you’ll see a cluster of thin, bright, arcuate patches southwest of the Mississippi Delta; these are very thin oil slicks caused by persistent natural oil and gas seeps on the seafloor. I’ve seen a few of these seeps up close and personal from a research submarine, the Johnson Sea-Link II.

This radar image from Canada’s RADARSAT-1 satellite (a real workhorse, still cranking after many years in orbit), also taken on May 22, shows detail of the main body of oil slick around the leaking well site and the Delta. Compare with the MODIS image above:

RADARSAT-1 image, May 22, 2010. Image courtesy CSTARS.

And this MODIS / Aqua image taken the next day, May 23, shows slick and sheen spread widely throughout the eastern Gulf, possibly covering as much as 18,670 square miles (48,356 km2) if we include both the high- and low-confidence areas:

MODIS / Aqua satellite image, May 23, 2010.

BP / Gulf Oil Spill – Deeper Into Loop Current (??)

The MODIS / Terra image taken today shows a very faint, long belt of anomalous ocean color that appears to follow the Loop Current. We have very tentatively identified this as possible oil slick and sheen carried far to the south. Consider this a low-confidence analysis; it’s possible that the Loop Current has a distinct ocean-color signature without any oil present:

MODIS / Terra satellite image, May 21, 2010.