Saturday, May 29, 2010

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.

Tuesday, May 25, 2010

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.

Monday, May 24, 2010

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.

Friday, May 21, 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.

Wednesday, May 19, 2010

BP / Gulf Oil Spill - Radar Image, May 18, 2010

This Envisat ASAR radar satellite image taken on May 18 shows oil slick entrained in the Loop Current and spreading out to the southeast. Slick and sheen covers 15,976 square miles (41,377 km2), about 50% larger than seen in yesterday's MODIS image and about twice the size of New Jersey:

Envisat ASAR image, May 18, 2010. Image courtesy CSTARS.

Some of that apparent rapid growth may be due to the fact that radar images are generally a lot better at showing areas of thin sheen than the MODIS imagery.

See all of our images related to this incident here.
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Tuesday, May 18, 2010

BP / Gulf Oil Spill - How Big Is It?

It's time to revisit this subject. NOAA and BP are still saying the spill rate is 210,000 gallons (5,000 barrels) per day, despite plenty of evidence to the contrary. Many in the media continue to uncritically accept this estimate.

Why is it important to get this number right? This is about more than just liability, or PR. You can bet that our future response capacity is going to be overhauled and retooled based on this spill. If we low-ball the spill amount and rate, we run the risk of designing an inadequate new spill-response system that is doomed to fail the next time something this big occurs.

A couple of thoughts:

1) Are we really being asked to believe that the spill-response capability of one of the world's biggest oil companies AND the United States Coast Guard has been totally overwhelmed by a spill of just 210,000 gallons per day? That's a big spill, but not nearly as big as could reasonably be anticipated. Plenty of wells in the Gulf produce more than that under controlled flow-rate conditions; plenty of tankers plying our waters hold millions of gallons of oil.

2) BP claims the siphon they've inserted into the end of the damaged riser pipe is diverting 84, 000 gallons (2,000 barrels) of oil per day from the main leak to a tanker at the surface. That is good news indeed. But it's worth remembering that for nearly a week BP stated the total spill rate was only 1,000 barrels per day.

3) Scientists analyzing video of that main leak, apparently shot on May 11 and released by BP on May 12, have estimated the flow rate from that leak to be anywhere from 20,000 to 100,000 barrels per day. This makes SkyTruth's 1.1 million gallon (26,500 barrel) per day estimate, based on our measurements of the oil slick as observed on satellite images and mapped by the Coast Guard, look fairly conservative. And it doesn't even include the additional 15-20% coming from the secondary leak. That means BP's siphoning effort is only capturing, at best, about 10% of the flow. This video of the main leak, shot on May 17 after the siphon was inserted and apparently working, shows the plume of oil continuing to spew into the Gulf; it hardly looks abated.

4) Speaking of which: video shot on May 15 and 16 has just been released showing the secondary leak, where the riser pipe is kinked and bent about 90 degrees a few feet above the blowout preventer stack. Unlike the short, blurry clip of the main leak, this video is several minutes long and quite sharp.

Monday, May 17, 2010

BP / Gulf Oil Spill - Slick Now Entrained In Loop Current?

Today's MODIS / Terra satellite image is the most cloud-free we've seen in many days, and what it reveals is disturbing: part of the still-massive Gulf oil slick has apparently been entrained in the strong Loop Current, and is rapidly being transported to the southeast toward Florida. The total area covered by slick and sheen, at 10,170 square miles (26,341 km2), is nearly double what it appeared to be on the May 14 radar satellite image, and is bigger than the state of Maryland:

MODIS/Terra image, May 17, 2010, showing slick apparently entrained in Loop Current.

From Weather.com today:
Per The Weather Channel's tropical expert Dr. Richard Knabb, "based on satellite images, model simulations, and on-site research vessel reports, I think it is reasonable to conclude that the oil slick at the surface is very near or partially in the loop current. The loop current is responsible in the first place for extending that stream of oil off to the southeast in satellite imagery."

Sunday, May 16, 2010

BP / Gulf Oil Spill - Video of Main Leak Supports SkyTruth Estimates - Nearly 30 Million Gallons Spilled So Far

By now everyone has seen this video, released on May 12 by BP, that is reportedly showing the main leak from the damaged well as a result of the fatal Deepwater Horizon blowout, explosion, fire and ongoing spill:

BP video, reportedly of main leak, released on May 13, 2010.

The main leak is located along the riser pipe about 460' from the blowout preventer; the pipe is laying on the seafloor. The second, smaller leak is just above the blowout preventer, and apparently accounts for about 15-20% of the total flow from the well. According to statements made by BP to the press on May 3:

The riser is kinked at a 90-degree angle about 5 feet above the blowout preventer, and oil is bleeding from an irregular crack, BP spokesman Bill Salvin said.

A second leak is 460 feet away on a section of the riser that lies on the gulf floor.

A third leak, about 800' down the riser pipe, was sucessfully capped on May 5 but that operation did not change the rate of flow, which was simply diverted to the other two leak points.

Multiple scientists have reviewed this video; their estimates of the flow range from 840,000 gallons (20,000 barrels) per day to as much as 2.9 million gallons (70,000 barrels) per day. Add another 15-20% to those estimates for the secondary leak, and it's clear that SkyTruth's early alarm back on April 27 -- that the spill is actually much worse than the official BP and government estimates -- was valid, and conservative. By May 1 we had exceeded the official estimate of oil spilled by the Exxon Valdez tanker disaster (about 11 million gallons); and by our count, at a rate of at least 1.1 million gallons (26,500 barrels) per day, we're closing in on 28.9 million gallons (689,000 barrels) spilled so far (it's Day 26 since the blowout began).

Where is all that oil? We don't think we're seeing that much at the surface in our satellite images. But scientists just announced they've discovered large underwater plumes of oil. Not all of the oil leaking from the well may be making it to the surface; dispersants, applied directly into the stream of leaking oil, and sprayed on the oil slick at the surface, are driving some of the oil underwater; and natural mechanical action of wind and waves can also cause oil to eventually sink. That may spare the beaches to some extent, but it raises questions about where all that oil is going, where will it ultimately end up, and what are the potential environmental and economic consequences.

Saturday, May 15, 2010

BP / Gulf Oil Spill - Slick Getting Bigger?

The COSMO-SkyMed radar image taken yesterday is somewhat ominous - it shows nearly all of the slick from the ongoing Deepwater Horizon oil spill, and at 4,922 square miles (12,748 km2) it's significantly larger than it appeared on May 13:

COSMO-SkyMed radar satellite image, May 14, 2010. Image courtesy CSTARS.

And we think we've discovered an unrelated leak from a nearby platform that was installed back in 1984. The MMS ID# for this platform is 23051 (look it up here). A small, dark slick appears next to this platform on radar satellite images from April 26, May 8, and May 13 as well as this May 14 image.

It's not a major leak but it may indicate a chronic problem. Somebody should check that out to make sure it doesn't get any worse.

Friday, May 14, 2010

BP / Gulf Oil Spill - Radar Image, May 13, 2010

NASA/MODIS images have been too cloudy to be much use for May 12 and 13 (see the most recent image we processed, for May 11). But a radar image taken by the Italian COSMO-SkyMed system clearly shows most of the slick in stark detail:

COSMO-SkyMed radar image (black-and-white) superimposed on cloudy NASA/MODIS image. Both images taken May 13, 2010. Radar image courtesy CSTARS.

The slick covers 4,922 square miles (12,748 km2) on the radar image, and is within about 25 miles of the Delta shoreline. The slick clearly extends south beyond the edge of the radar image; hints of it are visible on the MODIS image through the clouds and haze.

See all the images in our Flickr gallery.

Tuesday, May 11, 2010

BP / Gulf Oil Spill - MODIS Satellite Image - May 10, 2010

Yesterday's MODIS/Terra satellite image has some of the usual complications - clouds, haze, and turbidity again may be obscuring portions of the slick. Observable slick and sheen covers 4,683 square miles (12,129 km2). Thicker, fresh-looking oil is apparent in the vicinity of the leaking well, and still appears to be entrained in a counterclockwise gyre (a circular current):


See all of the images in our Deepwater Horizon oil spill gallery. Follow us on Twitter, and you'll know what we know as soon as we know it...

Monday, May 10, 2010

Spilltracker - Show Us What's Happening On Your Beach

In partnership with Surfrider and Ocean Conservancy, SkyTruth has launched an interactive website, the Gulf Oil Spill Tracker, that lets Gulf-area residents document what's happening to their coast. Anyone can search the site, using an interactive map, to find reports that others have submitted. Reports can include text descriptions, photos, and links to video and news articles. Anyone can submit their own report by clicking on the map to indicate the location, and uploading their own photos and info:

We intend to use this to document pre-spill and post-spill conditions, and to give cleanup volunteers a way to show the world the great work they're doing. The more people who participate, the better, so please send this link to your Gulf-area friends, members, and other organizations!

Sunday, May 9, 2010

BP / Gulf Oil Spill - MODIS Satellite Image - May 9, 2010

MODIS / Aqua satellite image, May 9, 2010.

Today's MODIS satellite image from NASA shows plenty of oil slick in the Gulf of Mexico from the ongoing BP / Deepwater Horizon spill - slicks and sheen cover about 4,384 square miles (11,355 km 2) although clouds, haze and turbidity (again...) are possibly obscuring portions of the slick. Fresh-looking oil is still moving southeast away from the site of the leaking well, and appears to be caught in a counterclockwise gyre (a circular current at the ocean's surface - not uncommon in the northern Gulf). This may be helping to keep most of the oil trapped close the the leaking well, although the slick also extends northwest to the fringes of the Mississippi Delta, and large patch of slicks is visible far to the west, in the vicinity of Port Fourchon.

We estimate this well is leaking at a rate of 1.1 million gallons (26,500 barrels) per day. At this rate, the spill has now exceeded 21 million gallons. Most news accounts of this spill are repeating a much lower estimate of 210,000 gallons (5,000 barrels) per day, an unexplained number that NOAA and the Coast Guard were using for a few days until they admitted a week ago that they couldn't accurately estimate the flow rate. We think it's better not to use any number at all than to lock in on an unrealistically low estimate that nobody currently supports. Read why we think that here.

BP / Gulf Oil Spill - How Big Is It?

Quite a lot bigger than the estimate being uncritically quoted throughout the media of 210,000 gallons (5,000 barrels) per day. That was the last "official" estimate made by NOAA and accepted by the Coast Guard back on April 29 (see timeline below). Before that, the Coast Guard estimates ranged from 336,000 gallons (8,000 barrels) per day, to zero, to 42,000 gallons (1,000 barrels) per day. None of these estimates has been publicly explained or substantiated. And on May 1, the Coast Guard and NOAA stopped trying to estimate the spill rate, with Admiral Thad Allen saying, "Any exact estimate is probably impossible at this time."

But the media continues to report that oil is leaking into the Gulf at 5,000 barrels per day. At SkyTruth we estimate the spill rate is closer to 1.1 million gallons (26,500 barrels) per day, based on the size of the slick on satellite images and Coast Guard maps, and thickness estimates derived from visual descriptions of the slick. That puts us at a total spill of 21 million gallons so far.

Considering that there are deepwater oil wells in the Gulf of Mexico capable of producing >1.26 million gallons (30,000 barrels) of oil per day under controlled flow rates; and that the oil slick continues to grow in size even though it's been under attack 24/7 by skimmer vessels, burning, chemical dispersants, and natural processes; our estimate seems quite conservative.

Why is it important to get this number right? This is about more than just liability, or PR. You can bet that our future response capacity is going to be overhauled and retooled based on this spill. If we low-ball the spill amount and rate, we run the risk of designing an inadequate new spill-response system that is doomed to fail the next time something this big occurs.

Here's the timeline of spill estimates:

  • 4/22 - Deepwater Horizon rig sinks; Coast Guard estimates "up to" 8,000 barrels per day (bpd) is leaking - source
  • 4/23 - Coast Guard reports no leaking at all from the damaged well - source
  • 4/24 - Coast Guard reports well is leaking, estimates 1,000 bpd - source
  • 4/25 - BP repeats 1,000 bpd estimate - source
  • 4/27 - 1,000 bpd still the official Coast Guard and BP estimate - source
  • 4/27 - SkyTruth and Dr. Ian MacDonald publish first estimate that spill rate is 20,000 bpd - source
  • 4/28 - NOAA weighs in and raises the official estimate to 5,000 bpd based on aerial surveys "and other factors"; BP disputes this higher estimate - source
  • 4/29 - Coast Guard and NOAA repeat their estimate of 5,000 bpd - source
  • 4/29 - BP's Chief Operating Officer admits new estimate of 5,000 bpd may be correct; "He said there was no way to measure the flow at the seabed and estimates have to come from how much oil makes it to the surface" - source
  • 5/1 - SkyTruth and Dr. Ian MacDonald publish revised estimate of at least 26,500 bpd - source
  • 5/1 - Coast Guard Admiral Thad Allen "acknowledged there was no way really to know the extent of the leak" - source - and stated that "Any exact estimate is probably impossible at this time" - source
  • 5/1 - Coast Guard and NOAA cease estimating the rate of the spill. BP continues to use 5,000 barrels per day as their estimate of the spill rate.

Saturday, May 8, 2010

Gulf Oil Spill - Radar Satellite Image May 8, 2010

Our friends at CSTARS just posted this stunning image. Taken by the Canadian-operated radar satellite, RADARSAT-2, it clearly shows oil slicks and sheen spread across a wide area (about 5,025 square miles, or 13,000 km2) in the Gulf of Mexico early this morning (May 8):

RADARSAT-2 image of the Gulf of Mexico, May, 8, 2010 - Source: CSTARS

We've added some analysis to help you armchair interpreters. Oil slicks look dark on radar images because the oil reduces the surface tension of the water, dampening (smoothing out) the small wavelets that normally roughen up the surface of the ocean. But any smooth water will look dark on radar, so not all dark patches are caused by oil:

RADARSAT-2 image with SkyTruth analysis, May 8, 2010.

UPDATE 5/8/10 7:00 pm - The first attempt to place a 70-ton containment box over the main leak failed today; the box has been moved aside and is being troubleshooted, and tar balls have begun to wash up in Alabama. The leak is continuing unabated, at a rate we calculate to be about 1.1 million gallons (26,500 barrels) per day - five times higher than the last official estimate (5,000 barrels per day) the Coast Guard made, before they quit making estimates a few days ago, admitting they had no accurate way to estimate the spill rate.

We estimate more than 18 million gallons of oil have spilled so far.

Now we can do a heads-up comparison of the RADARSAT-2 image with this MODIS/Terra image taken about four hours later. Still some clouds obscuring portions of the slick; observable slick and sheen spans about 4,100 square miles (10,624 km2). Fresh oil is apparent around the location of the leaking well; it seems to be carried to the southeast, then gets caught up in a counterclockwise gyre in the currents:

Friday, May 7, 2010

Gulf Oil Spill - May 7, 2010

Here's a look at some of the limitations of the NASA / MODIS satellite imagery. Today's Aqua image, like those of the past few days, has suffered from problems that make it impossible to map the full extent of the slick: clouds, haze, nearshore turbidity, and plumes of sediment issuing from the Mississippi River outlet channels (the Terra image today is even worse):


Only the thickest part of the slick is visible, as brown ropy-looking stringers in the vicinity of the leaking well. We think thinner slick and sheen could actually be spread across a much larger area. Compare with this map published by NOAA, showing oil slicks from May 2 to May 6 as mapped by aerial surveys, and May 7 (orange) as predicted by their oil spill trajectory model:

NOAA map showing oil slicks May 2 - May 7, 2010.

Thursday, May 6, 2010

Gulf Oil Spill - Where's The Latest Imagery?

We beg your patience. Our main source of imagery is from the NASA satellites, Terra and Aqua, that carry the MODIS sensor. This sensor measures visible to infrared wavelengths of light, so when it's cloudy or hazy in the Gulf, we get a nice picture of...clouds and haze. MODIS images also show a distinct pattern of glittery sunglint on the water (when there are no clouds in the way, and the geometry with the sun is just right). This can be very useful for mapping oil slicks because the oil flattens out the water, and will appear either very dark or very bright (depending, again, on the sun angle). But other things can make the water flat: calm winds, for example. So if we get a MODIS image that suffers from too many of these quality problems, we don't process and post it because it's not providing useful information about the spill.

See our Twitter feed (just glance to your right!) - that's where we post updates and info that's briefer and more timely than these blog entries. Follow us on Twitter and when we know it, you'll know it.

Tuesday, May 4, 2010

Gulf Oil Spill - More Imagery Coming

We're getting requests from folks wanting to see the latest satellite images of the oil slick in the Gulf of Mexico. It's been cloudy the last couple of days, so the NASA /MODIS imagery hasn't been very good; the latest we posted was from the afternoon of May 2. But observers tell me it's clear and sunny in the Gulf today, so we're hoping the MODIS images this afternoon will give us a clear look at the entire slick. We'll process and post those images as quickly as we can. Follow us on Twitter - we tweet as soon as we upload anything new - and keep checking here and in the SkyTruth image gallery.

There is a gallery of radar satellite images here - radar cuts through the clouds and haze to show the ocean surface, and the slicks are clearly visible on the May 3 image. The drawback - this image only covers part of the slick. We hope to see some better coverage in coming days.

We'd like to see a systematic, Gulf-wide monitoring program established, so that when emergencies like this happen the stream of images from multiple satellite systems is immediately available to all who want to see it - including folks like the Bay St. Louis-area local emergency response guy who just called SkyTruth for assistance.

MODIS satellite image from the afternoon of May 4, 2010.

UPDATE 5/4/10 6:30 pm - And here it is. Today's MODIS / Aqua image features a break in the clouds (just barely) to reveal much of the oil slick. Fresh upwelling oil is apparent around the location of the leaking well. Long tendrils of slick and sheen stretch to the east and southwest; the total area of slicks and sheen, possibly including patches of open water, is 3,260 square miles. Nearshore, things get complicated: there are pale bands of turbidity, probably caused by the recent stretch of high wind and waves; and a few dark streaks and elongated patches trending northeast that we interpret as low-wind zones (wind shadow, the result of light winds from the northeast this afternoon). But there could be patches of oil slick obscured by these features. To the south, heavy cloud may also be hiding some of the slick from this ongoing spill.

Saturday, May 1, 2010

Gulf Oil Spill - New Spill Calculation - Exxon Valdez Surpassed Today

Figure 1. US Coast Guard map showing size and appearance of oil slick on April 28, 2010.

Dr. Ian MacDonald at FSU just produced a new spill-size estimate based on the US Coast Guard aerial overflight map of the oil slick on April 28, 2010. This map shows the slick covering 1,786 square miles (4,627 square kilometers). The bottom line: on April 28 there was a total of 8.9 million gallons floating on the surface of the Gulf.

That suggests a minimum average flow rate of slightly more than 1.1 million gallons of oil (26,500 barrels) per day from the leaking well on the seafloor. Since we're now in Day 11 of the spill, which began with a blowout and explosion on April 20, we estimate that by the end of the today 12.2 million gallons of oil, at a minimum, have been spilled into the Gulf of Mexico.

The oft-quoted official estimate for the Exxon Valdez spill is 11 million gallons, although some think that is the lower limit of the likely range. It appears that we've just set a very sad new record.

Here is Dr. MacDonald's calculation:

Deepwater Horizon spill estimates derived from USCG fly-over data (28 April 2010)

These estimates of the total volume of oil released by the Deepwater Horizon spill were derived from the USCG fly-over map (Figure 1). The map was geo-referenced in Arc Map and the areas of each of the slick types (dull oil streamers, etc) were measured with a planimeter tool. Thickness estimates for each slick classification were taken from the BONN guidelines as published in the NOAA field manual (Figure 2). Conservative values were used for each slick types. Note that the predicted average layer thickness are still very small.
Figure 2. Chart of oil thickness and appearance.

A human hair is approximately 100 µm (microns). The main slick, which corresponds to
the cross-hatched area was assigned a low value of 0.5 µm. We calculate a total volume of oil for this slick as 8.94 million gallons (212,000 barrels) (Figure 3). Considering that the oil in the water on April 28 has been deposited since the blowout and explosion on April 20, the flow rate should be on the order of 26,500 barrels per day. Some fraction of the total oil released will have been evaporated or emulsified and sunk in the time since the spill began, or collected by the response crews, so this should be considered a minimum estimate.

Figure 3. Volume of oil based on Coast Guard map (Figure 1) and thickness (Figure 2).

UPDATE 5/1/10 5:15 pm - Lots of cloud and haze but this afternoon's MODIS satellite image shows the main body of the oil slick around the leaking well location.