SkyTruth and COVID-19: A message from the President

SkyTruth continuing to protect the environment from remote offices. 

Dear friends, partners and supporters: the staff, board and I wish all of you as much kindness, strength, good health, and good cheer as these difficult times allow. In case you were wondering, I can assure you that SkyTruth is well equipped to adapt to these extraordinary circumstances. We’re in a good financial position. Our staff and contractors are comfortable with, and experienced at, working as a distributed team: we have well-tested tools to facilitate remote work and data sharing, and a rigorous schedule for communications to keep everyone in touch and on track. To help slow the spread of coronavirus during this critical window of opportunity to “flatten the curve,” we closed our Shepherdstown office three weeks ago, and all staff are working from home until further notice.

I’m convinced the need for our work is even greater during this crisis: the White House assault on the environment continues at a breakneck pace. Despite the staff shortages and chaos resulting from the rapidly spreading COVID-19 pandemic, the Environmental Protection Agency, Bureau of Land Management, and other Federal agencies are under pressure to continue rolling back regulations that were put in place to protect human health and the environment. And the EPA just announced a “sweeping relaxation” of pollution reporting requirements for power plants, oil refineries, and other industrial sites, leaving the public in the dark about the ongoing leaks, spills and other toxic incidents happening at facilities that are often located right next door.

This tunnel we’re in may be long, but there will be an end to it. That’s why SkyTruth will continue to shine a light on the way our lands and waters are being managed, to support effective public participation in government decision making, and to inspire better protection of the environment that we need — now and in the future — to heal and sustain us.

As always, feel free to contact me if you’d like to give me some feedback or learn more about how we’re weathering this storm. I would love to hear from you.  – John

South Pesisir Regency, Indonesia ©2020 Map data: Google Earth View  imagery CNES / Airbus, Maxar Technologies.

What can we learn from the longest oil spill in US history?

[This is a guest post about the ongoing Taylor Energy oil spill from Dr. Ian MacDonald, oceanographer at Florida State University. Ian helped SkyTruth make independent estimates of the size of the Deepwater Horizon oil spill in 2010 that dwarfed the estimates told to the public by BP.]

As recently as two days ago — March 13, 2019 — pollution experts at the National Oceanic and Atmospheric Administration were reporting a 14 square-mile oil slick that originated out in the Gulf of Mexico about 12 miles from the Birdfoot Delta’s farthest bit of land.  By now there are hundreds of satellite and aerial images telling the same, sorry story. The source is the wreck of MC20A, an oil platform owned by Taylor Energy Company that was destroyed by winds, waves, and mudslides spawned by Hurricane Ivan in 2004. Last fall, the Coast Guard and other agencies federalized the response to an oil spill that has been going on for fourteen years and counting, disinviting the company from the latest effort to stem the flow by attaching a massive containment dome to what remains of the platform.  Although the company has long insisted that the spill is trivial–no more than 10 gallons per day–a growing chorus of scientists have disagreed, by orders of magnitude. My personal estimate is 96 barrels (4032 gallons) per day, and I tend toward the low end of the scientific opinions.

Why the Feds changed their mind, and how come it took so long, are questions I address in a report on the longest offshore oil spill in U.S. history.  I tell the story from my perspective as an oceanographer who studies natural and unnatural oil inputs to the ocean, and based on what is now over seven years of funded research on MC20A.  

Storms like Ivan seem to be growing more common.  The sediments lost from the drastic reduction of Louisiana wetlands have been deposited on the slope in huge mud lobes–some of which will inevitably slide toward the sprawling network of aging platforms and pipelines that surrounds the Delta.  The lessons we learn from MC20A, and the response by a unified command under the direction of the US Coast Guard, may be put to the test again, possibly much more severely than with MC20A.

Will we be ready?
Read my report to learn more.  

Sentinel 1 imagery showing a slick visible with Synthetic Aperture Radar that appears to be emanating from the stricken vessel on July 17.

Signs of oil from the SSL Kolkata

Followers of our work will recall the merchant vessel SSL Kolkata that was being towed by the Indian Navy after catching fire on June 13th off the Sundarbans in the Bay of Bengal.  The Indian Navy had to abandon the ship after a series of explosions and it has been stuck in shallow water ever since. There have been concerns that the 400 tonnes of heavy fuel oil might start leaking as the ship is listing and cracks are developing. The Sundarbans are the world’s largest collection of mangrove forests and a Unesco World Heritage site (, and a major oil spill here could be devastating. We see indications in this Sentinel 1 radar satellite image from July 17 that this is a legitimate concern: there appears to be a 17km slick coming from the vessel, being pushed by the strong currents from the Ganges Delta.

Sentinel 1 imagery showing a slick visible with Synthetic Aperture Radar that appears to be emanating from the stricken vessel on July 17.

Sentinel 1 imagery showing a slick visible with Synthetic Aperture Radar that appears to be emanating from the stricken vessel on July 17.

Considering the volume of oil onboard, the slick on July 17 is far smaller than what we would expect if there were a serious leak. This Sentinel 2 multispectral image from the 19th has also captured the slick. Though it doesn’t give us a complete image of the slick as a radar image would (due to interference from the clouds and cloud shadows), we do get an idea of how the slick is spreading not just south, but also north toward the Delta.

Oil slicks seen in Sentinel 2 imagery taken two days later on July 19.

Oil slicks seen in Sentinel 2 imagery taken two days later on July 19.

Attempts have been made to salvage the ship but were abandoned after cracks developed and the ship started listing. Now that the fuel tank is underwater, they will need to suck the oil out carefully using a method known as “hot tapping.” Although poor weather has delayed these plans, we have observed one tugboat, the Lewek Harrier, visiting the site as recently as the 19th according to its Automatic Identification System (AIS) signal. Though we couldn’t definitively identify the vessel visible in this image at the time it was collected, the Lewek Harrier was the only vessel that was broadcasting AIS in the area on that day. The MCS Elly II has also been operating in the area though we haven’t seen it in any images.

[ Image 3 ]

This vigilant tug, the Lewek Harrier, has been a regular visitor.

This vigilant tug, the Lewek Harrier, has been a regular visitor.

We hope this means an end to this leak and that the extent of the spill will be limited. We will continue to watch this area closely as there is still a real threat to the nearby Sundarbans.

You can find more info on the cleanup here. 

You can find more info from when the containers began slipping off the ship here

Pretty Parallax Planes

While scanning the European Space Agency’s (ESA) Sentinel-2 satellite images for signs of the Sanchi oil slick, I came across an unusual sight of what appeared to be three, brightly-colored aircraft flying in tight formation. I’m not enough of a GIS rookie to be fooled into thinking China’s latest stealth jets were malfunctioning, what I was observing was a single aircraft’s image split into three spectral bands of red, green, and blue.

This flight was snapped by Sentinel-2 on its way to Tokyo (flight data from

To explain why this happens, we need to take a look at the source of these images: Sentinel-2’s MultiSpectral Instrument (MSI) sensor. This can be thought of as a very advanced camera that can see beyond the usual visual spectrum and into the near-infrared (great for monitoring vegetation) and shortwave infrared. Instead of just one sensor in a camera, the MSI sensor has 12 in a row. For a more technical explanation, take a look at ESA’s guide on the MSI sensor here. Imagine a push-broom with 12, wide bristles and you’ll have an idea of how these sensors sweep across the Earth as the satellite flies overhead. Each sensor splits the image into 10 different spectral bands using a stripe filter which means not only is each band detected at a slightly different angle, they are also detected at slightly different times. What this means for an image like the one above, a “true color” composite made up of the MSI’s red, green, and blue bands, is that when the bands are combined, an assumption has to be made about how far away the object is to correct for the parallax and “focus” the image on the target — and for earth-observation systems like Sentinel, the target is the surface of the earth. An element of parallax is factored in when we combine the bands in the same way that our brains adjust for the parallax of the different angles our eyeballs are seeing. This is called orthorectification. For an example of this, hold your finger halfway between this screen and your face and focus on these words. As well as being a bit blurry, you should be seeing more than one finger. In the same way, the RGB bands are combined with the focus on the surface of the Earth so an aircraft at a higher altitude splits into three images, one for each band. Since this Airbus A321 was cruising at an altitude of about 33,000 feet, the aircraft’s position was projected onto the Earth’s surface resulting in three different images, one for each of the bands.

The time difference between when each band is detected also adds to the offset. This isn’t noticeable for stationary or slow-moving objects but an aircraft is moving fast enough to see a difference. In the image we found, the aircraft’s speed, about 550kts (according to, is probably the biggest cause of the shift between images but if you look closely at the contrails, you can see some sideways drift between the first and last image of the plane. The image below, from just off the east coast of Bulgaria, better highlights the two effects of the forward motion of the aircraft and the sideways shift due to parallax.

Example of parallax off the east coast of Bulgaria.

If we really wanted to fix the aircraft’s image, we would need to adjust for the parallax at that distance as well as the delay between each band’s detection (to account for the aircraft’s speed). The result would be that the aircraft would now be one, complete image but everything else would be a multicolor mess.

For more info on this effect, check out this post by Tyler Erickson, or some direct information from the European Space Agency (skip to chapter 2.5).

Transshipment in the Fishing Industry Getting a Critical Look

Our collaboration with Global Fishing Watch on the problem of transshipment at sea in the fishing industry is at the forefront of a growing movement to take a critical look at this practice, which is increasingly regarded as a key driver of overfishing, and an enabler of illegal fishing and other fisheries crime including crew enslavement. Our work is funded by the Walton Family Foundation and being led by Bay-area skytruthers Aaron Roan and Nate Miller.

Some hot-off-the-presses resources on this issue:

A new Walton Family Foundation blog post on our work — How Big Data is Helping in Battle Against Illegal Fishing: Satellite Monitoring Tracks ‘Pervasive Problem’ of Global Transshipments

Just-published research concluding transshipment at sea should be banned to curb illegal fishing — Potential Ecological and Social Benefits of a Moratorium on Transshipment on the High Seas

SkyTruth collaboration with DigitalGlobe to target transshipment with high-resolution satellite imagery — Satellites Leave No Place to Hide for Rogue Thai Fishing Fleet

Worldview-3 satellite image of likely transshipment courtesy DigitalGlobe.

Oceana report — No More Hiding at Sea: Transshipping Exposed

SkyTruth + Global Fishing Watch report, map and dataset showing 5,000 likely transshipment events over four years, detected using vessel tracking data — The Global View of Transshipment: Preliminary Findings