NOAA's Marine Debris Blog

Keepin' the Sea Free of Debris!


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Looking for debris from the sky, ctd

By Peter Murphy, Alaska Regional Coordinator, NOAA Marine Debris Program

One of the challenges NOAA faces when addressing marine debris is finding it.  That may seem odd when you think of bottles and trash on your nearest beach, but it becomes much more difficult in the open ocean.  Debris – including items from the 2011 tsunami in Japan – is difficult to locate reliably.

In addition to the fact that debris sometimes floats just below the water’s surface, it can be spread out across huge stretches of ocean. Imagine a search area roughly three times the size of the continental United States.  Even when we look at an area where we know there is likely to be debris, we may not detect anything.  That could be because there isn’t anything there to see (less likely) or because our sensors aren’t able to detect what is there (more likely).

However, NOAA is looking at many innovative ways to solve that challenge. Earlier this summer, we tested an Unmanned Aircraft System (UAS) off the coast of Oʻahu to see if it might be an effective new technology to help locate debris at sea.

The test was a good step forward in the process. Since then, many people have asked whether we’re ready to use the UAS to locate tsunami debris. The answer is no, not yet.

What did we do?

During the test, researchers placed simulated debris of varying sizes, shapes and buoyancies in the water and launched the UAS (which resembles a model airplane) from a vessel over the items. We also took advantage of the fact that we had control over the debris’ location to test whether different satellite sensors could detect it in the water.

In the end, the plane’s camera was able to capture clear images of the debris in the water and the vessel itself. We are still analyzing the satellite imagery, which can be tricky if there’s cloud cover, to see which sensors could detect the debris.

We still have many more questions to answer and logistics to work out before a UAS can be applied to real-world marine debris detection.  We’ll keep you updated on next steps, but until then, here are a few photos from the demonstration:


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Looking for debris from the sky

By: Dianna Parker, Communications Specialist, NOAA Marine Debris Program

*JUNE 22 UPDATE - The test went as expected, despite rough seas and some cloud cover. We’re in the process of analyzing the results.*

This week, NOAA researchers will launch a Puma Unmanned Aircraft System (UAS) to determine whether it can detect marine debris off the coast of Oʻahu. The test is one of NOAA’s efforts to identify effective technologies for locating marine debris at sea—including debris from the Japan tsunami.

During the test, NOAA staff aboard two vessels will have the UAS as well as debris of varying sizes, materials, and buoyancy, including fishing nets, wooden construction debris, small buoys, and large buoys. Researchers will place the debris in the ocean as a “control” and then launch the UAS over the different items—hoping that the UAS will identify the debris.

If all goes as planned, the UAS will then send information back to NOAA in the form of high-resolution imagery. Additionally, scientists will test seven different satellite sensors and their ability to detect debris’ location and shape.

Puma UAS over open ocean. Credit: Will von Dauster / NOAA

The operation is part of a larger, two-day demonstration by NOAA’s UAS Program to explore how this technology can enhance management of the Papahānaumokuākea Marine National Monument. If successful, the UAS could be used in remote marine protected areas worldwide for activities such as marine wildlife surveys for sea turtles, monk seals and sea birds.

After the debris test, scientists will come away with a better understanding of which satellites sensors are capable of seeing different items under certain conditions, or if the satellites don’t detect the debris, we’ll still come away with equally valuable information on what works and what doesn’t.

There’s no one thing that’s going to give us a clear picture of the Japan tsunami marine debris, but this is one of the many tools we’re using to complete the puzzle. NOAA will continue to explore other detection technologies, modeling, monitoring, and voluntary at-sea observation in our efforts to protect our trust resources and coastal communities.

We’ll be sure to give an update after the test. Stay tuned.


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I Spy… Marine Debris: At-sea detection adventures from the air

Here’s how science works sometimes. You plan and plan and then something breaks and it all falls apart. Or you plan and plan and later in the game, a new component gets added. Or both, in this case. A group of researchers, technical specialists, and people like me met a couple years ago at a workshop on at-sea detection of derelict fishing gear. For the last six or eight months, NOAA and NASA have been planning a test of a synthetic aperture radar (SAR) instrument that can see through cloud cover to detect ocean features that might accumulate marine debris. This particular SAR is designed to be mounted eventually on an unmanned aerial vehicle (UAV), so it’s called a UAVSAR. It’s not yet ready for flying on the UAV, so for this test it was going to be mounted on a Gulfstream 3 jet. Sadly, about a week before our planned flight, the antenna on the UAVSAR malfunctioned, and it had to go back home to California. However, we were lucky to have gotten the US Coast Guard interested in the project; they offered to fly people over the ocean to look for debris while the UAVSAR looked for those areas of the ocean that might accumulate marine debris. Even though we lost the NASA plane—and thus the UAVSAR—the Coast Guard offer stayed on the table.

Map of the N. Pacific Ocean showing the area of the STCZ.

It’s been six long years since the last flights to look for marine debris from an airplane over the North Pacific subtropical convergence zone, a known area of marine debris accumulation (see map above; for more info on this click here). On Monday, April 11, eight intrepid observers—representing five NOAA programs and Tetra Tech, Inc.—set out to join a Coast Guard training flight. The ocean area of interest was chosen based on our planning for the UAVSAR flight, and it worked just fine for the visual observations as well. Maps of likely debris accumulation locations were prepared using sea surface temperature and photosynthetic chlorophyll data from satellite sensors. The debris estimated likelihood index (DELI) map that averaged data from the two weeks before our flight shows the areas we expected to see more debris (below map image; darker reds) and our planned flight tracks. An explanation of the concept is located in previous posts, here and here. Our planned flight tracks covered areas with both high and low expected debris density.

DELI map image. Courtesy of NOAA.

We had a safety briefing at 7:30am and were in the air a little after 8:00. We transited about three-and-a-half hours north then dropped to between 500 and 1000 feet altitude for about four hours to look for marine debris. All of the observers had training on what we were looking for, how to call out sightings through the headset intercom system, how to record marine debris and weather observations, and what our roles would be. Each observer had a chance to work each of the stations: the four observing ones—left cockpit, right cockpit, left wing, and right wing; data recorder; and an additional recorder.

Photo of Kevin Kelly, Tetra Tech, demonstrating the headset intercom system (unplugged).

A few observing observations:

  • When you’re on a big airplane, 500 feet elevation seems startlingly close to the water. Still, we couldn’t distinguish small items, which may have been out there.
  • It’s a darn big ocean, and even with a fast plane and great conditions, you can’t sample much of it on a huge tank of gas. Even traveling for four hours at 300 km per hour (~200 mph), we did four lines totaling maybe 1200 km (~745 miles). Our swath of observations was at most 1000 meters wide (and honestly, the vast majority of our observations were much closer than 500 m from the plane), meaning that we covered about 1% of the box our tracks outlined.
  • Visibility was not bad but not great. We had to descend sometimes to get beneath the clouds, experienced fog that limited the distance away from the plane we could see clearly, and part of the time had to contend with whitecaps that mimicked white debris items. Still, much of the time we had a clear view at least close to the plane. Our chief scientist is working up the data, but in broad numbers, we saw just 56 items over four hours. Over half were unidentified marine debris, about one-quarter were fishing floats, and the remainder were buoys, lines, cardboard, and nets. How and if the marine debris observations correlate to estimates of debris density remains to be seen. But just getting out there and getting some eyeballs on the ocean surface was valuable.
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