Perseids or Sporadic Meteors? Maybe Both

August 17th, 2016 by Kathryn Hansen

On August 13, 2016, we published an image and video showing meteors streaking across the night sky. The perspective is a new one. Instead of looking up from the ground, the camera recorded the action from the vantage point of the International Space Station (ISS). In case you missed it, you can see the image and read the full story here. The video is reposted below.

At 6 and 16 seconds into the video, bright meteors dash across the sky over Pakistan. The video was acquired a few days before the annual Perseid meteor shower reached its peak. But as one reader pointed out to us via email, only one of these meteors can be associated with the shower. The reason? The view from orbit shows them travelling in different directions.

Meteors within a shower all travel in roughly the same direction and speed. The map below illustrates that point, showing the ground tracks and speed of all Perseids observed in the United States in July and August 2016 by the ground-based all sky camera network. The map shows all Perseids within range of a camera; blank areas are outside the range of a camera.

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“Note how their paths all move from top right to bottom left,” said Bill Cooke with NASA’s Meteoroid Environments Office. “This is what would be seen from the ISS or another space platform.”

Showers look vastly different to a person standing on the ground looking up at a wide view of the night sky. From this perspective, meteors associated with a shower can appear to radiate outward from a central point called the “radiant.” The central point in the night sky is linked to the shower’s name; the Perseids, for example, appear to stem from the area of sky near the constellation Perseus.

The phenomenon, however, is an illusion of perspective. The illusion has been compared to flakes that appear to radiate outward as you drive through a snowstorm, or parallel train tracks that appear to converge in the distance.

“The perspective from orbit is somewhat different, because you are not looking at the entire sky, just a small fraction of the total area,” Cooke said. “In this case, meteors from a particular shower will be all moving the same direction.”

So which meteors viewed from orbit are belong to a particular shower, and which are “sporadic meteors?” That’s the type of information that will ultimately be gleaned from the diffraction grating on the space station’s Meteor camera. It will collect spectroscopy data that can tell scientists about a meteor’s composition, which can ultimately be related back to the parent body—comet Swift-Tuttle, in the case of the Perseids.

A Watchful Eye on Rio

August 16th, 2016 by Adam Voiland
Many of the Olympic festivities are taking place in Barra da Tijuca, one of the youngest and most affluent neighborhoods in Rio.

Many of the Olympic festivities are taking place in Barra da Tijuca, one of the youngest and most affluent neighborhoods in Rio. Credit: Landsat 8/NASA Earth Observatory.

While gymnasts leap, cyclists pedal, and divers twirl for Olympic gold in Rio de Janeiro, sensors on several NASA Earth Observing satellites are catching glimpses of the city and its surroundings from space. The mix of satellites and sensors in orbit are nearly as varied and diverse as the athletes competing below.

The marathoner among NASA’s fleet would have to be Terra. Despite having a design life of six years, this reliable spacecraft has been in orbit since 2000. The multi-purpose satellite carries five scientific payloads and monitors everything from phytoplankton to forest cover to airborne particles called aerosols.

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NASA’s Earth Observing Fleet. Credit: NASA Earth Observing System Project Science Office

The swimmers would have to be Aquarius, Aqua, and the Global Precipitation Measurement (GPM). All three satellites, as their names suggest, specialize in studying water. Aquarius focuses on measuring the ocean’s salinity. Aqua, like Terra, is versatile: It studies water vapor, sea ice, snow ice, clouds, and more. GPM is the newest of the trio. Launched in 2014, it makes global maps of precipitation and sets standards for precipitation measurements worldwide.

The synchronized divers of space would have to be the Gravity Recovery and Climate Experiment (GRACE). While divers seem to temporarily defy gravity with their flips and turns, the pair of GRACE satellites actually measures Earth’s gravity from space.

The GRACE satellites. Credit: NASA

The twin GRACE satellites. Credit: NASA

The archers would be CALIPSO and CloudSat. These two satellites shoot laser pulses (CALIPSO) and radar waves (CloudSat) down toward features in the atmosphere such as clouds and smoke plumes. They measures precisely how long it takes for the light or radio waves to bounce back, making it possible to map the vertical structure of the atmosphere.

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Rio at night. Credit: VIIRS/NASA Earth Observatory.

The images above and below offer a glimpse of some of the types of imagery and data that NASA-Earth observing satellites collect. The image at the top of the page shows how Olympic Park in Rio appeared to the Operational Land Imager (OLI), a sensor on Landsat 8. The image immediately above shows Rio at night as seen by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite. The instrument can sense light 100,000 times fainter than conventional visible-light sensors, making it extremely sensitive to moonlight and city lights.

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Rio on August 6, 2016. Credit: Worldview/NASA.

The image directly above shows a view of Rio and Guanabara Bay on August 6, 2016, the day after the opening ceremony.  The fourth image (below) shows a view of aerosols observed over Rio by the Multi-Angle Imaging Spectrometer (MISR) on August 2, 2016.

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Observations of aerosols over Rio on August 2, 2016. Credit: NASA/Terra/MISR.

Scientists at NASA and officials in the Rio de Janeiro government recently signed an agreement about natural hazards preparedness. The hope is that satellite imagery and data—in conjunction with in situ data from the ground—will help scientists better understand, anticipate, and monitor drought, flooding, and landslides that occur in and around Rio. The collaboration will focus on integrating, visualizing, and sharing relevant data from NASA satellites.

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Severe mudslides and landslides affected Rio in 2011. Read more about this image here. Credit: EO-1/NASA Earth Observatory

In a NASA press release, Rio de Janeiro Mayor Eduardo Paes said that his city has historically suffered from massive rainstorms and subsequent floods and landslides, all of which can cause casualties and disrupt the economy. Discussions are underway to address those hazards and to plan future cooperative activities.

Just How Bad was the 2015 Fire Season in Indonesia?

August 5th, 2016 by Adam Voiland
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Image from MODIS/NASA Earth Observatory.

The 2015 fire season was the most severe ever observed by NASA Earth Observing System satellites, a new study shows. As we reported in December, 2015 was an intense fire season in Indonesia because the drying effects of El Niño exacerbated seasonal fires lit by growers. Many farmers lost control of fires, which then spread through dried-out peat deposits. Peat fires produce thick, acrid smoke rich with greenhouse gases.

Since our story was published, scientists tracking fire activity with several satellite sensors have further analyzed the 2015 data and compared the 2015 fire season with 2006, another severe burning season. The group of scientists looked at measurements of carbon monoxide from the Measurement of Pollution in the Troposphere (MOPITT), the Microwave Limb Sounder (MLS), and the Atmospheric Infrared Sounder (AIRS). They tracked aerosol pollution with Moderate Resolution Imaging Spectroradiometer (MODIS) and the Ozone Monitoring Instrument (OMI). They also used MODIS to track the number  of actively burning fires. Finally, they used the Tropical Rainfal Measuring Mission (TRMM) to track rainfall.

Some of the results from their analysis are shown in the chart below. Note that red lines indicate trends in 2006 (also a severe fire year); blacks lines indicate 2015. The tick marks on the X-axis indicate the month of the year. Comparing the two years, it is clear that 2015 was the more severe fire season. The sensors generally detected higher levels (or longer duration of emissions) of each pollutant in 2015. The peak number of fires observed by MODIS was slightly higher in 2006, but the sensor detected more fires overall in 2015. In both 2006 and 2015, fire activity increased rapidly as rainfall decreased.

 

 

To see how the 2015 fires compared to severe fire seasons before the Earth Observing System satellites were in space, Goddard Institute for Space Studies scientist Robert Field looked back at longer-term records of visibility collected at Indonesian airports. The chart below compares visibility in 2015 with 1997 and 1991—two other years that were dry because of El Niño. (Note: Bext stands for extinction coefficient; a higher extinction coefficient means more smoke was in the air. The upper part of the chart shows how much rain fell. In that chart, “CPC pcp” stands for precipitation from the Climate Prediction Center, a NOAA research group.) By that measure, 1997 was a far more severe fire season. In Sumatra, visibility was also lower in 1991, though in Kalimantan. visibility was about the same in 2015 and 1991.

Still, greenhouse gas emissions from the 2015 Indonesian fires were considerable. Using the Global Fire Emissions Database, the scientists estimate that 2015 released 380 teragrams of carbon—which is roughly more than the annual fossil fuel emissions of Japan.

“Without significant reforms in land use and the adoption of early warning triggers tied to precipitation forecasts, these intense fire episodes will reoccur during future droughts, usually associated with El Niño events,” the authors emphasized.

+Read a NASA press release about the study here.
+Read a more detailed story about the 2015 fires here.

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In Indonesia, dry weather can mean fire. September 2015 data from the TRMM satellite shows lack of rainfall in the areas where fire broke out. Image by NASA Earth Observatory.

 

 

If you are like me, you have probably fantasized about looking down and photographing Earth while floating in the zero gravity of space.

I suppose I should never say never, but my chances of becoming an astronaut do look pretty slim at this point in my life. But even if I can’t experience space firsthand, I may have have found the next best thing: merged panorama photographs that make me feel like I am up there. NASA astronaut Jeff Williams has been posting short video clips on his social media feeds and the results are stunning.

All of these panoramas were taken while he was orbiting about 250 miles (400 kilometers) above the surface of Earth on the International Space Station. At the time, he was moving about 17,150 miles (27,600 kilometers) per hour. The photos were taken from the Cupola, a dome-shaped module on the Space Station with bay windows that offer panoramic views of Earth. To make the videos, Williams (with help from NASA colleagues on the ground) stitched together several images into mosaics and then used computer software to pan across the mosaic.

I have posted a few of my favorites here: a sunset, the coastline of western Australia, the Andes Mountains, and Cuba’s Gulf of Batabano. Scroll down past the video for a view of one of the raw mosaics and some video of Williams explaining what it is like to take photographs from space. Browse more astronaut photography here and find more of Williams’ photography on Facebook, Twitter, and Instagram. In related stories from the Earth Observatory, learn more about sunsets seen from space, the Andes, and coastal Australia.

Here is how the raw mosaic of the Gulf of Batabano looked.

And here is Williams explaining the cameras he uses and how he makes the merged panoramas.

Research Roundup: The Latest on Methane

July 11th, 2016 by Adam Voiland

Global atmospheric concentrations of methane are rising—along with scientific scrutiny of this potent greenhouse gas. In March 2016, we published a feature story that took a broad look at why methane matters. Since that story came out, several new studies have been published. But first, some broader context from that feature story…

The long-term, global trend for atmospheric methane is clear. The concentration of the gas was relatively stable for hundreds of thousands of years, but then started to increase rapidly around 1750. The reason is simple: increasing human populations since the Industrial Revolution have meant more agriculture, more waste, and more fossil fuel production. Over the same period, emissions from natural sources have stayed about the same.

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The Zeppelin Observatory in Svalbard monitors methane concentrations. It is one of several stations that helps scientists assemble a global picture of atmospheric aerosols and pollutants. Photo courtesy of AGAGE.

If you focus on just the past five decades—when modern scientific tools have been available to detect atmospheric methane—there have been fluctuations in methane levels that are harder to explain. Since 2005, methane has been on the rise, and no one is quite sure why. Some scientists think tropical wetlands have gotten a bit wetter and are releasing more gas. Others point to the natural gas fracking boom in North America and its sometimes leaky infrastructure. Others wonder if changes in agriculture may be playing a role.

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A combination of historical ice core data and air monitoring instruments reveals a consistent trend: global atmospheric methane concentrations have risen sharply in the past 2000 years. (NASA Earth Observatory image by Joshua Stevens, using data from the EPA.)

The stakes are high when it comes to sorting out what is going on with methane. Global temperatures in 2014 and 2015 were warmer than at any other time in the modern temperature record, which dates back to 1880. The most recent decade was the warmest on the record.  The current year, 2016, is already on track to be the warmest. And carbon emissions — including methane — are central to that rise.

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Atmospheric methane has continued to increase, though the rate of the increase has varied considerably over time and puzzled experts. (NASA Earth Observatory image by Joshua Stevens, using data from NOAA.)

 

Isotope Data Suggests Fossil Fuels Not to Blame for Increase
Methane bubbles up from swamps and rivers, belches from volcanoes, rises from wildfires, and seeps from the guts of cows and termites (where is it made by microbes). Human settlements are awash with the gas. Methane leaks silently from natural gas and oil wells and pipelines, as well as coal mines. It stews in landfills, sewage treatment plants, and rice paddies. With so many different sources, many scientists who study methane are hesitant to pin the rising concentration of the gas on a particular source until more data is collected and analyzed.

However, an April 2016 study led by a researcher from New Zealand’s National Institute of Water and Atmospheric Research came down squarely on one side. After measuring the isotopic composition, or chemical structure, of carbon trapped in ice cores and archived air samples from a global network of monitoring stations, the scientists concluded that blaming the rise in atmospheric methane on fossil fuel production makes little sense.

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Chart from Schaefer et al.

 

When methane has extra neutrons in its chemical structure, it is said to be a “heavier” isotope; fewer neutrons make for “lighter” methane. Different processes produce different proportions of heavy and light methane. Lighter isotopes of a carbon (meaning they have a lower ratio of Carbon 13 to Carbon 12 than the atmosphere), for instance, are usually associated with methane recovered from fossil fuels.

As shown in the chart above, the authors observed a decrease in the isotopes associated with fossil fuels at all latitudes beginning in 2006. But at the same time, global concentrations of methane (blue line in the top chart) have risen. “The finding is unexpected, given the recent boom in unconventional gas production and reported resurgence in coal mining and the Asian economy. Either food production or climate-sensitive natural emissions are the most probable causes of the current methane increase,” the authors noted.

If fossil fuel production is not responsible for increasing concentrations of atmospheric methane, than what is? The authors say that more research is needed to be certain, but that there are indications that the agricultural sector in southeast Asia (especially rice cultivation and livestock production) is likely responsible.

Large Increase in U.S. Emissions over Past Decade
A March 2016 study led by Harvard researchers based on surface measurements and satellite observations  detected a 30 percent increase in methane emissions from the United States between 2002 and 2014 — an amount the authors argue could account for between 30 to 60 percent of the global growth in atmospheric methane during the past decade.

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Chart from Turner et al.

The most significant increase (in red, as observed with Japan’s Greenhouse Gases Observing Satellite) occurred in the central United States. However, the authors avoid making claims about why. “The U.S. has seen a 20 percent increase in oil and gas production and a nine-fold increase in shale gas production from 2002 to 2014, but the spatial pattern of the methane increase seen by GOSAT does not clearly point to these sources. More work is needed to attribute the observed increase to specific sources.”

First Time Satellite View of Methane Leaking from a Single Facility
For the first time, an instrument on a spacecraft has measured the methane emissions leaking from a single facility on Earth’s surface. The observation, detailed in a June 2016 study, was made by the hyperspectral spectrometer Hyperion on NASA’s Earth Observing-1 (EO-1) satellite. On three separate overpasses, Hyperion detected methane leaking from the Aliso Canyon gas leak, the largest methane leak in U.S. history.

“The percentage of atmospheric methane produced through human activities remains poorly understood. Future satellite instruments with much greater sensitivity can help resolve this question by surveying the biggest sources around the world and helping us to better understand and address this unknown factor in greenhouse gas emissions,” David Thompson, an atmospheric chemist at NASA’s Jet Propulsion Laboratory and an author of the study. For instance, the upcoming Environmental Mapping and Analysis Program (EnMAP) is a satellite mission (managed by the German Aerospace Center) that will provide new hyperspectral data for scientists for monitoring methane.

As detailed in a July 2016 study, scientists and engineering are also working on a project called GEO-CAPE that will result in the deployment of a new generation of methane-monitoring instruments on geostationary satellites that can monitor methane sources in North and South America on a more continuous basis. Current methane sensors operate in low-Earth orbit, and thus take several days or even weeks before they can observe the same methane hot spot. For instance, EO-1 detected the Aliso Canyon plume just three times between December 29, 2015 and February 14, 2016, due to challenges posed by cloud cover and the lighting angle. A geostationary satellite would have detected it on a much more regular basis.

July Puzzler

July 5th, 2016 by Adam Voiland

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Every month on Earth Matters, we offer a puzzling satellite image. The July 2016 puzzler is above. Your challenge is to use the comments section to tell us what part of the world we are looking at, when the image was acquired, what the image shows, and why the scene is interesting.

How to answer. Your answer can be a few words or several paragraphs. (Try to keep it shorter than 200 words). You might simply tell us what part of the world an image shows. Or you can dig deeper and explain what satellite and instrument produced the image, what spectral bands were used to create it, or what is compelling about some obscure speck in the far corner of an image. If you think something is interesting or noteworthy, tell us about it.

The prize. We can’t offer prize money, but, we can promise you credit and glory (well, maybe just credit). Roughly one week after a puzzler image appears on this blog, we will post an annotated and captioned version as our Image of the Day. In a blog post, we’ll acknowledge the person who was first to correctly ID the image. We’ll also recognize people who offer the most interesting tidbits of information about the geological, meteorological, or human processes that have played a role in molding the landscape. Please include your preferred name or alias with your comment. If you work for or attend an institution that you want us to recognize, please mention that as well.

Recent winners. If you’ve won the puzzler in the last few months or work in geospatial imaging, please sit on your hands for at least a day to give others a chance to play.

Releasing Comments. Savvy readers have solved some of our puzzlers after only a few minutes or hours. To give more people a chance to play, we may wait between 24-48 hours before posting the answers we receive in the comment thread.

Good luck!

Update: The answer is posted here.

May Puzzler Answer: Camp Springs Wind Farm

July 1st, 2016 by Adam Voiland

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Congratulations to Dan Mahr for being the first to solve our May puzzler. As Dan pointed out: “These are wind turbines, probably viewed from Landsat 8 OLI. The shadows of some turbines are visible from the diagonal roads connecting them.” Indeed, the Operational Land Imager on Landsat 8 captured this image of the Camp Springs Wind Farm in Scurry County, Texas, on April 29, 2015. You can learn more about these wind farms and surrounding landscape in our May 28, 2016, Image of the Day.

If you are interested in learning more about America’s wind infrastructure, check out WindFarm, an online database and interactive mapping tool from the U. S. Geological Survey. The database includes the location and other details about more than 47,000 wind turbines. Just choose one of the turbines and WindFarm will serve up key details (capacity, blade length, height, etc.) about it. The image below is a screenshot from WindFarm showing turbines that are part of the Camp Springs project in blue.

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To get a quick sense of where wind turbines in the United States are located, see the screenshot below. Turbines are shown with colored circles. The highest capacity turbines are red and yellow; lower capacity turbines are green and blue. Note the lack of turbines in the Southeast—a region known for having relatively weak winds. While development has lagged there as a result, the advent of a new generation of wind turbine with taller towers and more efficient blades is poised to change this.

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The U.S. Geological Survey developed the map by tapping publicly available data from the Federal Aviation Administration Digital Obstacle File and the using high-resolution aerial imagery to verify the locations of wind turbines. For more detailed description of the data used, see this report. For a more detailed overview of WindFarm, see this story and view this video.

Programming Note: The puzzler was on summer vacation in June, but it will return in July.

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1) In most of the world, water hyacinth (Eichhonria crassipes) — a fast-growing, aquatic plant — is loathed for its ability to reproduce so quickly that it can blanket large portions of lakes and ponds with a thick mat of vegetation.

2) In a lake with strongly entrenched water hyacinth, plants interlock into such dense masses that they are sturdy enough to hold people walking on them. On Inle Lake in Burma, people turn mats of water hyacinth into floating islands and grow vegetables and flowers on them.

3) Lakes that are overrun by water hyacinths undergo dramatic transformations. Submerged native plants became shaded and often die. The resulting decay processes depletes dissolved oxygen in the water and leads to fish kills. Boat travel can become impossible with severe infestations.

4) Water hyacinth is native to South America, the only continent where natural predators such as weevils and moths keep it at bay.

5) Cutting a water hyacinth plant into pieces will not kill it. The plants can reproduce using a process called fragmentation. Each plant also produces thousands of seeds each year.

6) The invasive plant is currently considered an invasive weed in more than 50 countries (including Central and North America, Asia, Europe, and Africa). Climate change may allow them to spread even farther.

7) Scientists use satellites to monitor lakes infested with water hyacinth. A NASA DEVELOP group recently devised an automated technique for monitoring water hyacinth in Lake Victoria’s Winam Gulf, an area that has struggled with water hyacinth infestation for decades. The researchers used satellite data collected by the OLI, MODIS, and MSI sensors. Winam Gulf communities have struggled with water hyacinth infestation for more than a decade. Learn more about the project in the video below.

Editor’s Note: DEVELOP, part of NASA’s Applied Sciences Program, addresses environmental and public policy issues through interdisciplinary research projects. To highlight the program’s work, the Earth Matters blog occasionally highlights some of the most interesting topics that DEVELOP teams are pursuing.

May Puzzler

May 24th, 2016 by Adam Voiland

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Every month on Earth Matters, we offer a puzzling satellite image. The May 2016 puzzler is above. Your challenge is to use the comments section to tell us what part of the world we are looking at, when the image was acquired, what the image shows, and why the scene is interesting.

How to answer. Your answer can be a few words or several paragraphs. (Try to keep it shorter than 200 words). You might simply tell us what part of the world an image shows. Or you can dig deeper and explain what satellite and instrument produced the image, what spectral bands were used to create it, or what is compelling about some obscure speck in the far corner of an image. If you think something is interesting or noteworthy, tell us about it.

The prize. We can’t offer prize money, but, we can promise you credit and glory (well, maybe just credit). Roughly one week after a puzzler image appears on this blog, we will post an annotated and captioned version as our Image of the Day. In a blog post, we’ll acknowledge the person who was first to correctly ID the image. We’ll also recognize people who offer the most interesting tidbits of information about the geological, meteorological, or human processes that have played a role in molding the landscape. Please include your preferred name or alias with your comment. If you work for or attend an institution that you want us to recognize, please mention that as well.

Recent winners. If you’ve won the puzzler in the last few months or work in geospatial imaging, please sit on your hands for at least a day to give others a chance to play.

Releasing Comments. Savvy readers have solved some of our puzzlers after only a few minutes or hours. To give more people a chance to play, we may wait between 24-48 hours before posting the answers we receive in the comment thread.

Good luck!

Update: The answer is posted here.

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Readers were quick to name the Caspian Sea as the location featured in our April 2016 puzzler. It took just a bit longer to puzzle out what caused the curious lines that crisscross the image. Are they gouges on the seafloor produced by trawling? Or are they are related to the movement of marine animals? Those are good guesses, but it turns out that the real culprit is ice.

Ice’s impact on the area becomes evident when you look back in time. The puzzler image (top) was acquired in springtime, on April 16, 2016; it shows open water in the vicinity of the Caspian Sea’s Tyuleniy Archipelago. On January 17, 2016, (second image) the same area is covered with fragmented ice.

Ice cover in some areas is easily deformed, rising upward and downward into hummocks. The keels of these hummocks can extend down through the shallow water to the seafloor. As wind and currents push the ice around, the keels drag along the seafloor like a rake to produce the gouges. Read more about the phenomenon in our April 23, 2016, image of the day.

 

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Go even farther back in time and you see that the phenomenon is not new. “These scratches were found on the aerial photographs as early as the fifties of the last century,” said Stanislav Ogorodov, a scientist at Lomonosov Moscow State University. “They were published in the Russian-language scientific literature and unambiguously interpreted as ice gouges.” The image above shows ice gouges photographed from aircraft in 1954 and is described in this 2015 paper.

A number of readers suspected early on that the gouge marks had icy origins. James Varghese and Rachel were the first to comment on the blog and correctly describe the location and phenomenon. On Facebook, Jaouhar Mosbahi was the first to post a correct description. And Rodney Forster contributed insight in a twitter conversation with @NASAOceans, where the image was first released.