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  • Partnership will use robotic network to explore Antarctic ice shelves
    Monday, December 18, 2017

    One of the biggest unknowns for the future of Earth’s climate is Antarctica, where the West Antarctic Ice Sheet holds so much ice that if it collapsed could bring several feet of rising seas.

    A new partnership between the University of Washington’s College of the Environment, the UW Applied Physics Laboratory and Paul G. Allen Philanthropies will use a robotic network to observe the conditions beneath a floating Antarctic ice shelf.

    cartoon of instruments under ice shelf

    This sketch shows how self-driving Seagliders and floats will track conditions below an Antarctic ice shelf. Inside these caves, warmer saltwater flows in on the bottom, carrying heat which may eat away at the ice, and fresher glacial meltwater flows out above.University of Washington

    Ice shelves act as buttresses that restrain the flow of inland ice into the sea, which under a warmer climate could trigger many feet of global sea level rise, on a timeline that is largely unknown. Observations in the water-filled caves under ice shelves could help explain how warmer seawater interacts with the glacier’s underbelly.

    The team members performed a final test Nov. 6 in Puget Sound before the instruments are deployed in the Southern Ocean from a Korean research ship, the R/V Araon, that departs from New Zealand in mid-December.

    “A project as experimental as this one would be impossible without the support of Paul G. Allen Philanthropies,” said Craig Lee, a UW professor of oceanography and oceanographer at the UW Applied Physics Laboratory. “This is a high-risk, proof-of-concept test of using robotic technology in a very risky marine environment.”

    The ice shelf is the floating portion of a glacier that extends seaward from inland ice, which rests on bedrock. Most of Antarctica does not yet show significant surface melt, but scientists think melt is happening at the glacier’s underbelly, where relatively warm ocean water meets its underside. What is learned with this new data will help scientists better understand the stability of these ice shelves and help make predictions about sea level rise.

    See also:

     

     

    “This is one of a series of philanthropic investments by Paul Allen to improve our understanding of how the Earth is changing and how it’s being impacted by climate change,” said Spencer Reeder, director of climate and energy for Paul G. Allen Philanthropies.

    UW oceanographers invented the Seaglider in the mid-1990s, with support from the National Science Foundation, and still build research models of the torpedo-shaped ocean drone. UW researchers adapted the Seaglider for operating under ice, and have been using it to sample below Arctic sea ice since 2008. In 2014, Lee used a Seaglider and other technology in the Arctic Ocean to track the breakup of summer sea ice.

    yellow glider hanging off ship

    UW researcher Jason Gobat, in the foreground, lowers a Seaglider into Puget Sound for an early November test. Three custom Seagliders will travel in December to explore the water below an Antarctic ice shelf.Paul G. Allen Philanthropies

    This new project will deploy a similar robotic network in the Southern Hemisphere. The environment is more challenging because the instruments must venture into the ocean cavities formed by ice shelves, which are very complex, but largely unknown, environments.

    “We have almost no information about the area where the glacier is floating on top of the ocean,” said glaciologist Knut Christianson, a UW assistant professor of Earth and space sciences. “The ice is 300 to 500 meters (1/5 to 1/3 of a mile) thick. There’s no light penetrating, it’s impossible to communicate with any instruments, and this environment is extremely hard on equipment -- picture big crevasses, rushing water and jagged ice.”

    This effort included figuring out how to develop gliders that can get in and out from the ice sheet’s edge without being crushed by moving ice, swept away by fast-flowing water or trapped in the complex of ridges and crevasses on the ice shelf's underside.

    yellow instrument in dark water

    This UW-designed autonomous float drifts with the current while changing its buoyancy to move up and down through the water. Four of these instruments will be released below an Antarctic ice shelf.Paul G. Allen Philanthropies

    This year’s test also will use complementary technology designed by James Girton, an oceanographer at the UW Applied Physics Laboratory, which drifts with the currents while moving up and down gathering data.

    The team has devised new navigation algorithms for the Seaglider and tested them in simulations to make sure the instrument can navigate and return safely. The plan is for the gliders to initially travel in and out of a cave several times a day in summer, surfacing between each trip to beam data back to shore.

    Once the ocean surface freezes for the Southern Hemisphere winter, the robots will continue to take measurements on their own, and will beam data back only when they emerge months later in the spring.

    “We’ve never been able to get really deep into an ice cave, where the floating ice shelf meets the seafloor,” Christianson said. “If we can do that, we'll be able to collect tons of new data. We often don’t even know what the topography of the seafloor is like beneath the shelf, which affects water flow, temperature and other factors that control the melting rate.”

    Team member Pierre Dutrieux, a glaciologist at Columbia University’s Lamont-Doherty Earth Observatory, has used other technologies to gather more limited observations below ice shelves. He and Jason Gobat, an oceanographer at the UW Applied Physics Laboratory, will travel to Antarctica in December for the first deployments under Pine Island Glacier, if conditions allow, or another nearby extension of the West Antarctic Ice Sheet. They plan to deploy three gliders and four floats and leave them down for a period of about a year.

    The Korean Polar Research Institute (KORPI) is also partnering for this mission. KOPRI will provide field support for the deployments from its ice breaking research vessel Araon, will conduct complementary measurements from the ship and will collaborate on the subsequent analysis of the resulting data.

    ###

    For more information, contact Lee at craiglee@uw.edu or Christianson at knut@uw.edu.

     

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  • UW astrobiologists to discuss work, introduce IMAX film 'The Search for Life in Space' Dec. 6 at Pacific Science Center
    Monday, December 4, 2017

    “The Search for Life in Space” is now playing at the IMAX theater at the Pacific Science Center.

    Three University of Washington astrobiologists will discuss their research and introduce the new 3-D IMAX movie “The Search for Life in Space” at 7 p.m. Wednesday, Dec. 6, in the PACCAR Theater of the Pacific Science Center.

    Speaking will be UW doctoral students Brett Morris of astronomy and Marshall Styczinski of physics and astronomy, as well as Erika Harnett, research associate professor of Earth and space sciences and associate director of the UW’s NASA Space Grant Consortium. All three are affiliated with the UW Astrobiology Program.

    Harnett uses physics-based computer programs to study how radiation and the sun’s magnetic fields influence the upper atmospheres and surfaces of planets and moons in the solar system. She investigates the evolutions of these environments over time, and how current conditions may affect how robotic probes, or even humans, could explore such worlds.

    Morris studies stars and planets with observations from ground- and space-based telescopes. He was a co-author on UW-led research on the TRAPPIST-1 system and has researched transmission spectroscopy and “transit timing variations” as well. Styczinski uses magnetic fields to study the icy crust of Jupiter’s moons, looking for places where life may be found. He was a speaker in the 2016 UW Science Now lecture series at Town Hall Seattle.

    As notes from producer December Media state, “The Search for Life in Space” takes the viewer on a journey “from the depths of the Pacific Ocean into the far reaches of space” to show how astrobiologists are searching for life beyond Earth.

    “With cutting-edge imagery from the world’s most powerful telescopes, (the film) takes audiences from the surface of Mars and the icy moons of Jupiter and Saturn, to the extreme lava fields of Hawaii and thermal vents deep beneath the sea.” Astrobiologists look in such harsh environments for clues to how life takes hold, on Earth or perhaps elsewhere.

    The IMAX documentary is narrated by film star Malcolm McDowell. It features Cornell astronomer Lisa Kaltenegger, who is director of the Carl Sagan Institute.

    The film was produced in association with Film Victoria Australia and Swinburne University of Technology. It is part of the Pacific Science Center’s Science in the City series of events.

    Tickets are $5 and doors open at 6:40 p.m. A Facebook page for the event is here.

    Watch the film’s trailer below:

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  • Less life: Limited phosphorus recycling suppressed early Earth's biosphere
    Tuesday, November 28, 2017

    As Earth’s oxygen levels rose to near-modern levels over the last 800 million years, phosphorus levels also increased, according to modeling led by the UW’s Michael Kipp and others. Accordingly, Kipp said, large phosphate deposits show up in abundance in the rock record at about this time. This is a Wyoming portion of The Phosphoria Formation, a deposit that stretches across several states in the western United States and is the largest source of phosphorus fertilizer in the country. The photo shows layers of phosphorus that are 10s of meters thick, shales that contain high concentrations of organic carbon and phosphorus. Kipp said many such deposits are documented over time but are rare in the Precambrian era. “Thus, they might represent a conspicuous temporal record of limited phosphorus recycling.”Michael Kipp

    As Earth's oxygen levels rose to near-modern levels over the last 800 million years, phosphorus levels increased, as well, according to modeling led by the UW's Michael Kipp and others. Accordingly, Kipp says, large phosphate deposits show up in abundance in the rock record at about this time. This is a Wyoming portion of The Phosphoria Formation, a deposit that stretches across several states in the western United States and is the largest source of phosphorus fertilizer in the country. The photo shows layers of phosphorus that are 10s of meters thick, shales the contain high concentrations of organic carbon and phosphorus. Kipp said many such deposits are documented over time but are rare in the Precambrian era.

    The amount of biomass - life - in Earth’s ancient oceans may have been limited due to low recycling of the key nutrient phosphorus, according to new research by the University of Washington and the University of St. Andrews in Scotland.

    The research, published online Nov. 22 in the journal Science Advances, also comments on the role of volcanism in supporting Earth’s early biosphere -- and may even apply to the search for life on other worlds.

    The paper’s lead author is Michael Kipp, a UW doctoral student in Earth and space sciences; coauthor is Eva St?eken, a research fellow at the University of St. Andrews and former UW postdoctoral researcher. Roger Buick, UW professor of Earth and space sciences, advised the researchers.

    Their aim, Kipp said, was to use theoretical modeling to study how ocean phosphorus levels have changed throughout Earth’s history.

    “We were interested in phosphorus because it is thought to be the nutrient that limits the amount of life there is in the ocean, along with carbon and nitrogen,” said Kipp. “You change the relative amount of those and you change, basically, the amount of biological productivity.”

    Kipp said their model shows the ability of phosphorus to be recycled in the ancient ocean “was much lower than today, maybe on the order of 10 times less.”

    All life needs abundant food to thrive, and the chemical element phosphorus - which washes into the ocean from rivers as phosphate -- is a key nutrient. Once in the ocean, phosphorus gets recycled several times as organisms such as plankton or eukaryotic algae that “eat” it are in turn consumed by other organisms.

    “As these organisms use the phosphorus, they in turn get grazed upon, or they die and other bacteria decompose their organic matter,” said Kipp, “and they release some of that phosphorus back into the ocean. It actually cycles through several times," allowing the liberated phosphorus to build up in the ocean. The amount of recycling is a key control on the amount of total phosphorus in the ocean, which in turn supports life.

    Buick explained: "Every gardener knows that their plants grow only small and scraggly without phosphate fertilizer. The same applies for photosynthetic life in the oceans, where the phosphate 'fertilizer' comes largely from phosphorus liberated by the degradation of dead plankton."

    But all of this requires oxygen. In today's oxygen-rich oceans, nearly all phosphorus gets recycled in this way and little falls to the ocean floor.

    Several billion years ago, in the Precambrian era, however, there was little or no oxygen in the environment.

    "There are some alternatives to oxygen that certain bacteria could use, said co-author St?eken. "Some bacteria can digest food using sulfate. Others use iron oxides." Sulfate, she said, was the most important control on phosphorus recycling in the Precambrian era.

    "Our analysis shows that these alternative pathways were the dominant route of phosphorus recycling in the Precambrian, when oxygen was very low," St?eken said. "However, they are much less effective than digestion with oxygen, meaning that only a smaller amount of biomass could be digested. As a consequence, much less phosphorus would have been recycled, and therefore total biological productivity would have been suppressed relative to today."

    Kipp likened early Earth's low-oxygen ocean to a kind of "canned" environment, with oxygen sealed out: "It's a closed system. If you go back to the early Precambrian oceans, there's not very much going on in terms of biological activity."

    St?eken noted that volcanoes were the biggest source of sulfate in the Precambrian, unlike now, and so they were necessary for sustaining a significant biosphere by enabling phosphorus recycling.

    In fact, minus such volcanic sulfate, St?eken said, Earth’s biosphere would have been very small, and may not have survived over billions of years. The findings, then, illustrate “how strongly life is tied to fundamental geological processes such as volcanism on the early Earth,” she said.

    Kipp and St?eken’s modeling may have implications as well for the search for life beyond Earth.

    Astronomers will use upcoming ground- and space-based telescopes such as the James Webb Space Telescope, set for launch in 2019, to look for the impact of a marine biosphere, as Earth has, on a planet’s atmosphere. But low phosphorus, the researchers say, could cause an inhabited world to appear uninhabited -- making a sort of “false negative.”

    Kipp said, “If there is less life -- basically, less photosynthetic output -- it’s harder to accumulate atmospheric oxygen than if you had modern phosphorus levels and production rates. This could mean that some planets might appear to be uninhabited due to their lack of oxygen, but in reality they have biospheres that are limited in extent due to low phosphorus availability.

    "These ‘false negatives’ are one of the biggest challenges facing us in the search for life elsewhere," said Victoria Meadows, UW astronomy professor and principal investigator for the NASA Astrobiology Institute’s Virtual Planetary Laboratory, based at the UW.

    “But research on early Earth’s environments increases our chance of success by revealing processes and planetary properties that guide our search for life on nearby exoplanets."

    The work was funded by grants from NASA and the National Science Foundation.

    ###

    For more information, contact Kipp at kipp@uw.edu, Buick at 206-543-1913 or buick@ess.washington.edu or St?eken at
    ees4@st-andrews.ac.uk.

    NASA Exobiology grant NNX16AI37G to Prof. Buick.

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  • A Bolt from the Brown: Why Pollution May Increase Lightning Strikes
    Thursday, November 16, 2017
    Scientific American reports on a University of Washington paper using World Wide Lightning Location Network data to show that pollution from ship exhaust in the Indian Ocean and South China Sea enhances the probability of lightning by a factor of two. This pollution problem and consequent increase in lightning was shown to occur every year over the last decade or more. Read More
  • Salt pond in Antarctica, among the saltiest waters on Earth, is fed from beneath
    Wednesday, November 15, 2017

    At the base of the Transantarctic Mountains lies a geological oddity. Don Juan Pond is one of the saltiest bodies of water on the planet, filled with a dense, syrupy brine rich in calcium chloride that can remain liquid to minus 50 degrees Celsius, far below the freezing point of water. But the source of water and salt to this unusual pond remains a mystery -- even as hints emerge that water in a similar form could exist on Mars.

    pond in bare valley with blue sky

    The liquid in Don Juan Pond is almost 45 percent salts by weight. It is in Wright Valley, one of the Antarctic valleys where the air is very cold and dry.Pierre Roudier/Flickr

    A new University of Washington study uses the pond’s bizarre chemistry to pinpoint the water’s source. The recent paper, published Sept. 15 in Earth and Planetary Science Letters, reports that it is fed by a regional deep groundwater system and not, as previously suggested, from moisture seeping down from local valley slopes.

    “Don Juan Pond is probably one of the most interesting ponds on Earth,” said lead author Jonathan Toner, a UW research assistant professor in Earth and space sciences. “After 60 years of extensive study, we still don't really know exactly where it’s coming from, what drives the fact that it’s visible on the surface, and how it’s changing.”

    The perennial pond measures about 100 by 300 meters, the size of a few football fields, and is about 10 centimeters (4 inches) deep on average. It was first visited in 1961 and named after the expedition’s helicopter pilots, Donald Roe and John Hickey, earning it the name Don Juan Pond. The unique salts in the pond lower the freezing point, which is why this saline pond can exist in a place where the temperature ranges from minus 50 to plus 10 degrees Celsius (-58 to +50 F).

    The pond was long believed to be fed by deep groundwater. But then a high-profile 2013 paper suggested that near-surface moisture seeps, similar to recurring slope lineae features recently observed on Mars, were transporting salts downhill to create the salt pond.

    aerial image of dark spot in white valley

    A satellite picture shows Don Juan Pond and surrounding slopes. Understanding the hydrology of this cold, dry environment could help explain conditions on Mars.NASA

    Toner is a geochemist specializing in the formation and properties of water in extreme environments on Earth, Mars and beyond. For the new study, Toner created a model to compute how salty water changes during evaporation, freezing, and with different water and salt inputs and outputs. In Antarctica’s appropriately named McMurdo Dry Valleys, water evaporation concentrates salts in the pond, which forces some salts to crystallize. These processes, along with inputs and outputs, cause the pond’s water to change over time.

    Toner ran his model for two situations: one where the water was gurgling up from beneath, and another where it was trickling down from near-surface seeps. Results show that the observed chemical makeup could only be produced from underneath.

    “You couldn't get Don Juan Pond from these shallow groundwaters,” Toner said. “It's definitely coming from the deep groundwater.”

    His calculations also show that upwelling groundwater cycles through the pond every six months, meaning the water must exit the pond via some unseen underground outflow.

    The pond’s hydrology is important to geologists because nowhere on Earth is more similar to Mars. The Red Planet is extremely cold and dry, and the McMurdo Dry Valleys are one of the coldest and driest locations on Earth.

    “If there is water on Mars, it’s probably going to look a lot like this pond,” Toner said. “Understanding how it formed has large implications for where would you expect to find similar environments on Mars.”

    Recent studies hint that liquid water might exist on the surface of Mars, potentially harboring life or even eventually supporting long-term human settlements. The darker lines on steep slopes, which look like moisture streaks observed above Don Juan Pond, could be caused by a similar groundwater system.

    researcher in red jacket

    Jonathan Toner in Antarctica doing field work toward his UW doctorate.Ronald Sletten/University of Washington

    Toner will be part of a team exploring Don Juan Pond and surrounding areas this December, sponsored by NASA and the National Science Foundation. Researchers will spend six weeks camping near the pond and taking repeated chemical measurements of its liquid. They will also explore the nearby slopes to measure the chemistry of the moisture seeps, and try to find further evidence for the source of salts to Don Juan Pond.

    “If we accept that the deep groundwater theory is true, then what we’re seeing could be part of a bigger process that involves quite an extensive aquifer,” Toner said. “When thinking about the implications for a similar environment on Mars, that’s much more exciting than just a localized surface phenomenon.”

    The research was funded by NASA. Other co-authors are Ronald Sletten and David Catling in the UW Department of Earth & Space Sciences.

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    For more information, contact Toner at toner2@uw.edu.

    NASA grant: NNX15AP19G

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  • Ships Cause their own Stormy Seas
    Thursday, November 9, 2017
    Physics Today (Search and Discovery) of the November 2017 edition reports on research using WWLLN lightning network data: 'Increased lightning frequency over maritime trade routes links pollution to the development of thunderclouds.' Underlying paper by Thornton (Atmos. Sci), Virts (NASA Huntsville), Holzworth (ESS) and Mitchell (JISAO) recently published in Geophysical Research Letters). Read More
  • 50 simulations of the 'Really Big One' show how a 9.0 Cascadia earthquake could play out
    Monday, October 23, 2017

    One of the worst nightmares for many Pacific Northwest residents is a huge earthquake along the offshore Cascadia Subduction Zone, which would unleash damaging and likely deadly shaking in coastal Washington, Oregon, British Columbia and northern California.

    The last time this happened was in 1700, before seismic instruments were around to record the event. So what will happen when it ruptures next is largely unknown.

    colored map of subduction zone

    Simulation parameters for the scenario that generated the least shaking in the Seattle area.Erin Wirth/University of Washington/USGS

    A University of Washington research project, to be presented Oct. 24 at the Geological Society of America’s annual meeting in Seattle, simulates 50 different ways that a magnitude-9.0 earthquake on the Cascadia subduction zone could unfold.

    “There had been just a handful of detailed simulations of a magnitude-9 Cascadia earthquake, and it was hard to know if they were showing the full range,” said Erin Wirth, who led the project as a UW postdoctoral researcher in Earth and space sciences. “With just a few simulations you didn’t know if you were seeing a best-case, a worst-case or an average scenario. This project has really allowed us to be more confident in saying that we’re seeing the full range of possibilities.”

    Off the Oregon and Washington coast, the Juan de Fuca oceanic plate is slowly moving under the North American plate. Geological clues show that it last jolted and unleashed a major earthquake in 1700, and that it does so roughly once every 500 years. It could happen any day.

    Wirth’s project ran simulations using different combinations for three key factors: the epicenter of the earthquake; how far inland the earthquake will rupture; and which sections of the fault will generate the strongest shaking.

    Results show that the intensity of shaking can be less for Seattle if the epicenter is fairly close to beneath the city. From that starting point, seismic waves will radiate away from Seattle, sending the biggest shakes in the direction of travel of the rupture.

    “Surprisingly, Seattle experiences less severe shaking if the epicenter is located just beneath the tip of northwest Washington,” Wirth said. “The reason is because the rupture is propagating away from Seattle, so it’s most affecting sites offshore. But when the epicenter is located pretty far offshore, the rupture travels inland and all of that strong ground shaking piles up on its way to Seattle, to make the shaking in Seattle much stronger.”

    The research effort began by establishing which factors most influence the pattern of ground shaking during a Cascadia earthquake. One, of course, is the epicenter, or more specifically the “hypocenter,” which locates the earthquake's starting point in three-dimensional space.

    Another factor they found to be important is how far inland the fault slips. A magnitude-9.0 earthquake would likely give way along the whole north-south extent of the subduction zone, but it’s not well known how far east the shake-producing area would extend, approaching the area beneath major cities such as Seattle and Portland.

    The third factor is a new idea relating to a subduction zone’s stickiness. Earthquake researchers have become aware of the importance of “sticky points,” or areas between the plates that can catch and generate more shaking. This is still an area of current research, but comparisons of different seismic stations during the 2010 Chile earthquake and the 2011 Tohoku earthquake show that some parts of the fault released more strong shaking than others.

    Wirth simulated a magnitude-9.0 earthquake, about the middle of the range of estimates for the magnitude of the 1700 earthquake. Her 50 simulations used variables spanning realistic values for the depth of the slip, and had randomly placed hypocenters and sticky points. The high-resolution simulations were run on supercomputers at the Pacific Northwest National Laboratory and the University of Texas, Austin.

    Overall, the results confirm that coastal areas would be hardest hit, and locations in sediment-filled basins like downtown Seattle would shake more than hard, rocky mountaintops. But within that general framework, the picture can vary a lot; depending on the scenario, the intensity of shaking can vary by a factor of 10. But none of the pictures is rosy.

    “We are finding large amplification of ground shaking by the Seattle basin,” said collaborator Art Frankel, a U.S. Geological Survey seismologist and affiliate faculty member at the UW. “The average duration of strong shaking in Seattle is about 100 seconds, about four times as long as from the 2001 Nisqually earthquake.”

    The research was done as part of the M9 Project, a National Science Foundation-funded effort to figure out what a magnitude-9 earthquake might look like in the Pacific Northwest and how people can prepare. Two publications are being reviewed by the USGS, and engineers are already using the simulation results to assess how tall buildings in Seattle might respond to the predicted pattern of shaking.

    As a new employee of the USGS, Wirth will now use geological clues to narrow down the possible earthquake scenarios.

    “We’ve identified what parameters we think are important,” Wirth said. “I think there’s a future in using geologic evidence to constrain these parameters, and maybe improve our estimate of seismic hazard in the Pacific Northwest.”

    Other co-authors are Nasser Marafi, a UW doctoral student in civil and environmental engineering; John Vidale, a former UW professor now at the University of Southern California; and Bill Stephenson with the USGS.

    ###

    For more information, contact Wirth at ewirth@uw.edu.

    Videos and images for two of the simulations are available here.

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  • Mountain glaciers shrinking across the West
    Friday, October 20, 2017

    Until recently, glaciers in the United States have been measured in two ways: placing stakes in the snow, as federal scientists have done each year since 1957 at South Cascade Glacier in Washington state; or tracking glacier area using photographs from airplanes and satellites.

    graphic and maps for Mount St. Helens

    The mapping technique uses a satellite to capture high-resolution images of a specific area from two angles. Then, the NASA Ame s Stereo Pipeline software creates an elevation map with accuracy of a few feet. This example shows Mount Baker.David Shean/University of Washington/DigitalGlobe/NextView License

    We now have a third, much more powerful tool. While he was a doctoral student in University of Washington’s Department of Earth and Space Sciences, David Shean devised new ways to use high-resolution satellite images to track elevation changes for massive ice sheets in Antarctica and Greenland. Over the years he wondered: Why aren’t we doing this for mountain glaciers in the United States, like the one visible from his department's office window?

    series of colored maps for Mount Rainier

    The full series of satellite elevation data for Mount Rainier from spring 2014 through summer 2017. The satellite-based instrument may or may not scan the entire mountain, and clouds can block portions of its view.David Shean/University of Washington

    He has now made that a reality. In 2012, he first asked for satellite time to turn digital eyes on glaciers in the continental U.S., and he has since collected enough data to analyze mass loss for Mount Rainier and almost all the glaciers in the lower 48 states. He will present results from these efforts Oct. 22 at the Geological Society of America’s annual meeting in Seattle.

    “I’m interested in the broad picture: What is the state of all of the glaciers, and how has that changed over the last 50 years? How has that changed over the last 10 years? And at this point, how are they changing every year?” said Shean, who is now a research associate with the UW’s Applied Physics Laboratory.

    map of Western U.S. with blue areas

    The satellites are currently imaging all the shaded areas in late spring and late fall. Mountain glaciers are shown in blue.David Shean/University of Washington

    The maps provide a twice-yearly tally of roughly 1,200 mountain glaciers in the lower 48 states, down to a resolution of about 1 foot. Most of those glaciers are in Washington state, with others clustered in the Rocky Mountains of Montana, Wyoming and Colorado, and in California’s Sierra Nevada.

    To create the maps, a satellite camera roughly half the size of the Hubble Space Telescope must take two images of a glacier from slightly different angles. As the satellite passes overhead, moving at about 4.6 miles per second, it takes images a few minutes apart. Each pixel of the image covers 30 to 50 centimeters (about 1 foot) and a single image can be tens of miles across.

    Shean’s technique uses automated software that matches millions of small features, such as rocks or crevasses, in the two images. It then uses the difference in perspective to create a 3-D model of the surface.

    aerial view of Mount Rainier with red zones

    This map shows the elevation change of Mount Rainier glaciers between 1970 and 2016. The earlier observations are from USGS maps, while the recent data use the satellite stereo imaging technique. Glacier surface elevations have dropped more than 40 meters (130 feet) in some places.David Shean/University of Washington

    The first such map of a Mount St. Helens glacier was obtained in 2012, and the first for Mount Rainier in 2014. The project has grown steadily since then to include more glaciers every year.

    The results confirm stake measurements at South Cascade Glacier in the North Cascades, showing significant loss over the past 60 years. Results at Mount Rainier also reflect the broader shrinking trends, with the lower-elevation glaciers being particularly hard hit. Shean estimates cumulative ice loss of about 0.7 cubic kilometers (900 million cubic yards) at Mount Rainier since 1970. Distributed evenly across all of Mount Rainier’s glaciers, that’s equivalent to removing a layer of ice about 25 feet (7 to 8 meters) thick.

    “There are some big changes that have happened, as anyone who’s been hiking on Mount Rainier in the last 45 years can attest to,” Shean said. “For the first time we’re able to very precisely quantify exactly how much snow and ice has been lost.”

    The left is costly aerial lidar data, collected in a 2007 survey, and the right is 2015 satellite data, both for the tip of Nisqually Glacier on Mount Rainier. Comparing these data shows roughly 300 meters (1,000 feet) of terminus retreat from 2007 to 2015.

    The left is costly aerial lidar data, collected in a 2007 survey, and the right is 2015 satellite data, both for the tip of Nisqually Glacier on Mount Rainier. Comparing these data shows roughly 300 meters (1,000 feet) of terminus retreat from 2007 to 2015.David Shean/University of Washington

    The glacier loss at Rainier is consistent with trends for glaciers across the U.S. and worldwide. Tracking the status of so many glaciers will allow scientists to further explore patterns in the changes over time, which will help pinpoint the causes -- from changes in temperature and precipitation to slope angle and elevation.

    “The next step is to integrate our observations with glacier and climate models and say: Based on what we know now, where are these systems headed?” Shean said.

    Those predictions could be used to better manage water supplies and flood risks.

    “We want to know what the glaciers are doing and how their mass is changing, but it’s important to remember that the meltwater is going somewhere. It ends up in rivers, it ends up in reservoirs, it ends up downstream in the ocean. So there are very real applications for water resource management,” Shean said. “If we know how much snow falls on Mount Rainier every winter, and when and how much ice melts every summer, that can inform water resource managers’ decisions.”

    person on glacier

    David Shean uses another technique, UW’s terrestrial laser scanner, to measure surface elevation at the South Cascade Glacier. Detailed measurements using this technique complement the satellite observations.Alex Headman/USGS

    Shean will begin a faculty position this winter in the UW’s Department of Civil & Environmental Engineering, where he will explore those questions further for the U.S. as well as for other regions, like high-mountain Asia, where over a billion people depend on glacier-fed rivers for irrigation, hydropower and drinking water.

    Co-authors are Anthony Arendt at the UW’s Applied Physics Laboratory, Erin Whorton at the USGS Washington Water Science Center, Jon Riedel at the National Park Service’s North Cascades National Park and Andrew Fountain at Portland State University. The work was funded by the National Park Service, the USGS and NASA.

    ###

    For more information, contact Shean at 206-221-8727 or dshean@uw.edu. Accompanying images also accessible on Flickr.

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  • Paul Bodin named interim director of Pacific Northwest Seismic Network
    Tuesday, October 10, 2017

    Paul Bodin, a research professor in the UW’s Department of Earth and Space Sciences, has been named the interim director of the UW-based Pacific Northwest Seismic Network. PNSN is a collaboration between the University of Washington, the University of Oregon and the U.S. Geological Survey that tracks earthquake and volcano activity throughout the two states, with the support of federal, state and private funding.

    photo of Paul Bodin

    Paul Bodin

    Former PNSN director John Vidale stepped down to accept a faculty position at the University of Southern California and direct the Southern California Earthquake Center in Los Angeles. The search for his permanent replacement is expected to take about one year.

    In the interim, Bodin will also serve as the Washington’s state seismologist, serving on the Washington state Seismic Safety Committee that makes seismic policy recommendations to the state’s Emergency Management Division and Gov. Jay Inslee, as well as answering questions from reporters and the public about earthquake and volcanoes.

    Bodin will join other regional earthquake experts for a Reddit “Ask Us Anything” Q&A Thursday, Oct. 19 from noon to 2 p.m. PDT

    Bodin is an observational seismologist whose research expertise includes studies of earthquake source physics, seismic wave propagation, and the impacts of strong ground shaking on soils. Bodin spent the first part of his career at the University of Memphis. In Tennessee he studied earthquake processes and hazards associated with earthquakes that occur far from tectonic plate boundaries. Such earthquakes are infrequent and poorly understood, but have very large impacts when they do occur. He also performed field studies in the aftermath of large earthquakes in Mexico, California, India and Taiwan, and was part of a U.S. team monitoring underground nuclear testing in the former Soviet Union.

    Bodin joined the UW faculty in 2006 to become manager of the PNSN. During more than a decade since he has overseen upgrades of the network’s technology to enable faster and more accurate detection, analysis and communication of ground shaking from a major earthquake. These network improvements have led to the inclusion of Washington and Oregon into ShakeAlert, a West Coast-wide earthquake early warning system that will provide advance warnings for imminent large earthquakes. Bodin has also published academic papers on triggered earthquakes and tremors; seismic wave propagation and aftershocks; exploring swarm seismicity in Richland and Spokane, Washington; and on the potential for developing earthquake early warning systems in Hawaii and Chile.

    Bodin earned his bachelor’s degree at the University of California, San Diego, his master’s at California’s Humboldt State University and his doctorate at the University of Colorado, Boulder.

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    For more information, contact Bodin at bodin@uw.edu or 206-616-7315 or PNSN communications manager Bill Steele at 206-685-5880 or wsteele@uw.edu.

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