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  • richardmitnick 8:12 pm on September 11, 2018 Permalink | Reply
    Tags: , Glaciology, ICESat-2-Ice andCloud and Land Elevation Satellite, Succeeds the original ICESat-1 satellite that operated from 2003 to 2009, Two areas of intense interest for long-term tracking: massive glaciers covering Antarctica and Greenland and sea surface height in the Arctic and other oceans, , UW’s Applied Physics Laboratory   

    From University of Washington: “UW polar scientists advised NASA on upcoming ICESat-2 satellite” 

    U Washington

    From University of Washington

    September 10, 2018
    Hannah Hickey

    NASA ICESat 2

    NASA plans to launch a new satellite this month that will measure elevation changes on Earth with unprecedented detail. Once in the air, it will track shifts in the height of polar ice, mountain glaciers and even forest cover around the planet.

    Two University of Washington polar scientists are advising the ICESat-2 mission scheduled to launch Sept. 15 from California’s Vandenberg Air Force Base. UW researchers provided expertise in two areas of intense interest for long-term tracking: massive glaciers covering Antarctica and Greenland, and sea surface height in the Arctic and other oceans.

    “ICESat-2 is designed to answer a simple glaciology question very, very well: It will tell us where, and how fast, the ice sheets are thickening and thinning,” said Benjamin Smith, a glaciologist at the UW’s Applied Physics Laboratory. “When these data start coming in we will immediately get a big-picture map of how Antarctica and Greenland have changed over the past decade.”

    Smith is a member of the science definition team and the lead author of the document that describes the data that ICESat-2 will provide for ice that covers land.

    “My specific role is to work out how to turn the raw data that NASA generates — which track the location of individual photons — into the answer we want to give the scientific community, which is how high the ice sheet surface is at a particular point,” Smith said.

    The instrument, whose full name is the Ice, Cloud, and Land Elevation Satellite, succeeds the original ICESat-1 satellite that operated from 2003 to 2009. Since then NASA has been running annual IceBridge flights to collect data over a few important parts of Antarctica and Greenland during the gap. The new satellite will provide nonstop, higher-resolution data for the Earth sciences community starting this October, one month after it launches.

    “For me, the most exciting aspect of ICESat-2 is its extremely fine resolution,” said Jamie Morison, a polar oceanographer and former leader of the North Pole Environmental Observatory. The new satellite uses six laser beams to get readings every 2-3 feet, each one focused over a 30-foot patch of the surface. For comparison, Morison said, today’s instruments measure surface elevation by averaging over many hundreds of feet to miles between each data point. The new instrument’s orbit is designed to collect more data over the poles, and it can detect very small elevation changes over long timescales.

    Morison is a physical oceanographer on the science definition team, and lead author the document that describes ICESat-2 data for the open oceans.

    “For the oceans, ICESat-2 will yield fine-scale measurements that are important to coastal oceanography, revealing smaller features in the open ocean and even down to the characteristics of larger surface waves,” Morison said. “ICESat-2 will also help measure sea-level change, particularly at high latitudes where the most established radar altimeters don’t go, and it will give us higher-resolution measurements of the sea surface slopes that drive changing ocean circulation.”

    The two UW researchers were members of a 12-person science team that consulted on the project over the years leading up to the launch. They also are among the hundreds of scientists who anticipate using the data in their research.

    “ICESat-2 observations will make it possible to study glaciers that are too remote for aircraft to reach, and it will make it possible to detect small changes over large areas, which were difficult to see clearly with older data,” Smith said. “There are a lot of places in Antarctica where we assume that not much is happening, but we don’t have great evidence one way or another. My guess is that when we look carefully, there will be a lot to see.”

    For more information, contact Smith at besmith@uw.edu or 206-616-9176 and Morison at jhm2@uw.edu or 206-543-1394. More ICESat-2 multimedia is here.

    See the full article here .


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  • richardmitnick 11:40 am on February 15, 2017 Permalink | Reply
    Tags: An entire landscape possibly reshaping itself, An iceberg nearly seven times the size of New York City, Antarctic Peninsula’s Larsen C ice shelf, , Glaciology, How ice shelves break, Iceberg calving on a grand scale, UK-based Project MIDAS monitoring the rift via satellites   

    From GIZMODO: “What Happens When That Enormous Antarctic Ice Shelf Finally Breaks?” 

    GIZMODO bloc


    Maddie Stone

    Rift in the Larsen C ice shelf photographed by NASA’s IceBridge aerial survey in November 2016. Image: NASA/John Sonntag

    For the past few months, scientists have watched with bated breath as a rift in the Antarctic Peninsula’s Larsen C ice shelf grows longer by the day. Eventually, the rift will make a clean break, expelling a 2,000 square mile chunk of ice into the sea. It’ll be an epic sight to behold—but what happens after the ice is gone?

    Glaciologists, who have been tracking the rift since it first appeared on the Larsen C ice shelf in 2014, are now scrambling to answer that very question. So-called iceberg calving is a natural geophysical process along the Antarctica’s frosty fringes; think of it as the planetary equivalent of your fingernails growing too long and breaking off. But this is one of the largest such events on record, with the potential to dramatically reshape the entire peninsula.

    Moreover, while there’s little direct evidence linking the Larsen C ice shelf breakup to climate change, scientists worry that the processes playing out here could be but a taste of what’s to come for West Antarctica, as rising air and sea temperatures cause this vast, icy mantle to weaken from above and below.

    “What we’re worried about is what we’re seeing here is going to happen everywhere else,” Thomas Wagner, director of NASA’s polar science program told Gizmodo. “[Larsen C] is a natural laboratory for understanding how ice shelves break.”

    Timelapse of the growing rift in the Larsen C ice shelf captured by ESA’s Sentinel-1 satellite. Image: Project MIDAS

    Over 100 miles long, up to two miles wide, and lengthening at a rate of five football fields per day, the rift in the Larsen C ice shelf has been in and out of the spotlight since it first emerged on the eastern flank of the Antarctic Peninsula in 2014. Since punching its way through a section of softer, more ductile ice, the rift has followed a predictable pattern—periods of quietude, punctuated by sudden growth spurts—that experts say is typical of ice shelf calving. But over the last two months, things have accelerated “quite a lot,” according to Martin O’Leary, a glaciologist with the UK-based Project MIDAS, which is monitoring the rift via satellites. “Now we’re paying attention to every satellite image that comes through to see if it jumps again,” he told Gizmodo.

    Having grown an impressive 17 miles (27 km) since December, the Larsen C rift has about 12 miles (20 km) to go before it reaches the other end of the shelf, snaps off, and spits out an iceberg nearly seven times the size of New York City.

    This could happen any day. “It could go tomorrow, it could go in a year’s time,” O’Leary said, adding that the ice “has to leave eventually.” That’s because additional ice is constantly pushing seaward from the peninsula’s interior, exerting a powerful shear force on the ever-weakening shelf.

    The good news is, we don’t have to worry about Larsen C’s breakup contributing to sea level rise. Ice shelves are, by definition, already sitting on top of water. “It’s already made its sea level rise contribution,” O’Leary said.

    The ice shelves at the tip of the Antarctic Peninsula have been changing dramatically in recent decades, as illustrated in this composite satellite photo showing the historic ice extent prior to calving events. Image: NASA Earth Observatory

    Aside from possibly setting a few penguins adrift, the real concern with Larsen C’s imminent calving is what it’ll mean for the rest of the shelf—and for the ice currently tethered to land on the Antarctic Peninsula, which can still contribute to sea level rise, albeit probably just a few millimeters. Glaciologists often liken ice shelves to corks in a champagne bottle: remove them, and all the stuff they’ve bottled up starts to escape. This may be especially true for the Larsen C ice shelf, which appears to be snapping off at two crucial pinning points where land meets ice.

    “We expect this to create a new zone where calving happens more readily, now that we’ve removed these pinning points,” Wagner said. “And when these ice shelves break up, the ice behind surges into the ocean, getting thinner.”

    In other words, Larsen C’s soon-to-be iceberg could be the tip of a much larger, proverbial iceberg, of an entire landscape reshaping itself. The changes glaciologists expect around Larsen C jibe with a bigger-picture pattern of ice retreat across the peninsula, including earlier calving events at the neighboring ice shelves Larsen A and B, which scientists have attributed to rising temperatures.

    Whether or not climate change is playing a direct role in the action on Larsen C, it’s a clearly force to be reckoned with across the Antarctic Peninsula, where average temperatures have risen a staggering 3 degrees Celsius (5.4 degrees Fahrenheit) since pre-industrial times. (Globally-averaged temperatures have risen roughly a single degree Celsius over the same time period.)

    “We may see that one this chunk of [ice] is gone, Larsen C [starts] becoming more vulnerable to climate impacts,” O’Leary said.

    Bird’s eye view of the Amundsen sea embayment, where major glaciers of the West Antarctic ice sheet empty into the ocean. Pope, Smith, and Kohler glaciers were the focus of this study. Image: NASA/GSFC/SVS

    Most importantly to researchers, the breakup of the Larsen C ice shelf could be a harbinger of what’s to come in other vulnerable parts of West Antarctica, particularly the Amundsen Sea embayment to the south, where warming waters are already causing the enormous Pine Island and Thwaites glaciers to melt and retreat. A summary of a scientific workshop compiled last year by the National Snow and Ice Data Center warns that “a significant retreat of the Thwaites Glacier system would trigger a wider collapse of most of the West Antarctic Ice Sheet.” That entire ice sheet contains enough water to raise global sea level by 3.3 meters (over ten feet), on a timescale of decades to centuries.

    “This is going to happen on other ice shelves,” Wagner said, adding that NASA and others have a unique opportunity with Larsen C, to study a massive iceberg calving event from satellites, airborne surveys like Operation IceBridge, and ground-based data. “We’re gonna watch how the ice shelf responds mechanically [as it breaks]. Larsen C is how we model what’s going to happen to Thwaites.”

    In other words, far more disturbing than the breakup of the Larsen C ice shelf is what it can tell us about our future.

    See the full article here .

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