Posts Tagged ‘Cape Disappointment’

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Return to the Larsen B and Scar Inlet Ice Shelf

January 28, 2016

Ted Scambos writes:

We have come back to this key area of Antarctica because it is on the ‘front line’ of how the continent is responding to warmer air and changing wind patterns. The Larsen B ice shelf, larger than Delaware in the 1990s, disintegrated in a matter of weeks in 2002. Between Jan 31 and March 17 of that year, 3250 km2 of ice 220 meters thick (over 700 feet) crumbled away after a very warm summer with extensive melting. However, one area of the Larsen B remained intact: a sheltered southern bay called Scar Inlet. In the past 14 years, this remnant shelf has changed dramatically, developing many new rifts and fractures. Moreover, since late 2011, the larger bay where the Larsen B once resided has been covered with a solid sheet of frozen ocean ice, called ‘fast ice’ because it is ‘fastened’ (frozen) to the coastline. We suspect that now this fast ice is supporting the weakened Scar Inlet shelf, and that the shelf is poised to break-up (at least partially) if the thin fast ice breaks away. This generally happens in late austral summer. Our mission is to set up a series of instruments for a few weeks to measure the structural state of both the fast ice and the Scar Inlet ice shelf plate.

larsenb_2002

The two color images are from NASA’s MODIS sensor, and record ‘before’ and ‘after’ conditions of the Larsen B ice shelf disintegration of 2002. The blue specks on the January 31st image are melt ponds from warm summer conditions. In the March 7 image, the blue areas are disintegrated ice blocks, often flipped on their side in the dynamic break-up event. The three images at the lower left record how the surface lakes disappeared over the weeks leading up to the break-up. At top right is a Landsat 7 image showing the melt ponds in more detail in a preceding summer. Image credit: T. Scambos, Scambos et al., 2003 AGU Antarctic Research Series v.79.

The images above are from satellite data taken during the break-up of the Larsen B in 2002. You can see why we are going at this time of year – this is exactly the part of the year, late summer, when these kinds of rapid break-ups can occur. The key factor is summer melting – in years when the shelf ice is covered with small blue melt ponds, there is a strong likelihood of disintegration. The lakes accelerate fracturing in the ice by filling cracks with water and breaking them open, a process called ‘hydrofracture’.

The remnant Scar Inlet ice shelf has remained intact but has evolved considerably in the years since 2002, developing new rifts, a more fractured margin, and deep troughs near the ice front. Below is a series of images showing how the ice has evolved, and the recent persistent fast ice.

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Evolution of Scar Inlet Ice shelf from Jan 2004, Jan 2009, and Jan 2014. Images from MOA2004, MOA2009, and (in preparation) MOA2014. Red dots in 2014 image show locations of LARISSA-installed instrument assets (G, GPS; A, AMIGOS with high-resolution camera; A*, AMIGOS with GPS and webcam).

The research team has spent the past few years installing sensors on the ice shelf and on the rocks nearby. We’ve talked about these in the OTI blog before – the “AMIGOS” stations, having cameras, a GPS, and weather and ice-measurement instruments, and the continuous precision GPS stations, which also measure weather as well as ice or rock motion down to millimeter precision. The station on Cape Disappointment has been very useful (not disappointing at all!) for tracking how the edge of the ice shelf has crumbled over the past few years and mixed with the sea ice. A recent set of pictures – a panorama – is shown below.

amigos6_2016-01-02

Looking south from the Cape Disappointment AMIGOS station toward the Scar Inlet Shelf on January 2, 2016. The near foreground is the rocky cape where the AMIGOS system is installed; just beyond that is a part of the ice front that has fractured and retreated slightly over the past five years. In the distance is the remainder of the Scar Inlet ice shelf and the mountains of the Antarctic Peninsula. The entire ice surface in view is at risk of more rapid break-up if warm summer conditions occur.

A new satellite tool is now available for tracking how the Scar Inlet region evolves. Landsat 8, launched in February of 2013, provides 15m resolution images of the world’s land and ice cover, with color channels at 30 m resolution and thermal data as well. A false color image (using near-infrared light for red, red light for green, and green light for blue, to create an image that enhances the ability to detect melting) is shown from January 6. The fast ice has partially flooded due to warm conditions in late December and early January, and there are several cracks in the ice. A few ponds appear on the ice shelf and adjacent glaciers.

Our plan is to visit several of the stations, and install additional GPS stations (from the air – that should be interesting…) and then bring our additional cameras and other instruments to Cape Disappointment to record ~2 to 3 weeks of summer conditions on the fast ice and ice shelf in detail. Stay tuned…..

landsat8_2016-01-06

Landsat 8 image from January 6, 2016, showing summer conditions on the fast ice, glaciers, and ice shelf in the study area. .

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Silence from Scar Inlet and Cape Disappointment

September 8, 2012

NSIDC researcher Terry Haran returns to Scar Inlet and Cape Disappointment this fall to figure out why two AMIGOS units have been silent.

Terry writes:

I return to Scar Inlet and Cape Disappointment in a month.

We haven’t received any communication from AMIGOS-2/4 at Scar Inlet since January 9, and AMIGOS-6 at Cape Disappointment has been silent since June 6. We think the AMIGOS-2/4 battery box may have shorted out due to the incursion of melt water. As for AMIGOS-6, that may have had its tower blown over or incurred some other kind of damage during a 60-knot wind event prior to its last communication. The UNAVCO continuous GPS units appear to be working but are in need of a communications upgrade, and the ones at Flask and Leppard glaciers may need their solar panels raised.

I’ve been busy preparing for the trip. I shipped AMIGOS replacement parts to Ronald Ross in Australia. Did the usual paper work for travel, began the physical qualification process required by the National Science Foundation-U.S. Antarctic Program, and collected a shipment of mechanical parts to be sent to Punta Arenas, Chile via Port Hueneme, California.

We’re not planning on visiting AMIGOS-3 since it continues to work well. It could probably use its solar panels raised, since the snow is just now touching the bottom panel. But that’s something we’ll leave for Ted during the upcoming Araon cruise with our Korean collaborators next year.

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Cape Disappointment, Antarctica

November 16, 2011

Ted writes:

We have been to the Cape of Disappointment. And we have prevailed.

As is often the case here, the oddest of circumstances led to an opportunity. It wasn’t the way we drew it up on the blackboard, but it worked. Constantly in the back of my mind is this sense of foreboding about this site. It’s the name. It’s like it whispers to me. “You’ll face defeat. My name is Cape Disappointment.”

Tuesday morning, we learned two things: weather at the Cape had been spectacular on Monday, much better than had been forecast, and the weather was a bit marginal for Tuesday. By mid-morning, further satellite pictures had scrubbed our flight for the day.

Or so we thought. Another group working in the area gave it a try at a glacier valley about 25 miles southwest of the Cape, and got in. After a couple of visits to their instruments, they realized that they could use some spare components that they did not have.

I was sitting at my desk, typing. Handheld radios are everywhere in Rothera, so one hears snippets of conversations all over the place.  I am not paying much attention to this background noise, when I notice they are talking about me. No, not a paranoid suspicion (this time), they really were.

“Well if we could get Ted Scambos up to the control tower we might be able to resolve this quickly.”  The verbal equivalent of the Batman signal flashing in the sky! I ran up the control tower stairs two at a time, and burst into the room at the top, breathless but at the same time trying to be nonchalant.

“I’m Ted Scambos,” I said, casually, ‘What’s up?’  A pause.  “Hilmar has forgotten a couple of items, can you fetch them from his office and the hangar?”  Cracks in the Batman light appeared.  “Okay.”

“You know you’re going out to Cape Disappointment to deliver them, right?” Batman light reformed. “And you’ll need to round up your gear. Tamsin and Malcolm are on their way from the skiway to help you install that camera.” Batman light burned brightly now.

It was late in the day, though. We didn’t take off until about 3:15 pm. And I learned that the weather was now not so great at the Cape, and we would be out there until quite late in the evening. We loaded the plane in record time. I  thought.  “This is not the plan I had in mind, it’s too rushed, we’re too distracted, the weather is going to be an added challenge. “But we were in the plane looking down the runway. There was only one thing to do: Close your eyes and floor it. “Here we go.”

It took us until 5:30 pm to get to the area of the Cape. And, the weather: the other Twin Otter with Hilmar Gudmundsson had landed earlier, when the weather was acceptable. They set out a line of flags in the snow. Cape Disappointment is no airstrip. The ice cap (see pictures from last blog) is quite lumpy. And now a layer of heavy clouds had moved in, cutting off the light and making everything flat: no contrast, like a white-out.

But Doug, our pilot, plopped the plane down like a ski jumper sticking the landing at the Olympics, and skidded to a stop. We taxied up to the other Otter. The other pilot, Steve, explained, “The weather has been declining all day. When we landed at 2, it was great.” We learned that the stuff we brought out won’t even be of use. It was the right stuff, but it was now a bit too cloudy and murky to try any more new landing sites for the day.

By now the clouds were fairly heavy over us, and a light snow had begun. But we set out with the gear on the sleds for the rock outcrop. A hill of ice obstructed our view, and I couldn’t even tell if we’d be able to see Scar Inlet Shelf from here.

We spotted the outcrop just a few hundred yards away as we rounded an icy knoll, and dragged the sleds with the gear over to it. The rock was shattered from freeze-thaw, so we couldn’t use the rock-bolts; but Malcolm had made wire baskets that we filled with rocks to attach the guy wires too. It went like clockwork. Everything fitted, we had parts for everything, the batteries were charged, and we moved in a very efficient sequence. Step by step.

The tower went up. Got secured. Solar panels bolted on. Sensor boom mounted. Main camera mounted. Camera direction looked good. Baskets filled with rocks. Guy wires tightened. I got out the laptop to poke around the inside of the mind of AMIGOS6. And it wouldn’t boot up. The battery was dead, or too cold. I warmed it up for 20 minutes against my stomach, but it still wouldn’t boot up the computer.  Wow. Now we had some gambling going on. It is now snowing and about 15 degrees Fahrenheit. Cold and dark, and 9:45 pm with hours to go. OK. We have to gamble that it is all good.

The plane was loaded, but the weather was marginal. There was sort of a fuzzy horizon, one could sort of see the ice shelf a distance away, but it was more like being inside a light bulb. Diffuse. We taxied to the end of the flag line, and Doug was thinking hard, looking around, going through possibilities, contingencies. We could see the eight flags, yes. But it looked like they were painted on a featureless grey screen, just poles in space. We knew there was a drop-off in front out there somewhere. And a cliff, and mountains to the west.  But Twin Otters are amazing, short take-off, tough as nails, and climb like an elevator. Light snow begins to accumulate on the windscreen. Doug ponders.

Close your eyes and floor it.

Cape Disappointment AMIGOS-6 is working perfectly. All the pictures are pointing right where we hoped they would, and the weather station, GPS, and solar sensor have sent data hourly. The Nikon is showing scenes from the front of the shelf, and already it’s clear that there has been some evolution in the past few weeks/months, relative to satellite images. A total success.

BAS and everyone that’s here have been outstanding. Everyone has a good attitude and are fun people to work with to boot. I can’t say enough about this base: its style and its efficiency in putting deep field projects into difficult places. Thank you all very much. (All photographs courtesy Ted Scambos)

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