Archive for the ‘Preparation’ Category

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Polar firn aquifers: Why are we doing this?

November 16, 2018

Often when people envision Greenland and Antarctica, they see desolate, snow-filled lands; and in general, that is pretty accurate. Other than a few coastal towns and seasonal base camps, these lands are uninhabited, except for a few tough species of animals. And, of course, there is lots of snow. As snowfall settles, it compacts under the weight of new snow and the battering ram of the wind. This compacted older snow, at least one winter old, is called firn—still porous, but between fresh snow and glacial ice in density.

Where we are going to in Antarctica the firn has a special feature. These regions are known for very warm summer conditions, with lots of melting and lots of snowfall over the course of the year. The summer melt can percolate through the snow and firn grains to form a water-saturated layer that sits above the denser glacier ice. Like a well in sandstone, this is a kind of aquifer in the firn, almost like a natural snow cone. Without the syrup.

Firn aquifers have been observed on a few mountain glaciers, usually for just part of the year, but never on ice sheets until a discovery on the Greenland Ice Sheet in April of 2011. Since then, NASA Operation Ice Bridge data has mapped their extent over several regions of Greenland. In some parts of Greenland, they appear to persist for decades.

More recently, a mapping algorithm using satellite data correctly located the firn aquifers in Greenland. We applied the same method to Antarctica—and there they were, a signal in the data just like Greenland’s aquifer areas. Antarctica’s potential for firn aquifers is at present unconfirmed, yet application of a similar technique indicates that they likely exist in coastal and ice shelf regions that have climate conditions similar to firn aquifer areas in Greenland. That is what we are going to check out.

Firn aquifers are important because they could cause a kind of water-driven fracturing on ice sheets or ice shelves called hydrofracture, where water seeps into cracks in the ice and breaks them open, leading to a speed-up of a glacier or crumbling of an ice shelf. This kind of fracturing has led to some spectacular break-ups in Antarctica, or significant acceleration of glaciers in Greenland.

The objective of the Antarctic Firn Aquifer expedition is to verify the presence of firn aquifers on the Antarctic Ice Sheet by surveying two key sites on the Antarctic Peninsula: the Wilkins Ice Shelf and the southern George VI Ice Shelf. These field sites were identified using our mapping method and data from two satellite microwave instruments: a C-band radar scatterometer (EUMETSAT’s Advanced SCATterometer – ASCAT) and an L-band microwave radiometer (aboard NASA’s Soil Moisture Active Passive Satellite–SMAP). The longer wavelength of ASCAT and SMAP microwaves, and their sensitivity to the presence of liquid meltwater, allow them to see firn aquifers on ice sheets or ice shelves as deep as ~60 meters (200 feet). Over time, distinct patterns in the microwave signals can be used to distinguish firn aquifers from areas that do not store meltwater at depth.

 

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Once again to the Antarctic Peninsula

April 5, 2013

Rob writes:

On April 6, Ted Scambos, Jenn Bohlander, and I will be flying to Punta Arenas, Chile to join researchers aboard the Research Vessel Araon, a South Korean icebreaker. Our team will travel to the Antarctic Peninsula, sailing across the Drake Passage, to maintain the network of automated stations we installed over the last three years. Working with Erin Pettit and Ronald Ross, the team will also conduct radar surveys of the Flask and Crane glaciers. We are planning on assisting South Korean researchers in the installation of their observing stations–these “K-AMIGOS” will overlook the dynamic Crane and Flask glaciers, providing near real-time observations of ice conditions and weather information.

Crane Glacier

Crane Glacier

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Much ado about batteries

October 30, 2012

A set of eight batteries left over from the 2010 Nathaniel B. Palmer LARISSA cruise that are to be sent to Rothera Research Station to replace any British Atlantic Survey batteries that I use on my current trip.


Terry writes:

Went for a bit longer run northeast of the hotel along the ocean highway. Walked over to the AGUNSA warehouse, which is next door to the DAMCO warehouse and is being used for staging the equipment for the Lake Ellsworth crew. Their leader, Chris Hill, asked if I had any extra batteries. I said I need five myself and would check back with him.

Back over at DAMCO, I met Gene Domack who had arrived on the Lawrence M. Gould (LMG) icebreaker around three in the morning. We started looking for some of Gene’s batteries that he had unloaded that morning off the LMG, but we immediately found a set of eight batteries with a C-514 TCN label assigned to Ted Scambos that were from our 2010 LARISSA Palmer cruise. I gave two to Chris Hall of the Lake Ellsworth drilling project, so when they make their big discovery of unique bugs in the lake this season, we can say, “Those guys used some of our batteries!” Chris was going to charge and test them, and let me know if they are okay. He and his crew will be stopping in Rothera next week.

Took a nostalgic tour with Chris Linden of DAMCO to the Nathaniel B. Palmer (NBP) icebreaker, which is in Punta Arenas until January. Got invited to the end of cruise dinner at Mamasita’s, drank too much wine, crawled to a couple of bars with the dwindling LMG crew, and staggered back to the hotel around 2:30 a.m.

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Prep work in Punta Arenas

October 29, 2012

Terry writes:

Took a fifteen-minute walk to the DAMCO warehouse from the hotel and met Octavio, Gonzalo, and Paul who helped me check out my Extreme Cold Weather (ECW) clothing. Gonzalo gave me my Iridium satellite phone, and Marcella brought me my four cases, which she had kept in the DAMCO van overnight since the warehouse was closed.

I was told that I wouldn’t be flying the next day due to delays in some British Atlantic Survey arrivals to Punta Arenas. Bought some crackers, cheese, cookies, and fruit at the local Unimarc, tested my satellite phone with a quick call to Sue, and the spent then entire evening until 11 p.m. watching the CNN International coverage of Hurricane Sandy as it came ashore.

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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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Antarctica for one, please.

November 2, 2011

Ted writes:

I’m beginning to feel like some kind of migrating bird. For the past three years, like clockwork, as the calendar passes Halloween and heads into the leafless days of November, I find myself boarding planes and flying south. Once again, I’m at South America’s jumping off point for Antarctica, Punta Arenas, Chile. Usually I have someone from our team with me, like the redoubtable Terry Haran, or the indomitable Rob Bauer, or the highly toutable Jenn Bohlander, but this year it’s just me. Me, and some top-drawer assistants at the British Antarctic Survey base, Rothera (I have yet to meet them).

I’ve heard Punta’s climate described as windy sunshine, and it’s a description that sticks. I’ve been here 4 or 5 of the calendar months, and the only question one seems to ask about the weather is, “How windy is it now?”  The answer ranges from “Kinda,” to “Holy vacuum cleaner, Batman!” A bad hair day here means actually having your hair blown off. There is an occasional spritz of stinging rain, but for the most part it is intense sunshine, scudding low clouds, haggard-looking llamas and, well, wind.

The goal this year for the LARISSA Glaciology project is to repair and upgrade two of the installed measurement stations (a GPS station on a rocky cape, and our AMIGOS compadres sitting on the Scar Inlet shelf, a remnant we suspect will someday disintegrate like the Larsen B Ice Shelf did nearly ten years ago. We don’t plan to visit the other AMIGOS, on Flask Glacier, although it now sits up to its mechanical neck in snow. (Later, we will return for it, too.) The most important part of this year’s visit is to install a new system, with a much better camera, on a cliff overlooking the Scar Inlet shelf. The camera will provide a series of images showing how the ice front and surface change during a summer, and hopefully some details of the processes during a break-up. All the gear is already waiting down in Rothera.  If we can manage this installation, it could be a fantastic record of one of the big open questions in glaciology: how does an ice shelf disintegrate? But we have to get it set up out there first. I suppose I should mention the name of the cliff is Cape Disappointment. Not a good omen. Stay tuned.

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Still waiting

November 16, 2010

Martin writes:

When I was thinking about the timing on this trip to the Peninsula, I imagined us sitting in the Rothera bar by this time, telling tall tales about the big snow pit we had dug. With every beer the pit would get a bit deeper, and the weather a bit nastier, but us Antarctic explorers prevailed, rescuing the AMIGOS and pushing the frontiers of science by another nanometer.

Instead we are still waiting to get off the ground. The daily routine is pretty repetitive. Ted gets up in the morning and looks out the window. “It looks a bit better today”. That means you can see the next building now. Full of hope for what this day will bring we drag ourselves to breakfast. Ted sometimes joins the morning weather briefing, where decisions about the day’s flights are made. I see him come into the breakfast room with the look of a rejected suitor, and no more questions need to be asked.

The rest of the day we spent in our office room catching up with things left unfinished before leaving on the trip south. Ted obsessively downloads weather forecast maps: “Look, there is a weather window of 2.3 hours on December 23. I’m sure we’ll make it.”

Jenn is trying to be productive and make the best of the situation. She regularly talks to school kids back home, so she decided to go around and figure out what various people do on base. She got us a guided tour to the marine lab yesterday, which was pretty cool. They have an aquarium with a variety of sea spiders, clams, sea stars, etc. Mostly they look at the impact of climate change, and how these guys react to warming water. They have nice laboratory facilities for dissecting, cooking or whatever else biologists subject their critters to. The most amazing thing though is that they have a regular year-round diving program, which comes with its special challenges in the icy water.

Yesterday we had a visitor. A lonely Emperor Penguin showed up. It’s the largest of the penguins, and they don’t usually make it to Rothera. Apparently they get one or two a year, so people are excited. Penguins are just always a lot of fun to watch.

A lone Emperor Penguin pays a visit to Rothera Station. Photo courtesy Martin Truffer.

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