Published in the Antarctic Sun
MacOps bills itself as the Voice of Antarctica. The radio operators there talk to people all over the continent and elsewhere around the world on high-frequency and very high-frequency radios.
Thursday, just before lunch, the continent got a sore throat.
All the HF radios went quiet, broadcasting white noise instead of voices from all over.
“It was pretty eerie,” said Paula Elliott of MacRelay, which also monitors all radio frequencies.
A solar flare had sent a mass of charged particles out from the sun into the Earth’s atmosphere. Those charged particles had disrupted the ionosphere, the layer of Earth’s atmosphere that
reflects HF radio waves, preventing transmission of HF waves around the globe.
The radiation, the fourth largest storm of its type since 1976, caused some rearrangement
of communications and transport schedules on the continent.
“Camps were unable to check in,” Elliott said. “People were technically overdue for their
check-ins, though we knew why.”
If camps miss their check-ins under normal circumstances, rescue missions are launched. This
time, though, radio operators waited and worked around the situation.
They had lost contact with South Pole Station, Byrd Surface Camp, Siple Dome, Byrd Glacier, as well as the Olympus Range and Lake Vida, which are in VHF “dead spots” in the Dry Valleys.
Communications with the Pole were possible on the Internet during the Pole’s satellite window. The people at Vida had to climb a hill to hit a VHF repeater.
“We didn’t expect it to be as big as it was,” said MacOps coordinator Shelly DeNike.
The camp at Icestream C was put in during the communications blackout.
Normally, an airplane can’t leave a camp put-in until the camp radios MacOps on HF. This time, though, the camp was only able to talk to the plane on the ground. The solar flare’s energy prevented them from talking farther away.
Other than that small glitch, everything was fine.
“We’ve been pretty much prepared for this to happen,” DeNike said.
The larger field camps have emergency beacons they can set off if all else fails, just like if an aircraft crashes or a boat is in distress at sea. Had anything truly disastrous happened, they could have activated the beacon.
After two days without contact from Byrd Surface Camp, an airplane went out of its way to fly over it to make contact. Pilots helped by contacting camps along their flight routes.
“When they would fly in the vicinity of field camps they would call them,” DeNike
said.
Camp managers knew this might be a problem. Before going into the field, they had been briefed that HF problems might occur in this year of high solar activity.
In terms of air traffic control, everything also went smoothly with what air traffic manager Dusty Barrett called “a little bit of creative scheduling.”
Before planes left McMurdo, controllers gave pilots instructions for flying both to and from the Pole; normally they clear flights for only one direction at a time. MacCenter, the hub of air traffic control at McMurdo was only able to talk to the planes while they were within line-of-sight.
In a contingency set up last year, they had two controllers in Christchurch, New Zealand.
The controllers in McMurdo talked over the phone to Christchurch, which relayed messages over a satellite communication link to the planes.
“Once the HF went down we had to be a little bit creative,” Barrett said.
They also used Iridium satellite phones, Barrett said. Pilots continued to use HF, sending their position reports “in the blind,” without knowing if they were received, in the hope that MacCenter could hear them.
“Sometimes you can receive but you can’t transmit,” Barrett said.
This is the second full blackout since Winfly, but there have been partial blackouts where only lower frequencies were cut off.
This type of event has happened in the past, but only for 24 to 48 hours, Elliott said. This time it was Saturday evening before things came back, a shutdown of nearly 60 hours.
“We’ve seen a lot more activity than we had last year,” Elliott said.
It may have to do with a peak in the 11-year cycle of solar activity. Sometimes these effects from flares are predictable, and this time there was some warning. But the loss of HF communications was rapid.
“It happened right away,” DeNike said.
Things are back to normal now, Elliott said, but it could happen again anytime, and without a lot of warning.
“They hit without much notice,” she said.
Sunday, November 19, 2000
Exploring the plateau
Published in the Antarctic Sun
The U.S. segment of the International Trans-Antarctic Scientific Expedition left Thursday for Byrd Surface Camp to begin this season’s traverse of the West Antarctic ice sheet.
The project is a multi-national effort in which the U.S. component this year involves 10 research institutions and five areas of study: meteorology, surface glaciology, geophysics, remote sensing and ice coring.
“It’s five coordinated disciplines,” said Paul Mayewski, coordinator of the U.S. traverse group.
Last year was the first of this four-year project that will end at the Pole in 2003. The information the team collected last year is already helping improve scientists’ understanding of the world’s climate.
The data is specific to the region of West Antarctica where the traverse will occur, but it shows effects of regional and even global weather and climate systems.
“What we’re looking for isn’t just an understanding of Antarctica,” Mayewski said.
By looking at snow layers in Antarctica ice sheets revealing the last 200 to 500 years of the Earth’s climatic history, ITASE groups across the continent have already learned about the
relationship of certain Antarctic weather patterns to large-scale climate phenomena like El Niño.
“We already have seen some very interesting results,” Mayewski said.
The team is also comparing the results from their work in the Antarctic to similar work in the North Atlantic, another powerful element in the engine of Earth’s weather. While small changes are localized, Mayewski said, larger alterations are visible in ice cores from both ends of the globe.
This field season, the traverse team will cover 1,200 kilometers in a triangular path starting and ending at Byrd Surface Camp. During the drive, they will use downward-looking radar to map the strata in the ice beneath the route. They will also have a shorter range crevasse detector radar unit operating to keep the vehicles and researchers safe out on the plateau.
At roughly 100-kilometer intervals, they will stop for a few days to drill a 200-meter ice core. The core itself and the hole it leaves show the chemical and physical properties of the layers of
snow.
They will identify specific layers in the cores that can be cross-referenced to the radar data, allowing them to follow snow layers for hundreds of miles.
“It’s almost like a three-dimensional ice core,” Mayewski said.
The data they get from the cores and from the radar shows indicators of the extent of the sea ice, activity of marine life and duration of polar stratospheric clouds in recent centuries, Mayewski said.
This year the team will be able to haul more equipment and better shelters, because they have a Challenger instead of one of the two Tucker Sno-Cats they used last year. The other Sno-Cat will
continue the journey this season.
As the project progresses, Mayewski said, the setup and takedown at either end of the traverse will become more streamlined, as vehicles and supplies are left to spend the winter on the plateau.
“We should be able to go in with a very small amount of C-130 support,” Mayewski said. This is a big efficiency advantage, he said, as compared with individual field camps.
“There are 10 institutions that can potentially be served by two to three flights in and two to three flights out,” Mayewski said, adding that fuel airdrops will also be part of the support of
the field traverses. This year they expect to use seven flights in and four flights out.
To choose its exact route, the team uses satellite photos to avoid crevassed areas and other potentially problematic sites. But they also confirm satellite pictures by reporting on surface conditions and comparing that information to the pictures taken from space.
In addition to their own work and contributions to wider projects like the International Geosphere and Biosphere Project, one of this year’s shallow cores is at a possible deep-core site like the one at Siple Dome.
“This is a return of the 1960s style of science in this region, with 21st century technology,” Mayewski said.
The U.S. segment of the International Trans-Antarctic Scientific Expedition left Thursday for Byrd Surface Camp to begin this season’s traverse of the West Antarctic ice sheet.
The project is a multi-national effort in which the U.S. component this year involves 10 research institutions and five areas of study: meteorology, surface glaciology, geophysics, remote sensing and ice coring.
“It’s five coordinated disciplines,” said Paul Mayewski, coordinator of the U.S. traverse group.
Last year was the first of this four-year project that will end at the Pole in 2003. The information the team collected last year is already helping improve scientists’ understanding of the world’s climate.
The data is specific to the region of West Antarctica where the traverse will occur, but it shows effects of regional and even global weather and climate systems.
“What we’re looking for isn’t just an understanding of Antarctica,” Mayewski said.
By looking at snow layers in Antarctica ice sheets revealing the last 200 to 500 years of the Earth’s climatic history, ITASE groups across the continent have already learned about the
relationship of certain Antarctic weather patterns to large-scale climate phenomena like El Niño.
“We already have seen some very interesting results,” Mayewski said.
The team is also comparing the results from their work in the Antarctic to similar work in the North Atlantic, another powerful element in the engine of Earth’s weather. While small changes are localized, Mayewski said, larger alterations are visible in ice cores from both ends of the globe.
This field season, the traverse team will cover 1,200 kilometers in a triangular path starting and ending at Byrd Surface Camp. During the drive, they will use downward-looking radar to map the strata in the ice beneath the route. They will also have a shorter range crevasse detector radar unit operating to keep the vehicles and researchers safe out on the plateau.
At roughly 100-kilometer intervals, they will stop for a few days to drill a 200-meter ice core. The core itself and the hole it leaves show the chemical and physical properties of the layers of
snow.
They will identify specific layers in the cores that can be cross-referenced to the radar data, allowing them to follow snow layers for hundreds of miles.
“It’s almost like a three-dimensional ice core,” Mayewski said.
The data they get from the cores and from the radar shows indicators of the extent of the sea ice, activity of marine life and duration of polar stratospheric clouds in recent centuries, Mayewski said.
This year the team will be able to haul more equipment and better shelters, because they have a Challenger instead of one of the two Tucker Sno-Cats they used last year. The other Sno-Cat will
continue the journey this season.
As the project progresses, Mayewski said, the setup and takedown at either end of the traverse will become more streamlined, as vehicles and supplies are left to spend the winter on the plateau.
“We should be able to go in with a very small amount of C-130 support,” Mayewski said. This is a big efficiency advantage, he said, as compared with individual field camps.
“There are 10 institutions that can potentially be served by two to three flights in and two to three flights out,” Mayewski said, adding that fuel airdrops will also be part of the support of
the field traverses. This year they expect to use seven flights in and four flights out.
To choose its exact route, the team uses satellite photos to avoid crevassed areas and other potentially problematic sites. But they also confirm satellite pictures by reporting on surface conditions and comparing that information to the pictures taken from space.
In addition to their own work and contributions to wider projects like the International Geosphere and Biosphere Project, one of this year’s shallow cores is at a possible deep-core site like the one at Siple Dome.
“This is a return of the 1960s style of science in this region, with 21st century technology,” Mayewski said.
Sunday, November 12, 2000
What's in a name? The seventh continent bears the names of heroic explorers and heavy equipment operators alike
Published in the Antarctic Sun
When explorers first set eyes on Antarctica, “Terra Incognita” wasn’t just an unknown land,
it was an unnamed land, too.
They soon took care of that, naming prominent geographic features after themselves, their ships and those who gave them financial backing.
In 1841 Capt. James Clark Ross named the Ross Ice Shelf in his own honor; he named mounts Erebus and Terror for his ships. Capt. Robert Scott, 60 years later, named Cape Armitage for his second-in-command and Minna Bluff for the wife of Sir Clements Markham, one of Scott’s primary sponsors.
But Antarctica is a big place. There are still a lot of points, bluffs, peaks, glaciers, nunataks and other formations that need labeling. Since 1947, the U.S. Board on Geographic Names and its Advisory Committee on Antarctic Names have handled that task.
To decide on designations names are first categorized as personal or non-personal.
The latter include commemoration of events (for instance, Jubilee Peak), ships (Glacier Bight), Antarctic-related organizations (USARP Mountains) and descriptions of features (Turtle Rock).
People’s names are, of course, also used.
They are assigned based on the level of a person’s contribution to Antarctic research or history, and on the type of geographic feature.
First-order features are large, such as regions of land, large glaciers, ice shelves and large
mountain ranges. They are named after leaders of major expeditions, towering figures in Antarctic history and donors to Antarctic research.
Second-order features include peninsulas, significant mountains, prominent coastal features and islands. They are named for people who have played significant but lesser roles.
Third-order features include nunataks, cliffs, rocks and anchorages. They are named for people who have supported Antarctic endeavors.
Various people in the U.S. Antarctic Program have been immortalized on the Ice, from top dogs at the National Science Foundation to long-term program employees (see sidebar). NSF director Rita Colwell was once an Antarctic field researcher; a mountain now bears her name. NSF representative Dave Bresnahan and his boss Erick Chiang both have mountains named for them.
Chuck Gallagher served in the U.S. Naval Support Force, Antarctica and then worked for Antarctic Support Associates before dying at McMurdo Station on May 1, 1997. A ridge bears his name.
In alphabetical order, here are some Antarctic geographic features named after some members
of the U.S. Antarctic Program who will be on the continent this season. Their accomplishments are listed in brief. For a complete list and searchable database, visit the U.S. Geological Survey’s Antarctic names web site at http://mapping.usgs.gov/www/gnis/antform.html.
Ainley Peak is named for David Ainley, penguin and skua researcher.
Alcorta Rocks is a nunatak named for Jesse Alcorta, hazardous waste specialist
and cryogenic technician.
DeVries Glacier is named for Art DeVries, long-time biologist at McMurdo Station.
Guthridge Nunataks are named after Guy Guthridge, director of polar information
services for the NSF and chair of the Advisory Committee on Antarctic Names.
Joyce Peak is named for Karen Joyce, who has worked in computer science support for 10 years.
Kennedy Ridge is a ridge named for Nadene Kennedy, NSF’s polar coordination specialist.
Kottmeier Mesa is named after Steve Kottmeier, who’s been a scientist and administrator with the program since 1988.
Krall Crags is a pair of summits named for Sarah Krall, who has worked in the program for over 10 years.
Kyle Hills is a group of hills on Ross Island named for Phil Kyle, who has studied Mount Erebus for 28 years.
Lettau Peak is named for Bernhard Lettau, ocean and climate sciences program manager at the Office of Polar Programs.
Mount Bresnahan is named for Dave Bresnahan, current NSF representative at McMurdo Station.
Mount Chiang is a mountain named after Erick Chiang, manager of operations for polar programs.
Mount Melton is a peak named for Terry Melton, who has worked as an engineer and manager at Palmer and McMurdo stations since 1981.
Palais Glacier is a glacier named after Julie Palais, field researcher in Antarctica and NSF polar glaciology program manager. Palais Bluff also bears her name.
Robbins Hill is named for Rob Robbins, science diving coordinator and 22-year program veteran.
Scanniello Peak is a peak named after Jeff Scanniello, surveyor at McMurdo and South Pole stations.
Uberuaga Island gets its name from Jules Uberuaga, long-time equipment operator.
When explorers first set eyes on Antarctica, “Terra Incognita” wasn’t just an unknown land,
it was an unnamed land, too.
They soon took care of that, naming prominent geographic features after themselves, their ships and those who gave them financial backing.
In 1841 Capt. James Clark Ross named the Ross Ice Shelf in his own honor; he named mounts Erebus and Terror for his ships. Capt. Robert Scott, 60 years later, named Cape Armitage for his second-in-command and Minna Bluff for the wife of Sir Clements Markham, one of Scott’s primary sponsors.
But Antarctica is a big place. There are still a lot of points, bluffs, peaks, glaciers, nunataks and other formations that need labeling. Since 1947, the U.S. Board on Geographic Names and its Advisory Committee on Antarctic Names have handled that task.
To decide on designations names are first categorized as personal or non-personal.
The latter include commemoration of events (for instance, Jubilee Peak), ships (Glacier Bight), Antarctic-related organizations (USARP Mountains) and descriptions of features (Turtle Rock).
People’s names are, of course, also used.
They are assigned based on the level of a person’s contribution to Antarctic research or history, and on the type of geographic feature.
First-order features are large, such as regions of land, large glaciers, ice shelves and large
mountain ranges. They are named after leaders of major expeditions, towering figures in Antarctic history and donors to Antarctic research.
Second-order features include peninsulas, significant mountains, prominent coastal features and islands. They are named for people who have played significant but lesser roles.
Third-order features include nunataks, cliffs, rocks and anchorages. They are named for people who have supported Antarctic endeavors.
Various people in the U.S. Antarctic Program have been immortalized on the Ice, from top dogs at the National Science Foundation to long-term program employees (see sidebar). NSF director Rita Colwell was once an Antarctic field researcher; a mountain now bears her name. NSF representative Dave Bresnahan and his boss Erick Chiang both have mountains named for them.
Chuck Gallagher served in the U.S. Naval Support Force, Antarctica and then worked for Antarctic Support Associates before dying at McMurdo Station on May 1, 1997. A ridge bears his name.
In alphabetical order, here are some Antarctic geographic features named after some members
of the U.S. Antarctic Program who will be on the continent this season. Their accomplishments are listed in brief. For a complete list and searchable database, visit the U.S. Geological Survey’s Antarctic names web site at http://mapping.usgs.gov/www/gnis/antform.html.
Ainley Peak is named for David Ainley, penguin and skua researcher.
Alcorta Rocks is a nunatak named for Jesse Alcorta, hazardous waste specialist
and cryogenic technician.
DeVries Glacier is named for Art DeVries, long-time biologist at McMurdo Station.
Guthridge Nunataks are named after Guy Guthridge, director of polar information
services for the NSF and chair of the Advisory Committee on Antarctic Names.
Joyce Peak is named for Karen Joyce, who has worked in computer science support for 10 years.
Kennedy Ridge is a ridge named for Nadene Kennedy, NSF’s polar coordination specialist.
Kottmeier Mesa is named after Steve Kottmeier, who’s been a scientist and administrator with the program since 1988.
Krall Crags is a pair of summits named for Sarah Krall, who has worked in the program for over 10 years.
Kyle Hills is a group of hills on Ross Island named for Phil Kyle, who has studied Mount Erebus for 28 years.
Lettau Peak is named for Bernhard Lettau, ocean and climate sciences program manager at the Office of Polar Programs.
Mount Bresnahan is named for Dave Bresnahan, current NSF representative at McMurdo Station.
Mount Chiang is a mountain named after Erick Chiang, manager of operations for polar programs.
Mount Melton is a peak named for Terry Melton, who has worked as an engineer and manager at Palmer and McMurdo stations since 1981.
Palais Glacier is a glacier named after Julie Palais, field researcher in Antarctica and NSF polar glaciology program manager. Palais Bluff also bears her name.
Robbins Hill is named for Rob Robbins, science diving coordinator and 22-year program veteran.
Scanniello Peak is a peak named after Jeff Scanniello, surveyor at McMurdo and South Pole stations.
Uberuaga Island gets its name from Jules Uberuaga, long-time equipment operator.
A long journey for three little planes
Published in the Antarctic Sun
Nine people and three small planes recently arrived at McMurdo Station after a journey of over 11,000 miles (17,700 km) from Canada to spend four months flying in the Antarctic.
Each year, three de Havilland Twin Otter airplanes owned and operated by Kenn Borek Air travel from the company’s base in Calgary, Alberta, through North and South America and across Antarctica to support the U.S. and Italian programs on the Ice.
This year the planes left Calgary on Oct. 23 and flew to Boise, Idaho, where two were inspected before continuing on to Houston, Texas, where they spent the night before flying to Grand Cayman Island for the second night of the journey. The trip affords them a luxury they don’t have in Antarctica.
“Every night we go out for dinner and relax,” said Kenn Borek’s chief Antarctic pilot Sean Loutitt.
Leaving Grand Cayman, they flew the three planes over Panama and on past the Equator to Guayaquil, Ecuador.
Though government procedures in that area of the world can be difficult to deal with, three similarly-painted planes get friendly attention.
“They’re pretty smooth for us,” Loutitt said, though he noted that Ecuadorian officials inspect the planes carefully with drug dogs.
After a night in Ecuador, they leave the next morning for Arica, Chile, just over the border from Peru.
“We don’t land in Peru,” Loutitt said. “It’s hard to get landing permits.”
But they do just fine in Chile, with help from a few locals, including an air traffic controller who assists with paperwork.
“We seem to have built a good network of friends in Chile,” Loutitt said.
After a night in Arica, they normally fly halfway down the length of Chile to Puerto Montt.
This year the pilots were in a bit of a hurry to make it to McMurdo as soon as possible to start work. They continued to Punta Arenas, an extra 800 miles (1,200 km).
In Punta Arenas, they changed into their cold-weather clothes. They learned the weather was bad at Rothera, the British Antarctic Survey base on Adelaide Island, their next stop.
After a day’s layover, strong headwinds made what is normally a six-hour flight take eight hours. The winds, Loutitt said, included a 50 mph (80 kph) direct headwind, and crosswind gusts of over 80 mph (129 kph).
The gravel runway at Rothera is normally covered with snow in October, but this year it was not. Instead of just changing landing gear from wheels to skis on the snow-covered gravel runway, they had to shuttle planes one by one to a glacier runway for the conversion.
“Nine of us were working on this for 12 hours,” Loutitt said.
After Rothera, the usual flight path calls for the planes to refuel at Patriot Hills before continuing to the South Pole. This year, though, two of the three went directly to the Pole, while one
stopped at Patriot Hills to refuel and check the fuel cache the U.S. Antarctic Program maintains there.
All three made it to the Pole that day, Nov. 1, but then the weather came in.
“The next morning we woke up and couldn’t even see the airplanes,” Loutitt said.
Two days later the fliers were able to make it to McMurdo to begin the season’s work, which will include flying over 100 hours per month, supporting deep-field camps and aerial surveying
projects. One plane continued north to the Italian station at Terra Nova Bay.
At the end of the season, the planes will fly back to Canada again to work during the boreal summer before coming back down again next year.
“It’s a trek,” Loutitt said. “It’s actually kind of fun.”
Nine people and three small planes recently arrived at McMurdo Station after a journey of over 11,000 miles (17,700 km) from Canada to spend four months flying in the Antarctic.
Each year, three de Havilland Twin Otter airplanes owned and operated by Kenn Borek Air travel from the company’s base in Calgary, Alberta, through North and South America and across Antarctica to support the U.S. and Italian programs on the Ice.
This year the planes left Calgary on Oct. 23 and flew to Boise, Idaho, where two were inspected before continuing on to Houston, Texas, where they spent the night before flying to Grand Cayman Island for the second night of the journey. The trip affords them a luxury they don’t have in Antarctica.
“Every night we go out for dinner and relax,” said Kenn Borek’s chief Antarctic pilot Sean Loutitt.
Leaving Grand Cayman, they flew the three planes over Panama and on past the Equator to Guayaquil, Ecuador.
Though government procedures in that area of the world can be difficult to deal with, three similarly-painted planes get friendly attention.
“They’re pretty smooth for us,” Loutitt said, though he noted that Ecuadorian officials inspect the planes carefully with drug dogs.
After a night in Ecuador, they leave the next morning for Arica, Chile, just over the border from Peru.
“We don’t land in Peru,” Loutitt said. “It’s hard to get landing permits.”
But they do just fine in Chile, with help from a few locals, including an air traffic controller who assists with paperwork.
“We seem to have built a good network of friends in Chile,” Loutitt said.
After a night in Arica, they normally fly halfway down the length of Chile to Puerto Montt.
This year the pilots were in a bit of a hurry to make it to McMurdo as soon as possible to start work. They continued to Punta Arenas, an extra 800 miles (1,200 km).
In Punta Arenas, they changed into their cold-weather clothes. They learned the weather was bad at Rothera, the British Antarctic Survey base on Adelaide Island, their next stop.
After a day’s layover, strong headwinds made what is normally a six-hour flight take eight hours. The winds, Loutitt said, included a 50 mph (80 kph) direct headwind, and crosswind gusts of over 80 mph (129 kph).
The gravel runway at Rothera is normally covered with snow in October, but this year it was not. Instead of just changing landing gear from wheels to skis on the snow-covered gravel runway, they had to shuttle planes one by one to a glacier runway for the conversion.
“Nine of us were working on this for 12 hours,” Loutitt said.
After Rothera, the usual flight path calls for the planes to refuel at Patriot Hills before continuing to the South Pole. This year, though, two of the three went directly to the Pole, while one
stopped at Patriot Hills to refuel and check the fuel cache the U.S. Antarctic Program maintains there.
All three made it to the Pole that day, Nov. 1, but then the weather came in.
“The next morning we woke up and couldn’t even see the airplanes,” Loutitt said.
Two days later the fliers were able to make it to McMurdo to begin the season’s work, which will include flying over 100 hours per month, supporting deep-field camps and aerial surveying
projects. One plane continued north to the Italian station at Terra Nova Bay.
At the end of the season, the planes will fly back to Canada again to work during the boreal summer before coming back down again next year.
“It’s a trek,” Loutitt said. “It’s actually kind of fun.”
Sunday, November 5, 2000
Cracking up: Sea ice under stress
Published in the Antarctic Sun
It’s strong enough to land planes on, too thick for a small drill to get through and cracks under pressure.
Sea ice is vital to the early-season research based at McMurdo Station.
Scientists base themselves on the frozen ocean to study the marine world. And when it breaks up and blows north, it leaves a spectacular expanse of open water.
David Cole and John Dempsey have forged a partnership out of the study of fracture of sea ice. Their work has involved lab work and field research in Alaska and now Antarctica.
Cole, from the U.S. Army Corps of Engineers Cold Regions Research and Engineering Lab, and Dempsey, from Clarkson University, are studying how ice behaves when under stress, in the breaking process.
Their project has faced some difficulty this year. The sea ice is thicker than usual, which is hard on their equipment.
They were expecting to find some ice as thin as 36 inches, and have equipment that can cut ice up to 84 inches, though very slowly. The thinnest they’ve found is 45 inches, with most of the ice 55 to 60 inches thick.
The amount of time required to cut through this thickness of ice is more than the team has.
“Because of ice thickness we can’t do the research we proposed,” Dempsey said. “We probably need a Ditch Witch,” a trenching machine for cutting through the ice faster.
Right now it takes too long to cut blocks the size they need. The biggest piece they’ve been able to study was three meters square. They would like to be studying deformation and fracture of blocks of sea ice up to 30 meters on a side, 100 times larger than they can get.
“The underlying theme of our research is to look at scale,” Dempsey said. Without large blocks of ice to study, they can’t get the data they would like.
Cole’s part of the study happens first. He wants to know how ice deforms when under stress. His work stops when the ice actually cracks, but the information he gathers helps Dempsey watch the right area of a floe when they do crack it.
“It starts with the microstructure,” Cole said.
The way ice crystals form and align themselves as the ocean freezes makes a difference in how the ice will crack, even months later. When there is a small current, ice crystals line up in one general direction.
That, in turn, makes the ice relatively weak in one direction, so it tends to crack for long distances in straight lines, Cole said.
“The properties are different depending on the direction,” Cole said. “It’s not just a homogeneous material.”
Some things are very different in the field from in the lab. For example, brine drains out of the ice when it’s brought into the lab, which changes the characteristics of the ice.
They have a camp about three miles (five km) from the ice edge, on fast ice. Their cutting area is a short distance away, but on much thinner, floating ice.
Cole and Dempsey and their two students mark out an area in which they want to work. They cut a block free of the ice sheet and then cut a starter crack, into which they insert a balloon-like loading device.
This “flat jack” has a computer-controlled inflation valve, which lets the team vary the pressure in the crack. The computer is set to stress the block of ice until they are ready to break it.
“We don’t want to accidentally break it,” Cole said.
As the ice deforms, they monitor it for stresses and tensions, as well as how it deforms in response to the pressure on the crack. Some of these processes, Cole said, vary with the size of the piece of ice, while others do not.
Eventually, though, they are ready to break the floe.
Ice breaking
“Ice fracture is a very complicated process,” Dempsey said.
They have learned that at the tip of a crack that is about to break further, a series of micro-cracks form. They have equipment listening for the noise of those tiny cracks, to warn them before the block actually breaks.
Cole always looks carefully at the structure of the ice as well as these micro-cracks, to estimate where the block will break.
“It’s nice to have nature verify your direction,” Cole said. But he’s never sure if he’ll be right until the chunk of ice opens up entirely,
“Until you come down and try to do some tests you don’t know,” Dempsey said. “There are so many different types of ice.”
The ice thickness affects the breakup, but the more significant factor is the nature of the ice itself, which depends on how old the ice is, how it formed, local landforms and other environmental factors.
“We’re getting different ice wherever we move,” Dempsey said.
The models Dempsey and Cole have made about the behavior of ice under tension are based on smaller, more homogeneous sections of ice. They are checking to see how well those models predict the behavior of the ice they find in McMurdo Sound, and in larger sections.
They’ve wrapped up for this season, but are ready to come back and keep working, perhaps with better equipment and ice conditions.
“We have two field seasons,” Cole said.
It’s strong enough to land planes on, too thick for a small drill to get through and cracks under pressure.
Sea ice is vital to the early-season research based at McMurdo Station.
Scientists base themselves on the frozen ocean to study the marine world. And when it breaks up and blows north, it leaves a spectacular expanse of open water.
David Cole and John Dempsey have forged a partnership out of the study of fracture of sea ice. Their work has involved lab work and field research in Alaska and now Antarctica.
Cole, from the U.S. Army Corps of Engineers Cold Regions Research and Engineering Lab, and Dempsey, from Clarkson University, are studying how ice behaves when under stress, in the breaking process.
Their project has faced some difficulty this year. The sea ice is thicker than usual, which is hard on their equipment.
They were expecting to find some ice as thin as 36 inches, and have equipment that can cut ice up to 84 inches, though very slowly. The thinnest they’ve found is 45 inches, with most of the ice 55 to 60 inches thick.
The amount of time required to cut through this thickness of ice is more than the team has.
“Because of ice thickness we can’t do the research we proposed,” Dempsey said. “We probably need a Ditch Witch,” a trenching machine for cutting through the ice faster.
Right now it takes too long to cut blocks the size they need. The biggest piece they’ve been able to study was three meters square. They would like to be studying deformation and fracture of blocks of sea ice up to 30 meters on a side, 100 times larger than they can get.
“The underlying theme of our research is to look at scale,” Dempsey said. Without large blocks of ice to study, they can’t get the data they would like.
Cole’s part of the study happens first. He wants to know how ice deforms when under stress. His work stops when the ice actually cracks, but the information he gathers helps Dempsey watch the right area of a floe when they do crack it.
“It starts with the microstructure,” Cole said.
The way ice crystals form and align themselves as the ocean freezes makes a difference in how the ice will crack, even months later. When there is a small current, ice crystals line up in one general direction.
That, in turn, makes the ice relatively weak in one direction, so it tends to crack for long distances in straight lines, Cole said.
“The properties are different depending on the direction,” Cole said. “It’s not just a homogeneous material.”
Some things are very different in the field from in the lab. For example, brine drains out of the ice when it’s brought into the lab, which changes the characteristics of the ice.
They have a camp about three miles (five km) from the ice edge, on fast ice. Their cutting area is a short distance away, but on much thinner, floating ice.
Cole and Dempsey and their two students mark out an area in which they want to work. They cut a block free of the ice sheet and then cut a starter crack, into which they insert a balloon-like loading device.
This “flat jack” has a computer-controlled inflation valve, which lets the team vary the pressure in the crack. The computer is set to stress the block of ice until they are ready to break it.
“We don’t want to accidentally break it,” Cole said.
As the ice deforms, they monitor it for stresses and tensions, as well as how it deforms in response to the pressure on the crack. Some of these processes, Cole said, vary with the size of the piece of ice, while others do not.
Eventually, though, they are ready to break the floe.
Ice breaking
“Ice fracture is a very complicated process,” Dempsey said.
They have learned that at the tip of a crack that is about to break further, a series of micro-cracks form. They have equipment listening for the noise of those tiny cracks, to warn them before the block actually breaks.
Cole always looks carefully at the structure of the ice as well as these micro-cracks, to estimate where the block will break.
“It’s nice to have nature verify your direction,” Cole said. But he’s never sure if he’ll be right until the chunk of ice opens up entirely,
“Until you come down and try to do some tests you don’t know,” Dempsey said. “There are so many different types of ice.”
The ice thickness affects the breakup, but the more significant factor is the nature of the ice itself, which depends on how old the ice is, how it formed, local landforms and other environmental factors.
“We’re getting different ice wherever we move,” Dempsey said.
The models Dempsey and Cole have made about the behavior of ice under tension are based on smaller, more homogeneous sections of ice. They are checking to see how well those models predict the behavior of the ice they find in McMurdo Sound, and in larger sections.
They’ve wrapped up for this season, but are ready to come back and keep working, perhaps with better equipment and ice conditions.
“We have two field seasons,” Cole said.
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