Tag Archives: Antarctica

2012 Antarctic Ozone Hole Update

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NASA and NOAA announced today that the hole in the ozone layer over Antarctica reached its annual maximum size on Sept. 22. Highlights include:

  • The Antarctic ozone hole reached its annual maximum size on Sept. 22, covering 8.2 million square miles — the area of the United States, Canada and Mexico combined.
  • That’s smaller than the record maximum of 11.5 million square miles reached on Sept. 6, 2000, and also smaller than last year’s maximum size of 10.1 million square miles.
  • Scientists attribute the smaller ozone hole in 2012 to warmer temperatures in the Antarctic lower stratosphere.

“The ozone hole mainly is caused by chlorine from human-produced chemicals, and these chlorine levels are still sizable in the Antarctic stratosphere,” said NASA atmospheric scientist Paul Newman of NASA’s Goddard Space Flight Center in Greenbelt, Md. “Natural fluctuations in weather patterns resulted in warmer stratospheric temperatures this year. These temperatures led to a smaller ozone hole.”

Read the full story here. Also read about the history of the ozone hole and its path toward recovery, and then check out the satellite-based image that in 1985 revealed for the first time the size and magnitude of the ozone hole. Finally, visit NASA’s Ozone Hole Watch to follow the state of the Antarctic ozone hole throughout the year.

AGU 2011: New Map of Antarctica's Rock Bed

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A new, updated map reveals how the Antarctic continent looks under the ice, detailing each mountain range and valley. Beyond its undeniable beauty, this high-resolution map of Antarctica’s bed topography, dubbed BEDMAP2, will help scientists model how ice sheets and glaciers respond to changes in the environment.

A large international consortium of Antarctic field programs, including NASA IceBridge, contributed information to this updated map of bed elevation and ice thickness for Antarctica and the Southern Ocean. The first version of BEDMAP was completed in 2000. The new version, which was presented on Dec. 5 at the American Geophysical Union’s 2011 Fall Meeting, incorporates seismic and radar data from about 265,000 km of airborne surveys over the ice.

“We are lacking fundamental data on ice thickness and bedrock elevation over large parts of Antarctica, because these areas are hard to reach,” said IceBridge project scientist Michael Studinger. “We’ll continue to fill in critical information gaps on places such as the Recovery Glacier in Coats Land, East Antarctica. This area has long been on the wish list of ice sheet modelers, but it is very far away from all research bases.”

This year, IceBridge’s DC-8 aircraft was able to fly four times over Recovery Glacier from Punta Arenas, Chile. “We have collected a landmark data set that will fill a critical hole in new BEDMAP compilations,” Studinger said.

Text by Maria-José Viñas. Image courtesy of the BEDMAP Consortium. The new version of BEDMAP will soon be freely available. Read more about the BEDMAP2 on the project’s website.

Pine Island Glacier: A Quest to Understand Antarctic Ice Loss

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NASA recently posted a press release about an upcoming expedition to Pine Island Glacier Ice Shelf, a key piece of real estate in Antarctica that’s slipping into the ocean at an increasingly worrisome pace. This month, in fact, an aircraft participating in Operation IceBridge spotted a lengthy crack cutting across the massive sheet of floating ice. There wasn’t much room for many details in the release, so here’s a longer description of the upcoming expedition from Goddard’s cryosphere writer, María José Viñas, for polar science aficionados.


An international team of researchers will helicopter onto thePine Island Glacier ice shelf, one of Antarctica’s most active, remote andharsh spots, in mid-December — weather permitting. Their objective: to determinehow changes in the waters circulating under the fast-melting ice sheet arecausing the glacier to accelerate and drain into the sea.

If all goes to plan,the multidisciplinary group of 13 scientists, led by NASA’s emeritusglaciologist Robert Bindschadler and funded by the National Science Foundation(NSF) and NASA, will depart from McMurdo stationin mid-December and spend six weeks on the ice shelf. The team will use acombination of traditional tools and sophisticated new oceanographicinstruments to measure the ocean cavity shape underneath the ice shelf. Theyaim to determine how streams of warm water enter this cavity, move toward thevery bottom of the glacier and melt its underbelly, making it dump more than 19cubic miles of ice into the ocean each year.

“The project aims to determine the underlying causesbehind why Pine Island Glacier has begun to flow more rapidly and dischargemore ice into the ocean,” saidScott Borg, director of NSF’s Division of Antarctic Sciences, the group thatcoordinates all U.S. research in Antarctica on the southernmost continent and surrounding oceans.”This could have a significant impact on global sea-level rise over thecoming century.”


“Darn hard to get to”

Pine Island Glacier has long been on the radar screen of Antarcticresearchers.

“Once satellite measurementsof Antarctica started to accumulate and we began to see which places werechanging, this area lit up as a spot where there was a large change going on,”Bindschadler said.

Bindschadler was the first person to ever set foot on thisisolated, wind-stricken corner of the world in January 2008. Previously,scientists doubted it was even possible to reach the crevasse-ridden ice shelf.But Bindschadler used satellite imagery to identify an area where planes couldland safely.

“The reason we haven’t gone therebefore is that it’s so darn hard to get to,” Bindschadler said. “So provingthat landing was doable was a relief.”

The glaciologist’s joydidn’t last: the ground proved to be too hard for the planes transporting theinstruments to land repeatedly. Logistics experts determined they would have touse helicopters to transport scientists and instrumentation in and out the iceshelf, and the whole plan for field campaigns had to be redesigned around thehelicopters’ availability.

Almost four years after thisfirst landing, Bindschadler and his team will be returning to the ice shelf tostudy its innards.

Scientists have determined that it’s the interaction ofwinds, water and ice that’s driving ice loss. Gusts of increasingly stronger westerlywinds push the Antarctic Circumpolar Current’s cold surface waters away fromthe continent: then, warmer waters that normally hover at depths below thecontinental shelf rise. The lifting warm waters spill over the border of thecontinental shelf and move along the floor, all the way back to the groundingline—the spot where the glacier comes afloat— causing it to melt. The warmsalty waters and fresh glacier meltwater combine to make a lighter mixture thatrises along the underside of the ice shelf and moves back to the open ocean, meltingmore ice on its way out. But, how much more ice melts?  Bindschadler and his team need to findout to improve projections of how the glacier will melt and contribute to sealevel rise.

“All existing data (satellite images, variability of winds,submarine measurements) say this a highly variable system”, said Bindschadler.“But they’re all snapshots in time. Our team will be deploying instrumentationthat will get a longer record of the variability.”

Profiling oceanwaters
One of the first tasks for the teamwill be using a hot water drill to make a 500-meter deep hole through the iceshelf. Once the drill hits the ocean, the scientists will send a camera to peerinto the ocean cavity, observe the underbelly of the ice shelf and analyze theseabed lying 500 meters below the ice.

Then, they will lower a setof instruments that Tim Stanton, an oceanographer with the Naval PostgraduateSchool, has built. The primary instrument in the package is
an ocean profiler, which will move up and down avertical cable that connects it to a communication instrument package on thesurface of the ice shelf. As it moves, the profiler will measure temperature,salinity and currents from 3 meters below the ice to just above theseabed. It can also be instructed to park at specific depths and gauge waterturbulence and vertical transport of heat and salt along the water column. Thedevice will send all data to the surface tower that will then transmit it toStanton’s laboratory via a satellite phone.

The profiler is controlled remotely, and Stanton can vary its sampling rate.I
t will initially do fast sampling,to observe daily changes in water properties and circulation withinthe ocean cavity.

“After about a month of fast sampling, we’ll make it reduce the numberof profiles it takes each day, to capture seasonal changes in water propertiesand circulation,” Stanton said. “If it survives its first year, we’ll switch tosuper slow sampling, to measure how much heat is coming into the cavity everyyear.”

A second holewill support another instrument array similar to the profiler but fixed toa pole stuck to the underside of the ice shelf. The fixed-depth flux packagewill make measurements very close to the interface where ice and water exchangeheat.

Another gadget connected tothe fixed-depth package will be a string of 16 small temperaturesensors deployed within the lowermost ice to freeze in and become part of theice shelf. Their mission: to measure the vertical temperature profile,data that can tell scientists how fast heat is transmitted upwards through theice whenever hot flushes of water enter the ocean cavity.

“Since the temperature of the ice shelf determines its strength, we hypothesizethat strength may decrease as warmmelting events occur within the ocean cavity,” Stanton said.
 
Stanton plans on deploying up to two sets of instruments during this fieldseason, and a third one next year. “If we get one in, I’ll be happy. If I get two, I’ll be extraordinarily happy,”he said. One of the biggest challenges in building his pack of instruments,Stanton said, was designing it to fit the hole in the ice shelf, only 20centimeters wide and 500 meters long. A tight, long hole also means that theteam will only get one shot at deploying the instruments: once the package islowered into the ocean cavity, it cannot be pulled out.

 
“I have been deploying instruments intoice floes in the Arctic for the last 10 years, so I got quite used tojust putting them in and turning on my heels and walking away. But it’s stillquite hard to do,” Stanton said.

Explosions and sledgehammers
A geophysicist with Penn StateUniversity,
Sridhar Anandakrishnan, will create tiny earthquakes to studythe shape of the ocean cavity and the properties of the bedrock under the PIGice shelf. He will be doing measurements in about three-dozen spots in theglacier, using helicopters to hop from oneplace to another.
Anandakrishnan’s technique, formally called reflectionseismology, involves generating waves of energy by setting up small explosionsor by using instruments similar to sledgehammers to bang the ice. He’ll recordhow long it takes for the waves to travelthrough ice and water, bounce off the seabed and return, and he’ll analyze thestrength of the echo. Both factors will tell him about the thickness of the iceand water.

“[The technique] is identicalto the way bats and dolphins do echolocation: they send out a sound and listento the echo – both the time and direction of the echo tell them about thedistance to their prey,” he said.

Anandakrishnan also wants tostudy the properties of the bedrock beneath the ice.

“When glaciers are slidingover the bedrock, they do it very differently depending on whether it is roughor smooth,” he said.

Finally, the geophysicistwill inspect a mysterious ridge that runs across the ocean cavity under the icesheet. This ridge was unknown to researchers when they designed their projectin the early 2000s; it wasn’t until 2009 that an unmanned submarine operated bythe British Antarctic Survey detected it. Its existence has made the scientistsrethink where they will place their oceanographic instruments under the iceshelf, so that they don’t hit the ridge while the glacier advances toward thesea.

“ThePine Island Glacier ice shelf continues to be the place where the action istaking place in Antarctica,” Bindschadler said. “It only can beunderstood by making direct measurements, which is hard to do. We’re doing thishard science because it has to be done. The question of how and why it ismelting is even more urgent than it was when we first proposed the project overfive years ago.”

Text by Maria-José Viñas. Pine Island Glacier ice tongue image originally published on the Pine Ice Glacier Ice Shelf page. Image of Bob Bindschadler on the ice shelf originally published here. Ocean profiler image originally published on the Pine Island Oceanography Program website. Image of Sridhar Anandakrishnan originally posted by the National Science Foundation.

What On Earth (Sound) Was That #4? Seismic Music From Earth, Of Course…

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Last week, we posted our first mystery sound in our latest installment of “What on Earth is That?”> We had some interesting guesses; one reader guessed the noisemaker was an earthquake and another guessed it was a calving ice. The answer is somewhere in the middle.

Giant icebergs may sink ships, but they also have their weaknesses. The sound you heard is the seismic signal recorded in October 2005 when a monstrous iceberg drifting off the coast of Antarctica’s Cape Adare crashed into the previously unknown Davey Shoal and broke apart. (Science News covered the collision in this July article.)  The full length of the audio file, sped up by a factor of 100, can be heard below. Within just 90 seconds, you can experience the full 2.5-hour event.

The “tap, tap, tap” is from cracks propagating through the massive chunk of ice. The effect is similar to what you hear if you drop ice cubes into a glass of water. The cracking noise crescendos until about 1:15, followed by a subtle hum resembling a muffled chain saw. That noise, from the phenomenon of ice pieces rubbing against each other, becomes most noticeable after the breakup. The same saw-like noise heard prior to 1:15 is thought to be the bottom of the berg rubbing on the shoal.

The audio comes from a study published June 18 in Journal of Geophysical Research. Looking at images from the Moderate Resolution Imaging Spectroradiometer on NASA’s Terra and Aqua satellites, the team noticed that between 1989 and 2005, at least three large bergs drifting off Cape Adare had suddenly stopped and broke apart. To discover the cause behind the bergs’ unusual behavior, the team turned to an iceberg called B15A.

Fortunately, plenty of information about the behemoth berg, which measured about 820 feet vertically and spanned some 75 miles by 19 miles, was available. Before the breakup, scientists had deployed an instrument package on B15A that included GPS and a seismometer. Later, a separate research group mapped the seafloor topography within the same area. “We knew from breakup that there ought to be something there,” said Seelye Martin, of University of Washington in Seattle, who led the study.

Overlaying the satellite images on the seafloor map, researchers recreated the series of events. On October 28, the berg hit the top of an underwater shoal 5.6 miles long and 705 feet below the surface at its highest point. The seismic information, heard in this post, matched the collision observed in the satellite imagery. Listening to the seismic music of the Earth is not new; geologists have long listened to the “rock music” of seismic waves from earthquakes. “But the iceberg has a very different signature,” Martin said. “Earthquakes sound like a big boom or slip, while in this case you can actually hear something breaking up.”

So what does it all mean? “It’s an interesting result, but it’s not a world changer,” Martin said. “We now know a little more about the obstacles — and sound — of some ill-fated icebergs leaving the Ross Sea.”

— Kathryn Hansen, NASA’s Earth Science News Team

Images and sound are courtesy of Seelye Martin, University of Washington

Up Close with Ice Bridge

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NASA and partners are nearing the end of the 2009 Antarctic campaign of Operation Ice Bridge — a multi-year airborne survey to study Earth’s polar ice sheets, ice shelves and sea ice. Data collected from the DC-8 aircraft will help scientists monitor changes in West Antarctica and bridge the gap between the ICESat and ICESat-2 satellites. Also, the close-up look — not possible from satellites — will help scientists learn more about the region’s ice dynamics.

Ice Bridge scientist Seeyle Martin.  Credit: NASA

The detailed look with lasers and radar, sometimes from just 1,000 feet above the ice, is now returning a wealth of scientific information about the ice surface and what’s below. And to the human eye, the low-altitude view shows West Antarctica’s intricacies: the vast expanse of white giving way to deep crevasses and volcanoes, and sea ice resembling pancakes and oil slicks.

The 2009 Operation Ice Bridge campaign concludes no later than Nov. 21. Want to follow the remainder of the flights? Here’s how to connect:

  • Webisodes – Watch this series of YouTube videos for a behind-the-scenes look at Ice Bridge mission planning and flights in Antarctica.

  • Image gallery – Curious what pancake ice looks like or want to take a peek inside the DC-8? Check out the image gallery for photos added throughout the mission

  • Blog – Read about the campaign straight from the scientists and public affairs officers on site.

  • Twitter – Be among the first to know if a flight took off or if it was grounded due to weather, and discover the target of most flights — glacier, ice sheet or sea ice?

–Kathryn Hansen, NASA’s Earth Science News Team

An Award-Winning Scientist Who Came in from the Cold

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NASA-funded researcher Ben Smith digs a snow pit at a West Antarctic Ice Sheet Divide core
site to try to infer the annual rate of snowfall. Credit: Ben Smith

Researchers who study glaciers and polar dynamics often get into it for the love of the field work — the challenging terrain, technicological adventures, and thigh-deep snow.

Benjamin Smith, a researcher at the Polar Science Center at the University of Washington’s Applied Physics Laboratory, was no exception. As a fledgling physicist in the 1990s, his first summer job after college turned into an eye-opening adventure — a 3-month stint at the Kamb Ice Stream in Antarctica as a field assistant mapping buried crevasses with snow-penetrating radar. The rest, as they say, was history.

These days, Smith is enjoying a rare honor as one of two NASA-supported researchers to receive the Presidential Early Career Award for Scientists and Engineers (PECASE), awarded at a White House ceremony last month.

WhatOnEarth: Field work was your entry into studying glaciers. Are you involved  in Arctic or Antarctic field work now?

Smith: After a few years of field work, I discovered that though being out in cold is great, the quicker way to learn about glacier change is by doing remote sensing work. That requires a great deal of data analysis indoors. So with that notion, I got onboard as part of NASA’s ICESat I mission while working on my doctorate in physics.

WhatOnEarth: What work do you believe was the basis for your presidential award?

Smith: Well, I have a few projects that I’ve been fortunate enough to be involved in.

Not too long ago, I wrote a paper where we found that several lakes beneath the glaciers in Antarctica have gained or lost water in the last five years, and at a rate much faster than things usually happen in Antarctica. We’ve been seeing lakes that fill or drain in half a year. In one case, 3 cubic kilometers of water drained last year from one of these lakes. That’s about the size of Lake Washington in Seattle.

My main objective in all of this is to figure out where that water went and how it has affected other subglacial lakes and glaciers downstream. Have those glaciers sped up from the water flowing under them? The warmth of the surface bed beneath glaciers allows them to slide faster. If you add more water, there’s potential for glaciers to slide faster. 

I’m also part of a team that is helping to design the ICESat II satellite – a project we hope will build on the success of ICESat I. The satellite will boast several laser beams rather than one, so it’ll provide much better spatial coverage of the Earth’s surface to measure glacier mass and area.

 
President Obama honored PECASE awardees, including Ben Smith and Josh Willis, in January at the White House.
Credit: The White House


WhatOnEarth: Were you aware that you’d been nominated for the PECASE award?

Smith: No. I was completely unaware of it until I was notified by the FBI about a background check! I can tell you I was relieved when I found out the background check regarded my visit to the White House. I understand now that my nomination was put forward by colleagues at NASA. Somehow, my nomination came out on top of the pile, and that’s pretty cool.

To read a few of Ben Smith’s ICESat-related scientific papers, click the topics below.

Ice stream elevation changes observed by ICESat

Increased flow speed on an East Antarctic glacier

An inventory of subglacial lakes detected by ICESat

Gretchen Cook-Anderson, NASA’s Earth Science News Team