NASA : Rift in Antarctica's Larsen C Ice Shelf .- Grieta en la plataforma Larsen de hielo en la Antártida...

https://www.nasa.gov/image-feature/rift-in-antarcticas-larsen-c-ice-shelf

On Nov. 10, 2016, scientists on NASA's IceBridge mission photographed an oblique view of a massive rift in the Antarctic Peninsula's Larsen C ice shelf. Icebridge, an airborne survey of polar ice, completed an eighth consecutive Antarctic deployment on Nov. 18.

Ice shelves are the floating parts of ice streams and glaciers, and they buttress the grounded ice behind them; when ice shelves collapse, the ice behind accelerates toward the ocean, where it then adds to sea level rise. Larsen C neighbors a smaller ice shelf that disintegrated in 2002 after developing a rift similar to the one now growing in Larsen C.

The IceBridge scientists measured the Larsen C fracture to be about 70 miles long, more than 300 feet wide and about a third of a mile deep. The crack completely cuts through the ice shelf but it does not go all the way across it – once it does, it will produce an iceberg roughly the size of the state of Delaware.

The mission of Operation IceBridge is to collect data on changing polar land and sea ice and maintain continuity of measurements between NASA's Ice, Cloud and Land Elevation Satellite (ICESat) missions. The original ICESat mission ended in 2009, and its successor, ICESat-2, is scheduled for launch in 2018. Operation IceBridge, which began in 2009, is currently funded until 2019. The planned overlap with ICESat-2 will help scientists validate the satellite’s measurements.

More: NASA Nears Finish Line of Annual Study of Changing Antarctic Ice

Image Credit: NASA/John Sonntag

Last Updated: Dec. 2, 2016

Editor: Sarah Loff

Tags:  Earth, Ice, IceBridge, Image of the Day,

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NASA - NASA Begins New Season of Arctic Ice Science Flights

 

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The NASA P-3B sits in the hangar at Thule Air Base while the IceBridge team waits for fog to clear on the morning of Mar. 20, 2013. Credit: NASA / Michael Studinger.

Opposite Behaviors? Arctic Sea Ice Shrinks, Antarctic Grows

10.23.12

 

September 2012 witnessed two opposite records concerning sea ice. Two weeks after the Arctic Ocean's ice cap experienced an all-time summertime low for the satellite era (left), Antarctic sea ice reached a record winter maximum extent (right). But sea ice in the Arctic has melted at a much faster rate than it has expanded in the Southern Ocean, as can be seen in this image by comparing the 2012 sea ice levels with the yellow outline, which in the Arctic image represents average sea ice minimum extent from 1979 through 2010 and in the Antarctic image shows the median sea ice extent in September from 1979 to 2000. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio and NASA Earth Observatory/ Jesse Allen
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The steady and dramatic decline in the sea ice cover of the Arctic Ocean over the last three decades has become a focus of media and public attention. At the opposite end of the Earth, however, something more complex is happening.

A new NASA study shows that from 1978 to 2010 the total extent of sea ice surrounding Antarctica in the Southern Ocean grew by roughly 6,600 square miles every year, an area larger than the state of Connecticut. And previous research by the same authors indicates that this rate of increase has recently accelerated, up from an average rate of almost 4,300 square miles per year from 1978 to 2006.

"There's been an overall increase in the sea ice cover in the Antarctic, which is the opposite of what is happening in the Arctic,” said lead author Claire Parkinson, a climate scientist with NASA's Goddard Space Flight Center, Greenbelt, Md. "However, this growth rate is not nearly as large as the decrease in the Arctic.”

The Earth’s poles have very different geographies. The Arctic Ocean is surrounded by North America, Greenland and Eurasia. These large landmasses trap most of the sea ice, which builds up and retreats with each yearly freeze-and-melt cycle. But a large fraction of the older, thicker Arctic sea ice has disappeared over the last three decades. The shrinking summer ice cover has exposed dark ocean water that absorbs sunlight and warms up, leading to more ice loss.

On the opposite side of the planet, Antarctica is a continent circled by open waters that let sea ice expand during the winter but also offer less shelter during the melt season. Most of the Southern Ocean’s frozen cover grows and retreats every year, leading to little perennial sea ice in Antarctica.

Using passive-microwave data from NASA's Nimbus 7 satellite and several Department of Defense meteorological satellites, Parkinson and colleague Don Cavalieri showed that sea ice changes were not uniform around Antarctica. Most of the growth from 1978 to 2010 occurred in the Ross Sea, which gained a little under 5,300 square miles of sea ice per year, with more modest increases in the Weddell Sea and Indian Ocean. At the same time, the region of the Bellingshausen and Amundsen Seas lost an average of about 3,200 square miles of ice every year.

› View larger The ice covering the Bellingshausen Sea, off the coast of Antarctica, as seen from a NASA Operation IceBridge flight on Oct. 13, 2012. Credit: NASA/Michael Studinger

Parkinson and Cavalieri said that the mixed pattern of ice growth and ice loss around the Southern Ocean could be due to changes in atmospheric circulation. Recent research points at the depleted ozone layer over Antarctica as a possible culprit. Ozone absorbs solar energy, so a lower concentration of this molecule can lead to a cooling of the stratosphere (the layer between six and 30 miles above the Earth's surface) over Antarctica. At the same time, the temperate latitudes have been warming, and the differential in temperatures has strengthened the circumpolar winds flowing over the Ross Ice Shelf.

"Winds off the Ross Ice Shelf are getting stronger and stronger, and that causes the sea ice to be pushed off the coast, which generates areas of open water, polynyas,” said Josefino Comiso, a senior scientist at NASA Goddard. "The larger the coastal polynya, the more ice it produces, because in polynyas the water is in direct contact with the very cold winter atmosphere and rapidly freezes.” As the wind keeps blowing, the ice expands further to the north.

This year's winter Antarctic sea ice maximum extent, reached two weeks after the Arctic Ocean's ice cap experienced an all-time summertime low, was a record high for the satellite era of 7.49 million square miles, about 193,000 square miles more than its average maximum extent for the last three decades.

The Antarctic minimum extents, which are reached in the midst of the Antarctic summer, in February, have also slightly increased to 1.33 million square miles in 2012, or around 251,000 square miles more than the average minimum extent since 1979.

The numbers for the southernmost ocean, however, pale in comparison with the rates at which the Arctic has been losing sea ice – the extent of the ice cover of the Arctic Ocean in September 2012 was 1.32 million square miles below the average September extent from 1979 to 2000. The lost ice area is equivalent to roughly two Alaskas.

Parkinson said that the fact that some areas of the Southern Ocean are cooling and producing more sea ice does not disprove a warming climate.

"Climate does not change uniformly: The Earth is very large and the expectation definitely would be that there would be different changes in different regions of the world,” Parkinson said. "That's true even if overall the system is warming.” Another recent NASA study showed that Antarctic sea ice slightly thinned from 2003 to 2008, but increases in the extent of the ice balanced the loss in thickness and led to an overall volume gain.

The new research, which used laser altimetry data from the Ice, Cloud, and land Elevation Satellite (ICESat), was the first to estimate sea ice thickness for the entire Southern Ocean from space.

Records of Antarctic sea ice thickness are much patchier than those of the Arctic, due to the logistical challenges of taking regular measurements in the fierce and frigid waters around Antarctica. The field data collection is mostly limited to research icebreakers that generally only travel there during spring and summer – so the sole means to get large-scale thickness measurements is from space.

"We have a good handle of the extent of the Antarctic sea ice, but the thickness has been the missing piece to monitor the sea ice mass balance,” said Thorsten Markus, one of the authors of the study and Project Scientist for ICESat-2, a satellite mission designed to replace the now defunct ICESat. ICESat-2 is scheduled to launch in 2016. "The extent can be greater, but if the sea ice gets thinner, the volume could stay the same."

 

 

Maria-José Viñas
NASA's Earth Science News Team

NASA

Guillermo Gonzalo Sánchez Achutegui

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NASA'S Operation Icebridge Resumes Flights Over Antarctica

WASHINGTON -- Scientists and flight crew members with Operation IceBridge, NASA's airborne mission to study Earth's changing polar ice, are beginning another campaign over Antarctica. Now in its fourth year, IceBridge's return to the Antarctic comes almost a year after the discovery of a large rift in the continent's Pine Island Glacier.

The first science flight of the campaign began Friday at 8 a.m. EDT when NASA's DC-8 research aircraft left Punta Arenas, Chile, for an 11-hour flight that will take it over the Thwaites Glacier in west Antarctica. This year, IceBridge will survey previously unmeasured areas of land and sea ice and gather further data on rapidly changing areas like Pine Island Glacier. The IceBridge Antarctic campaign will operate out of Punta Arenas through mid-November.

Several of IceBridge's planned flights focus on previously unmeasured ice streams feeding into the Weddell Sea. These flights will gather data on what lies beneath these ice streams, something vital for understanding how changing conditions might affect the flow of ice into the ocean and sea-level rise.

"We have added surveys of ice streams flowing into the Ronne and Filchner ice shelves," said IceBridge project scientist Michael Studinger at NASA's Goddard Spaceflight Center in Greenbelt, Md. "This is something we haven't done before."

The large crack in Pine Island Glacier's floating ice shelf has been the focus of worldwide attention as it has grown. The ice shelf now threatens to calve, or break off, a large iceberg into Pine Island Bay in the Amundsen Sea. Researchers have been using imagery from NASA's Aqua and Terra spacecraft and synthetic aperture radar data from the German Aerospace Center's TerraSAR-X satellite to monitor the rift since its discovery last year.

IceBridge also will gather data on sea ice in the Weddell and Bellingshausen seas. Because of geographical differences, Antarctic sea ice behaves differently from ice in the Arctic and presents unique challenges.

"Sea ice in the Antarctic is a very different physical system," Goddard sea ice researcher Nathan Kurtz said.

Ocean currents, precipitation patterns and the shape of land masses are just a few of the differences. Instead of compacting ice against land like in the Arctic basin, currents in the Southern Ocean push much of it farther out to sea. Also, the Antarctic averages more snowfall, which weighs sea ice down and allows ocean water into the bottom layer of the snow on top of the sea ice. The Antarctic has more frequent strong wind events and large temperature swings than the Arctic, which causes layers of ice to form in snow cover. Both of these factors make getting accurate readings of snow on top of sea ice challenging.

Arctic sea ice extent and volume reached record lows this year, but Antarctic sea ice volume has been holding steady and the extent has been increasing. Predictive models have a hard time pinpointing what Antarctic sea ice might do under a warming global climate. Having more data to work with could make these models more useful. Further observations will give researchers more data on how Antarctic sea ice changes over time.

"This is why having observations is really important," Kurtz said. "We want to make sure these models are getting the physics right.

IceBridge will gather information on many different aspects of land and sea ice using a variety of scientific sensors onboard the DC-8. These instruments include a laser altimeter to measure surface elevation changes, various radar instruments for determining snow depth and ice thickness, a gravimeter that will gather data on the size and shape of water cavities under ice shelves, and a digital camera instrument that takes high-resolution images useful for building maps and digital elevation models of the ice.

By flying previously surveyed tracks in rapidly changing areas like Pine Island Glacier, IceBridge is building on a legacy of measurements started by NASA's ICESat satellite that will continue with the launch of ICESat-2 in 2016.

"This area is changing so rapidly we need to survey every year," Studinger said.

In addition, IceBridge will fly along tracks for the European Space Agency's ice-monitoring satellite, CryoSat-2.

This year's campaign also will see visits to IceBridge by school teachers. Two English-speaking Chilean science teachers will meet with IceBridge scientists and instrument operators this month and ride on a survey flight to learn more about polar science research with the goal of using their new knowledge to better engage and teach students.

The IceBridge project science office is based at Goddard. The DC-8 is based at NASA's Dryden Aircraft Operations Facility in Palmdale, Calif.
For more information, images and video of Operation IceBridge, visit:
http://www.nasa.gov/icebridge

For more information about ICEsat-2, visit:  

http://icesat.gsfc.nasa.gov/icesat

 Arctic Sea Ice Hits Smallest Extent In Satellite Era

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Satellite data reveal how the new record low Arctic sea ice extent, from Sept. 16, 2012, compares to the average minimum extent over the past 30 years (in yellow). Sea ice extent maps are derived from data captured by the Scanning Multichannel Microwave Radiometer aboard NASA's Nimbus-7 satellite and the Special Sensor Microwave Imager on multiple satellites from the Defense Meteorological Satellite Program. Credit: NASA/Goddard Scientific Visualization Studio

 The frozen cap of the Arctic Ocean appears to have reached its annual summertime minimum extent and broken a new record low on Sept. 16, the National Snow and Ice Data Center (NSIDC) has reported. Analysis of satellite data by NASA and the NASA-supported NSIDC at the University of Colorado in Boulder showed that the sea ice extent shrunk to 1.32 million square miles (3.41 million square kilometers).

The new record minimum measures almost 300,000 square miles less than the previous lowest extent in the satellite record, set in mid-September 2007, of 1.61 million square miles (4.17 million square kilometers). For comparison, the state of Texas measures around 268,600 square miles.

NSIDC cautioned that, although Sept. 16 seems to be the annual minimum, there's still time for winds to change and compact the ice floes, potentially reducing the sea ice extent further. NASA and NSIDC will release a complete analysis of the 2012 melt season next month, once all data for September are available.

Arctic sea ice cover naturally grows during the dark Arctic winters and retreats when the sun re-appears in the spring. But the sea ice minimum summertime extent, which is normally reached in September, has been decreasing over the last three decades as Arctic ocean and air temperatures have increased. This year's minimum extent is approximately half the size of the average extent from 1979 to 2000. This year's minimum extent also marks the first time Arctic sea ice has dipped below 4 million square kilometers.

"Climate models have predicted a retreat of the Arctic sea ice; but the actual retreat has proven to be much more rapid than the predictions," said Claire Parkinson, a climate scientist at NASA Goddard Space Flight Center, Greenbelt, Md. "There continues to be considerable inter-annual variability in the sea ice cover, but the long-term retreat is quite apparent."

The thickness of the ice cover is also in decline.

"The core of the ice cap is the perennial ice, which normally survived the summer because it was so thick", said Joey Comiso, senior scientist with NASA Goddard. "But because it's been thinning year after year, it has now become vulnerable to melt".

The disappearing older ice gets replaced in winter with thinner seasonal ice that usually melts completely in the summer.

Related Links:

› NSIDC's Arctic Sea Ice News & Analysis
› NASA Sea Ice Imagery

NASA
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The Earth : Aurora Australis over Concordia station 18 July

Hi My Friends: A VUELO DE UN QUINDE EL BLOG., A stunning image showing Aurora Australis – the Southern Lights – glowing over Concordia station in the Antarctic, one of the remotest places on Earth, on 18 July 2012. It was taken by ESA-sponsored scientist Alexander Kumar and his colleague Erick Bondoux from about 1 km from the station, located in the Antarctic at 75°S latitude.

The ethereal green glow of Aurora Australis high over Concordia station on 18 July 2012. It was taken by ESA-sponsored scientist Alexander Kumar and his colleague Erick Bondoux from about 1 km from the station, located in the Antarctic at –75°S latitude.

The French–Italian Concordia station's programme of research includes glaciology, human biology and the atmosphere. ESA uses the base to prepare for future long-duration missions beyond Earth. During the winter, Concordia is under almost total darkness, with an average temperature of –51°C and a record low of –85°C. It is an ideal place to study the effects on small, multicultural teams isolated for long periods in an extreme, hostile environment.

Auroras occur frequently over both the North and South polar regions, but are often difficult to see from populated areas. During periods of increased solar activity, the lights sometimes extend to populated latitudes. This year has seen unusually high solar activity; most recently, on 14 July, Northern Lights could be seen as far south as Duluth, Minnesota, USA. 

Credits: ESA/IPEV/ENEAA/A. Kumar & E. Bondoux

A stunning image showing Aurora Australis – the Southern Lights – glowing over Concordia station in the Antarctic, one of the remotest places on Earth, on 18 July 2012. It was taken by ESA-sponsored scientist Alexander Kumar and his colleague Erick Bondoux from about 1 km from the station, located in the Antarctic at 75°S latitude.

The French–Italian Concordia station's programme of research includes glaciology, human biology and the atmosphere. ESA uses the base to prepare for future long-duration missions beyond Earth.

During the winter, Concordia is under almost total darkness, with an average temperature of –51°C and a record low of –85°C. It is an ideal place to study the effects on small, multicultural teams isolated for long periods in an extreme, hostile environment.  

Auroras occur frequently over both the North and South polar regions, but are often difficult to see from populated areas. During periods of increased solar activity, the lights sometimes extend to populated latitudes.

This year has seen unusually high solar activity; most recently, on 14 July, Northern Lights could be seen as far south as Duluth, Minnesota, USA.
 

Solar activity remains unusually high

On 17 July, the ESA/NASA SOHO mission captured an image of a spectacular solar flare, which unfolded over a period of several hours.

 

 On 17 July 2012, the ESA/NASA SOHO mission captured an image of a spectacular solar flare, which unfolded over a period of several hours around 15:24 UTC. 

Credits: ESA/NASA

 It was an M1-class flare, and produced a coronal mass ejection that will reach the region of Venus on 19 July and may deliver a glancing blow to Earth on 20 July.
 The effects at Earth are expected to be minor, but could include some effects on satellites in orbit or interference in high-frequency radio communications. 

On 19 July 2012, the ESA/NASA SOHO mission captured an image of a solar flare, which occurred around 5:58 UTC. The CME associated with this flare seems to be directed to the west and will most likely not reach Earth. 

Credits: ESA/NASA

 And still more...

Yet another flare occurred on 19 July, when solar active region NOAA AR 1520 produced an M7.7-class flare around 05:58 GMT.

The flare generated a coronal mass ejection that is directed to the west and will most likely not reach Earth.

However, a rapid increase in proton particles has been detected, and these have some effects on satellites.
 

Tracking space weather

“It is important to monitor, track and assess space weather events such as solar flares and especially the solar energetic particle events and coronal mass ejections sometimes associated with them,” says Juha-Pekka Luntama, manager of the space weather segment in ESA’s Space Situational Awareness programme office.

“Such events are capable of affecting space-based telecommunications, broadcasting, meteorological observations and navigation through to power distribution and terrestrial communications, especially at northern latitudes.”

 ESA
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