NASA - NASA Administrator Tours Earth Missions Under Construction in California

NASA Administrator Charles Bolden will visit the agency's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., Tuesday, Aug. 13, to see progress on two Earth-observing missions currently undergoing preparation for launch in 2014.

Media are invited to accompany Bolden and JPL Director Charles Elachi on the tour at 1:30 p.m. PDT. Bolden will meet with the spacecraft teams, give some brief comments to media and answer questions.
Journalists who want to participate must arrange access through Elena Mejia of JPL Media Relations by 3 p.m. Monday, Aug. 12, by sending an email to elena.mejia@jpl.nasa.gov.
Media who have responded and would like to enter the clean room where the two spacecraft are located must arrive at JPL no later than 12:15 p.m. Aug. 13 to don special gear and have any recording equipment cleaned. Media entering the clean room must wear flat, close-toed shoes and long pants.
Media who do not want to enter the clean room should arrive by 12:45 p.m. to view the event from an enclosed overhead gallery, where an audio feed will be available. Contact Mejia if you have any questions regarding the technical setup and allowable equipment in the clean room.
The spacecraft Bolden will see are the Soil Moisture Active Passive (SMAP) mission, scheduled to launch in October 2014, and the International Space Station (ISS)-RapidScat instrument, which is set for launch to the orbiting laboratory in April 2014.
These missions will add to NASA’s suite of space and airborne research that contribute to scientists' understanding of weather and climate and efforts to improve life on Earth and protect our planet.
SMAP will produce global maps scientists can use to track water availability around our planet and guide policy decisions. It will improve the accuracy of short-term weather forecasts and long-term projections of climate change and provide vital early-warning information on agricultural crop yields.
ISS-RapidScat is a scatterometer that will be mounted on the exterior of the International Space Station to collect information on the speed and direction of winds near the ocean surface in Earth’s low and mid-latitudes. The instrument also will be used to calibrate other ocean winds satellites. The data it generates will help improve weather forecasts, including tracking of storms and hurricanes, and our understanding of how interactions between Earth’s ocean and atmosphere influence our climate.
JPL manages SMAP for NASA’s Science Mission Directorate in Washington. ISS-RapidScat is a joint partnership of JPL and NASA's International Space Station Program Office at the agency's Johnson Space Center in Houston, with support from the agency's Science Mission Directorate in Washington.
For more information on NASA's Earth science program, visit:

http://www.nasa.gov/earth/

 

'Like Butter': Study Explains Surprising Acceleration of Greenland's Inland Ice

Surface meltwater draining through cracks in an ice sheet can warm the sheet from the inside, softening the ice and letting it flow faster, a new NASA-funded study finds.

During the last decade, researchers have captured compelling evidence of accelerating ice flow at terminal regions, or “snouts,” of Greenland glaciers as they flow into the ocean along the western coast. Now, the new research shows that the interior regions are also flowing much faster than they were in the winter of 2000-2001, and the study authors propose a reason for the speedup.

“Through satellite observations, we determined that an inland region of the Sermeq Avannarleq Glacier, 40 to 60 miles from the coast, is flowing about 1.5 times faster than it was about a decade ago,” said Thomas Phillips, lead author of the new paper and a research associate at the time of the study with the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, Boulder.

The researchers used ice-sheet-wide velocity maps for Greenland from a NASA program called Making Earth System Data Records for Use in Research Environments. Studying the velocity maps, the researchers saw that in 2000-2001 the inland segment of the Sermeq Avannarleq Glacier was flowing at about 130 feet (40 meters) per year. In 2007-2008, that speed was closer to 200 feet (60 meters) per year.

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This animation shows how ice is naturally transported from interior topographic divides on Greenland to its coast via glaciers. The colors represent the speed of ice flow, with areas in red and purple flowing the fastest at rates of kilometers per year. The vectors indicate the direction of flow.

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“At first, we couldn’t explain this rapid interior acceleration,” Phillips said. “We knew it wasn’t related to what was going on at the glacier’s terminus. The speedup had to be due to changes within the ice itself.”

To shed light on the observed acceleration, Phillips and his team developed a new model to investigate the effects of meltwater on the ice sheet’s physical properties. The team found that percolating meltwater carries heat from the sun and warms the ice sheet, which then—like a warm stick of butter—softens, deforms and flows faster.

Previous studies estimated that it would take centuries to millennia for new climates to increase the temperature deep within ice sheets. But when the influence of meltwater is considered, warming can occur within decades and, thus, produce rapid accelerations. The paper has been accepted for publication in the Journal of Geophysical Research: Earth Surface, a journal of the American Geophysical Union.

The researchers were tipped off to this mechanism by the massive amount of meltwater they observed on the ice sheet’s surface during their summer field campaigns, and they wondered if it was affecting the ice sheet. During the last several decades, atmospheric warming above the Greenland Ice Sheet has caused an expanding area of the surface to melt during the summer, creating pools of water that gush down cracks in the ice. The meltwater eventually funnels to the interior and bed of the ice sheet.

“The sun melts ice into water at the surface, and that water then flows into the ice sheet carrying a tremendous amount of latent energy,” said William Colgan, a coauthor and adjunct research associate with the University of Colorado’s Cooperative Institute for Research in Environmental Sciences. “The latent energy then heats the ice.”

The new model shows that this speeds up ice flow in two major ways: One, the retained meltwater warms the bed of the ice sheet and preconditions it to accommodate a basal water layer, making it easier for the ice sheet to slide by lubrication. Two, warmer ice is also softer (less viscous), which makes it flow more readily.

“Basically, the gravitational force driving the ice sheet flow hasn’t changed over time, but with the ice sheet becoming warmer and softer, that same gravitational force now makes the ice flow faster,” Colgan said.

This transformation from stiff to soft only requires a little bit of extra heat from meltwater. “The model shows that a slight warming of the ice near the ice sheet bed—only a couple of degrees Celsius—is sufficient to explain the widespread acceleration,” Colgan said.

The findings have important ramifications for ice sheets and glaciers everywhere. “It could imply that ice sheets can discharge ice into the ocean far more rapidly than currently estimated,” Phillips said. “It also means that the glaciers are not finished accelerating and may continue to accelerate for a while. As the area experiencing melt expands inland, the acceleration may be observed farther inland.”

The study’s results suggest that to understand future sea-level rise, scientists need to account for a previously overlooked factor — meltwater’s latent energy — and its potential role in making glaciers and ice sheets flow faster into the world’s oceans. In 2007, the Intergovernmental Panel on Climate Change wrote that one of the most significant challenges in predicting sea-level rise was “limited” understanding of the processes controlling ice flow. The panel’s next assessment is due out in 2014.

“Traditionally, latent energy has been considered a relatively unimportant factor, but most glaciers are now receiving far more meltwater than they used to and are increasing in temperature faster than previously imagined,” Colgan said. “The chunk of butter known as the Greenland Ice Sheet may be softening a lot faster than we previously thought possible.”

The study was funded through a NASA ROSES grant, NASA’s Greenland Climate Network and the National Science Foundation. Other coauthors on the paper were CIRES Director Waleed Abdalati, who is also former chief scientist for NASA; former CIRES Director Konrad Steffen; and CU-Boulder engineering professor Harihar Rajaram.

Adapted by NASA/Maria-José Viñas Garcia

Based on press release by CIRES/Katy Human and AGU/Peter Weiss

NASA

Guillermo Gonzalo Sánchez Achutegui

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