Featured Research

from universities, journals, and other organizations

NASA uses new method to estimate Earth mass movements

Date:
September 18, 2010
Source:
NASA/Jet Propulsion Laboratory
Summary:
NASA and European researchers have conducted a novel study to simultaneously measure, for the first time, trends in how water is transported across Earth's surface and how the solid Earth responds to the retreat of glaciers following the last major Ice Age, including the shifting of Earth's center of mass.

Global present-day trends in the transport of water mass around Earth, as determined using data from GRACE, surface measurements and an ocean model. Darker areas represent greater loss of mass.
Credit: NASA-JPL/-Caltech

NASA and European researchers have conducted a novel study to simultaneously measure, for the first time, trends in how water is transported across Earth's surface and how the solid Earth responds to the retreat of glaciers following the last major Ice Age, including the shifting of Earth's center of mass.

To calculate the changes, scientists at NASA's Jet Propulsion Laboratory, Pasadena, Calif.; Delft University of Technology, Delft, Netherlands; and the Netherlands Institute for Space Research, Utrecht, Netherlands, combined gravity data from the NASA/German Aerospace Center Gravity Recovery and Climate Experiment satellites with direct measurements of global surface movements from GPS and other sources and a JPL-developed model that estimates the mass of Earth's ocean above any point on the ocean floor. Results are reported in the September issue of Nature Geoscience.

Using the new methodology, the researchers, led by Xiaoping Wu of JPL, calculated new estimates of ice loss in Greenland and Antarctica that are significantly smaller than previous estimates. According to the team's estimates, mass losses between 2002 and 2008 measured 104 (plus or minus 23) gigatonnes a year in Greenland, 101 (plus or minus 23) gigatonnes a year in Alaska/Yukon, and 64 (plus or minus 32) gigatonnes a year in West Antarctica. A gigatonne is one billion metric tons, or more than 2.2 trillion pounds. The smaller but significant ice loss estimates reflect the revised role that post-glacial rebound was found to play in relation to current ice mass loss in Greenland and Antarctica. Post-glacial rebound (known as glacial isostatic adjustment) is the response of the solid Earth to the retreat of glaciers following the last Ice Age. After the weight of ice from the land surface was removed, the land under the ice rose and continues to slowly rise.

In addition, the team found that the shift of water mass around the globe, combined with the post-glacial rebound of Earth's surface, is shifting Earth's surface relative to its center of mass by 0.88 millimeters (.035 inches) a year toward the North Pole. The estimate of the shift due to rebound-0.72 millimeters (.028 inches) per year--is believed to be the first estimate based on actual data, rather than a model prediction.

Wu said the shift of Earth's surface is due primarily to the melted Laurentide ice sheet, which blanketed most of Canada and a part of the northern United States around 21,000 years ago. "The new estimate of shift is much larger than previous model estimates of 0.48 millimeters [.019 inches] per year," said Wu. "This suggests that either Earth's lower mantle must be much more viscous than previously believed, or that the history of Earth's deglaciation needs to be significantly revised."

Wu said previous GRACE-based estimates of the movement of mass at Earth's surface have been calculated by correcting the data using a post-glacial rebound model, while estimates of post-glacial rebound itself have been estimated using a hydrological model. These models are not as precise as the geodetic data, however, and contain unknown and potentially large errors that will throw off estimates of the other process.

GRACE project scientist Michael Watkins of JPL, who was not an author on the paper, said that although some of the new results, such as those for Greenland, are surprising, they are not due to a reanalysis of GRACE or GPS data alone. Rather, they are a result of the simultaneous use of GRACE, GPS and other geodetic measurements to help objectively sort out the relative sizes of post-glacial rebound and present-day ice mass loss. "Both the GPS and gravity measurements are accurate on their own, but untangling the relative contributions of the two processes as observed by satellites is difficult. This technique provides a first global attempt at doing that," Watkins said.

"The Earth system is so complex that measuring and understanding it requires scientists to combine observations from as many satellites and ground-based measurements as possible," Watkins added. "With each new study like this one, we learn more and more about how to conduct future studies and interpret their data. The more data, and different types of data we collect, the better we'll be able to answer fundamental questions about how our planet works."


Story Source:

The above story is based on materials provided by NASA/Jet Propulsion Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

NASA/Jet Propulsion Laboratory. "NASA uses new method to estimate Earth mass movements." ScienceDaily. ScienceDaily, 18 September 2010. <www.sciencedaily.com/releases/2010/09/100916090841.htm>.
NASA/Jet Propulsion Laboratory. (2010, September 18). NASA uses new method to estimate Earth mass movements. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2010/09/100916090841.htm
NASA/Jet Propulsion Laboratory. "NASA uses new method to estimate Earth mass movements." ScienceDaily. www.sciencedaily.com/releases/2010/09/100916090841.htm (accessed July 25, 2014).

Share This




More Earth & Climate News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Bill Gates: Health, Agriculture Key to Africa's Development

Bill Gates: Health, Agriculture Key to Africa's Development

AFP (July 24, 2014) Health and agriculture development are key if African countries are to overcome poverty and grow, US software billionaire Bill Gates said Thursday, as he received an honourary degree in Ethiopia. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Higgins Breaks Record at Mt. Washington

Higgins Breaks Record at Mt. Washington

Driving Sports (July 24, 2014) Subaru Rally Team USA drivers David Higgins and Travis Pastrana face off against a global contingent of racers at the annual Mt. Washington Hillclimb in New Hampshire. Includes exclusive in-car footage from Higgins' record attempt. Video provided by Driving Sports
Powered by NewsLook.com
Storm Kills Three, Injures 20 at Virginia Campground

Storm Kills Three, Injures 20 at Virginia Campground

Reuters - US Online Video (July 24, 2014) A likely tornado tears through an eastern Virginia campground, killing three and injuring at least 20. Linda So reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins