Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Arctic and Antarctic Sea Ice Marching to Different Drivers

11.11.2003


Average Arctic Sea Ice Extent in September, 1973 to 1976

These figures show averages of Arctic sea ice extent for four Septembers, from 1973 to 1976. Credit: Don Cavalieri, NASA GSFC


Average Arctic Sea Ice Extent in September, 1999 to 2002



These figures show averages of Arctic sea ice extent for four Septembers, from 1999 to 2002. Credit: Don Cavalieri, NASA GSFC


A 30-year satellite record of sea ice in the two polar regions reveals that while the Northern Hemisphere Arctic ice has melted, Southern Hemisphere Antarctic ice has actually increased in more recent years. However, due to dramatic losses of Antarctic sea ice between 1973 and 1977, sea ice in both hemispheres has shrunk on average when examined over the 30-year time frame.

This study presents the longest continuous record of sea ice for both hemispheres based primarily on satellites, and the longer reading already begins to highlight some new information about sea ice trends over time, like the fact that more recently the Arctic has been losing ice at a faster rate.

"If you compare the rate of loss in the Arctic for the last two decades, it is 20 percent greater than the rate of loss over the last three decades," said Don Cavalieri, lead author of the study, and a senior researcher at NASA’s Goddard Space Flight Center. The study appeared in a recent issue of Geophysical Research Letters.



Over 30 years, from 1972 to 2002, the Arctic sea ice cover decreased per decade by roughly the size of the state of Arizona, some 300,000 square kilometers (almost 116,000 square miles) per decade. However, between 1979 and 2002 the sea ice area shrunk by the greater rate of 360,000 square kilometers (139,000 square miles) per decade.

The greater rate of sea ice loss in the Arctic may be due to a general warming trend in the Arctic as well as the influence of long-term oscillations or other changes in atmospheric pressure systems, which could pull in more warm air from the south.

In contrast, there was a dramatic loss of Antarctic sea ice cover from 1973 to 1977, and since then the ice has gradually spread in area.

"The increase has been slow enough that it does not totally wipe out the earlier decreases," said Claire Parkinson, senior researcher at NASA’s Goddard Space Flight Center, and a co-author of the paper. Another co-author is Konstantin Y. Vinnikov, of the department of meteorology at the University of Maryland, College Park.

Overall, from 1972 to 2002, the Antarctic ice declined on average by 150,000 square kilometers per decade (almost 58,000 square miles).

In the Antarctic, the gradual advance of ice from the late 1970s may be related to long-term atmospheric oscillations in the Southern Hemisphere resulting in stronger westerly winds and cooler temperatures.

"Trying to explain why these things happen becomes tricky," said Parkinson. "The temperature connection where warmer temperatures lead to greater melt is reasonably direct, but far from the complete story. Winds and waves move ice around, and consequently the ice can move to places where it is warm enough that it wouldn’t have formed."

While the study represents the longest continuous record comparing the two polar regions, there was a major gap in the satellite sea ice data between early 1977 and late 1978. This gap was filled by maps of sea ice created from ship and other reports in polar areas and conveyed to the National Ice Center.

The study uses satellite data from NASA’s Nimbus 5 Electrically Scanning Microwave Radiometer (ESMR), NASA’s Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR), and the Defense Meteorological Satellite Program Special Sensor Microwave Imagers (SSMIs). The Nimbus 5 ESMR data covered from December 1972 to March 1977, with the Nimbus 7 SMMR combined with the Defense Program’s SSMIs picking up data from October 1978 to December 2002. For the year and a half in between 1977 and 1978, the researchers used data and maps from the National Ice Center.

"The National Ice Center all along created operational maps of sea ice cover to help ships in the region trying to navigate around or through the ice," Parkinson said. These maps, while not as comprehensive as satellite data, had to be created every week, using the best data available at the time. The researchers figured it was the most accurate data to bridge the gap between the satellite records.

Previously, NASA scientists had blended the SMMR and SSMI data sets together to generate a 20-year time series of sea ice extents from 1979 to 1998.

By having a 30 year record, the researchers have a much longer baseline to see the trends in both the Arctic and the Antarctic, and they can see seemingly unusual events like the rapid loss of ice in Antarctica in the mid-70s.

"It seems the two regions are responding to different hemispheric variations," said Cavalieri. "What remains is to sift out and understand how these variations are driving the sea ice in each hemisphere."

Contact: Krishna Ramanujan
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 607/273-2561)


Krishna Ramanujan | GSFC
Further information:
http://www.gsfc.nasa.gov/feature/2003/1105ice.html

More articles from Earth Sciences:

nachricht Better model of water under extreme conditions could aid understanding of Earth's mantle
21.06.2018 | University of Chicago

nachricht The Janus head of the South Asian monsoon
21.06.2018 | Max-Planck-Institut für Chemie

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Better model of water under extreme conditions could aid understanding of Earth's mantle

21.06.2018 | Earth Sciences

What are the effects of coral reef marine protected areas?

21.06.2018 | Life Sciences

The Janus head of the South Asian monsoon

21.06.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>