Alaska Satellite Facility - Distributed Active Archive Center

Sea Ice MEaSUREs – About

Sea Ice: Central Player in a Dynamic System

Sea ice is the central player in a dynamic system that affects the planet’s oceans and climate. Sea ice is also a force to be reckoned with as polar waters open to human activity, such as shipping that is already taking place through the Northern Route along the coast of Russia and is potentially slated for the fabled Northwest Passage along the coast of Canada. Sea-ice motion, revealed in the data available here, is a critical factor in the thinning and melting of Arctic sea ice as it forms, raftsridges, and opens into leads and polynyas — and as winds and currents move it through and out of the Arctic.

Sea Ice Moves: Radar helps reveal the global effects of sea-ice motion.

Sea Ice in the Bering Strait: See an animation of synthetic aperture radar (SAR) images of the Bering Strait from 2007 and 2008.

Dramatic changes: Though the extent of sea ice fluctuates, overall it is shrinking and substantially thinner than in past decades, and in spring and summer it is retreating earlier and faster. The melting, along with the absorption of solar energy by newly exposed, darker water, alters the circulations of oceans and the atmosphere, affecting climate and weather globally.

Observable through remote sensing: Remote sensing has been central to observing and researching changes in sea ice. Synthetic aperture radar (SAR), used to create the majority of the imagery available in the ASF archive, is among the power tools of remote sensing and has been used extensively in the science of sea ice. SAR bounces a microwave radar signal off the Earth’s surface, including water and ice, to detect physical properties. Unlike optical technology, SAR can “see” through darkness, clouds, and rain.

Critical for seafood: Sea ice also plays a substantial role in feeding the world. The ice serves as a farm for tiny organisms that drive the entire ecosystem. Seasonal sea ice in the Bering Sea is an integral part of an international fishery that provides more than half of the U.S. seafood catch. In addition, sea ice provides wildlife nurseries, molting sites, dens, hiding places, feeding grounds, resting platforms, and even transportation for Pacific walruses that migrate by riding on melting ice floes.

Sea-ice data, images, and data products available through the Alaska Satellite Facility (ASF) are supported under NASA’s Making Earth System data records for Use in Research Environments (MEaSUREs) program.


Sea-ice imagery and data products are supported under NASA’s Making Earth System data records for Use in Research Environments (MEaSUREs) program. These data have been used in a variety of applications.

Arctic and Southern Ocean imagery, data, and data products available at no cost to approved users from the Alaska Satellite Facility (ASF) DAAC data pool include:

  • More than 11 years of RADARSAT-1, nearly uninterrupted, three-day radar snapshots of Arctic and Southern Ocean sea ice.
  • Original synthetic aperture radar (SAR) images.

RADARSAT-1 data have been processed to:

  • Construct a near decadal record of small-scale ice motion of the Arctic and Southern Oceans.
  • Produce a record of ice motion of the northern Bering Sea.
  • Assemble monthly high-resolution image mosaics of the Arctic Ocean.

These datasets are available from the ASF DAAC and NASA’s Jet Propulsion Laboratory (JPL) through the project’s principal investigator, Ron Kwok. The original RADARSAT-1 images used to generate the products are available for download at no cost from the Alaska Satellite Facility datapool. Through ASF’s datapool, products such as SeasatRADARSAT-1ERS-1ERS-2JERS, and PALSAR sea ice images are offered at no cost to approved users. To become an approved user, please submit the required Research Agreement. Additional sea ice data is offered through Polar Year 07-08, a part of the Global Inter-agency International Polar-Snapshot Year (GIIPSY), which contains satellite snapshots of polar regions.

MEaSUREs supports the NASA Earth-science research community in providing Earth science data products and services driven by NASA’s Earth-science goals. MEaSUREs projects focus on the creation of Earth System Data Records (ESDRs), including Climate Data Records. An ESDR is a unified and coherent set of observations of a given parameter of the Earth system that is optimized to meet specific requirements in addressing science questions.

These records are critical to understanding Earth system processes; assessing variability, long-term trends, and change in the Earth system; and providing input and validation means for modeling efforts.