Sea Ice Research Group

5-Year Trend in Arctic Sea Ice Freeboard from ICESat: 2003 - 2008

Change in Arctic Sea Ice Freeboard from ICESAT: March 2003 - March 2008

 

Sea ice is an important indicator of climate change, and a key component of the polar climate system. Areal shrinkage of Arctic sea ice has been observed over the last 30 years [Comiso et al., 2008], and its decline is now proceeding faster than forecasted [Stroeve et al., 2007]. A record minimum ice extent was reached in September 2007 [Stroeve et al., 2008]. However, direct observations of sea ice thinning have been mostly limited to sparse submarine measurements of ice draft [Rothrock et al., 1999]. Satellite monitoring now offers dense, near-total coverage of the ice pack and provides observations of sea ice thinning on basin scales.

The main goal is to precisely determine changes in sea ice volume and the nature of such changes. The specific objective of this sea ice research is improved remote sensing techniques for monitoring sea ice thickness. Laser and radar altimeters, on board the NASA and ESA satellites ICESat and Envisat, provide synoptic measurements of Arctic sea ice freeboard, a proxy for ice thickness. A critical step in exploiting satellite altimeter data for the effective monitoring of sea ice thickness is validation of these measurements. We validate satellite data by making comparisons with "ground-truth" observations from low altitude aircraft under-flights and in-situ measurements collected on the sea ice itself.

The latest ICESat measurements of sea ice freeboard can be seen on the right.