Sea ice is frozen seawater floating on the surface of the ocean. Some sea ice is permanent, persisting from year to year, and some is seasonal, melting and refreezing from season to season. Sea ice is almost always in motion, reacting to ocean currents and to winds. The AMSR-E instrument on the Aqua satellite acquires high resolution measurements of the 89 GHz brightness temperature near the poles. Because this is a passive microwave sensor and independent of atmospheric effects, this sensor is able to observe the entire polar region every day, even through clouds and snowfalls . This animation of AMSR-E 89 GHz brightness temperature in the northern hemisphere during late 2002 and early 2003 clearly shows the dynamic motion of the ice as well as its seasonal expansion and contraction.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 18.104.22.168.0