In preparation for Operation IceBridge's Antarctica 2011 campaign, flight crews at NASA Dryden worked to outfit the DC-8 aircraft — NASA's long-haul "workhorse" — with an array of different instruments designed to measure sea ice, ice sheets, and even the bedrock below Antarctic glaciers.
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 188.8.131.52.0