We are pleased with the increased interest and use of the Global Change Master Directory's (GCMD) Earth science keywords. At this time, we are requesting that the following citation be used by those individuals and groups using the GCMD keywords.

Olsen, L.M., G. Major, S. Leicester, K. Shein, J. Scialdone, H. Weir, S. Ritz, C. Solomon, M. Holland, R. Bilodeau, T. Northcutt, R. Vogel. 2004. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 4.2.2 [online: http://gcmd.nasa.gov/Resources/valids/keyword_list.html]

The GCMD Earth science parameters evolve as new metadata records are added and existing records modified to meet the changing needs of the Earth science community. These keywords were first offered to the public on April 24, 1995 as Version 1.0.0. They are organized in a hierarchy constructed of TOPICs, TERMs, and VARIABLEs. Any change at the TOPIC level (top level) requires a change in the key version number. TERM changes are indicated through the second digit, with VARIABLE level changes indicated through the third digit of the version number. A third TOPIC change was made in early 2003 when the new TOPIC, Climate Indicators, was added - bringing the current version to 4.2.2.

Please visit the GCMD keyword list.