The GCMD Keywords are a hierarchical set of controlled Earth Science vocabularies that help ensure Earth science data and services are described in a consistent and comprehensive manner and allow for the precise searching of collection-level metadata and subsequent retrieval of data and services. Initiated over twenty years ago, the GCMD Keywords continue to be refined and expanded in response to user needs. The sets of GCMD Keywords are as follows.
Global Change Master Directory (GCMD). 2016. GCMD Keywords, Version 8.4. Greenbelt, MD: Global Change Data Center, Science and Exploration Directorate, Goddard Space Flight Center (GSFC) National Aeronautics and Space Administration (NASA). URL (GCMD Keyword Forum Page): http://earthdata.nasa.gov/gcmd-forum