The NASA Global Change Master (GCMD), http://globalchange.nasa.gov, is a service designed to assist scientists in locating Earth Science data and data-related services. The GCMD provides over 11,000 data set descriptions and 300 services descriptions (metadata). A recent enhancement to the GCMD that links the metadata describing data to the data-related services metadata and vice versa has permitted the GCMD to become an even more useful service. Overall, the GCMD provides metadata describing atmospheric, oceanographic, geologic, geographic, ecologic, and socioeconomic data holdings from around the world.

Data from two recent satellite launches will provide additional data products important in enhancing our understanding of the interaction among the Earth's atmosphere, oceans, and land surface. These two satellites, Terra (launched in December of 1999) and Aqua (launched in May of 2002) carry 9 important instruments and are part of a series of spaceborne platforms central to NASA's Earth Science Enterprise program. Currently, the GCMD's metadata collection holds 309 entries describing Terra data and 33 descriptions for Aqua. These numbers will continue to grow as more data become available.

Because these missions will produce a large amount of data, it is crucial that a comprehensive and searchable metadata database is provided for scientists to locate data and the services required to handle data. NASA's Global Change Master Directory provides this service with its metadata search interfaces. Furthermore, the GCMD's portal technology makes available a search interface customized to show only the metadata associated with a certain project, data center, platform, or sensor. Terra and Aqua data are accessible through the Earth Science Information Partners (ESIP) portal, which focuses on ESIP related data sets featuring the data offered by NASA's Earth Observing System (EOS) program. The GCMD's search interfaces and portals will be presented with a focus on the GCMD's role in assisting scientists and the public in locating Terra and Aqua related products. The usefulness of linking data to a related service will also be demonstrated with Terra and Aqua data as the example.