Global Change Master Directory (GCMD)
Encyclopedia
The Global Change Master Directory is a directory of Earth Science data sets and related tools/services, many of which are targeted for the use, analysis, and display of the data. The directory holds more than 23,000 data set descriptions, known as DIFs (Directory Interchange Format). This format is compatible with the Federal Geographic Data Committee's (FGDC) standard and the international ISO 19115 standard. More than 2,300 descriptions of tools and services, known as SERFs (Services Entry Resource Format), are also available to users. The purpose of the directory is to provide users with information on the availability of data and services that will meet their needs, along with efficient access to those data and services. Links are provided, when available, to connect directly to the data or services of interest.
The directory is part of NASAs Earth Observing System Data and Information System (EOSDIS
) and also serves as NASA's contribution to the Committee on Earth Observation Satellites (CEOS), through which it is also known as the International Directory Network (IDN). The international participants contribute descriptions of data and services that are held around the world and have provided valuable guidance in the development and direction of the project over the years.
The directory also offers an online metadata
authoring tools for those wishing to share knowledge of available data. One of the cornerstones to effective searches within the directory is twelve sets of controlled keywords that assist in normalizing the search. The development of these keywords was initiated over a decade ago. Currently, over 7,000 keywords are controlled, with new sets created for better search refinements, as time permits. The keyword sets are widely used throughout the world and are being translated into many languages. Within the GCMD and the IDN, these controlled keywords can be used in combination with a full-text search engine and also for search refinements.
In addition, virtual subsets of the directory can be created as "portals" for groups wishing to identify their contributions or for those wishing to select a subset for their special interest group. The directory currently receives approximately 5 million hits per month.
The directory is part of NASAs Earth Observing System Data and Information System (EOSDIS
EOSDIS
The is a key core capability in NASA’s Earth Science Data Systems Program. It provides end-to-end capabilities for managing NASA’s Earth science data from various sources – satellites, aircraft, field measurements, and various other programs...
) and also serves as NASA's contribution to the Committee on Earth Observation Satellites (CEOS), through which it is also known as the International Directory Network (IDN). The international participants contribute descriptions of data and services that are held around the world and have provided valuable guidance in the development and direction of the project over the years.
The directory also offers an online metadata
Metadata
The term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...
authoring tools for those wishing to share knowledge of available data. One of the cornerstones to effective searches within the directory is twelve sets of controlled keywords that assist in normalizing the search. The development of these keywords was initiated over a decade ago. Currently, over 7,000 keywords are controlled, with new sets created for better search refinements, as time permits. The keyword sets are widely used throughout the world and are being translated into many languages. Within the GCMD and the IDN, these controlled keywords can be used in combination with a full-text search engine and also for search refinements.
In addition, virtual subsets of the directory can be created as "portals" for groups wishing to identify their contributions or for those wishing to select a subset for their special interest group. The directory currently receives approximately 5 million hits per month.
See also
- Climate changeClimate changeClimate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
- OPeNDAPOPeNDAPOPeNDAP, an acronym for "Open-source Project for a Network Data Access Protocol", is a data transport architecture and protocol widely used by earth scientists. The protocol is based on HTTP and the current specification is . OPeNDAP includes standards for encapsulating structured data, annotating...
- OzoneOzoneOzone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...
- SunspotSunspotSunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection by an effect comparable to the eddy current brake, forming areas of reduced surface temperature....
- Geospatial metadataGeospatial metadataGeospatial metadata is a type of metadata that is applicable to objects that have an explicit or implicit geographic extent, in other words, are associated with some position on the surface of the Globe...
- Solar variationSolar variationSolar variation is the change in the amount of radiation emitted by the Sun and in its spectral distribution over years to millennia. These variations have periodic components, the main one being the approximately 11-year solar cycle . The changes also have aperiodic fluctuations...
- IDNIDNIDN can refer to:* Internationalized domain names* Institut Industriel du Nord, the former name of École Centrale de Lille* Indonesia, the ISO 3-letter country code* International Data Number, in the context of an X.121 address* Identity driven networking...