Metadata Standards and ConventionsThese metadata formats have been approved by the NASA Earth Science Division (ESD) for use in Earth science data systems. The full list of NASA ESD approved standards and technical notes, as well as information on the standards submission and approval process, is available on the Standards Process Group (SPG) page.
NASA ESD-approved Metadata FormatsThe role of metadata elements vary based on their scope. The following terms are frequently used to categorize metadata by scope: Collection or aggregate metadata – These are metadata elements that describe an entire set of data products or files. Values of collection metadata apply to all of the products in a specific collection. Collections may represent the same release of any given data product, sets of data generated during an experiment, a campaign or an algorithmic test. Granule or product metadata – These are metadata elements that describe a single instance of a data product. Values of granule metadata apply to all of the data in that one granule. Typical metadata in this category describe spatial and temporal extent of the data as well as the quality and lineage of the data. Local or parameter metadata – These are metadata elements that describe a specific component of the data product. Values of local metadata apply specifically to the component with which they are associated. These elements often specify units of measure, the range of data within the array, the dimension sizes and identifying names for each dimension. GCMD DIFNASA ESD-approved Standard NASA ESD Technical Note The NASA Global Change Master Directory (GCMD) is an on-line system with information about Earth Science Data sets, and is intended for the use in the research science community. The GCMD offers descriptions of Earth Science Data sets (metadata) using a defined set of fields known as the Directory Interchange Format (DIF). The DIF has been endorsed by NASA’s Earth Science Data Systems Working Groups (ESDSWG) as a recommended standard. ECHONASA ESD Note The EOS Clearinghouse (ECHO) is a spatial and temporal metadata registry that enables the science community to more easily use and exchange NASA’s data and services. ECHO stores metadata from a variety of science disciplines and domains held at 12 EOSDIS data centers. ECHO provides a single point of discovery, understanding and access for users, eliminating their need to have knowledge of location and type of data. ECHO metadata are specifically designed for use in ECHO. NetCDF-CFNASA ESD-approved Standard NetCDF (network Common Data Form), a data model for array-oriented scientific data, is a freely-distributed collection of access libraries implementing support for that data model, and a self descriptive machine-independent format. The NetCDF-CF (Climate and Forecast) conventions are a set of codified reommendations for practices built around published specifications. While CF is a convention rather than an established metadata standard, CF is a critically important step towards better interoperability. FGDC–CSDGMNASA ESD Heritage Standard The Federal Geographic Data Committee (FGDC) is an interagency committee that promotes the coordinated development, use, sharing, and dissemination of geospatial data on a national basis. The current Federal standard for geospatial data is the Content Standard for Digital Geospatial Metadata (CSDGM). The standard provides a common set of terminology and definitions for the documentation of digital geospatial data. Efforts are underway to develop and finalize a new national (ANSI) standard - The North American Profile (NAP) of ISO 19115. This profile was developed to facilitate the transition from CSDGM to ISO. The FGDC recently endorsed ISO 19115, 19115-2, and other ISO Standards, along with the NAP, as U.S. National Standards, so Federal Agencies can use the standard(s) that most closely fits their needs. NASA Earth Science Data ModelNASA ESD Heritage Standard The NASA Earth Science Data Model (ESDM) was developed for NASA’s EOSDIS Core System (ECS). ESDM supports data management and search services for the diversity of Earth Science Data available through NASA’s Data Centers. It consists of a bounded set of attributes intended to cover the essential characteristics of all Earth Science Data sets, as well as provisions for product-specific metadata. Other Metadata Catalog SystemsSome NASA Earth science data systems are using alternate catalog systems in addition to the NASA standards, in order to extend interoperability and user search options to the wider community. OGC CS/WNASA ESD Technical Note The Open Geospatial Consortium’s Catalog Service for the Web (CS/W) provides catalog services for clients to find needed data and data-related services. CS/W specifies the interfaces, bindings, and a framework for defining application profiles that are required to publish and access digital catalogues for geospatial data and services. The CS/W specification does not require the use of a specific catalog schema. However, CS/W encourages the adoption of standard schemas for maximum interoperability. Specifically, OGC developed two application profiles for CS/W: the ISO19115/19119 profile and the electronic business Registry Information Model (ebRIM) profile. THREDDS Catalog Service MetadataThe Thematic Realtime Environmental Distributed Data Services (THREDDS) metadata addresses information stored in catalogs that contain information related to THREDDS Data Server (TDS) behavior, dataset grouping, and to dataset description. Most of the information that can be included in the catalogs overlaps with various ISO metadata standards. This overlap is explored on three levels: datasets, catalog structure, and service definitions. The THREDDS catalog specification defines a small but easy-to-use set of metadata and its XML schema. |
