地球科学数据的元数据研究

A STUDY ON THE METADATA OF EARTH SCIENCE DATA (GEO-METADTA)

元数据是数据库领域中一个基本的概念，地球科学数据的无数据系统的建立有助于地学数据的开发和利用，文中说明了无数据在地学数据中的应用，论述了地学元数据的分类、获取、管理等问题。

Metadata is an important concept in the field of database management, and the metadata ofearth science data which is called geo-metadata is valuable for earth-scientists to use and exploreearth science data. metadata is not a new concept, but the application of metadata of earth sciencedata is extended only by the utility of computer technology and the development of geographical in-formation system (GIS). Geo-metadata are used to prompt management and utility of earth sciencedatabase which is different from ordinary database because of its spatial characteristics. Up to now,an universally accepted definition of metadata have not been created yet, but general views about theutility, contents, characteristics, function of metadata have been universally accepted. Metadata is a concept which has relations with Data dictionary, Data Encyclopedia, Data Repository, meta-Database, and metadata information management system through which metadata can be manipulat-ed and managed. The classification system of metadata varies due to contents, utility field, andfunction of metadata. The general methods for metadata collection are key-in (through computerkeyboard), look-up tables (relates), inferring (from existing metadata or primary data), measure-ment ( by some experiments), and computation (by existing data items). The function of geo-meat-data includes: (1) to help earth science data users to get specified data easier, (2) to control dataquality, (3) to convert data formats and transform data between different projection system, and(4) to descend the cost of earth science data management. Being at its infant stage, the develop-ment of GIS and data industry is eagerly necessary in China, so the study on the standards and thenormalization of earth science data and its metadata is urgent. At the end of the paper, the authorlists the purposes for the construction of geo-metadata in China.