GLOBAL GEOGRAPHICAL DATABASES FOR MODELING TRACE GAS FLUXES

The design and development of global digital databases and their integ rated use in studies of terrestrial sources and sinks of trace gases a re discussed. Generic design characteristics that expand the utility o f these databases are outlined including: hierarchical classification systems that provide for encoding and accessing data at several levels of detail, and fine spatial and thematic resolution which accommodate adaptations to a broad base of applications. The discussion follows t he sequence of (1) developing primary databases on major surface chara cteristics, (2) selectively integrating combinations of data bases to produce secondary data sets of source categories, and (3) combining in formation on source categories with fluxes to produce tertiary data se ts of emissions. These procedures are demonstrated with the example of estimating and evaluating alternative global methane emissions from n atural wetlands.