Global gridded inventories of anthropogenic emissions of sulfur and nitrogen

Two sets of global inventories of anthropogenic emissions of both oxides of sulfur and oxides of nitrogen for circa 1985 have been produced under the umbrella of the Global Emissions Inventory Activity (GEIA) of the International Global Atmospheric Chemistry Program. The two sets of inventories have different temporal, sectoral, and vertical resolution. Both were compiled using the same data sets; default data sets of global emissions have been refined via the use of more detailed regional data sets. This article reports on the compilation of the annual, one-vertical-level inventories, called version 1A; the inventory files are available to the scientific community via anonymous file transform protocol (FTP). Existing global inventories and regional inventories have been updated and combined on a 1 degrees x 1 degrees longitude/latitude grid. The resulting global anthropogenic emissions are 65 Tg S yr(-1) and 21 Tg N yr(-1); qualitative uncertainty estimates have been assigned on a regional basis. Emissions of both SOx and NOx are strongly localized in the highly populated and industrialized areas of eastern North America and across Europe; other smaller regions of large emissions are associated with densely populated areas with developed industries or in connection with exploitation of fuels or mineral reserves. The molar ratio of nitrogen to sulfur emissions reflects the overall character of sources; its value is generally between 0.33 and 10 for industrialized and heavily populated areas but varies over a wide range for other areas. We suggest that those requiring sulfur or nitrogen emission inventories standardize on the GEIA inventories, which we believe are authoritative and which are freely available to all users by anonymous FTP.