CGEIC, Annual SOx/NOx Global Emissions Inventory (GEIA Global
SOx/NOx Inventory, Version 1A)
								97/04/07

This file contains information about the Sulphur and Nitrogen data sets 
available on the CGEIC web site <http://www.ortech.ca/cgeic>. The emission
inventory described in this reference is known as the
"GEIA 1A, annual sulphur and nitrogen global emission inventory".

Version 1A gives gridded total annual emission.

This inventory is referred to as the "Global Emissions Inventory Activities
(GEIA) Version 1A, sulphur and nitrogen global inventory".
Details of the regional and national data sets used in the compilation 
of this global emissions data set are available in Benkovitz Carmen M.,
M. Trevor Scholtz, Jozef Pacyna, Leonor Tarrason, Jane Dignon, Eva C. Voldner,
Peter A. Spiro, Jennifer A. Logan and T. E. Graedel, Global gridded inventories
of anthropogenic emissions of sulphur and nitrogen, J. Geophysical Research,
101 (22), pp29,239 - 29,253, (1996). The Versions 1A (annual total) and
1B (two level, seasonal version) were prepared in parallel using exactly
the same regional and global data sets. The global totals, obtained by 
collapsing the two level 1B inventory into a single total, differ only
slightly due to differences in merging national data sets.   

For further information on the two level 1B inventory please see the
description file for the Sulphur and Nitrogen Data Information File (Version 1B)
[filename=soxnox.txt] located at the CGEIC Web Site.

The annual sulphur file 1a_so2.dat, consists of two space delimited fields as
follows:

     1) Grid Number
     2) Emissions

There are 9068 data records in 1a_so2.dat

Definition of Data Fields:
--------------------------

Field 1     Grid Number

            The GEIA grid is used, which is a 180x360 grid with 1 degree latitude
            x 1 degree longitude cells. The latitude - longitude coordinates of a 
            cell are those of the southwest corner of the grid cell. Note: Only grid
            cells which contain emissions are included in this file. Grid cell numbers
            are a packed integer representing both latitude and longitude as described
            below:
            
            Grid number= (latitude+91)*1000+(longitude+181)

            The origin, packed cell number 1001 for this grid system is located
            at the lower left edge of the grid, which corresponds to -90 degrees
            latitude, -180 degrees longitude.

            To unpack the grid number into Latitude and Longitude follow these
            steps:
            
	    1) Divide Grid Number by 1000
               example: 1003 / 1000 = 1.003 

            2) To calculate Latitude take the integer portion of the number in
               Step 1) and subtract 91.
               example: Latitude = 1 - 91 = -90 degrees latitude

            3) To calculate Longitude take the decimal portion of the number
               in Step 1) and multiply by 1000 (e.g. 1.003 = 3) and subtract 181.
               example: Longitude = 3 - 181 = -178 degrees longitude

Field 2     Sulphur Emissions
            Units= Tonnes of Sulphur Per Grid Per Year


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