Spatial distribution of emissions to air - the SPREAD model

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Figure 2.2 Segment around Avedøre of the map of the Danish 1x1 km grid net.
To be able to distribute the emissions on 1x1 km it is necessary to split
the industrial polygons between the grid cells and thereby be able to calculate
the industrial area in each grid cell. These functionalities are available
in a geographical information system (GIS) – in the present work
ArcMap is used. The split is made using the intersect tool and afterwards
the areas are applied to each cell using the Calculate Area function.
Figure 2.3 Segment around Avedøre of the map of industrial areas and the Danish 1x1
km grid net.
The remaining part of the emission distribution is carried out in a database.
The share of the emissions that should be allocated to each grid cell
is calculated as the industrial area of the cell divided by the total industrial
area. The same distribution key is applied for all pollutants.
In the case of the Industrial Processes sector only one map is combined
with the grid, but more maps or layers could be combined to make a distribution
key. This is the case for some sources in the agricultural sector,
e.g. emissions from organic soils where the distribution key is based on a
map of organic soils, a map of the agricultural fields and the Danish Grid
Net. A number of area sources are distributed on line features, e.g. emissions
from railways and road traffic. In these cases the lines are split into
segments by intersection with the 1x1 km grid net. The emission in each
grid cell is calculated as the national emission multiplied by the length of
the line segment(s) in the cell and divided by the total length of the line
feature.