Spatial distribution of emissions to air - the SPREAD model

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The SPREAD model has been prepared as part of the emission inventory
project at the National Environmental Research Institute, Aarhus University.
SPREAD will be applied for the next mandatory reporting of
gridded emissions to CLRTAP primo 2012.
Former spatial distributions have had a rather low resolution (50x50 km
and 17x17 km) compared to the Danish area and are considered less useful
for air quality modelling, health effect estimation and associated costbenefit
analysis. As emissions in the national inventory in most cases are
based on very detailed data and as the resulting emissions are considered
to have small uncertainties, a high spatial resolution distribution
will improve the use of emission data in many contexts.
To ensure that the spatial distribution reflect the degree of detail in the
inventory, the emissions are distributed on a highly disaggregated level.
Therefore the SPREAD model is based on SNAP categories rather than
the NFR and CRF categories used in the national emission reporting.
This has lead to demand for setting up a larger number of distribution
keys.
A large workload has been put in the distribution of emissions in the energy
sector. The inventory system handles Large Point Sources and area
sources, but as the calculations in the national inventory system include
data from a large number of point sources, these emissions are allocated
on the site of each single plant. As this approach differ from the approach
in the inventory system, much work has been done to re-allocate
fuel consumptions on SNAP categories and to apply corrections to ensure
that the emissions in the inventory and in the distribution are exactly
the same.
The distribution of emissions from agriculture is based on a complex bottom-up
approach including more very large and very detailed datasets.
Emissions related to animals are based on information on all registered
animals in Denmark and thereby it is possible to allocate the emissions
very accurately. Emissions related to soils and crops are calculated on
field level in consideration of crop types and soil types, and this emission
allocation is very accurate as well. As is the case for the energy sector,
the emission calculation approach differs between the inventory system
and the bottom-up methodology, and the latter is corrected to make sure
the emissions in the distribution and in the national emission inventory
equal.
A number of point sources have been geo-coded manually either by use
of the public Information Server (OIS) administrated by the Danish Enterprise
and Construction Authority, where coordinates can be found via
addresses, or via visual identification in Google Earth. Manual geocoding
has been used for e.g. municipal solid waste disposals and waste
water treatment plants.
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