140
W. Lefebvre et al.
were taken. First of all, a land use regression model was introduced at an hourly scale
at 4 × 4 km
2 resolution. Secondly, a Gaussian model was added for both point and
line sources, correcting for emission double counting. Finally, a street canyon model
was added to the chain, leading to improved resolution in these street canyons. In this
work, we will discuss the problems encountered in these years such as how to account
for double counting of emissions, how to correct the locations of the simplified road
network and how to determine when street canyon calculations must be performed
and how we solved them.
22.1 Introduction
Assessing the air quality for a whole region is not an easy task. One way of doing this
is using measurements. This results in a list of locations where the concentrations are
known. However, it is difficult to determine for which areas these measurements are
representative [4]. Furthermore, a sufficiently dense network covering the territory
with air quality sensors will need a lot of resources. Therefore, model data can be
used to complement the information provided by the measurements. However, it is
well-known that model results are biased and uncertain. As a result, a hybrid approach
combining measurements and model data is often applied. This paper denotes the
different steps that have been taken in the region of Flanders (northern Belgium) in
order to arrive at the current high-resolution air quality maps. It shows the problems
that were encountered and the solutions that were found to deal with them.
22.2 The Initial State
In the middle of the first decade of the 21st century, two tools were available for
assessment in Flanders. The first were the measurements of the official measurement
C. Mensink
e-mail: clemens.mensink@vito.be
S. Van Looy
e-mail: stijn.vanlooy@vito.be
G. Driesen
e-mail: guy.driesen@vito.be
N. Smeets
e-mail: nele.smeets@vito.be
B. Degraeuwe
Air and Climate Unit, Directorate C—Energy, Transport and Climate, European
Commission—Joint Research Centre, Brussels, Belgium
e-mail: bart.degraeuwe@ec.europa.eu
W. Lefebvre et al.
were taken. First of all, a land use regression model was introduced at an hourly scale
at 4 × 4 km
2 resolution. Secondly, a Gaussian model was added for both point and
line sources, correcting for emission double counting. Finally, a street canyon model
was added to the chain, leading to improved resolution in these street canyons. In this
work, we will discuss the problems encountered in these years such as how to account
for double counting of emissions, how to correct the locations of the simplified road
network and how to determine when street canyon calculations must be performed
and how we solved them.
22.1 Introduction
Assessing the air quality for a whole region is not an easy task. One way of doing this
is using measurements. This results in a list of locations where the concentrations are
known. However, it is difficult to determine for which areas these measurements are
representative [4]. Furthermore, a sufficiently dense network covering the territory
with air quality sensors will need a lot of resources. Therefore, model data can be
used to complement the information provided by the measurements. However, it is
well-known that model results are biased and uncertain. As a result, a hybrid approach
combining measurements and model data is often applied. This paper denotes the
different steps that have been taken in the region of Flanders (northern Belgium) in
order to arrive at the current high-resolution air quality maps. It shows the problems
that were encountered and the solutions that were found to deal with them.
22.2 The Initial State
In the middle of the first decade of the 21st century, two tools were available for
assessment in Flanders. The first were the measurements of the official measurement
C. Mensink
e-mail: clemens.mensink@vito.be
S. Van Looy
e-mail: stijn.vanlooy@vito.be
G. Driesen
e-mail: guy.driesen@vito.be
N. Smeets
e-mail: nele.smeets@vito.be
B. Degraeuwe
Air and Climate Unit, Directorate C—Energy, Transport and Climate, European
Commission—Joint Research Centre, Brussels, Belgium
e-mail: bart.degraeuwe@ec.europa.eu