Dispersion modelling work at
King’s College London
David Carslaw
Environmental Research Group
King’s College London
London Air Quality Network-LAQN
0m
20000m
40000m
60000m
80000m
Insight from measurements
90
80
70
PM 10 (24 h mean)
– Secondary
pollutants from
UK/Europe
– Natural particle
episodes e.g.
Saharan dust in
March 2000
– Very localised
conditions e.g.
congested traffic
and the specific
configuration of
buildings
60
50
40
30
20
10
0
14-Feb-03 16-Feb-03 18-Feb-03 20-Feb-03 22-Feb-03 24-Feb-03 26-Feb-03 28-Feb-03
Particle episode, February 2003
Model development
• Data from LAQN has been used in the
development of practical models for
London
– NO2 and PM10 regression and receptor models
(Carslaw et al., 2001; Fuller et al., 2002)
– Techniques used in tandem with ADMS to
predict concentrations London-wide
Carslaw, D.C., Beevers, S.D., Fuller, G., 2001. An Empirical Approach for the Prediction of Annual Mean
Nitrogen Dioxide Concentrations in London. Atmospheric Environment, Vol. 35, 1505-1515.
Fuller, G.W., Carslaw, D.C., Lodge, H.W., 2002. An Empirical Approach for the Prediction of Daily Mean
PM10 Concentrations. Atmospheric Environment, Vol. 36, 1431-1441.
Met pre-processors
– Addition of anthropogenic
heat flux
– Approach is too simplistic
– Need for more appropriate
met data for urban modelling
(heat fluxes, energy balances)
1800
1600
boundary layer height (m)
• Some account has been
taken of urban meteorology
based on parameterisations
in the literature
1400
H (standard)
H (urban)
1200
1000
800
600
400
200
0
1/1/00 0:00
1/1/00 12:00
1/2/00 0:00
1/2/00 12:00
1/3/00 0:00
1/3/00 12:00
1/4/00 0:00
Application of dispersion models
in London
• Projections of future base
case concentrations of
NO2 and PM10
• Analysis of the efficacy of
different potential policies
in London e.g. a low
emission zone and the use
of new vehicle
technologies
Congestion charging (CCS)
• ERG will be working with
Transport for London to
monitor the CCS scheme
(AQ measurement,
emissions, prediction)
• It will provide an
unprecedented level of
traffic activity information
– Continuous traffic counters
– Manual counts – specific
vehicle types
– Automatic number plate
recognition (ANPR)
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Congestion charging
• Many interesting research questions:
• CCS is a large natural experiment i.e. the effect of a
perturbation
• How atmospheric composition responds to a specific policy in
a large urban area
• Potential effects of displacing emissions to hours of the day
where dispersion is less efficient
• How secondary pollutants respond to emissions changes over a
comparatively small area
• Re-suspended particulate matter from vehicle-induced
turbulence
Research priorities
• Urban meteorology
– Significantly more information is required
• Connecting the different scales
– No one model works at all scales
• Developments in dispersion modelling needs to be
matched with developments in emissions
inventories
– Emission factors, spatial and temporal scales, species
considered
– A wider context: urban morphology, heat release etc.
– Data management e.g. expertise with GIS