developments in adms-airport to take account of · developments in adms-airport to take account of...

Developments in ADMS-Airport to take account of

near-field dispersion and its applications to Heathrow Airport

David David CarruthersCarruthers, Christine McHugh,, Christine McHugh,Mark Jackson & Kate JohnsonMark Jackson & Kate Johnson

Cambridge Environmental Research ConsultantsCambridge Environmental Research Consultants

Harmo11, July 2007

11th Harmonisation Conference

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Outline of talk

• Key factors affecting air quality at airports• Features of ADMS-Airport• Model performance and sensitivities -

Department for Transport PSDH (Project for the Sustainable Development of Heathrow) Model Inter-comparison (MIC)11th Harmonisation Conference

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1) Key factors affecting air quality at airports


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Key factors affecting air quality at airports

• Emissions • Background concentrations• Meteorology• Near field dispersion processes• Chemical reactions


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2) Features of ADMS-Airport


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Features of ADMS-Airport

• An extension of ADMS-Urban – Gaussian type model nested in regional trajectory model

• Includes chemical reaction scheme, meteorological preprocessor, Monin-Obukhov and mixed layer scaling for boundary layer structure

• Other airport features- Hour by hour time varying data


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Features: MODELLING EXHAUSTS AS MOVING JETS & THE IMPACT OF WAKE VORTICES

• Models engine exhausts as moving jet sources• As the aircraft accelerates

- buoyancy and emissions increasingly spread along the runway

- the exhaust jet sees a faster ambient wind speed, this affects the plume rise

• The plume from the faster aircraft rises less than that from a slower aircraft

• Allows for the impact wake vortices may have on jet plume rise – reduce buoyancy


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Features: MODELLING EXHAUSTS AS MOVING JETS

• Conservation of mass, momentum, heat and species• Modifications within ADMS-Airport

- Allowance for movement of jet engine sources; reduces effective buoyancy

- Allowance for impact of wake vortices on jet plume trajectory

Drag depends on velocity perpendicular to plume axis- drag coefficient

Entrainment – depends on relative motion and ambient turbulence –entrainment coefficients.

Source


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Neutral met conditions, plume trajectory (zp ) (1st), vertical spread (σz ) (2nd) and zp - σz (3rd)

Plume centreline height of the jet exhaust emitted at different points along the runway during take-off

The take-off roll starts at x = 0 with the aircraft moving in the negative x-direction

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Neutral conditions, 5m/s windRelease temperature 232.4 degrees C

Vertical plume spread of the jet exhaust emitted at different points along the runway during take-offThe take-off roll starts at x = 0 with the aircraft moving in the negative x-direction

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Neutral conditions, 5m/s windRelease temperature 232.4 degrees C

Difference between plume centreline height and vertical plume spread (Zp - sigma-z) of the jet exhaust emitted at different points along the runway during take-off

The take-off roll starts at x = 0 with the aircraft moving in the negative x-direction

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Neutral conditions, 5m/s windRelease temperature 232.4 degrees C11th Harmonisation Conference

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All source buoyant First 4 sources buoyant No source buoyant

absolute difference

percentage difference

Impacts of reduced buoyancy to simulate possible effect of wake vortices B747 long term concentration contour and difference plots

Features: IMPACT OF WAKE VORTICES


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3) Model performance and sensitivities:

MODEL SET UP


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Heathrow: METEOROLOGICAL DATA


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• Gridded sources for all of London• Roads – local to Heathrow from LAEI

(London Atmospheric Emissions Inventory) and the Heathrow Inventory

• LTO: taxi-in, taxi-out, landing, approach, initial climb, climb out

• Other: APU, airside vehicles, car parks, taxi ranks modelled as area or volume sources

Heathrow: EMISSION SOURCES


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Heathrow: MONITORING DATA

● LHR2


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%%

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%Harwell Rochester

Wicken Fen

Lullington Heath

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(b) PM10

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Wicken Fen

Lullington Heath

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(a) NOx, NO2 and Ozone

2002

NOx as NO2 (µg/m3) Annual averageMaximum hourly average99.79th percentile

15215127

NO2 (µg/m3) Annual averageMaximum hourly average99.79th percentile

128462

O3 (µg/m3) Annual averageMaximum hourly average99.79th percentile

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PM10 (μg/m3) Annual averageMaximum hourly average90.41st percentile of 24 hour averages98.08th percentile of 24 hour averages

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NOX NO2 O3

PM10

Heathrow : BACKGROUND CONCENTRATIONS


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3) Model performance and sensitivities:

ANALYSIS OF

RESULTS


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LHR2 LHR5 LHR6 LHR8 LHR10 LHR11 LHR14 LHR15 LHR16 LHR17 OverallMean

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NOX

(dark blue and red) and NO2

(yellow and light blue) monitored and calculated annual mean calculated annual mean concentrations at the automatic monitoring sitesconcentrations at the automatic monitoring sites

NO2

NO2


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2002 NO2 box and whisker plot

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LHR2 “Box and whisker” plots for the ratio of

(calculated/monitored) concentrations, NOX

(top) and NO2

(bottom).

The lines indicate the 75th, 50th

and 25th

percentiles and the lines extend from the 95th

to 5th

percentile.11th Harmonisation Conference

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Comparison of LHR2 monitored and calculated NO2

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Detailed time series comparison

of monitored (blue) and calculated (red) hourly concentrations at receptor LHR2. 2I Jan 2002 –

mid February 2002


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Departure 27R (all wind speeds)

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No Departure 27R (all wind speeds)

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Arrival 27R (all wind speeds)

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LHR2 diurnal variation

ADMS-Airport (solid line) compared with measured data

(dotted line), different

runway use

Arrival on 27R

Departure on 27 R No departure on 27 R


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Comparison of monitored and calculated NO2 in μg/m3 at LHR2 as a function of wind speed for the hours when 27R is operational (blue an red) and the hours when it is not operational (cream and pale blue) separately.


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Polar plots

of NOx

at LHR2 with background concentrations subtracted. Radius: wind speed

in m/s.

Measured v ADMS modelled

Measured v Model 2

Measured v Model 3


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Source apportionment:

AIRCRAFT SOURCES

Annual average NOX

concentration (μg/m3) (aircraft sources only)


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Contours: ANNUAL AVERAGE NO2

40 μg/m3

limit shown in bold


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Emissions: SENSITIVITY TO PRIMARY NO2

• Annual average NO2 2010

• Primary NO2, 10% (top) and 20% (bottom)

NO2 (µg/m³)> 5652 - 5648 - 5244 - 4840 - 4436 - 4032 - 3628 - 3224 - 2820 - 24< 20

CERC

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London 2010 - 10% NO2Annual average NO2 concentrationModelled using ADMS-Urban

Figure 4.1a

NO2 (µg/m³)> 5652 - 5648 - 5244 - 4840 - 4436 - 4032 - 3628 - 3224 - 2820 - 24< 20

Figure 4.1bLondon 2010 - 20% NO2Annual average NO2 concentrationModelled using ADMS-Urban

0 5 10 Kilometers


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Conclusions

Key factors affecting pollutant concentrations in the neighbourhood of airports that should be modelled include the following:

• Emissions including primary NO2• Background concentrations e.g. O3• Meteorology• Near field dispersion processes, buoyancy of

the aircraft exhausts• Chemical reactions


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developments in adms-airport to take account of · developments in adms-airport to take account of...

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