Intercomparison of five modelling methods including ADMS-Airport and EDMS for. Airport. David Carruthers

Transcription

1 Intercomparison of five modelling methods including ADMS-Airport and EDMS for predicting air quality at London Heathrow Airport presented by David Carruthers Cambridge Environmental Research Consultants, UK at the AWMA Speciality Conference Guideline on Air Quality Models Denver 27 April 26

2 Project for the Sustainable Development of Heathrow Panels for Emissions, i Monitoring, i Modelling Model Intercomparison Exercise Models to represent emissions of all source types including aircraft and road traffic emissions and regional background. Dispersion of pollutants from the sources to include the impact of meteorology and other confounding factors. Models to includes conversion of NO to the NO 2 key pollutant. Model intercomparisons, comparisons with data and an exacting set of model diagnostic tests.

3 Candidate Models Netcen Methodology - semi empirical, uses ADMS 3 EDMS - FAA model, uses AERMOD ADMS-Airport ERG semi empirical uses ADMS 3 LASPORT lagrangian particle model

4 ADMS-Airport ADMS-Airport is an extension of ADMS-Urban designed to model pollutant concentrations in the neighbourhood of an airport. It includes all features of ADMS-Urban including the following: Allowance for up to 6 sources: road (15, each with upto 5 vertices), industrial (15), area sources (3); Fully integrated street canyon model based on Danish OSPM model/impacts dl/i of noise barriers; Local and regional NO x chemistry calculation (NO, NO 2 and O 3 ) ADMS-Urban based on ADMS 3; Local ADMS dispersion model nested within trajectory model Integrated with GIS and Emissions Database. Output via GIS includes high resolution pollutant concentration maps; ADMS dispersion based on ADMS 3.

5 ADMS-Airport ADMS 3 is listed as an EPA Alternative model; a new generation quasi gaussian type plume model (first version 1991) with many similar features to AERMOD. Significant differences/additions to AERMOD include: Plume may follow local streamline and is affected by variations in wind field; The integral plume rise jet model can take account of non vertical sources; Complex flow model FLOWSTAR allows treatment of hill wake effects; Concentration ti fluctuations ti model allows probabilistic bili assessment for short averaging times no deterministic solution. ADMS-Airport makes us of the jet model to explicitly model the impact of aircraft jet sources.

6 Schematic of ADMS 3 Integral Jet/Plume Model used in ADMS-Airport Airport Source Entrainment depends on relative motion and ambient turbulence entrainment coefficients. Conservation of mass, momentum, heat and species drag depends on velocity perpendicular to plume axis - drag coefficient Modifications within ADMS-Airport: -Allowance for movement of jet engine source; reduces effective bouyancy -Allowance for inpact of wake vortices on jet plume trajectory

7 Neutral met conditions, plume trajectory (z p ) (top), vertical spread (σ z ) (middle) and z p - σ z (bottom) Plume centreline height of the jet exhaust emitted at different points along the runway during takeoff The take-off roll starts at x = with the aircraft moving in the negative x-direction Plum me centreline height Zp (m) 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 = with the aircraft moving in the negative x-direction 2 Neutral conditions, 5m/s wind Release temperature degrees C X (m) 4 2 Vertical plume spread of the jet exhaust emitted at different points along the runway during take-off The take-off roll starts at x = with the aircraft moving in the negative x-direction Zp - sigma-z (m) Neutral conditions, 5m/s wind Release temperature degrees C X (m) sigma-z (m) Neutral conditions, 5m/s wind Release temperature degrees C X (m)

8 Local and Regional Scales Box model domain Main model domain First source Backgound monitoring site U Main model nested within large, area-wide trajectory model

9 Explicitly modelled road sources NOx (g/(km/s)) Kilometers

10 Example of emissions data -- Aircraft APUs

11 Monitoring Locations for model intercomparison Red = automatic monitoring sites; Green = diffusion tube sites; Blue = receptors for modelling.

12 (a) NOx, NO2 and Ozone (b) PM1 % Wicken Fen % Wicken Fen % Harwell 22 to to 6 % 135 to 22 6 to 135 % Rochester % Harwell 184 to 4 % 4 to 184 % Rochester Lullington Heath % Lullington Heath % Background concentrations for NO x, NO 2, O 3 and PM 1 22 NO x as NO 2 (µg/m 3 ) Annual average 15 Maximum hourly average th percentile 127 NO 2 (µg/m 3 ) Annual average 12 Maximum hourly average th percentile 62 O 3 3 (µg/m ) Annual average 52 Maximum hourly average th percentile 135 PM (μg/m 3 ) Annual average 19 1 Maximum hourly average st percentile of 24 hour averages th percentile of 24 hour averages 48

13 Model set up parameters Minimum Monin-Obukhov length (m) 2m Grid depth (m) 1 Surface roughness (m).5 Meteorology Heathrow 22 Surface roughness at met site (m) 2.2 Percentage of primary NO 2 in NO x by volume 1% all sources

14 Comparison of monitored and calculated NO X, NO 2 and ozone at automatic monitoring sites

15 S tt l t f it d d ADMS Ai t l l t d Scatter plot of monitored and ADMS-Airport calculated concentrations of NO X (left) and NO 2 (right).

16 Time series of monitored and calculated NO X (top) and NO 2 (bottom) in μg/m 3 at LHR2

17 Time series of monitored and calculated NO X (top) and NO 2 (bottom) in μg/m 3 at LHR2 (zoomed in view of previous slide).

18 NO x box and whisker plot Box and whisker plots for the ratio of (calculated/monitored) concentrations, NO X (top) and NO 2 (bottom). The lines indicate the 75 th, 5 th and 25 th percentiles and the lines extend from the 95 th to 5 th percentile..1 LHR2 LHR5 LHR6 LHR8 LHR1 LHR11 LHR14 LHR15 LHR16 LHR NO 2 box and whisker plot LHR2 LHR5 LHR6 LHR8 LHR1 LHR11 LHR14 LHR15 LHR16 LHR17

19 Average concentration at LHR2 during 22 with 27R operational and non-operational

20 Contribution of different components of aircraft sources to annual average NO X concentrations at LHR2

21 Measured LHR2 CERC predicted Measured LHR2 Cambridge predicted Measured LHR2 MMU predicted Polar plots of NO x at LHR2 with background concentrations subtracted.

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23 Annual average NO X concentration (μg/m 3 ) (all sources)

24 Annual average NOX concentration (mg/m3) (aircraft sources only) km 2 km 4 km 6 km 8 km

25 Modelled Annual average NO2 concentration (mg/m3) (all sources)- ADMS-Airport

26 Conclusions o s Model Intercomparison (MIC) of five different modelling methods for air quality in vicinity of airports Focus of the presentation ADMS-Airport includes representation of jet engine emissisions as jet sources. An exacting series of model tests included annual means and statistics, sensitivity to windspeed, sensitivity to runway usage, transects including source apportionment, contour plots and areas of exceedences with comparisons with measured data where appropriate. The study was sponsored by the UK Department for Transport. The full study will be published on