THE PUMA PROJECT AND SUBSEQUENT AIR QUALITY

MODELLING AT THE UNIVERSITY OF BIRMINGHAM

ROY M. HARRISON AND XIAOMING CAI

SCHOOL OF GEOGRAPHY, EARTH AND ENVIRONMENTAL SCIENCES

THE UNIVERSITY OF BIRMINGHAM

MODELLING URBAN AIR POLLUTION

• In the PUMA project funded through the NERC URGENT programme two numerical models of atmospheric chemistry across the West Midlands were developed:

- RAMS/UAM Eulerian model by University of Birmingham

- UM/NAME Lagrangian model by the Meteorological Office

(Professor Derwent, Drs Ryall, Redington and Manning)

• RAMS describes meteorological fields within the conurbation on a 2x2 km grid

• UAM, using the CBM IV chemical mechanism simulates atmospheric chemistry of NOx, VOC and ozone

• Major adjustments to UAM were needed to accommodate the very different balance between advection and local formation of pollutants compared to the U.S. west coast

NERC URGENT PROGRAMME

POLLUTION OF THE URBAN MIDLANDS ATMOSPHERE (PUMA)

CONSORTIUM:UNIV. OF BIRMINGHAM HARRISON, CAI, McGREGOR

UNIV. OF CAMBRIDGE JONES

UNIV. OF LEEDS PILLING, SEAKINS, HEARD

UNIV. OF EAST ANGLIA PENKETT

MET. OFFICE RYALL, MALCOLM, DERWENT

CLOSELY ASSOCIATEDUNIV. OF LEICESTER MONKS, GALLAGHERUMIST

DESIGN OF PUMA CAMPAIGNS

UMIST AIRCRAFTParticle Measurements; NO2

HALFPENNY GREEN(25 km WEST)Gases: NO, NO2, CO, O3

Particles: mass

CENTRAL SITE(EDGBASTON)Gases: CO, SO2, NO, NO2, O3, HCHO, PAN, HONO, HNO3

Particles: number, mass, size distribution; major component compositionFree radical intermediates: OH, HO2, NO3

Meteorological and photochemical variables: w/s, w/d, turbulence, photolysis frequencies

WITHYBROOK(35 km EAST)Gases: NO, NO2, CO, SO2, O3

RAMS Configuration Two nested grids are configured

Surface land dataTerrain: Met Office (1km) and US SGS (30”)Landuse type: Institute of Territorial Ecology (1km)Roughness: Met Office (1km) and ITE-derived

Meteorological initial and boundary conditionsUK Met Office’s Unified model output

Grid Lx(km)

Ly(km)

Lz(km)

Nx Ny Nz x (km) y (km)

1 480 248 18 60 48 31 8.0 8.0

2 132 100 18 66 50 31 2.0 2.0

Fig.1 Configuration of the nested grids. The figure box is the boundary of Grid 1 and the embedded box is the boundary of Grid 2. Solid squares are synoptic scale

surface stations.

Fig.2 Modelling domain for Grid 2. Solid squares are synoptic scale surface stations and solid triangles are

PUMA sites.

URBAN AIRSHED MODEL: UAM IV

• Driven by RAMS meteorology

• Contains CBM IV chemical scheme

• Eulerian grid model formulation. 1 x 1 km emissions from NAEI

• Reasonable predictions of CO and NOx with slight tendency to under-predict

• Produces insufficient ozone in simplest form of model

• Modified to:

– Allow for downward mixing of ozone-rich air as the morning boundary layer expansion occurs

– Assimilate hourly boundary condition information for ozone

COMPARISON OF O3 FOR 10 JUNE – 10 JULY 1999

Comparison of O3 for 10 June - 10 July 1999

0

10

20

30

40

50

60

70

80

90

100

10-Jun 15-Jun 20-Jun 25-Jun 30-Jun 5-Jul 10-Jul

Time

O3

(pp

b)

O3 UAM

O3 Obs

k

NOX DURING WINTER CAMPAIGN

Birmingham East

0

50

100

150

200

250

300

16/0

1/19

00

17/0

1/19

0018

/01/

1900

19/0

1/19

0020

/01/

1900

21/0

1/19

0022

/01/

1900

23/0

1/19

0024

/01/

1900

25/0

1/19

0026

/01/

1900

27/0

1/19

0028

/01/

1900

29/0

1/19

0030

/01/

1900

31/0

1/19

0001

/02/

1900

02/0

2/19

0003

/02/

1900

04/0

2/19

0005

/02/

1900

06/0

2/19

0007

/02/

1900

08/0

2/19

0009

/02/

1900

10/0

2/19

0011

/02/

1900

12/0

2/19

0013

/02/

1900

14/0

2/19

0015

/02/

1900

16/0

2/19

0017

/02/

1900

18/0

2/19

0019

/02/

1900

date

[NO

x] p

pb

NOx obs

NOx UAM

Surface concentration of NO, NO2 and O3 on 24/6/1999

NO NO2 O3

NO2 and O3 on 11-12 June 1999

Obtain information on rates of emission of particles from road surfaces into the atmosphere (R Kinnersley and T Huggins)

Use the data obtained, together with other ongoing wind tunnel work, to predict particulate concentration at the end of vehicle near wakes (C Baker and T Huggins)

Develop a large eddy simulation model of street canyon geometries to predict the unsteady wind fields, particle concentrations within the canyon and fluxes from the canyon (C Baker, X Cai and Z Cui)

Experimental quantification and modelling of dispersion of particles in

urban street canyons (URGENT)