DAPPLE December 2003 D ispersion of A ir P ollutants & their P enetration into the L ocal E nvironment Background Activities to date Results - tracer & wind tunnel Future plans EPSRC Infrastructure & Environment Programme

DAPPLE December 2003 Consortium University of Surrey Alan Robins Imperial College Roy Colvile University of Bristol Dudley Shallcross University of Cambridge Rex Britter University of Leeds Margaret Bell University of Reading Stephen Belcher A 4 year EPSRC funded project, supported by: London -> ALG/APRIL/EA/Local Government/TfL DEFRA, AEQ Division DSTL (Porton Down), HSE Meteorological Office

DAPPLE December 2003 DAPPLE aims:  to enhance understanding of pollutant dispersion and individual exposure to pollutants in urban areas  to improve predictive ability  to enable better planning and management of urban air quality and ‘incidents’ Background “… We do not yet have the understanding needed to answer fundamental questions about pollution behaviour over short distances in the urban environment. …”

DAPPLE December 2003 The basic understanding gained will be used:  in the evaluation and development of appropriate decision support tools and risk assessment methodologies  in the evaluation and development of best practice guidelines for their application  in assessing the inherent uncertainty in their use  in assessing their contribution to the sustainable development of safer, more pleasant cities. As far as possible, DAPPLE deliverables will be of generic value and applicable both within UK urban areas and others overseas. Output

DAPPLE December 2003 Street intersections - the urban environment Relative flow rates at the intersection; off-set 0.6H

DAPPLE December 2003 Intersection modelling LDA mean velocity measurements within canyons Highly unsteady exchanges Block size: 4H x 6H x H Orientation 10degs 1:1 C measured C predicted Regulatory models (ADMS) don’t model intersections - CFD does a reasonable job for a simple 4 block geometry.

DAPPLE December 2003 Classic street canyons Measured Street Canyon Pollution Levels in Jagtvej N 300 degs receptor

DAPPLE December 2003 Classic street canyons?

DAPPLE December 2003  How do we predict the movement of pollutants in & over a street network?  What are best practices in the urban context?  How much detail is necessary?  What area needs to be modelled and to what resolution?  How do we best go about managing & improving local urban air quality?  What tools are needed to deal with these matters?  How should these be developed for incident management? In an urban setting:

DAPPLE December 2003 Activities  Vehicle movement analysis  Emissions modelling  Tracer experiments  Individual dose measurement  Air quality monitoring  Wind tunnel studies  Model evaluation & development Marylebone Rd - Gloucester Place intersection

DAPPLE December 2003 Key times 2002April: project start 2003 Spring: initial field trials Monitoring studies: 28 April to 23 May Tracer study: 15th May Summer: results analysis, interim output & workshop 2004Spring: main field trials 19th April to 28th May 2005Continued analysis; results, workshop, dissemination 2006March - project end; final reports and workshops

DAPPLE December 2003 Site features

DAPPLE December 2003 First field trials 28/4/ /5/03 Instrumentation installed courtesy of TfL

DAPPLE December 2003 York Street Library Bickenhall St. Gloucester Place Thornton Place Bickenhall Mansions Baker Street Marylebone Road WU roof not accessible due to pair of nesting falcons! SITE 1 SITE 2 SITE 3 SITE 4 SITE 5 SITE 6 SITE 7 SITE 8 Super-site WCC WCC INDOORS VOC - basement, reception & 4 th floor rooms particles - basement & first floor room sonics street boxes AWS lamp post direction of bracket EXTERNAL EQUIP Schematic site plan

DAPPLE December 2003 Weather stations AWS at 15mAWS at 64m

DAPPLE December 2003 York Street Library Bickenhall St. Gloucester Place Thornton Place Bickenhall Mansions Baker Street Marylebone Road X tracer release tracer samplers (10) Marylebone Road x Super-site WCC sonics street boxes AWS EXTERNAL EQUIP Schematic site plan

DAPPLE December 2003 Trial achievements Meteorology - 7 Sonic anemometers - at 4 and 8m on lamp posts - 4, 12 and 15m on WCC Hall) - logged at 20Hz or 5Hz - 3 Automatic Weather Stations - 30 secs wind, temperature and humidity - synoptic - forecasts & back trajectories (Met Office) - meso-scale model output, data for tracer release Pollution - 10 Street boxes (CO & NO2) - 4 & 7m giving 5 minute averages; along Marylebone Rd between Super-site & WCC Hall - ITS instrumented vehicle

DAPPLE December 2003 Ultrasonic anemometers Lamp post and building mounted

DAPPLE December 2003 Trial achievements AURN Super-site- CO, PM10, PM2.5, NO2, O3, SO2, Wind, etc. WCC Hall Site - NO, NO2, PM10 + Opsis Traffic - SCOOT data (TfL) - Leeds instrumented vehicle and traffic counts Tracer - SW winds from York Street (15 TH May) - 10 sampling boxes deployed within 2-3 blocks Exposure - 4 people, 3 times a day (particulates & CO) - different routes & modes of transport, 40 minute exposure - indoor/outdoor VOC & particles (MSc students)

DAPPLE December 2003 Example day - 15 May AWS mean 30s data for wind speed, direction, temp & humidity WCC Rooftop AWS Tracer exp. started at 5pm

DAPPLE December 2003 SCOOT DAPPLE 5 mins, hourly & daily average traffic flows Verification by manual counts Emission estimates Traffic flow modelling 2 way data network I/O progs Online traffic model Optimiser Signal timings signal controllers traffic detectors Operator

DAPPLE December 2003 CO box data

DAPPLE December 2003 CO box data - 15 May Circulation: high CO to S ---- low CO to N

DAPPLE December 2003 Wind field - SSW winds Site 1 Site 2 Site 3 Typical 10Hz wind direction data for SSW winds SSW winds

DAPPLE December 2003 Wind field Marylebone - Rd Gloucester Place intersection Street wind conditions ‘roof’ level wind from SSW Generally: Wind channelling and direction switching: e.g. Gloucester Place wind direction changes by 180 degrees depending on above roof wind having north or south component.

DAPPLE December 2003 Wind channelling dominates horizontal motion Weak vortex-like motion driven by cross-flow only apparent in time averaged results. Vertical mixing - other processes Analysis continues

DAPPLE December 2003

DAPPLE December 2003 OBJECTIVES a)CAMPAIGN1 – Collect co-ordinated data-set of traffic flow (SCOOT data and manual counts for verification purposes) and air quality data (Learian streetboxes); b)Verify the SCOOT data using manual count data and automatic count site data; c)Process and average the SCOOT data into 5, 15 and 60 minute time intervals; d)Calculate Emissions using NAEI factors; e)Implement ETEM (Enhanced Traffic Emission Model – uses SCOOT data, congestion algorithm and ADMS-Urban to predict roadside concentrations); f)Implement microscopic traffic simulation model in the study area using as demand input, the raw SCOOT detector data. The simulations will predict emissions using the transient CMEM emission factor database; working with TfL staff Conduct an integrated analysis of traffic activity, emission prediction, meteorology and ambient concentrations.

DAPPLE December 2003 We have developed, and attempted to justify a “simple correlation” for dispersion in urban areas for use on the neighbourhood and city scales ( see DAPPLE web site). This was used in the design of the first field tracer experiment. We have compared the “simple correlation” with the experimental data from the first field tracer experiment (only PMCH tracer). The correlation overpredicts by about a factor of two. We have compared the baseline dispersion model for urban areas developed in Hanna, Britter and Franzese (2004) with the experimental data from the first field tracer experiment (only PMCH tracer). The correlation overpredicts by about a factor of two.

DAPPLE December 2003 We have worked with Bristol to review the tracer experimental data collected in the first DAPPLE study to quality assure them and then to archive them on the DAPPLE web site. This has been completed for the PMCH tracer release and the data should appear in an archived for on the DAPPLE web site imminently. A problem was found with the SF 6 data, ascribable to an unsuspected non-linear response at high concentrations. The results are currently being recalculated.

DAPPLE December 2003

DAPPLE December 2003 The PM 2.5 and ultra-fine particle count personal exposure databases are now complete and are undergoing final post-processing checks. They have been constructed by Surbjit Kaur in MS Excel and will be available to the consortium via the ftp site at the beginning of February Accompanying transcripts for the real-time data will also be made available. The construction of the CO database has started; estimated date for availability of the preliminary database is end of February Statistical analysis in progress. Currently, pollutant concentration fluctuations at a fixed receptor have been modelled for these steady emissions from a single point source. This indicates that much of the short-term exposure variability (on a timescale of seconds to minutes) is attributable to the unsteadiness of the flow field under constant meteorological conditions, provided real traffic sources are not so homogeneous as to remove much of the variability by spatial averaging. Regulatory and exposure use of ADMS etc Exposure modelling - empirical

DAPPLE December 2003 good data capture levels throughout SCOOT calibration needs further attention to allow for loops that cross two lanes which can give ambiguous data when heavily congested - statistical methods being developed

DAPPLE December 2003 Personal exposure 5 modes of transport: bus, taxi, car, cycle, foot 3 x 40 minute ‘trips’ per day measuring: CO, Fine particles & PM2.5 plus video & voice records

DAPPLE December 2003 Equipment CO T15 Langan Measures carbon monoxide every 10 seconds TSI P-Trak Measures ultra-fine particles every second Casella Ultraflow Pump + Filter Measures average PM 2.5 concentration for the route

DAPPLE December 2003 Personal exposure Walkers Cyclists

DAPPLE December 2003 Tracer study Sample intake Source outlet

DAPPLE December 2003 Tracer study Tracers: PMCH, SF6 15 minute release SF6 1.5 minute offset 10 sampling units 10x5L tedlar bags per unit 3 min samples NICI mass spectrometry negative ion chemical ionisation perfluorocarbon

DAPPLE December 2003 Tracer study - I Three minute averaged concentration values

DAPPLE December 2003 Tracer study York Street Library Bickenhall Street Westminster Council House Gloucester Place Thornton Place Bickenhall Mansions Baker Street Marylebone Road x Distance ~ 125m Time of flight ~ 4.5min Travel speed ~ 0.5m/s Reference wind, 3m/s Source failed ~ 0 CU H H 2 /Q 114 mg release

DAPPLE December 2003 Tracer study - II Travel speed = 0.10 to 0.35U(H) C ~ 1/R 2 R/H=3.4 R/H=12.5

DAPPLE December 2003 Tracer study Conclusions from an ensemble of one  For R/H between 3.4 and 20:  Maximum concentration, C max U H /Q ~ 5/R 2  Travel time, TU H /H ~ 30 to to 5 minutes  Travel speed, U/U H ~ 1/10 to 1/3

DAPPLE December 2003 Tracer study Enhancements for next trials: Capability for releasing three different perfluorocarbon tracers from three locations Development of 1 minute real time instrumentation Ditto for SF6 Improved logistics Greater freedom in choice of source locations (limited by traffic and other concerns) and sampler deployment

DAPPLE December 2003 Wind tunnel study EnFlo wind tunnel 20x3.5x1.5m working section, 0-3.5m/s

DAPPLE December 2003 Wind tunnel study

DAPPLE December 2003 Wind tunnel study Scale 1:200 Reference wind speed 2.5m/s, direction SW Source in York Street Ground level concentration data

DAPPLE December 2003 Simulation of field trial

DAPPLE December 2003 Wind tunnel study Upper bound: CU ref /Q = 50/R 2

DAPPLE December 2003 Wind tunnel study Upper bound: CU ref /Q = 50/R 2

DAPPLE December 2003 Salt Lake City Upper bound: CU H /Q = 50/R 2

DAPPLE December 2003 Wind tunnel study Block averaging T, s  c / c 99 / raw data 3 s block average Concentration - Time 300 secs

DAPPLE December 2003 Wind tunnel study Short duration emissions 0.5 to 10s Determine travel, rise and decay time scales, dilution rate

DAPPLE December 2003 Wind tunnel study U advection ≈ U H /4 R is straight line separation Field: R/H = 3.4 to 12.5, T non = 30 to 41

DAPPLE December 2003 Wind tunnel study

DAPPLE December 2003 Wind tunnel study

DAPPLE December 2003 Wind tunnel study Conclusions Plumes: C max U H /Q ~ 50/R 2 Significant variations across streets Puffs: U advection ≈ U H /4 Rise time/Travel time ≈ 1/3; ditto decay time Peak/Mean ≈ Future work: detailed mapping of flow and concentration fields flux exchange at intersection exchanges with flow above roof level effects of modelling detail

DAPPLE December 2003 Computer modelling Themes:  Simulations of field and wind tunnel exp;  Urban Air Quality and Accidental releases  Evaluation of model performance - sensitivity studies - best practice Models:  Simple rules of thumb  Operational models (e.g UDM, ASUDM, ESUDM, ADMS-URBAN)  CFD models (e.g. RANS, LES) Purposes:  Prediction/forecasting  Design of response strategies

DAPPLE December 2003 State of play First field trials a complete success - all data on web site for project members (not yet publicly available) Data analysis still in progress Important wind tunnel results on travel and decay times, dilution rates and fluctuations Second field trials: 19th April to 28th May open for collaborative third party work Current news and project updates are on our public site at: