Dispersion of Air Pollution & Penetration into the Local Environment


Archives and links

News for 2003: Archive for 2003.
News for 2004: Archive for 2004.
News for 2005: Archive for 2005.

First field campaign: Fieldwork 2003.
Second field campaign: Fieldwork 2004.
Third field campaign: Fieldwork 2007.
Wind tunnel studies: Wind Tunnel Modelling.
Computer modelling: Numerical & Analytical Modelling.

Papers and presentations: Publications
Link to other sites: Links

November, 2009

The project overview in the Bulletin of the American Meteorological Society has been published as: Wood, C.R., S.J. Arnold, A.A. Balogun, J.F. Barlow, S.E. Belcher, R.E. Britter, H. Cheng, A. Dobre, J.J.N. Lingard, D. Martin, M.K. Neophytou, F.K. Petersson, A.G. Robins, D.E. Shallcross, R.J. Smalley, J.E. Tate, A.S. Tomlin, and I.R. White, 2009: Dispersion Experiments in Central London: The 2007 DAPPLE project. Bull. Amer. Meteor. Soc., 90, 955-969.
Link to the American Met. Soc.: (BMS).

April, 2009

Getting towards the end now ... final reporting to be completed by the end of May. Then we're looking to continue, probably by working on indoor exposure to outdoor emissions. There's very likely to be a great deal of investment in the Marylebone area (and elsewhere in London) to put instrumentation in place that will support future urban boundary layer research (link).

NCAS Urban Meteorology Workshop, 30-31 March 2009, University of Reading, UK. Good two day conference in Reading covering almost everything from the smallest to the largest of scales. Three DAPPLE papers:

January, 2009, 89th American Meteorological Society Annual Meeting

Session 15 of the 8th Symposium on the Urban Environment at the 89th Annual Meeting of the American Meteorological Society (Phoenix, AZ), was entitled: "Dispersion and Air Quality in Cities - DAPPLE Experiment." Papers J15.1 to 15.7 were from the DAPPLE consortium, Paper 15.8 related UK work. The session was well attended and well received.

The papers:

Close of 2008 Update

Most effort now is in getting data analysed, papers and reports published. We've a very ambitious programme, so far going more or less to plan. We've submitted 7 papers to the 89th Annual Meeting of the American Meteorological Society (Phoenix, January, 2009), planning for a DAPPLE session.

Another meeting in Birmingham shortly before Christmas to review the Phoenix papers.

Wind tunnel work continues and the model will be in the tunnel again in October/November. The work will concentrate on simulating the latest field trials as well as exploring some of the issues raised by the results.

15th May, 2008, Project Review Meeting

The meeting was held in the Central Library Meeting Room, Birmingham and began with a review of recent scientific work, in particular field work. All the latest experiments had been successful - preliminary results were presented and plans for further analysis agreed. The whole programme of tracer studies, now completed, had exceeded expectations in terms of the number of releases completed.

The main agenda item was a thorough review of the status of all project papers being prepared for journal publication. Detailed content and progress reports were discussed and schedules for completion agreed. The current list contains 13 published papers and 24 in preparation - and there will undoubtedly be more. The day wasn't long enough and we will meet again in July to continue the discussion, also to consider progress with and opportunities for new research proposals.

13th March, 2008, Field Experiments

Eight experiments were completed on the day, between 11:00 and 16:45. These all included a mobile release from a vehicle travelling along Marylebone Road and a static release from outside Westminster Council House. Fourteen sampling locations were deployed in the locality collecting 30 minute integrated samples. The weather conditions comprised mainly moderate south westerly winds with light rain experienced from 15:00 onwards. Ultrasonic anemometers were in operation on the BT Tower, the roof of Westminster Council House, the intersection lighting columns and two ground level locations.

The day was even more productive than planned and, given that we thought the plan ambitious, this reflects the working efficiency that has developed during the extensive programme of DAPPLE fieldwork. Once again, we were indebted to the "volunteers" who operated the sampling units.

The next DAPPLE science meeting is planned for May 15th in Birmingham.

September - November, 2007, Science Meetings

Project science days were held at the Universities of Bristol and Leeds to review the 2007 dispersions trials, discuss progress with analysis and reporting of DAPPLE research and to plan for further field work.

The key point with the trials was that they had all been successful, meaning that all the objectives of that part of the work (i.e. dispersion from fixed sources) had now been met. The DAPPLE dispersion data set contains results from more than 50 experiments - a number of this magnitude is essential if the performance of dispersion models is to be properly assessed. Future work can therefore concentrate on other source types.

31st May - 28th June, 2007, Tracer Studies

May-June, 2007 First period of field work
Lords Hansard text for 17 May 2007; Column WS23

The Minister of State, Home Office (Baroness Scotland of Asthal): My honourable friend the Minister of State for the Home Department (Tony McNulty) has today made the following Written Ministerial Statement.

The Home Office would like to inform Parliament of a series of tracer gas trials that are due to commence in the Westminster area as part of the Home Office's chemical, biological, radiological and nuclear (CBRN) science and technology programme. The trials will improve our understanding of the movement of airborne material in the urban environment, and will enable enhancements in public protection to be developed. The work is part of the Home Office's commitment to improve security and counter terrorism. It will improve the UK's ability to deal with the consequences of a CBRN release through an increased knowledge of the dispersion of material in the urban environment. This knowledge will assist in planning for CBRN response and in public and emergency responder safety. The trials will involve the release of small amounts of non-toxic, odourless gases in the Marylebone area of Westminster starting from 20 May 2007. The trials will run for a four- to six-week period during which time information leaflets will be available to the public. The tracer trials will pose no adverse effect on public health or on the daily routine in the Marylebone area of Westminster. Similar tracer trials led by the Department for Transport were undertaken on 25 March and 1 April 2007 as part of a study looking at air movement within the London Underground environment.

Home Office tracer trials leaflet

28/2/07, Reading; 27/03/07, Imperial College - Detailed planning

Proposed plan (to be agreed with HO and TfL): April 22nd is the date recommended for the deployment of instrumentation on lamp-posts, with the experimental period commencing on April 27th and continuing for 4 to 6 weeks and all tracer dispersion work completed by the end of May. Tracer releases will take place on about four or five days during the period. Between 15 and 20 people will be on-site on each such occasion, mainly manning sampling units but also emission equipment and related operations.

We noted that reference ultra-sonic anemometers were installed in October 2006 on the BT Tower (at 189m above street level) and on the roof of the Westminster Council House (at 18m above street level). Both are now in operation and will operate for at least a year, gathering important information of the wind conditions over central London. Ultrasonic anemometers will also be installed around the Marylebone Road - Gloucester Place intersection prior to the first period of tracer experiments. A site lay-out was agreed that was designed to reveal details of the flow at the intersection. The flow here is known to be extremely complex and unsteady and, of course, it is intimately linked to the exchange of pollutants between the streets at the intersection.

Tracer emissions from either a single source or three separate sources were discussed. Priorities were set as follows, to conduct:

with the aim of the Spring 2007 work being to fulfil (1) and contribute to (2).

Experimental procedures have been further developed and now enable dispersion experiments to take place in whatever wind conditions arise. The basic meteorological requirements for experiments to proceed are dry conditions with a reasonably well defined wind speed and direction at roof level. During a dose experiment, a single sample covering the passage time of the whole tracer cloud will be taken at each sampling point, whereas during a time-resolved experiment a series of ten samples will be taken during the passage time. Up to twenty sampling units can be deployed in any experiment, limited by manpower and sample bag numbers.

Both tracers are inert, harmless gases and, especially in the quantities to be used, have no local environmental impacts. However, they are gases with large greenhouse warming potentials and this aspect of their use has to be considered. Analysis shows that there are no significant concerns with the use of PFCs but possibly some for SF6. Because release of SF6 was soon to become impossible because of legislation affecting its use, only PFC tracer will be used in the trials.

September/November, 2006

The first equipment to be installed on-site was the reference ultrasonic anemometer on the BT Tower (at 189m above street level). The installation, which was co-ordinated with another project using the BT Tower (REPARTEE - see below), took place at the end of September, 2006; the anemometer will be removed at the end of October, 2007. A second reference anemometer was installed on the roof of the Westminster Council House (at 18m above street level) on 12th October. Both are in operation and procedures in place to archive the full data set that will result. These measurements will provide much needed detailed information on wind and dispersion climatology in central London.

REPARTEE (REgent's PArk and Tower Environmental Experiment)

REPARTEE, REgent's PArk and Tower Environmental Experiment, (see APRIL) brings together the UK's leading atmospheric scientists to investigate the vertical profile of particles in relation to chemical processes, pollution concentrations and meteorology from ground level to a height of nearly 200 metres. The ground field site is located in Regent's Park and the elevated site is on top of the BT Tower.

The project is led by Professor Roy Harrison of the University of Birmingham, with funding from the BOC Foundation, who is joined by the CityFlux team (see City Flux), the Environment Agency, DAPPLE and others with an interest in the chemical processes and pollutants formed over and imported into London.
Summary of schedule:

July & September, 2006

Filming - flow visualisation studies in the EnFlo wind tunnel.

6th July, 2006, Imperial College - First planning meeting

This dealt with the overall details of the project and on revising plans to match the actual start date. The key planning factor was the timing and extent of the field tracer campaigns and these were set as two full four week periods, the first in spring 2007. The objective of the first campaign is to a conduct a large number of dispersion studies for releases from fixed point sources, co-ordinated with detailed street canyon wind field measurements. This will be achieved by the use of multiple tracers and sources with samples collected at between 10 and 16 locations in whatever wind directions arise. The second tracer release campaign will be used to add to the data-base, having reviewed the results from spring 2007.

September 2006 - Final Report

The final report to EPSRC was submitted towards the end of the month. It can be seen here and the summary reports from each member of the DAPPLE consortium here.

Through its success, DAPPLE has collected an extremely large set of data, a good deal of which remains to be analysed in full. This work continues. Increasingly, DAPPLE's results are being used by third parties; e.g. the detailed flow and turbulence data collected in the wind tunnel have been used for LES evaluation in the UWERN Urban Boundary Layer programme.

Flow visualisation, using video from the wind tunnel, is being used to provide training material, also in the public communication of science and in explaining policy issues.

May 16th 2006 - Open Conference

The DAPPLE open conference was held at Kings College London and attracted about 100 people from central and local government, industry, research institutes and universities. The programme for the day can be seen here.

March 2006, HO-DAPPLE begins

Details are to be found at: DAPPLE-HO. HO-DAPPLE is a three year project funded by the Home Office that involves all the consortium members plus Golder Associates (UK) Ltd. It continues the meteorological and tracer dispersion work of DAPPLE, again using the Marylebone Road area as the site for experiments. A smaller associated project will evaluate the French SIRANE computer model against the DAPPLE tracer data.

February 15th 2006 - Meteorological Society Meeting

DAPPLE is on the agenda of a Meteorological Society "Wednesday" meeting on urban meteorology at the Regents Park Conference Centre. The full programme:

January 2006 - DAPPLE in the news

DAPPLE's research on personal exposure appears of the BBC News web-site, under the "Health" heading, linked from the front page; the report discusses our results on exposure in different modes of transport. A similar but shorter article had appeared on the New Scientist news service web-site in November 2005 (Walking near the road boosts pollution intake, 05 November 2005, NewScientist.com news service).

The UWERN (Universities Weather Research Network) conference took place on the 13-15th Dec in Salford. A number of DAPPLE consortium members attended and gave presentations. Please see www.uwern.ac.uk for details of the annual UWERN conference.

Archived news for 2003 can be found here.
Archived news for 2004 can be found here.
Archived news for 2005 can be found here.