Dispersion of Air Pollution & Penetration into the Local Environment

DAPPLE-HO (2006-2009)

HO-DAPPLE is a continuation of the EPSRC funded DAPPLE project that concentrates on flow and dispersion in the urban canopy. Detailed knowledge of short-range dispersion in UK cities is used to assist emergency response planning. Some useful information already exists (e.g. data obtained in London within the EPSRC DAPPLE project and its extensions) but this is limited in extent and the HO-DAPPLE work aims to extend the information collected.

HO tracer trials leaflet


The objectives are:

1) to build on the essentially preliminary EPSRC-DAPPLE experience and produce substantial data sets for a range of source types and meteorological conditions, including those likely to lead to extreme exposure,

2) to characterise street level wind and dispersion conditions with respect to prevailing meteorological conditions, and

3) to use this knowledge to assess the performance of urban dispersion models.

As before, the fieldwork is based at and around the Marylebone Road and Gloucester Place intersection in Central London. The work involves long-term wind measurements above the urban canopy (at roof level and on the BT Tower at 190m above street level) and related measurements within the canopy, two periods of intense measurements and tracer studies, wind tunnel simulations and urban dispersion model evaluations.

The dispersion of material released over a relatively short period in the urban environment is highly variable and a large number of repeat experiments (in nominally identical conditions) is needed to characterise the statistics of the dispersion processes and resulting exposure levels. This is easily undertaken in the highly controlled and repeatable environment of wind tunnel simulation. However, at best three or four repeats might be feasible at full scale before wind and weather conditions change significantly. Because of this, different strategies must be adopted in the way wind tunnel (or for that mater LES) and field data are used to examine urban dispersion model performance.

All DAPPLE projects

A list of DAPPLE (EPSRC and HO) project publications and conference presentations can be seen here. Further details of outputs can be found on the "Outputs" page.

Link to the EPSRC DAPPLE project: DAPPLE-EPSRC

If you need further information or would like to become involved in the development of related project proposals, please contact Alan Robins.