Transport and mixing in fronts was a NERC Polluted Troposphere Research Programme project (Round 1 - NER/T/S/2002/00149 - Duration 2002 - 2005) and was led by DR SL Gray, University of Reading.

The aim of this research was to provide improved quantitative estimates of the rate at which frontal regions in weather systems transport polluted air from the boundary layer to the free troposphere.

Modelling studies performed using typical mesoscale to regional-scale resolution cannot resolve certain frontal mixing processes which are clearly visible in high resolution radar observations; namely multiple shear layers and large-amplitude Kelvin-Helmholtz billows. To perform very high-resolution (of order 2 km by 90 vertical levels) model simulations of frontal cases using the new dynamics (non-hydrostatic) Met Office model. The dynamical representation of these mixing processes and the transport and mixing of passive tracers in the model were evaluated using observations. The climatological impact of these individual fronts was determined using a climatological frontal database.

The Polluted Troposphere Programme was a 5-year NERC thematic research programme was centred upon the study of polluted boundary layer air and its transport to the free troposphere. The programme focussed on the regional scale, defined as intermediate between urban and hemispheric.