Measurements were made using the FAAM BAE-146 aircraft throughout the troposphere in the locality of the Tropospheric Organic Chemistry (TORCH) field campaign in Writtle, Essex to determine the influence of regional transport and local chemistry on ozone concentrations.

The Production of Ozone of South-east England (POSE) project aimed to further the understanding of the factors governing ozone chemistry during summer periods in the UK. In particular, the relative sources of ozone: general Northern Hemisphere background, regionally produced products and local/in situ generation. The transport of pollutants from Europe within the boundary layer has been implicated in the very high levels of ozone seen in the UK during summer 2003. During the TORCH field campaign in Writtle, Essex, high levels of ozone and other reactive species were seen during the 2003 heatwave, and results suggest that this may be a result of mixing down of polluted air from aloft during the collapse of the night-time shallow inversion layer to form the day time boundary layer. In order to better understand this behaviour, the FAAM BAE-146 aircraft perfomed a series of profiles close to the Writtle site, to determine the influence of regional transport and local chemistry on ozone concentrations. Measurements included CO, ozone, hydrocarbons and oxygenated VOCs, throughout the troposphere.