Comparison of urban and rural boundary layer development during ISB52 from amdar and lidar data

A field trial was conducted in July 2003 on the border of west London in the UK. The trial was funded by the UK Treasury under the Invest-to-Save budget, and was termed ISB52. During the trial two pulsed Doppler lidars were used to measure the wind flow and backscatter properties with the aim of investigating the behaviour of the boundary layer over an urban / rural transition zone.

During the trial amdar data were also retrieved. Amdar data are meteorological measurements taken automatically on commercial aircraft. The amdar data are used to produce temperature profiles for an urban London airfield and a more rural airfield outside of London. These profiles are used with the lidar data and automatic weather station data to compare the urban /rural differences.

Two days of data that showed urban /rural differences were of particular interest. These were the 8th and 9th of July 2003. The meteorological conditions on the 8th July were high pressure with a very low boundary layer top (approximately 600 m). During the night of the 8th July a warm front passed over the region. The following day, 9th July, was very convective with light winds and a high boundary layer top height (approximately 2000 m).

Both days showed urban / rural differences in both the amdar temperature profiles and the lidar data. This paper will aim to highlight the differences and explore the reasons behind them. The effect on the local air pollution in the city of London will be discussed.