Following a large explosion at the Buncefield oil depot, on December 11th 2005 a major oil-fire burned for 3 days. This was probably the largest fire in the UK since 1945, and offered a rare opportunity for ground-based measurements of the composition and consequences of a major smoke plume at close range, with the aim of better understanding the potential atmospheric and environmental perturbations of such events.
The main previous studies of emissions from large oil fires followed the 1991 Gulf war when Kuwaiti oil wells were ignited. At the time there was concern that these plumes would have a global impact, with nuclear-winter type scenarios, diversion of monsoons and harvest failure suggested (Brimblecombe 1994). However aircraft measurements of the plume suggested limited potential for such far-reaching effects as (i) the particle emissions were less than expected, (ii) the smoke was not as black as expected (more efficient combustion), (iii) the smoke was not carried high into the atmosphere, and (iv) the smoke had a short atmospheric residence time (Hobbs & Radke, 1992). Regional effects, however, included impacts on cloud properties and formation, radiative budgets, air quality and tropospheric ozone levels.
The chronology and details of the 2005 incident have been summarised in recent reports (e.g., Targa et al. 2006). The incident was initiated in a major explosion on December 11th at 06:01.32 UT, triggered by the ignition of ~300 tonnes of unleaded petrol, which had overspilled from a storage tank. At the time, there was a strong inversion layer in the atmosphere, which trapped the lofted plume and its products at a moderate altitude. Ground-level concentrations of a range of pollutants remained low to moderate over local, regional and national scales, the high plume buoyancy and favourable meteorological conditions meant that the plume was trapped aloft, with minimal mixing to the ground (Targa et al. 2006).