CLEARFLO

Clean Air for London (CLEARFLO), Detling, UK

15 January 2012 - 15 February 2012

Lead Scientist: Douglas Worsnop

Observatory: OSC

Clean Air for London (ClearfLo) is a large, multidisciplinary study of the London urban atmosphere aimed at understanding the relationships between surface meteorology, gas-phase composition and particulate matter at a city street site, a city background site (away from local traffic sources) and at a rural location that samples the outflow from the London megacity. In addition to long term measurements, two intensive operating periods (IOPs) were planned for January-February and July-August, 2012. ARM deployed a suite of instruments to measure particulate chemical composition, including organics, inorganics and black carbon, size distributions, optical properties and hygroscopic properties, as well as gas-phase oxidants and aerosol precursors, at the rural site southeast of London at Detling, UK during the January-February intensive. These instruments made in-situ, quantitative, high time-resolution measurements of aerosol chemical composition, optical properties and hygroscopic properties in the outflow of a megacity during wintertime. These measurements complemented the successful study of megacity outflow from Mexico City during MILAGRO/MCMA 2006. A particular focus of this study was on understanding the processing of black carbon particles. Results from the CalNex/CARES campaign in 2010 suggest that our understanding of the morphology of coated black carbon particles is incomplete, and this study provided a second test case. We formed a consortium of 5 research groups to provide the Detling rural site with continuous, high time resolution measurements of aerosol chemistry and microphysics, measurements of gas-phase tracers and secondary organic aerosol (SOA) precursors, and radiative and meteorological measurements. Aerodyne Research, Inc. (ARI) provided instruments to monitor aerosol chemical composition, including black carbon, extinction, and single scattering albedo, as well as instruments for precise measurements of trace gas species. Prof. Sally Ng at the Georgia Institute of Technology provided a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) for high time resolution measurements of detailed aerosol chemical composition, including oxygen/carbon (O/C) and hydrogen/carbon (H/C) ratios. Prof. Joel Thornton at the University of Washington, Seattle deployed a newly developed, high sensitivity mass spectrometer system capable of near real-time measurements of molecular level composition of both gas and particle-phase organics. Dr. Manvendra Dubey at Los Alamos National Laboratory (LANL) provided measurements of in-situ aerosol optical properties and Dr. Richard Coulter at Argonne National Laboratory (ANL) provided remote sensing and meteorology measurements.