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AGU: Geophysical Research Letters

 

Index Terms

  • Atmospheric Composition and Structure: Chemical kinetic and photochemical properties
  • Atmospheric Composition and Structure: Pollution—urban and regional
  • Atmospheric Composition and Structure: Troposphere—composition and chemistry
  • Atmospheric Composition and Structure: Troposphere—constituent transport and chemistry

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L18112, 5 PP., 2004
doi:10.1029/2004GL020544

High levels of the hydroxyl radical in the winter urban troposphere

D. E. Heard

School of Chemistry, University of Leeds, UK

L. J. Carpenter

School of Chemistry, University of Leeds, UK

D. J. Creasey

School of Chemistry, University of Leeds, UK

J. R. Hopkins

School of Chemistry, University of Leeds, UK

J. D. Lee

School of Chemistry, University of Leeds, UK

A. C. Lewis

School of Chemistry, University of Leeds, UK

M. J. Pilling

School of Chemistry, University of Leeds, UK

P. W. Seakins

School of Chemistry, University of Leeds, UK

N. Carslaw

Environment Department, University of York, UK

K. M. Emmerson

Environment Department, University of York, UK

Measurements of the OH radical during winter show that noon-time concentrations at an urban site in Birmingham are only a factor of 2 less than during summer at the same site, despite a factor of 15 reduction in OH production from the photolysis of ozone. Noon-time concentrations of HO2 were similar for summer and winter. These high winter concentrations are quantitatively reproduced by a detailed box-model, showing that the winter radical pool (OH, HO2, RO2) is sustained by reactions of unsaturated hydrocarbons with ozone and by the photolysis of carbonyls. The high OH concentrations show there is significant chemical processing of volatile organic compounds (VOCs) in winter at mid-to-high latitudes in the northern hemisphere where emissions are high.

Received 18 May 2004; accepted 30 August 2004; published 28 September 2004.

Citation: Heard, D. E., L. J. Carpenter, D. J. Creasey, J. R. Hopkins, J. D. Lee, A. C. Lewis, M. J. Pilling, P. W. Seakins, N. Carslaw, and K. M. Emmerson (2004), High levels of the hydroxyl radical in the winter urban troposphere, Geophys. Res. Lett., 31, L18112, doi:10.1029/2004GL020544.

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