Articles | Volume 10, issue 20
Atmos. Chem. Phys., 10, 9781–9795, 2010

Special issue: Atmospheric chemistry and physics in the atmosphere of a developed...

Atmos. Chem. Phys., 10, 9781–9795, 2010

  19 Oct 2010

19 Oct 2010

Night-time chemistry above London: measurements of NO3 and N2O5 from the BT Tower

A. K. Benton1,*, J. M. Langridge1,**, S. M. Ball2, W. J. Bloss3, M. Dall'Osto3,***, E. Nemitz4, R. M. Harrison3, and R. L. Jones1 A. K. Benton et al.
  • 1Centre for Atmospheric Science, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
  • 2Department of Chemistry, University of Leicester, University Road, Leicester, LE1 7RH, UK
  • 3National Centre for Atmospheric Science, School of Geography, Earth & Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
  • 4Centre for Ecology and Hydrology (Edinburgh), Bush Estate, EH26 0QB, Penicuik, UK
  • *now at: British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
  • **now at: Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado at Boulder, and NOAA Earth System Research Laboratory (ESRL), Boulder, Colorado, USA
  • ***now at: Instituto de Diagnóstico Ambiental y Estudios del Agua (IDAEA), Consejo Superior de Investigaciones Científicas (CSIC), C/ LLuis Solé i Sabarís s/n; 08028, Barcelona, Spain

Abstract. Broadband cavity enhanced absorption spectroscopy (BBCEAS) has been used to measure the sum of concentrations of NO3 and N2O5 from the BT (telecommunications) Tower 160 m above street level in central London during the REPARTEE II campaign in October and November 2007. Substantial variability was observed in these night-time nitrogen compounds: peak NO3+N2O5 mixing ratios reached 800 pptv, whereas the mean night-time NO3+N2O5 was approximately 30 pptv. Additionally, [NO3+N2O5] showed negative correlations with [NO] and [NO2] and a positive correlation with [O3]. Co-measurements of temperature and NO2 from the BT Tower were used to calculate the equilibrium partitioning between NO3 and N2O5 which was always found to strongly favour N2O5 (NO3/N2O5=0.01 to 0.04). Two methods are used to calculate the lifetimes for NO3 and N2O5, the results being compared and discussed in terms of the implications for the night-time oxidation of nitrogen oxides and the night-time sinks for NOy.

Final-revised paper