Articles | Volume 10, issue 21
Atmos. Chem. Phys., 10, 10607–10620, 2010

Special issue: OP3/ACES: Oxidant and particle photochemical processes above...

Atmos. Chem. Phys., 10, 10607–10620, 2010

  11 Nov 2010

11 Nov 2010

NOx and O3 above a tropical rainforest: an analysis with a global and box model

R. C. Pike1, J. D. Lee2, P. J. Young1,3,4, G. D. Carver1,5, X. Yang1, N. Warwick1, S. Moller6, P. Misztal7,8, B. Langford9, D. Stewart10,*, C. E. Reeves10, C. N. Hewitt9, and J. A. Pyle1,5 R. C. Pike et al.
  • 1Centre for Atmospheric Science, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
  • 2National Centre for Atmospheric Science (NCAS), University of York, Heslington, York, YO10 5DD, UK
  • 3Cooperative Institute for Research in the Environmental Sciences, University of Colorado, Boulder, CO, USA
  • 4NOAA Earth System Research Laboratory, Boulder, CO, USA
  • 5National Centre for Atmospheric Science - Climate, University of Cambridge, USA
  • 6Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
  • 7Centre for Ecology and Hydrology Edinburgh, Bush Estate, Penicuik, Midlothian, EH26 0QB, UK
  • 8The University of Edinburgh, School of Chemistry, Joseph Black Building, West Mains Road, Edinburgh, EH9 3JJ, UK
  • 9Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
  • 10School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
  • *now at: Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AH, UK

Abstract. A cross-platform field campaign, OP3, was conducted in the state of Sabah in Malaysian Borneo between April and July of 2008. Among the suite of observations recorded, the campaign included measurements of NOx and O3 – crucial outputs of any model chemistry mechanism. We describe the measurements of these species made from both the ground site and aircraft. We then use the output from two resolutions of the chemistry transport model p-TOMCAT to illustrate the ability of a global model chemical mechanism to capture the chemistry at the rainforest site. The basic model performance is good for NOx and poor for ozone. A box model containing the same chemical mechanism is used to explore the results of the global model in more depth and make comparisons between the two. Without some parameterization of the nighttime boundary layer – free troposphere mixing (i.e. the use of a dilution parameter), the box model does not reproduce the observations, pointing to the importance of adequately representing physical processes for comparisons with surface measurements. We conclude with a discussion of box model budget calculations of chemical reaction fluxes, deposition and mixing, and compare these results to output from p-TOMCAT. These show the same chemical mechanism behaves similarly in both models, but that emissions and advection play particularly strong roles in influencing the comparison to surface measurements.

Final-revised paper