Articles | Volume 11, issue 9
Atmos. Chem. Phys., 11, 4371–4389, 2011
Atmos. Chem. Phys., 11, 4371–4389, 2011

Research article 11 May 2011

Research article | 11 May 2011

Evaluation of a photosynthesis-based biogenic isoprene emission scheme in JULES and simulation of isoprene emissions under present-day climate conditions

F. Pacifico1,2,*, S. P. Harrison2,3, C. D. Jones1, A. Arneth4,5, S. Sitch6, G. P. Weedon1, M. P. Barkley7,**, P. I. Palmer7, D. Serça8, M. Potosnak9, T.-M. Fu10, A. Goldstein11, J. Bai12, and G. Schurgers4 F. Pacifico et al.
  • 1Met Office Hadley Centre, Exeter, EX1 3PB, UK
  • 2School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS,UK
  • 3School of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia
  • 4Department of Earth and Ecosystem Sciences, University of Lund, Lund, 22362, Sweden
  • 5Karlsruhe Institute for Technology, Institute of Meteorology and Climate Research (KIT/IMK-IFU), Kreuzeckbahnstr. 19, 82467 Garmisch-Partenkirchen, Germany
  • 6School of Geography, University of Leeds, Leeds, LS2 9JT, UK
  • 7School of GeoSciences, University of Edinburgh, Edinburgh, EH9 3JW, UK
  • 8Laboratoire d'Aérologie, Université deToulouse, Toulouse, 31400, France
  • 9DePaul University, Environmental Science Program, Chicago, IL 60614, USA
  • 10Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China
  • 11Dept. of Environmental Science, Policy, and Management, University of California at Berkeley, Berkeley, CA94720, USA
  • 12LAGEO, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
  • *now at: College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, EX4 4QF, UK
  • **now at: EOS Group, Department of Physics and Astronomy, University of Leicester, LE1 7RH, UK

Abstract. We have incorporated a semi-mechanistic isoprene emission module into the JULES land-surface scheme, as a first step towards a modelling tool that can be applied for studies of vegetation – atmospheric chemistry interactions, including chemistry-climate feedbacks. Here, we evaluate the coupled model against local above-canopy isoprene emission flux measurements from six flux tower sites as well as satellite-derived estimates of isoprene emission over tropical South America and east and south Asia. The model simulates diurnal variability well: correlation coefficients are significant (at the 95 % level) for all flux tower sites. The model reproduces day-to-day variability with significant correlations (at the 95 % confidence level) at four of the six flux tower sites. At the UMBS site, a complete set of seasonal observations is available for two years (2000 and 2002). The model reproduces the seasonal pattern of emission during 2002, but does less well in the year 2000. The model overestimates observed emissions at all sites, which is partially because it does not include isoprene loss through the canopy. Comparison with the satellite-derived isoprene-emission estimates suggests that the model simulates the main spatial patterns, seasonal and inter-annual variability over tropical regions. The model yields a global annual isoprene emission of 535 ± 9 TgC yr−1 during the 1990s, 78 % of which from forested areas.

Final-revised paper