National Aeronautics and Space Administration

Publication Abstracts

Wu et al. 2007

Wu, S., L.J. Mickley, D.J. Jacob, J.A. Logan, R.M. Yantosca, and D. Rind, 2007: Why are there large differences between models in global budgets of tropospheric ozone? J. Geophys. Res., 112, D05302, doi:10.1029/2006JD007801.

Global 3-D tropospheric chemistry models in the literature show large differences in global budget terms for tropospheric ozone. The ozone production rate in the troposphere, P(O_x), varies from 2300 to 5300 Tg/yr across models describing the present-day atmosphere. The ensemble mean of P(O_x) in models from the post-2000 literature is 35% higher than that compiled in the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR). Simulations conducted with the GEOS-Chem model using two different assimilated meteorological data sets for 2001 (GEOS-3 and GEOS-4), as well as 3 years of GISS GCM meteorology, show P(O_x) values in the range 4250-4700 Tg/yr; the differences appear mostly because of clouds. Examination of the evolution of P(O_x) over the GEOS-Chem model history shows major effects from changes in heterogeneous chemistry, the lightning NO_x source, and the yield of organic nitrates from isoprene oxidation. Multivariate statistical analysis of model budgets in the literature indicates that 74% of the variance in P(O_x) across models can be explained by differences in NO_x emissions, inclusion of nonmethane volatile organic compounds (NMVOCs, mostly biogenic isoprene), and ozone influx from stratosphere-troposphere exchange (STE). Higher NO_x emissions, more widespread inclusion of NMVOC chemistry, and weaker STE in the more recent models increase ozone production; however, the effect of NMVOCs does not appear generally sensitive to the magnitude of emissions within the range typically used in models (500-900 Tg C/yr). We find in GEOS-Chem that P(O_x) saturates when NMVOC emissions exceed 200 Tg C/yr because of formation of organic nitrates from isoprene oxidation, providing an important sink for NO_x.

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@article{wu01000b,
  author={Wu, S. and Mickley, L. J. and Jacob, D. J. and Logan, J. A. and Yantosca, R. M. and Rind, D.},
  title={Why are there large differences between models in global budgets of tropospheric ozone?},
  year={2007},
  journal={J. Geophys. Res.},
  volume={112},
  pages={D05302},
  doi={10.1029/2006JD007801},
}

TY  - JOUR
ID  - wu01000b
AU  - Wu, S.
AU  - Mickley, L. J.
AU  - Jacob, D. J.
AU  - Logan, J. A.
AU  - Yantosca, R. M.
AU  - Rind, D.
PY  - 2007
TI  - Why are there large differences between models in global budgets of tropospheric ozone?
JA  - J. Geophys. Res.
VL  - 112
SP  - D05302
DO  - 10.1029/2006JD007801
ER  -

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