Publication Abstracts

Houweling et al. 2000

Houweling, S., F. Dentener, J. Lelieveld, B. Walter, and E. Dlugokencky, 2000: The modeling of tropospheric methane: How well can point measurements be reproduced by a global model? J. Geophys. Res., 105, 8981-9002, doi:10.1029/1999JD901149.

Global model simulations of tropospheric methane are presented using state of the art representations of its terrestrial sources. Parameters critical for its tropospheric sink and transport have been evaluated using CH3CCl3 and SF6. We assess how ell available methane measurements can be reproduced by the model, and how model and measurements can most efficiently be compared. Using European Centre for Medium-Range Weather Forecasts reanalyzed meteorological fields, direct comparisons between model results and flask or in situ measurements are presented, as opposed to comparing multiannual averaged seasonal cycles and trends as was done in previous studies. When comparing monthly means derived from weekly flask sampling and the model, the agreement at situations as Bermuda East and Mace Head is improved if, instead of sampling the model at each model time step, samples are taken at the same times as the measurements were taken. A method is presented to estimate the potential influence of subgrid variability using a marked tracer that is emitted in the vicinity of observational stations only. From the contribution of this tracer to the computed methane concentration at a particular station, the potential contribution of subgrid sources can be estimated. Radon 222 is used to select baseline conditions in the model to improve the comparability of model and measurements when a clean air sector is selected for sampling. Comparisons of model results and measurements, screened for local influences and artifacts of wind sector selection, indicate that the model has in particular difficulty reproducing seasonal cycles at higher latitude stations of the Northern Hemisphere. Sensitivity simulations show that the simulated annual variation at these stations is sensitive to the parameterizations of wetland emissions. Also at the South China Sea, model simulations point to errors in the representation of methane sources. Marked tracer simulations indicate that this is most likely related to emissions from natural wetlands and rice paddies, in line with recent inverse modeling and up-scaling estimates.

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BibTeX Citation

@article{ho02000x,
  author={Houweling, S. and Dentener, F. and Lelieveld, J. and Walter, B. and Dlugokencky, E.},
  title={The modeling of tropospheric methane: How well can point measurements be reproduced by a global model?},
  year={2000},
  journal={Journal of Geophysical Research},
  volume={105},
  pages={8981--9002},
  doi={10.1029/1999JD901149},
}

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RIS Citation

TY  - JOUR
ID  - ho02000x
AU  - Houweling, S.
AU  - Dentener, F.
AU  - Lelieveld, J.
AU  - Walter, B.
AU  - Dlugokencky, E.
PY  - 2000
TI  - The modeling of tropospheric methane: How well can point measurements be reproduced by a global model?
JA  - J. Geophys. Res.
JO  - Journal of Geophysical Research
VL  - 105
SP  - 8981
EP  - 9002
DO  - 10.1029/1999JD901149
ER  -

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