Biogenic hydrocarbon emission modeling
The multi-layer canopy environment model MOHYCAN developed in collaboration with A. Guenther at NCAR (Boulder, USA) calculates the attenuation of light due to the canopy and the temperature of the leaves, based on an energey balance equation. A complete description is provided in the Supplement of “Inversion of and emissions using the adjoint of the IMAGES model” (.pdf, 75KB).
Coupled with the emission algorithm of the MEGAN model (Model of Emissions of Gases and Aerosols from Nature, cfr. Guenther et al. (2006)), it is used to estimate the emissions of isoprene by vegetation.
The emissions depend on factors like the light intensity and temperature, the plant species, the conditions experienced by the leaves in the past days or weeks, the age of the leaves, and the stress associated to drought. The MEGAN algorithms attempt to represent these impacts.
The coupled model has been tested against measurement campaigns in different ecosystems: a temperate forest in Massachusetts, a tropical forest in Brazil. The short-term variability (diurnal cycle, day-to-day variations) is very well captured by the model. In some cases, however, the seasonal variation of the emissions is not well reproduced.
Global emission inventories
Based on MEGAN and MOHYCAN, global inventories of isoprene and methanol emissions have been realized, at a resolution of 0.5° (Müller et al., 2008, Stavrakou et al. 2010). They are driven by ECMWF meteorological analyses.
References
- Stavrakou, T., A. Guenther, A. Razavi, L. Clarisse, P.-F. Coheur, D. Hurtmans, F. Karagulian, M. De Mazière, C. Vigouroux, C. Amelynck, N. Schoon, Q. Laffineur, B. Heinesch, M. Aubinet, and J.-F. Muller : First space-based derivation of the global atmospheric methanol emission fluxes, Atmos. Chem. Phys., 2010, submitted.
- Müller, J.-F.,T Stavrakou, S. Wallens, I. De Smedt, M. Van Roozendael, M. Potosnak, J. Rinne, B. Munger, A. Goldstein, A. Guenther : Global isoprene emissions estimated using MEGAN, ECMWF analyses and a detailed canopy environment model, Atmos. Chem. Phys., 8, 1329-1341, 2008. [Full article]
- Guenther, A., T. Karl, P. Harley, C. Wiedinmeyer, P.I. Palmer, and C. Geron :Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature), Atmos. Chem. Phys., 6, 3181-3210, 2006 [Full article]
- S. Wallens, PhD Thesis, Modélisation des émissions de composés organiques volatils par la végétation, Univesité Libre de Bruxelles, 2004. (.pdf, 7.5MB)
- Description of the canopy environment model MOHYCAN (.pdf, 75KB)
