Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 10 3 2010 10.5194/acpd-10-6923-2010 http://www.atmos-chem-phys-discuss.net/10/6923/2010/ http://www.atmos-chem-phys-discuss.net/10/6923/2010/acpd-10-6923-2010.html http://www.atmos-chem-phys-discuss.net/10/6923/2010/acpd-10-6923-2010.pdf 6923 6953 2010-03-11 Isoprene emissions modelling for West Africa using MEGAN J. Ferreira jferreira@ua.pt C. E. Reeves J. G. Murphy L. Garcia-Carreras D. J. Parker D. E. Oram School of Environmental Sciences, University of East Anglia, Norwich, UK Department of Chemistry, University of Toronto, Toronto, Canada Institute for Climate and Atmospheric Science, University of Leeds, Leeds, UK now at: CESAM & Department of Environment and Planning, University of Aveiro, 3810-193 Aveiro, Portugal Isoprene emissions are the largest source of reactive carbon to the atmosphere, with the tropics being a major source region. These natural emissions are expected to change with changing climate and human impact on land use. As part of the African Monsoon Multidisciplinary Analyses (AMMA) project the Model of Emissions of Gases and Aerosols from Nature (MEGAN) has been used to estimate the spatial and temporal distribution of isoprene emissions over the West African region. During the AMMA field campaign, carried out in July and August 2006, isoprene mixing ratios were measured on board the FAAM BAe-146 aircraft. These data have been used to evaluate the model performance. <br><br> MEGAN was firstly applied to a large area covering much of West Africa from the Gulf of Guinea in the south to the desert in the north and was able to capture the large scale spatial distribution of isoprene emissions as inferred from the observed isoprene mixing ratios. In particular the model captures the transition from the forested area in the south to the bare soils in the north, but some discrepancies have been identified over the bare soil, mainly due to the emission factors used. Sensitivity analyses were performed to assess the model response to changes in driving parameters, namely Leaf Area Index (LAI), Emission Factors (EF), temperature and solar radiation. <br><br> A high resolution simulation was made of a limited area south of Niamey, Niger, where the higher concentrations of isoprene were observed. This is used to evaluate the model's ability to simulate smaller scale spatial features and to examine the influence of the driving parameters on an hourly basis through a case study of a flight on 17 August 2006. <br><br> This study highlights the complex interactions between land surface processes and the meteorological dynamics and chemical composition of the PBL. This has implications for quantifying the impact of biogenic emissions on the atmospheric composition over West Africa and any changes that may occur with changing climate. Aghedo, A. M., Schultz, M. G., and Rast, S.: The influence of African air pollution on regional and global tropospheric ozone, Atmos. Chem. Phys., 7, 1193–1212, 2007. AMMA web site: http://www.amma-international.org, last access: December~2009. Andreae, M. O., Chapuis, A., Cros, B., Fontan, J., Helas, G., Justice, C., Kaufman, Y. J., Minga, A., and Nganga, D.: Ozone and Aitken Nuclei over Equatorial Africa – Airborne Observations During Decafe-88, J. Geophys. Res.-Atmos., 97, 6137–6148, 1992. Agust\'i-Panareda, A., Beljaars, A., Cardinali, C., Genkova, I., and Thorncroft, C.: Impact of assimilating AMMA soundings on ECMWF analyses and forecasts, Weather Forecast., in press, doi:10.1175/2010WAF2222370.1, 2010. Bechara, J., Borbon, A., Jambert, C., Colomb, A., and Perros, P. E.: Evidence of the impact of deep convection on reactive volatile organic compounds in the upper tropical troposphere during the AMMA experiment in West Africa, Atmos. Chem. Phys. Discuss., 9, 20309–20346, 2009. Cros, B., Fontan, J., Minga, A., Helas, G., Nganga, D., Delmas, R., Chapuis, A., Benech, B., Druilhet, A., and Andreae, M. O.: Vertical profiles of ozone between 0~meters and 400~meters in and above the African Equatorial Forest, J. Geophys. Res.-Atmos., 97, 12877–12887, 1992. Delmas, R., Lacaux, J. P., Menaut, J. C., Abbadie, L., Leroux, X., Helas, G., and Lobert, J.: Nitrogen Compound Emission from Biomass Burning in Tropical African Savanna Fos/Decafe-1991 Experiment (Lamto, Ivory-Coast), J. Atmos. Chem., 22, 175–193, 1995. Delmas, R. A., Druilhet, A., Cros, B., Durand, P., Delon, C., Lacaux, J. P., Brustet, J. M., Serca, D., Affre, C., Guenther, A., Greenberg, J., Baugh, W., Harley, P., Klinger, L., Ginoux, P., Brasseur, G., Zimmerman, P. R., Gregoire, J. M., Janodet, E., Tournier, A., Perros, P., Marion, T., Gaudichet, A., Cachier, H., Ruellan, S., Masclet, P., Cautenet, S., Poulet, D., Biona, C. B., Nganga, D., Tathy, J. P., Minga, A., Loemba-Ndembi, J., and Ceccato, P.: Experiment for Regional Sources and Sinks of Oxidants (EXPRESSO): An overview, J. Geophys. Res.-Atmos., 104, 30609–30624, 1999. Dudhia, J.: A nonhydrostatic version of the Penn State – NCAR Mesoscale Model: Validation tests and simulation of an Atlantic cyclone and cold front, Mon. Weather Rev., 121, 1493–1513, 1993. Fehsenfeld, F., Calvert, J., Fall, R., Goldan, P., Guenther, A. B., Hewitt, C. N., Lamb, B., Liu, S., Trainer, M., Westberg, H., and Zimmerman, P.: Emissions of volatile organic compounds from vegetation and the implications for atmospheric chemistry, Global Biogeochem. Cy., 6, 390–430, 1992. Flaounas, E., Bastin, S., and Janicot, S.: Regional climate modelling of the West African monsoon, Sensitivity to different physics schemes with WRF, submitted to Clim. Dynam., 2010. Fontan, J., Druilhet, A., Benech, B., Lyra, R., and Cros, B.: The Decafe Experiments – Overview and Meteorology, J. Geophys. Res.-Atmos., 97, 6123–6136, 1992. Garcia-Carreras, L., Parker, D. J., Taylor, C. M., Reeves, C. E., and Murphy, J. G.: Impact of mesoscale vegetation heterogeneities on the dynamical and thermodynamic properties of the planetary boundary layer, J. Geophys. Res., 115, D03102, doi:10.1029/2009JD012811, 2010. Greenberg, J. P., Guenther, A. B., Madronich, S., Baugh, W., Ginoux, P., Druilhet, A., Delmas, R., and Delon, C.: Biogenic volatile organic compound emissions in central africa during the experiment for the regional sources and sinks of oxidants (expresso) biomass burning season, J. Geophys. Res.-Atmos., 104, 30659–30671, 1999. Greenberg, J. P., Guenther, A., Harley, P., Otter, L., Veenendaal, E. M., Hewitt, C. N., James, A. E., and Owen, S. M.: Eddy flux and leaf-level measurements of biogenic voc emissions from mopane woodland of botswana, J. Geophys. Res.-Atmos., 108, 8466–8474, 2003. Grell, G. A., Dudhia, J., and Stauffer, D. R.: A description of the fifth-generation Penn State/NCAR mesoscale model~(MM5), NCAR/TN-398_STR, Penn State/NCAR, 1994. Guenther, A., Baugh, B., Brasseur, G., Greenberg, J., Harley, P., Klinger, L., Serca, D., and Vierling, L.: Isoprene emission estimates and uncertainties for the central african expresso study domain, J. Geophys. Res.-Atmos., 104, 30625–30639, 1999. Guenther, A., Hewitt, C. N., Erickson, D., Fall, R., Geron, C., Graedel, T., Harley, P., Klinger, L., Lerdau, M., McKay, W. A., Pierce, T., Scholes, B., Steinbrecher, R., Tallamraju, R., Taylor, J., and Zimmerman, P.: A global model of natural volatile organic compound emissions, J. Geophys. Res., 100, 8873–8892, 1995. Guenther, A., Karl, T., Harley, P., Wiedinmyer, C., Palmer, P. I., and Geron, C.: Estimates of global terrestrial isoprene emissions using MEGAN (Model of Emissions of Gases and Aerosols from Nature), Atmos. Chem. Phys. Discuss., 6, 107–173, 2006. Guenther, A., Otter, L., Zimmerman, P., Greenberg, J., Scholes, R., and Scholes, M.: Biogenic hydrocarbon emissions from southern african savannas, J. Geophys. Res.-Atmos., 101, 25859–25865, 1996. Harley, P., Monson, R., and Lerdau, M.: Ecological and evolutionary aspects of isoprene emission from plants, Oecologia, 118, 109-123, 1999. Janicot, S., Thorncroft, C. D., Ali, A., Asencio, N., Berry, G., Bock, O., Bourles, B., Caniaux, G., Chauvin, F., Deme, A., Kergoat, L., Lafore, J.-P., Lavaysse, C., Lebel, T., Marticorena, B., Mounier, F., Nedelec, P., Redelsperger, J.-L., Ravegnani, F., Reeves, C. E., Roca, R., de Rosnay, P., Schlager, H., Sultan, B., Tomasini, M., Ulanovsky, A., and ACMAD forecasters team: Large-scale overview of the summer monsoon over West Africa during the AMMA field experiment in 2006, Ann. Geophys., 26, 2569–2595, 2008. Jonquieres, I., Marenco, A., Maalej, A., and Rohrer, F.: Study of ozone formation and transatlantic transport from biomass burning emissions over West Africa during the airborne Tropospheric Ozone Campaigns TROPOZ~I and TROPOZ~II, J. Geophys. Res.-Atmos., 103, 19059–19073, 1998. Kavouras, I. G., Mihalopoulos, N., and Stephanou, E. G.: Formation of atmospheric particles from organic acids produced by forests, Nature, 395, 683–686, 1998. Klinger, L. F., Greenberg, J., Guenther, A., Tyndall, G., Zimmerman, P., M'Bangui, M., and Moutsambote, J. M.: Patterns in volatile organic compound emissions along a savanna-rainforest gradient in central africa, J. Geophys. Res.-Atmos., 103, 1443–1454, 1998. Lamb, B., Guenther, A., Gay, D., and Westberg, H.: A national inventory of biogenic hydrocarbon emissions, Atmos. Environ., 21, 1695–1705, 1987. Loreto, F. and Sharkey, T. D.: A gas-exchange study of photosynthesis and isoprene emission in Quercus rubra~L., Planta, 182, 523–531, 1990. MEGAN Data Portal: http://acd.ucar.edu/~guenther/MEGAN/MEGAN.htm, last access: January~2010, http://cdp.ucar.edu/, last access: January~2010. Monson, R., Hills, A., Zimmerman, P., and Fall, R.: Studies of the relationship between isoprene emission rate and CO₂ or photon-flux density using a real-time isoprene analyzer, Plant Cell Environ., 14, 517–523, 1991. Murphy, J. G., Oram, D. E., and Reeves, C. E.: Measurements of volatile organic compounds over West Africa, Atmos. Chem. Phys. Discuss., 10, 3861–3892, 2010. Müller, J.-F., Stavrakou, T., Wallens, S., De Smedt, I., Van Roozendael, M., Potosnak, M. J., Rinne, J., Munger, B., Goldstein, A., and Guenther, A. B.: Global isoprene emissions estimated using MEGAN, ECMWF analyses and a detailed canopy environment model, Atmos. Chem. Phys., 8, 1329–1341, 2008. National Centre for Environmental Prediction (NCEP) global 1-degree reanalysis data updated every 6-hours: http://dss.ucar.edu/datasets/ds083.2/data/, last access: October~2008. Otter, L. B., Guenther, A., and Greenberg, J.: Seasonal and spatial variations in biogenic hydrocarbon emissions from southern african savannas and woodlands, Atmos. Environ., 36, 4265–4275, 2002. Otter, L., Guenther, A., Wiedinmyer, C., Fleming, G., Harley, P., and Greenberg, J.: Spatial and temporal variations in biogenic volatile organic compound emissions for africa south of the equator, J. Geophys. Res.-Atmos., 108, SAF41.1–SAF41.12, 2003. Pfister, G. G., Emmons, L. K., Hess, P. G., Lamarque, J. F., Orlando, J. J., Walters, S., Guenther, A., Palmer, P. I., and Lawrence, P. J.: Contribution of isoprene to chemical budgets: A model tracer study with the ncar ctm mozart-4, J. Geophys. Res.-Atmos., 113, D05308, doi:10.1029/2007JD008948, 2008. Reeves, C. E., Formenti, P., Afif, C., Ancellet, G., Attie, J.-L., Bechara, J., Borbon, A., Cairo, F., Coe, H., Crumeyrolle, S., Fielri, F., Flamant, C., Gomes, L., Hamburger, T., Jambert, C., Law, K. S., Mari, C., Matsuki, A., Methven, J., Mills, G. P., Minikin, A., Murphy, J. G., Nielsen, J. K., Oram, D. E., Parker, D. J., Richter, A., Schlager, H., Schwarzenboeck, A., and Thouret, V.: Chemical and aerosol characterisation of the troposphere over West Africa during the monsoon period as part of AMMA, submitted to Atmos. Chem. Phys., 2010. Sauvage, B., Thouret, V., Cammas, J.-P., Gheusi, F., Athier, G., and Nédélec, P.: Tropospheric ozone over Equatorial Africa: regional aspects from from the MOZAIC data, Atmos. Chem. Phys., 5, 311–335, 2005. Sauvage, B., Thouret, V., Cammas, J. P., Brioude, J., Nedelec, P., and Mari, C.: Meridional ozone gradients in the African upper troposphere, Geophys. Res. Lett., 34, L03817, doi:10.1029/2006GL028542, 2007. Serca, D., Guenther, A., Klinger, L., Vierling, L., Harley, P., Druilhet, A., Greenberg, J., Baker, B., Baugh, W., Bouka-Biona, C., and Loemba-Ndembi, J.: Expresso flux measurements at upland and lowland congo tropical forest site, Tellus~B, 53, 220–234, 2001. Sijikumar, S., Roucou, P., and Fontaine, B.: Monsoon onset over Sudan-Sahel: Simulation by the regional scale model MM5, Geophys. Res. Lett., 33(3), L03814, doi:10.1029/2005GL024819, 2006. Sowden, M., Zunckel, M., and Van Tienhoven, A. M.: Assessment of the status of biogenic organic emissions and impacts on air quality in southern Africa, Tellus, 59B, 535–541, 2007. Williams, J. E., Scheele, M. P., van Velthoven, P. F. J., Cammas, J.-P., Thouret, V., Galy-Lacaux, C., and Volz-Thomas, A.: The influence of biogenic emissions from Africa on tropical tropospheric ozone during 2006: a global modeling study, Atmos. Chem. Phys., 9, 5729–5749, 2009. WRF Weather Research and Forecasting Model: http://www.wrfmodel.org/, last access: January~2010.