Model of Emissions of Gases and Aerosols from Nature (MEGAN)

MEGAN is a modeling system for estimating the net emission of gases and aerosols from terrestrial ecosystems into the atmosphere. Driving variables include landcover, weather, and atmospheric chemical composition. MEGAN is a global model with a base resolution of ~ 1 km and so is suitable for regional and global models. A FORTRAN code is available for generating emission estimates for the CMAQ regional air quality model. The algorithms have also been incorporated as an on-line component in several regional and global chemistry and transport models. Global distributions of landcover variables (Emission Factors, Leaf Area Index, and Plant Functional Types) are available for spatial resolutions ranging from ~ 1 to 100 km and in several formats (ARCGIS, netcdf).

It should be noted that running this version of MEGAN requires both access to and knowledge of a Unix operating system and working knowledge of FORTRAN. If you need to regrid the MEGAN input files then you will also need knowledge/access to Python computer language and ESRI ArcMAP software (or some alternative regridding software). Users who have never been exposed to Unix-type operating systems (i.e., if you are only familiar with Windows) unfortunately will find it difficult to run MEGAN. Although you do not need to be a computer programmer to run the model, you should have a basic understanding of computer programming and Unix (i.e., you should know how to unzip/untar files and other basic commands in Unix, install libraries and link files within Unix, and know basic FORTRAN commands such as how to invoke a code). If you need to regrid landcover data then you should also be familiar with (and have access to) ArcMAP or a similar program. In summary, you should have a working knowledge of ArcMap, Unix, FORTRAN, and Python before attempting to use MEGAN. We have listed information and resources at the bottom of this page that we hope will be helpful to those individuals interested in learning more about the tools and programs necessary to run MEGAN.

MEGANv2.04 (released October 29, 2007)

User Guides:

1. FORTRAN code User Guide: Describes how to download and run a FORTRAN code that generates biogenic emission estimates for CMAQ.

2. Data Portal User Guide: Describes how to access the code and input data.

Landcover datasets that can be used as inputs for the FORTRAN code v2.04. include version 2.0 and version 2.1

• Leaf Area Index version 2.0
• Plant Functional Type version 2.1
• Emission Factors version 2.1

MEGAN2.1beta

1. MEGAN2.1 User Guide: Describes how to install and run a FORTRAN code that generates biogenic emission estimates for CMAQ or CAMx. Weather and landcover driving variables are also described.

2. MEGAN2.1 code: MEGANv2.1 FORTRAN code.

3. Input variables preprocessor tool: A tool that can be used to generate input files for MEGANv2.1.

4. North America Leaf Area Index (version 2011) input files: 30 arc-second 8-day average LAI input files for North America for years 2003 to 2011 based on NASA MODIS data. Files are in netcdf format with a file naming convention of lainaYYYYDDD.nc where YYYY is year and DDD is day of year.

5. North America Plant Functional Type (version 2011) input files: 30 arc-second (aggregated from 30 m data) PFT (CLM 16 PFT classification system) input file for year 2008. Files are in netcdf format with a file naming convention of pftNNdddYY.nc where NN is CLM PFT number, ddd is description and YY is year (08 for 2008).

6. Global emission factor input files (version 2011): Emission factor input files. Files are in netcdf format with a file naming convention of cccc.nc where cccc is compound class. Note that this file is optional- the alternative is to have MEGAN generate emission factors from PFTs.

7. MEGAN2.1 test case: MEGANv2.1 input and output data for U.S. test case to see if you are able to run MEGAN2.1 correctly.

MEGAN development and description

• Guenther, A. B., Jiang, X., Heald, C. L., Sakulyanontvittaya, T., Duhl, T., Emmons, L. K., and Wang, X.: The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1): an extended and updated framework for modeling biogenic emissions, Geosci. Model Dev. Discuss., 5, 1503-1560, doi:10.5194/gmdd-5-1503-2012, 2012. This manuscript describes MEGAN2.1.

· Duhl, T., A. Guenther and D. Helmig. Estimating urban vegetation cover fraction using Google Earth® images, J. of Land Use Science, doi: 10.1080/1747423X.2011.587207, 2011. MEGAN landcover technique.

• Stavrakou, T., Guenther, A., Razavi, A., Clarisse, L., Clerbaux, C., Coheur, P.-F., Hurtmans, D., Karagulian, F., De Mazière, M., Vigouroux, C., Amelynck, C., Schoon, N., Laffineur, Q., Heinesch, B., Aubinet, M., Rinsland, C., and Müller, J.-F.: First space-based derivation of the global atmospheric methanol emission fluxes, Atmos. Chem. Phys., 11, 4873-4898, doi:10.5194/acp-11-4873-2011, 2011. This manuscript describes MEGAN2.1 methanol emissions.
• Boy, M., A. Sogachev, J. Lauros, L. Zhou, A. Guenther, and S. Smolander, SOSA - a new model to simulate the concentrations of organic vapours and sulphuric acid inside the ABL - Part 1: Model description and initial evaluation, Atmos. Chem. Phys. J1 - ACP, 11 (1), 43-51, 2011. 1D version of MEGAN incorporated into the SOSA model
• Millet, D. B., Guenther, A., Siegel, D. A., Nelson, N. B., Singh, H. B., de Gouw, J. A., Warneke, C., Williams, J., Eerdekens, G., Sinha, V., Karl, T., Flocke, F., Apel, E., Riemer, D. D., Palmer, P. I., and Barkley, M.: Global atmospheric budget of acetaldehyde: 3-D model analysis and constraints from in-situ and satellite observations, Atmos. Chem. Phys., 10, 3405-3425, doi:10.5194/acp-10-3405-2010, 2010. This manuscript describes MEGAN2.1 acetaldehyde and ethanol emissions.
• Emmons, L. K., Walters, S., Hess, P. G., Lamarque, J.-F., Pfister, G. G., Fillmore, D., Granier, C., Guenther, A., Kinnison, D., Laepple, T., Orlando, J., Tie, X., Tyndall, G., Wiedinmyer, C., Baughcum, S. L., and Kloster, S.: Description and evaluation of the Model for Ozone and Related chemical Tracers, version 4 (MOZART-4), Geosci. Model Dev., 3, 43-67, 2010. Describes incorporation of MEGAN into MOZART model.
• Guenther et al., J. Geophys. Res., 104, 30625-30639 (1999): This manuscript describes the canopy environment model used in MEGAN.
• Guenther et al., ACP 6, 3181-3210 (2006). Also read the Corrigendum which corrects typographical errors in some equations. This manuscript describes MEGAN2.0 isoprene emission algorithms, emission factors and landcover data.
• Sakulyanontvittaya et al. Environ. Science and Technology, 42, 1623-1629, 2008. This manuscript investigates the sensitivity of MEGAN emission estimates to the monoterpene and sesquiterpene parameters.

MEGAN application

• Mogensen, D., Smolander, S., Sogachev, A., Zhou, L., Sinha, V., Guenther, A., Williams, J., Nieminen, T., Kajos, M. K., Rinne, J., Kulmala, M., and Boy, M.: Modelling atmospheric OH-reactivity in a boreal forest ecosystem, Atmos. Chem. Phys., 11, 9709-9719, doi:10.5194/acp-11-9709-2011, 2011.
• Arneth, A., Schurgers, G., Lathiere, J., Duhl, T., Beerling, D. J., Hewitt, C. N., Martin, M., and Guenther, A.: Global terrestrial isoprene emission models: sensitivity to variability in climate and vegetation, Atmos. Chem. Phys., 11, 8037-8052, doi:10.5194/acp-11-8037-2011, 2011.
• Hewitt, C.N., K. Ashworth, A. Boynard, A. Guenther, B. Langford, A.R. MacKenzie, P.K. Misztal, E. Nemitz, S.M. Owen, M. Possell, T.A.M. Pugh, A.C. Ryan, and O. Wild, Ground-level ozone influenced by circadian control of isoprene emissions, Nature Geosciences, 4 (10), 671-674, 2011.
• Geng, F., X. Tie, A. Guenther, G. Li, J. Cao, and P. Harley, Effect of isoprene emissions from major forests on ozone formation in the city of Shanghai, China, Atmos. Chem. Phys., 11, 10449-10459, 2011.
• Kurtén, T.; Zhou, L.; Makkonen, R.; Merikanto, J.; Räisänen, P.; Boy, M.; Richards, N.; Rap, A.; Smolander, S.; Sogachev, A.; Guenther, A.; Mann, G. W.; Carslaw, K.; Kulmala, M., Large methane releases lead to strong aerosol forcing and reduced cloudiness. Atmos. Chem. Phys. 2011, 11 (14), 6961-6969.
• Wang X., Situ S., A. Guenther, F. Chen, Z. Wu and B. Xia, Study of spatiotemporal variability of biogenic terpenoid emissions with high-resolution land-cover and meteorological data, Tellus 63B, 241-254, 2011.
• Warneke, C. J. de Gouw, L. Del Negro, J. Brioude, S. McKeen, H. Stark, W. Kuster, P. Goldan, M. Trainer, F. Fehsenfeld, C. Wiedinmyer, A. Guenther, A. Hansel, A. Wisthaler, E. Atlas, J. Holloway, T. Ryerson, J. Peischl, L. G. Huey, A. Hanks. Biogenic emission measurement and inventories determination of biogenic emissions in the eastern United States and Texas and comparison with biogenic emission inventories, J. Geophys. Research, 115, D00F18, doi:10.1029/2009JD012445, 2010.
• Leung, D. Y. C., P. Wong, B. K. H. Cheung, and A. Guenther, Improved land cover and emission factors for modeling biogenic volatile organic compounds emissions from Hong Kong, Atmospheric Environment, 44, 1456-1468, 2010.

· Chen, J., J. Avise, A. Guenther, C. Wiedinmyer, E. Salathe, R. Jackson and B. Lamb, Future land use and land cover influences on regional biogenic emissions and air quality in the United States, Atmospheric Environment, 43, 5771-5780, 2009.

• Heald, C., M. Wilkinson, R. Monson, C. Alo, G. Wang and A. Guenther, Response of isoprene emission to ambient CO2 changes and implications for global budgets Global Change Biology, 15, 1127–1140, 2009.
• Karl, M., A. Guenther, R. Köble, and G. Seufert, A new European plant-specific emission inventory of biogenic volatile organic compounds for use in atmospheric transport models, Biogeosciences, 6, 1059-1087, 2009.
• Papiez, M., M. Potosnak, W. Goliff, A. Guenther, S. Matsunaga, and W. Stockwell, The Impacts of Reactive Terpene Emissions from Plants on Air Quality in Las Vegas, Nevada, Atmos. Environ., 43, 4109-4123, 2009.
• Stavrakou, T. J.-F. Müller, I. De Smedt, M. Van Roozendael, G. R. van der Werf, L. Giglio, and A. Guenther, Global emissions of non-methane hydrocarbons deduced from SCIAMACHY formaldehyde columns through 2003–2006, Atmos. Chem. Phys., 9, 3663-3679, 2009.
• Tsui, J., A. Guenther, W. Yip, F. Chen, A biogenic volatile organic compound emission inventory for Hong Kong, Atmospheric Environment, 43, 6442-6448, 2009.
• Barkley, M. P., P. I. Palmer, I. De Smedt, T. Karl, A. Guenther, and M. Van Roozendael, Regulated large-scale annual shutdown of Amazonian isoprene emissions?, Geophys. Res. Lett., 36, L04803, doi:10.1029/2008GL036843, 2009.
• Avise, J., Chen, J., Lamb, B., Wiedinmyer, C., Guenther, A., Salathé, E., and Mass, C.: Attribution of projected changes in summertime US ozone and PM_2.5 concentrations to global changes, Atmos. Chem. Phys., 9, 1111-1124, 2009.

· Chen, J., J. Avise, B. Lamb, E. Salathe, C. Mass, A. Guenther, C. Wiedinmyer, J.-F. Lamarque, S. O’Neill, D. McKenzie, and N. Larkin, The effects of global changes upon regional ozone pollution in the United States, Atmos. Chem. Phys., 9, 1125-1141, 2009.

· Stavrakou, T., J.-F. Muller, I. De Smedt, M. van Roozendael, . van der Werf, L. Giglio, and A. Guenther, Evaluating the performance of pyrogenic and biogenic emission inventories against one decade of space-based formaldehyde columns, Atmos. Chem. Phys., 9, 1037-1060, 2009.

· Wang, X., F. Chen, C. Wiedinmyer, A. Guenther, M. Tewari and Z. Chai, Impacts of weather conditions modified by urban expansion on surface ozone: Comparison between the Pearl River Delta and Yangtze River Delta regions, Advances in Atmospheric Sciences, 26, 962-972, 2009.

• Barkley, M. P., P. I. Palmer, U. Kuhn, J. Kesselmeier, K. Chance, T. P. Kurosu, R. V. Martin, D. Helmig, and A. Guenther, Net ecosystem fluxes of isoprene over tropical South America inferred from Global Ozone Monitoring Experiment (GOME) observations of HCHO columns, J Geophys Res-Atmos, 113(D20), D20304, 2008.
• Boy, M., J. Kazil, E. Lovejoy, A. Guenther and M. Kulmala, Relevance of ion-induced nucleation of sulfuric acid and water in the lower troposphere over the boreal forest at northern latitudes, Atmospheric Research 90 151-158, 2008.
• Heald, C.L., D.K. Henze, L.W. Horowitz, J. Feddema, J.-F. Lamarque, A. Guenther, P.G. Hess, F. Vitt, J.H. Seinfeld, A.H. Goldstein and I. Fung, Predicted change in global secondary organic aerosol concentrations in response to future climate, emissions, and land-use change, J. Geophys. Res., 113 D05211, doi:10.1029/2007JD009092, 2008.
• Matsunaga, S. N., A. B. Guenther, M. J. Potosnak, M. J., and E. C. Apel, Emission of sunscreen salicylic esters from desert vegetation and their contribution to aerosol formation, Atmos. Chem. Phys., 8, 7367-7371, 2008.
• Megonigal, J. P. and A. B. Guenther, Methane emissions from upland forest soils and vegetation, Tree Physiology, 28, 491-498, 2008.
• Millet, D. B., D. J. Jacob, K. F. Boersma, T. Fu, T. P. Kurosu, K. Chance, C. L. Heald, and A. Guenther (2008), Spatial distribution of isoprene emissions from North America derived from formaldehyde column measurements by the OMI satellite sensor, J. Geophys. Res., 113, D02307, doi:10.1029/2007JD008950.
• Pfister, G., L. Emmons, P. Hess, J.-F. Lamarque, J. Orlando, S. Walters, A. Guenther, P. Palmer, P. Lawrence, Contribution of isoprene to chemical budgets: A model tracer study with the NCAR CTM MOZART-4, J. Geophys. Res., 113 D05308, doi: 10.1029/2007JD008948, 2008.
• Sakulyanontvittaya, T., A. Guenther, D. Helmig, J. Milford, and C. Wiedinmyer, Secondary organic aerosol from sesquiteprene and monoterpene emissions in the United States, Environmental Science and Technology, 42, 8784-8790, 2008.

· Müller, J.-F., T. Stavrakou, S. Wallens, I. De Smedt, M. Van Roozendael, M. J. Potosnak, J. Rinne, B. Munger, A. Goldstein, and A. B. Guenther , Global isoprene emissions estimated using MEGAN, ECMWF analyses and a detailed canopy environment model, Atmos. Chem. Phys., 8, 1329-1341, 2008.

• Karl, T., A. Guenther, J. Greenberg, R. Yokelson, D. Blake, M. Potosnak and P. Artaxo, The tropical forest and fire emissions experiment: Emission, chemistry, and transport of biogenic volatile organic compounds in the lower atmosphere over Amazonia, J. Geophys. Res., 112, D18302, doi:10.1029/2007JD008539, 2007.
• Helmig, D., J. Ortega, T. Duhl, D. Tanner, A. Guenther, P. Harley, C. Wiedinmyer, J. Milford, T. Sakulyanontvittaya, Sesquiterpene emissions from pine trees- Identifications, emission rates and flux estimates for the contiguous United States, Environ. Sci. Tech., 41, 1545-1553, 2007.
• Shim, C., Y. Wang, H. Singh, D. Blake, and A. Guenther, Source characteristics of oxygenated volatile organic compounds and hydrogen cyanide, J. Geophys. Res., 112, D10305, doi: 10.1029/2006JD007543, 2007.
• Ortega, J., D. Helmig, A. Guenther, P. Harley, S. Pressley, and Christoph Vogel, Flux estimates and OH reaction potential of reactive biogenic volatile organic compounds (BVOCs) from a mixed northern hardwood forest, Atmos. Environ., 41, 5479-5495, 2007.
• Donkelaar, A., R. Martin, R. Park, C. Heald, T.-M. Fu, A. Guenther, Model evidence for a significant source of secondary organic aerosol from isoprene, Atmospheric Environment , 41, 1267-1274, 2007.

Contact:

Xiaoyan Jiang <xjiang@ucar.edu>

Alex Guenther <guenther@ucar.edu>

Resources for using MEGAN:

FORTRAN is a general purpose language mainly developed to perform mathematical operations, (compilers may be found at http://www.fortran.com/compilers.html), while Python (http://python.org/) is a general-purpose, high-level language. ArcMAP is a Geographic Information System (GIS) software platform that is used (in the case of MEGAN processing) for the input data preprocessing steps (specifically to average the various input dataset values within each cell of your model domain), and is not needed if a user is programming-savvy enough to write spatial allocation code that can perform the same task without ArcMAP. You can find out more about ArcMAP, including how to download a 60-day trial version at: http://www.esri.com/software/arcgis/arcgis-for-desktop/index.html. It is possible that the free trial version of ArcMAP does not include some of the processing tools needed to complete MEGAN input data preprocessing, but is at least a starting point for becoming familiar with ArcMAP.

You may also find the following online tutorials useful:

1. FORTRAN tutorial: http://folk.uio.no/steikr/doc/f77/tutorial/index.html

2. UNIX tutorial: http://www.ee.surrey.ac.uk/Teaching/Unix/

3. ArcMAP tutorial (version 9.3): http://webhelp.esri.com/arcgisdesktop/9.3/tutorials/tutorials.htm

4. Python tutorials: http://python.org/