Data and Code
The current version of MEGAN, MEGAN3.1, was released in October 2019 and a final version is expected to be available in Spring 2020. MEGAN3.1 is illustrated in the above diagram and is described in a user guide .
To run MEGAN3.1 you will need 1) input data (geogridded and bio-characteristics) and 2) code (preprocessor, emission factor processor, emission calculator and chemical mechanisms). Each of these are described below:
Geogridded input data (for the preprocessor Fortran code)
Use the preprocessor to regrid these data to fit your model domain
Leaf Area Index of vegetation covered surfaces: US, North America and Global datasets are available and described here: LAIvdata
Growth form and ecotypes: Global datasets are available and described here: GFecotypedata
2. Soil nitrogen emission module inputs
Soil NO model inputs (Global)
3. Stress response algorithm inputs (Optional- use only if you want to include stress responses)
These are netcdf format files with monthly values of gammaSM on a global 0.5 degree grid. They were calculated using the approach described by Jiang et al. Atmos Environ , 2018 https://doi.org/10.1016/j.atmosenv.2018.01.026.
W126 ozone index (US)
4. Physical weather
Biogenics input data (for the Emission Factor Processor Python code)
Plant species composition:
These files define plant species composition for each growth form in each ecotype. An example is the MEGAN2019a speciation dataset which has detailed tree speciation data for the continuous US (based on USFS FIA data) but minimal information for other regions and other growth forms.
Vegetation type BVOC emission factors:
These files include a definition of vegetation types and a database of BVOC emission factors reported for those vegetation types. An example is the MEGAN2019b vegetation type EF data.
Preprocessor (Fortran code)
MEGAN3.1beta Preprocessor: Download the preprocessor (FORTRAN code).
Use this code to regrid input data to your domain. The output of the preprocessor is used as input to the Emission Factor Processor (Python code) and the Emission Calculator (Fortran code)
Emission Factor Processor (Python code)
MEGAN3.2 Emission Factor Processor is under development. This code can be used to integrate growth form, ecotype, plant species composition and species-specific emission factor data to generate landscape average emission factors for your model domain.
Emission Calculate and Speciate (Fortran code)
MEGAN3.1beta Emission Calculate and Speciate. Download the emission calculate and speciate Fortran code
Use this code to calculate biogenic emissions.
Emission calculator test cases: example input/output data for some specific model domains
MEGAN3: Released in July 2017. Replaced by MEGAN3.1
MEGAN2.1: The MEGAN2.1 code was released in 2013. User guide, code, driving variables and a test case are still available.
MEGAN2.04: Released in 2007 on the UCAR Community Data Portal.