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JGCRI / gcam-core

GCAM -- The Global Change Analysis Model
http://jgcri.github.io/gcam-doc/
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Calculation of forest fire emissions in GCAM #481

Open CGL5230 opened 5 days ago

CGL5230 commented 5 days ago

Hello GCAM team,

I'm looking to understand how GCAM-core models carbon emissions from forest or vegetation fires. Specifically, could you point me to the sections or modules where fire emissions are parameterized or configured?

I see “Emissions in the agriculture and land use system can be driven by output (e.g., for crop production) or land area (e.g., for forest fires). in the documentation(doc), but I can't find the corresponding code under this path, am I looking for the wrong one?

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In Carbon Emissions section,It looks like forest fires are considered a type of land use type conversion, if I want to get emissions from forest fires separately, where are the corresponding formulas and codes?

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Thanks for your help!

pkyle commented 4 days ago

The modeling approach is different for the non-CO2 emissions, as compared to the CO2 emissions, for open biomass burning. Non-CO2 emissions are more or less taken directly from inventories, though there is a distinction in the model between emissions related to deforestation (i.e. clearing of forest for other uses) as opposed to forest fires on lands that are assumed to remain as forests afterwards. From the model's perspective, forest fires do not amount to land use change, and do not produce net CO2 emissions, but do produce non CO2 emissions. Deforestation (i.e., net transition of land from forest to other uses, at the scale of the land use regions in the model) produces net CO2 emissions based on the difference in carbon density between forest and the land use types that increased. The net carbon emissions or sequestration from changes in land use is estimated using a simple carbon cycle model. To your question about where in the model to find the relevant information, most of the key parameters for the carbon cycle modeling (and LUC CO2 emissions) are found in the input/gcamdata/xml/land_input_*.xml files, where each land use type is assigned terminal vegetative carbon density, terminal soil carbon density, and mature age, which is the number of years for reaching terminal vegetative carbon density. Non-CO2 emissions and emissions factors are assigned in (same folder) all_unmgd_emissions.xml and all_aglu_emissions_IRR_MGMT.xml