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GEOS-Chem "Science Codebase" repository. Contains GEOS-Chem science routines, run directory generation scripts, and interface code. This repository is used as a submodule within the GCClassic and GCHP wrappers, as well as in other modeling contexts (external ESMs).
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Changes in GFED4 Emissions Factors between 14.1 and 14.4 #2575

Closed JFBrewer closed 6 days ago

JFBrewer commented 6 days ago

Your name

Jared Brewer

Your affiliation

University of Minnesota

Please provide a clear and concise description of your question or discussion topic.

I am curious about the origin of the changes in the species-specific Emissions Factors between GC 14.1 and 14.5, specifically those in HEMCO/src/Extensions/hcox_gfed_include_gfed4.H. The changes for ethane in particular are very significant, and I'd love to read something detailed about them. I figured I'd find it here, but I'm not seeing what I expected.

Two separate changes seem to have been made between 14.1 and 14.5: one to the GFED files (transitioning from v2020-02 to v2023-03) and one to the actual species-specific emission factors in HEMCO/src/Extensions/hcox_gfed_include_gfed4.H. Of these, I am interested in the latter. The change to the various ethane emissions factors shifts the timing of the peak of biomass burning emissions, as well as decreasing the magnitude of the peak, even when run on the same set of input files. The emissions factors in 14.1 appear (based on my brief perusal) to correspond to Akagi 2011. So where are the new ones coming from?

It looks to me like the main changes in GFED during the relevant versions are the changes to GFED by Makoto and @msulprizio, in which they added GFED4 climatology options and extended the GFED4 data through October 2022. However, the paper cited is just the 2013 GFED paper from Giglio et al. I assume this update pertains to the change from v2020-02 to v2023-03 input files. But does it also account for the changed emission factors?

@kelvinhb added some additional emissions factors for his alkanes, but I don't think this accounts for the changes I'm seeing (the ethane and many other species as well).

Thanks, Jared

yantosca commented 6 days ago

Thanks for writing @JFBrewer. So there is a neat way to look at which commit corresponds to each line of code, and that is to use the Git Blame feature. If you point your browser to any file in a GitHub repo and then click on the "Blame" button you will see the lines of code and the last commit that touched them.

For example, if you look at the C2H6 lines in hcox_gfed_include_gfed4.H, you will see this output:

c2h6

Then we see the last commit was made 1 year ago. If you click on the commit name it'll take you to this screen:

c2h6-2

which has the commit message. Thankfully @msulprizio placed the journal article references in the commit message, so you see that the updates are either in the Tess Carter et al. 2022 or the Andreae et al 2019 paper.

kelvinhb commented 6 days ago

Hey Jared -- if you click the "blame" tab on github when you're on the relevant file, you can see what commit the change was part of, and in this case it looks like it was from last year when Tess Carter updated some of the emission factors to Meinrat Andreae's 2019 paper.

kelvinhb commented 6 days ago

Ha, Bob, you beat me to it :)

yantosca commented 6 days ago

@kelvinhb: Great minds think alike. :-)

JFBrewer commented 6 days ago

Thank you both! I appreciate both the information and the tutorial!