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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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Differences between different versions of the "soilNOx.fert_res.generic.05x05.nc" file #2429

Closed hlbutterfly closed 3 weeks ago

hlbutterfly commented 4 weeks ago

Your name

Ling Huang

Your affiliation

Shanghai University

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

I am recently looking at the fertilizer input file to drive the BDSNP algorithm to calculate the soil NO emissions. It seems that two versions of the nitrogen reservoir files (both with file name "soilNOx.fert_res.generic.05x05.nc") are provided by GEOS-Chem: version 2012: https://ftp.as.harvard.edu/gcgrid/data/ExtData/GEOS_NATIVE/soil_NOx_201208/ version 2014 (last modified 2021): https://ftp.as.harvard.edu/gcgrid/data/ExtData/HEMCO/SOILNOX/v2014-07/

The v2012 file has a unit of "ng/m2" while the v2014 file has a unit of "kg/m3". According to the readme, the unit in the v2014 file (changed from kg/m2 to kg/m3) was because of the automatic unit conversion of HEMCO. Other than that, these two files should be identical. However, when I compared the totals between the two files, they differ roughly by a factor of 2 (with the v2014 file being higher).

I am wondering what got changed between the two versions. And if I want to use the file to drive offline BDSNP algorithm, which file should I use?

Thanks Ling

yantosca commented 4 weeks ago

Thanks for writing @hlbutterfly. I believe the 2012 files use ng N/m2 and the 2014 files use kg NO/m3. Thus the 2014 files would have (14 + 16) / 14 = 2x higher totals.

We would recommend using the 2014 data (HEMCO/SOILNOX/v2014-07/) as this has been validated with GEOS-Chem benchmark simulations.

hlbutterfly commented 4 weeks ago

Thanks for the reply, Bob!

My follow-up question is: if using the 2014 data, is there any intermediate step within GEOS-Chem that converts NO to N before the BDSNP algorithm? I am asking this because I want to make sure the scaling factor (0.0068) is derived based on the value of 'NO' or the value of 'N'.

image

Thanks again! Ling

yantosca commented 4 weeks ago

@hlbutterfly. I do not know the answer to how the scaling factor was computed. I presume it is based on NO. You can do a quick calculation to verify.

hlbutterfly commented 3 weeks ago

@yantosca Thanks Bob! The information on NO vs. N is really helpful.