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geoschem / geos-chem

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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What are all the computations for which GEOS-Chem needs data about the surface properties? #2193

Closed garvitagarwal290 closed 7 months ago

garvitagarwal290 commented 7 months ago

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Name: Garvit Agarwal Institution: TCS Research, Pune, India

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Description of your issue or question

What are all the computations for which GEOS-Chem needs data about the various surface properties (including oceans, ice etc)? As far as I understand surface properties are needed for information on elevation which affects winds, and land-use data which affects emissions. But since we are supposed to provide the meteorological data (on winds, pressure etc) and the emission data explicitly to GEOS-Chem, why are surface properties needed?

My guess is that it is needed for processes like deposition and PBL mixing. Then my follow-up question is that, if I just use TPCORE transport and switch off everything else in geoschem_config.yml, are surface properties used at all in the simulation? Thank you.

yantosca commented 7 months ago

Hi @garvitagarwal290, thanks for writing. We have a list of the MERRA-2 met fields and in which operations they are used on the GEOS-Chem wiki. See:

NOTE: The ReadTheDocs manuals contain instructions on e.g. download/setup/use of GEOS-Chem. We still have information about met fields, science info, etc. on the wiki. You can check on the wiki if you don't see anything on ReadTheDocs.

garvitagarwal290 commented 7 months ago

Hi, I had already looked into the information at https://wiki.seas.harvard.edu/geos-chem/index.php/List_of_MERRA-2_met_fields which implies that if I use only advection, no surface properties are needed. I just wanted to confirm whether no surface properties (like elevation, land/ocean fraction) are used to adjust other meteorological quantities like winds, pressure etc. Could you point me to someone who might help in this more science-oriented question? I couldn't find this minute information on the GEOS-Chem wiki.

yantosca commented 7 months ago

Ah I see @garvitagarwal290, The surface properties are more used in e.g. computation of dry deposition velocities and biogenic emissions. They should not feed back onto other meteorological quantities within GEOS-Chem.

Tagging the GEOS-Chem Surface and Atmosphere Working Group co-chairs: @jgeddes85 @cdholmes @amospktai

jgeddes85 commented 7 months ago

Hi @garvitagarwal290, I write just to confirm what @yantosca has mentioned. The surface properties in GEOS-Chem are used to calculate biogenic emissions of VOCs and NOx, and to calculate dry deposition velocities. Note that each of these processes uses slightly different land use/land cover schemes, and so aren't entirely harmonized (I'll plug my paper here, where we tried to harmonize these processes to the same input source from CLM files, but this is not in the public release of the model). But as @yantosca explains, the meteorology is not coupled to our land surface inputs. Let me know if you have more questions!

garvitagarwal290 commented 7 months ago

Thank you @yantosca and @jgeddes85 !