# About HNO3 dry deposition velocity

**URL:** <https://forum.cmascenter.org/t/about-hno3-dry-deposition-velocity/4032>\
**Category:** Chemistry and Aerosols\
**Tags:** cmaq\
**Created:** [March 29, 2023, 11:17am UTC](https://forum.cmascenter.org/t/about-hno3-dry-deposition-velocity/4032 "2023-03-29T11:17:22Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![hycho1](https://avatars.discourse-cdn.com/v4/letter/h/bbe5ce/32.png) [@hycho1](https://forum.cmascenter.org/u/hycho1)\
**Post date:** [March 29, 2023, 11:17am UTC](https://forum.cmascenter.org/t/about-hno3-dry-deposition-velocity/4032/1 "2023-03-29T11:17:22Z")

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I’d like to perform a sensitivity test of HNO3 dry deposition velocity.  
I’m studying the code in the CMAQ, but I’m not sure, so I’m asking for help.

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**Author:** ![lizadams](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@lizadams](https://forum.cmascenter.org/u/lizadams)\
**Post date:** [April 4, 2023, 5:42pm UTC](https://forum.cmascenter.org/t/about-hno3-dry-deposition-velocity/4032/2 "2023-04-04T17:42:04Z")

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Please review the following paper.

> **[gmd-2021-129.pdf](https://gmd.copernicus.org/preprints/gmd-2021-129/gmd-2021-129.pdf)**
>
> 1631.11 KB

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**Author:** ![jbash](https://avatars.discourse-cdn.com/v4/letter/j/8e8cbc/32.png) [@jbash](https://forum.cmascenter.org/u/jbash)\
**Post date:** [April 5, 2023, 12:36pm UTC](https://forum.cmascenter.org/t/about-hno3-dry-deposition-velocity/4032/3 "2023-04-05T12:36:45Z")

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How you approach this depends on what processes you are considering and the CMAQ model options. If

you are using the M3Dry deposition option:

Constants related to cuticular and soil resistances by deposition species are found in:

AS\_DATA\_MOD.F

All other surface resistances are estimated in:

m3dry.F

The aerodynamic and stomatal resistances are passed down from the meteorological model

All modifications will require a recompile of the code. Documentation can be found in Pleim and Ran 2011 ([Atmosphere | Free Full-Text | Surface Flux Modeling for Air Quality Applications](https://doi.org/10.3390/atmos2030271))

If you are using the STAGE compile time deposition option:

Constants related to cuticular and soil resistances by deposition species are found in:

CMAQ\_Control\_STAGE.nml

All other surface resistances are estimated in

STAGE\_FUNCTIONS.F

Aerodynamic and stomatal resistances are currently normalized to the meteorological model output and can be modified in:

MOSAIC\_MOD.F

Modifications to do not require a re-compile while modifications to STAGE\_FUNCTIONS.F or MOSAIC\_MOD.F will require recompiling the code.

Additionally, there is a box model version of the STAGE option Walker et al. 2023 ([BG - Atmospheric deposition of reactive nitrogen to a deciduous forest in the southern Appalachian Mountains](https://doi.org/10.5194/bg-20-971-2023)) available here (Bash and Wu 2023; [STAGE bidirectional air-surface exchange model | Zenodo](https://zenodo.org/record/7667344#.ZC1mO3bMJD8)). I have found this to be useful in the development of updated deposition parameters.