CMAQ STM species

phy · December 9, 2020, 3:26am

Hi, all!
I have a question related to Sulfur Tracking Model(STM) species.
There are several species such as ‘ASO4AQH2O2J’, ‘ASO4AQGASI’, ‘ASO4AQFEMNJ’, ‘ASO4EMISJ’ etc.
Then, can I call these STM species ‘counter species’ in CMAQ ??

I’ve read CMAQ science documentation chapter 8 and 10.
And ‘counter species’ and ‘aerosol yields’ were introduced in these documentations.
So, I thought that STM species could be called ‘counter species’ or ‘aerosol yields’ in CMAQ.
But I’m so confused because I don’t know which one is correct.

Also, I want to know calculation method of these species concentration.
For example, in case of H2O2 aqueous-phase reaction of sulfate formation,
I think that ‘ASO4AQH2O2J’ concentration is calculated by a reaction such as
‘SO2 + H2O2 --> ASO4AQH2O2J+H2O’ in CMAQ chemical mechanism.
I want to know whether my thinking is right or not.

So, If you guys know about that, please let me know.

Thanks.

HyeonYeong Park

lizadams · December 9, 2020, 3:49pm

This table contains the reactions: (please click on the link)
Table 1. Sulfur Tracking Species

github.com

USEPA/CMAQ/blob/master/DOCS/Release_Notes/sulfur_tracking.md

# Sulfur Tracking Method

**Author/P.O.C.:** [Shawn Roselle](mailto:roselle.shawn@epa.gov), Computational Exposure Division, U.S. EPA

## Brief Description

CMAQv5.3 includes a runtime diagnostic model option that provides detailed information on the modeled sulfur budget. This option, referred to as the "Sulfur Tracking Method (STM)", tracks sulfate production from gas- and aqueous-phase chemical reactions, as well as contributions from emissions and initial and boundary conditions. Each tracked species is treated as other modeled species, undergoing transport (advection, diffusion, cloud-mixing) and removal by deposition (both wet and dry).  Several notable features in the CMAQv5.3 release of STM include:

- The STM is now a runtime option enabled by an environment variable.
- In addition to the standard sulfate tracking species (Table 1), new species have been included to track the loss of inorganic sulfate to organosulfate for chemical mechanisms that include this loss pathway (Table 2).

Table 1. Sulfur Tracking Species

|Species Group|Species Name| MW   | Description |
|:------------|:-----------|:-----|:------------|
|AE           |ASO4AQH2O2J | 96.0 |Accumulation mode sulfate (ASO4J) produced by aqueous-phase hydrogen peroxide oxidation reaction:  H<sub>2</sub>O<sub>2</sub> + S(IV) -> S(VI) + H<sub>2</sub>O |
|AE           |ASO4AQO3J   | 96.0 |ASO4J produced by aqueous-phase ozone oxidation reaction:  O<sub>3</sub> + S(IV) -> S(VI) + O<sub>2</sub> |
|AE           |ASO4AQFEMNJ | 96.0 |ASO4J produced by aqueous-phase oxygen catalyzed by Fe<sup>3+</sup> and Mn<sup>2+</sup> oxidation reaction: O<sub>2</sub> + S(IV) -> S(VI) |
|AE           |ASO4AQMHPJ  | 96.0 |ASO4J produced by aqueous-phase methyl hydrogen peroxide oxidation reaction:  MHP + S(IV) -> S(VI) |
|AE           |ASO4AQPAAJ  | 96.0 |ASO4J produced by aqueous-phase peroxyacetic acid oxidation reaction:  PAA + S(IV) -> S(VI) |

This file has been truncated. show original

phy · December 9, 2020, 4:02pm

Hi, lizadams!
Thank you for your replying
But I want to know whether STM species such as ‘ASO4AQH2O2J’ is calculated by independent reaction not ‘ASO4’ formation reaction.
So, I think that ‘ASO4AQH2O2J’ is calculated by the reaction ‘SO2+H2O2 --> ASO4AQH2O2J + H2O’. Is it right??? And this reaction is included in CMAQ source code???

HyeonYeong

sergey · December 11, 2020, 10:48pm

Check inside the aqchem.F file for your CMAQ version. Inside, you will find the different pathways for SO2 oxidation in the aqueous phase. The rate for the H2O2 pathway is exactly:

    DSIVDT( 1 ) = -RH2O2 * H2O2L * HSO3 * HPLUS / ( 1.0D0 + 13.0D0 * HPLUS )

You can see it depends on various quantities that are also calculated in that subroutine.

I am not really sure I understand what exactly you are asking, so let me know if this is not helpful.

Sergey

phy · December 13, 2020, 5:33am

Hi, sergey!
I’m so appreciate for your replying.
I’ve just checked aqchem.F of my CMAQ source file, and finally I found it!
Your replying is so helpful for me and that is a answer that I want.
Once again, thank you for your replying

HyeonYeong

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