# CMAQ STM ICBC species

**URL:** <https://forum.cmascenter.org/t/cmaq-stm-icbc-species/2228>\
**Category:** Chemistry and Aerosols\
**Created:** [April 7, 2021, 3:10am UTC](https://forum.cmascenter.org/t/cmaq-stm-icbc-species/2228 "2021-04-07T03:10:30Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![phy](https://avatars.discourse-cdn.com/v4/letter/p/35a633/32.png) [@phy](https://forum.cmascenter.org/u/phy)\
**Post date:** [April 7, 2021, 3:10am UTC](https://forum.cmascenter.org/t/cmaq-stm-icbc-species/2228/1 "2021-04-07T03:10:30Z")

</div>

Hi, all!  
I’m doing a simulation with ‘sulfur tracking method’ (STM) in CMAQv5.3.1.  
I’ve got some hints of calculating ‘aqueous-phase sulfate formation’ in aqchem.F.  
But I can’t find any codes for calculating ‘sulfate from boundary and initial condition’ (ASO4ICBC) in CMAQv5.3.1 source codes.

Do you guys know where the calculation source code of ‘sulfate from boundary and initial condition’ is located ??

I wish I can get any responses from you all 🙂

---

<div class="post-metadata">

**Author:** ![Ben\_Murphy](https://avatars.discourse-cdn.com/v4/letter/b/74df32/32.png) [@Ben\_Murphy](https://forum.cmascenter.org/u/Ben_Murphy)\
**Post date:** [April 8, 2021, 9:01pm UTC](https://forum.cmascenter.org/t/cmaq-stm-icbc-species/2228/2 "2021-04-08T21:01:23Z")

</div>

Hi Phy,

The source code for sulfate from boundary and initial conditions is located in two places. It is applied in CGRID\_SPCS.F ([CMAQ/CGRID\_SPCS.F at master · USEPA/CMAQ · GitHub](https://github.com/USEPA/CMAQ/blob/master/CCTM/src/spcs/cgrid_spcs_nml/CGRID_SPCS.F)). Beginning on line 446 you can see the implementation of the preloaded STM species into the transported aerosols array.

Each species loaded here has every field from the AE namelist determined already in the STM module. You can find that table in STM\_VARS.F , beginning on line 81 ([CMAQ/STM\_VARS.F at master · USEPA/CMAQ · GitHub](https://github.com/USEPA/CMAQ/blob/master/CCTM/src/stm/STM_VARS.F)).

Cheers,  
Ben

---

<div class="post-metadata">

**Author:** ![phy](https://avatars.discourse-cdn.com/v4/letter/p/35a633/32.png) [@phy](https://forum.cmascenter.org/u/phy)\
**Post date:** [April 9, 2021, 5:48am UTC](https://forum.cmascenter.org/t/cmaq-stm-icbc-species/2228/4 "2021-04-09T05:48:59Z")

</div>

Dear Dr. Murphy

Hi, I’m HyeonYeong Park, having a question of STM ICBC species.  
First, Thank you for your previous response 🙂

But I think that CGRID\_SPCS.F and STM\_VARS.F assign and define CMAQ species array and also STM species.

I also want to know the calculation routine of ICBC species concentration similar to sulfate aqueous-phase concentration routine (e.g. H2O2, O3, Fe and Mn reactions in aqchem.F).

Can you let me know another location of source code of ASO4ICBC ??

Thank you.

HyeonYeong Park

---

<div class="post-metadata">

**Author:** ![Ben\_Murphy](https://avatars.discourse-cdn.com/v4/letter/b/74df32/32.png) [@Ben\_Murphy](https://forum.cmascenter.org/u/Ben_Murphy)\
**Post date:** [May 14, 2021, 5:09pm UTC](https://forum.cmascenter.org/t/cmaq-stm-icbc-species/2228/5 "2021-05-14T17:09:44Z")

</div>

Hi HyeonYeong,

Sorry for my severely delayed response. I’m not sure I completely follow the question. The IC and BC species for STM are just assigned directly from the IC and BC file. This is done completely analogously to the other CMAQ species.

Specifically, load\_cgrid.F is responsible for loading the initial conditions, and rdbcon.F is responsible for loading boundary conditions.

Best,  
Ben

---

<div class="post-metadata">

**Author:** ![phy](https://avatars.discourse-cdn.com/v4/letter/p/35a633/32.png) [@phy](https://forum.cmascenter.org/u/phy)\
**Post date:** [May 17, 2021, 12:47pm UTC](https://forum.cmascenter.org/t/cmaq-stm-icbc-species/2228/7 "2021-05-17T12:47:17Z")

</div>

Hi, Dr. Murphy!  
Thank you for your answering to my question.

I confirmed those source files, and I think those files what I want.

Thank you for your response again.

HyeonYeong Park