# WRFchemi to CMAQ emissions

**URL:** <https://forum.cmascenter.org/t/wrfchemi-to-cmaq-emissions/2242>\
**Category:** Emissions\
**Created:** [April 12, 2021, 5:00pm UTC](https://forum.cmascenter.org/t/wrfchemi-to-cmaq-emissions/2242 "2021-04-12T17:00:33Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![kamitoteles](https://avatars.discourse-cdn.com/v4/letter/k/7ab992/32.png) [@kamitoteles](https://forum.cmascenter.org/u/kamitoteles)\
**Post date:** [April 12, 2021, 5:00pm UTC](https://forum.cmascenter.org/t/wrfchemi-to-cmaq-emissions/2242/1 "2021-04-12T17:00:33Z")

</div>

Hello everyone!!

I encountered some difficulties trying to convert a set of WRF chemi files to CMAQ emissions.  
Does someone know if there is a program to do this in a faster way?  
Does SMOKE have support for this task?

Thank you so much!!!

---

<div class="post-metadata">

**Author:** ![kamitoteles](https://avatars.discourse-cdn.com/v4/letter/k/7ab992/32.png) [@kamitoteles](https://forum.cmascenter.org/u/kamitoteles)\
**Post date:** [May 3, 2021, 9:20pm UTC](https://forum.cmascenter.org/t/wrfchemi-to-cmaq-emissions/2242/2 "2021-05-03T21:20:05Z")

</div>

If someone is facing the same issue, I made a python script to automate this process that is in my repository [GitHub - kamitoteles/Mozart2CMAQemis](https://github.com/kamitoteles/Mozart2CMAQemis).  
It’s a simple program but please read the documentation because there are some speciall information that you must provide for the conversion.  
Hope it helps someone!

---

<div class="post-metadata">

**Author:** ![BEINNNNN](https://avatars.discourse-cdn.com/v4/letter/b/858c86/32.png) [@BEINNNNN](https://forum.cmascenter.org/u/BEINNNNN)\
**Post date:** [March 31, 2022, 8:05am UTC](https://forum.cmascenter.org/t/wrfchemi-to-cmaq-emissions/2242/3 "2022-03-31T08:05:23Z")

</div>

Hi,

I would like to ask about the units for emission data in CMAQ. In wrfchemi, we have emissions with mol km^-2 hr^-1 and ug m^-2 s^-1. But in CMAQ the unit is moles/s and g/s. Are the units in CMAQ per grid? So that if I have 3km\*3km grid cells, I need to multiply the emission data by 9.

Cheers,  
Bessie

---

<div class="post-metadata">

**Author:** ![cjcoats](https://avatars.discourse-cdn.com/v4/letter/c/ac8455/32.png) [@cjcoats](https://forum.cmascenter.org/u/cjcoats)\
**Post date:** [March 31, 2022, 11:19am UTC](https://forum.cmascenter.org/t/wrfchemi-to-cmaq-emissions/2242/4 "2022-03-31T11:19:27Z")

</div>

Exactly – there is an implicit non-MKS “per grid cell” in the CMAQ units.

BTW, do you know why _wrfchemi_ uses such inconsistent units for emissions – _km_ vs _m_ and _hr_ vs _sec_? I’ve run into that before and completely fail to understand it…

---

<div class="post-metadata">

**Author:** ![BEINNNNN](https://avatars.discourse-cdn.com/v4/letter/b/858c86/32.png) [@BEINNNNN](https://forum.cmascenter.org/u/BEINNNNN)\
**Post date:** [March 31, 2022, 12:06pm UTC](https://forum.cmascenter.org/t/wrfchemi-to-cmaq-emissions/2242/5 "2022-03-31T12:06:48Z")

</div>

Thanks for your reply!

Sorry that I also don’t know why the gas and aerosols use different units in space and time ☹