# Issues with Species Allocation when Converting CB05 to CB6AE7

**URL:** <https://forum.cmascenter.org/t/issues-with-species-allocation-when-converting-cb05-to-cb6ae7/5788>\
**Category:** CMAQ\
**Created:** [May 7, 2025, 1:58pm UTC](https://forum.cmascenter.org/t/issues-with-species-allocation-when-converting-cb05-to-cb6ae7/5788 "2025-05-07T13:58:08Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![yan2024](https://avatars.discourse-cdn.com/v4/letter/y/59ef9b/32.png) [@yan2024](https://forum.cmascenter.org/u/yan2024)\
**Post date:** [May 7, 2025, 1:58pm UTC](https://forum.cmascenter.org/t/issues-with-species-allocation-when-converting-cb05-to-cb6ae7/5788/1 "2025-05-07T13:58:08Z")

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Hi teachers,

I am using a Python allocation tool ([GitHub - Airwhf/MEIAT-CMAQ: MEIAT-CMAQ是一个模块化的CMAQ排放清单分配工具。](https://github.com/Airwhf/MEIAT-CMAQ/tree/main)) to process the MEIC inventory, but I have encountered some issues during the species allocation step (converting from the CB05 mechanism to the CB6AE7 mechanism). The species allocation file of the program is as shown below (see Figure 1).

I would like to know if there are any issues other than the fact that XYL should actually correspond to XYLMN. Since the MEIC emission inventory is based on the CB05 mechanism, many species are missing. Should I simply skip these species (e.g., ACET, BENZENE, etc.)? When comparing with the document provided by Ben in a previous post, I noticed that many species are missing (see Figure 2).

Is it feasible to run the CMAQ model with the CB6r5AE7 mechanism in this way?

> [@Does old emission input data work with new version of CMAQ-5.3.1?](https://forum.cmascenter.org/t/does-old-emission-input-data-work-with-new-version-of-cmaq-5-3-1/1271):
>
> Hi everyone, I am a new learner of CMAQ and i use the latest CMAQ-5.3.1 version. I am now rerunning one of my senior’s simulation and got the emission input data directly from her. She is using CMAQ-5.0.2 and SMOKE-4.0. So the emission data i got is generated using SMOKE-4.0 and the chemical mechanism is cb05. But in CMAQ-5.3.1 the cb05 chemical mechanism is updated to cb6. Could i use the emission inventory directly? Do i need to regenerate the emission input data myself because of the update …

Figure 1:

 ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/2X/3/344b689989539075ff1c601038fc7504fc686a99.png)

Figure 2:

 ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/2X/3/3a1a4729fc61f3d0795a0f857d0dca9a2ca5b0af.png)

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**Author:** ![wong.david-c](https://avatars.discourse-cdn.com/v4/letter/w/bcef8e/32.png) [@wong.david-c](https://forum.cmascenter.org/u/wong.david-c)\
**Post date:** [May 20, 2025, 3:07pm UTC](https://forum.cmascenter.org/t/issues-with-species-allocation-when-converting-cb05-to-cb6ae7/5788/2 "2025-05-20T15:07:55Z")

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Hi yan2024,

As far as I know, MEIC inventory does have a version based on CB6. Please consult with the MEIC web site or contact MEIC group at Tsinghua University.

Cheers,  
David

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**Author:** ![yan2024](https://avatars.discourse-cdn.com/v4/letter/y/59ef9b/32.png) [@yan2024](https://forum.cmascenter.org/u/yan2024)\
**Post date:** [May 20, 2025, 3:20pm UTC](https://forum.cmascenter.org/t/issues-with-species-allocation-when-converting-cb05-to-cb6ae7/5788/3 "2025-05-20T15:20:53Z")

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Thank you, Wong! I’ve already changed to SAPRC mechanism and seems to work well until now.

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**Author:** ![system](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/1X/9a72c78e529465c3f1053af404e3033b0875428c.png) [@system](https://forum.cmascenter.org/u/system)\
**Post date:** [May 27, 2025, 3:21pm UTC](https://forum.cmascenter.org/t/issues-with-species-allocation-when-converting-cb05-to-cb6ae7/5788/4 "2025-05-27T15:21:19Z")

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