# How do I use CB05 in cmaq5.3 **URL:** \ **Category:** Chemistry and Aerosols\ **Created:** [July 26, 2020, 12:47pm UTC](https://forum.cmascenter.org/t/how-do-i-use-cb05-in-cmaq5-3/1672 "2020-07-26T12:47:24Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![qinch18](https://avatars.discourse-cdn.com/v4/letter/q/71e660/32.png) [@qinch18](https://forum.cmascenter.org/u/qinch18)\ **Post date:** [July 26, 2020, 12:47pm UTC](https://forum.cmascenter.org/t/how-do-i-use-cb05-in-cmaq5-3/1672/1 "2020-07-26T12:47:24Z")
Hello,How do I use CB05 in cmaq5.3. ---
**Author:** ![esm](https://avatars.discourse-cdn.com/v4/letter/e/f08c70/32.png) [@esm](https://forum.cmascenter.org/u/esm)\ **Post date:** [July 26, 2020, 10:23pm UTC](https://forum.cmascenter.org/t/how-do-i-use-cb05-in-cmaq5-3/1672/2 "2020-07-26T22:23:07Z")
Hi You must choose the mechanism of CB05 in bldit\_cctm and compile CCTM again. ---
**Author:** ![qinch18](https://avatars.discourse-cdn.com/v4/letter/q/71e660/32.png) [@qinch18](https://forum.cmascenter.org/u/qinch18)\ **Post date:** [July 27, 2020, 12:19am UTC](https://forum.cmascenter.org/t/how-do-i-use-cb05-in-cmaq5-3/1672/3 "2020-07-27T00:19:26Z")
> [@esm](#): > > You must choose the mechanism of CB05 in bldit\_cctm and compile CCTM again However, there is no installation package related to the chemical mechanism of CB05 in CMAQ5.3(CMAQ53/CCTM/src/MECHS). ---
**Author:** ![esm](https://avatars.discourse-cdn.com/v4/letter/e/f08c70/32.png) [@esm](https://forum.cmascenter.org/u/esm)\ **Post date:** [July 27, 2020, 6:07am UTC](https://forum.cmascenter.org/t/how-do-i-use-cb05-in-cmaq5-3/1672/4 "2020-07-27T06:07:47Z")
Hi I work with CMAQ5.2. I checked 5.3 and all mechanisms were CB6! Did you try it is working or not when you copy the mechanism of CB05 from 5.2 in 5.3? ---
**Author:** ![qinch18](https://avatars.discourse-cdn.com/v4/letter/q/71e660/32.png) [@qinch18](https://forum.cmascenter.org/u/qinch18)\ **Post date:** [July 27, 2020, 6:48am UTC](https://forum.cmascenter.org/t/how-do-i-use-cb05-in-cmaq5-3/1672/5 "2020-07-27T06:48:08Z")
I’ve tried this approach, but it doesn’t compile successfully.That’s why I asked questions on the forum. ---
**Author:** ![hogrefe.christian](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)\ **Post date:** [July 27, 2020, 5:12pm UTC](https://forum.cmascenter.org/t/how-do-i-use-cb05-in-cmaq5-3/1672/7 "2020-07-27T17:12:10Z")
As documented in the [CMAQv5.3 Release Notes](https://github.com/USEPA/CMAQ/blob/5.3/DOCS/Release_Notes/obsolete_mechanisms.md), a number of obsolete chemical mechanisms are no longer available in CMAQv5.3. This includes all of the CB05 mechanisms. As noted in these release notes, we recommend that users migrate to mechanisms that are more consistent with our current understanding of atmospheric chemistry and the types of applications for which air quality models are applied. Recreating older mechanisms in CMAQv5.3 is more complicated than simply copying the entire content of the MECH directories from earlier CMAQ releases since these directories also contain namelist files whose format has changed. For some general information on implementing chemical mechanisms, please see the description of the [chemmech](https://github.com/USEPA/CMAQ/blob/5.3/UTIL/chemmech/README.md) utility program. ---
**Author:** ![liyi](https://avatars.discourse-cdn.com/v4/letter/l/2acd7d/32.png) [@liyi](https://forum.cmascenter.org/u/liyi)\ **Post date:** [September 18, 2022, 9:13am UTC](https://forum.cmascenter.org/t/how-do-i-use-cb05-in-cmaq5-3/1672/8 "2022-09-18T09:13:42Z")
Hi，I’ve also tried to copy the mechanism of CB05 from 5.2.1 to 5.3.2,failed,too.Have you solved it?