# There is a problem when running the cb6r3m\_ae7\_kmtbr mechanism, and the Oceanfile file lacks CHLO variables **URL:** \ **Category:** CMAQ\ **Created:** [October 21, 2020, 8:21am UTC](https://forum.cmascenter.org/t/there-is-a-problem-when-running-the-cb6r3m-ae7-kmtbr-mechanism-and-the-oceanfile-file-lacks-chlo-variables/1853 "2020-10-21T08:21:34Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![lihongli](https://avatars.discourse-cdn.com/v4/letter/l/f17d59/32.png) [@lihongli](https://forum.cmascenter.org/u/lihongli)\ **Post date:** [October 21, 2020, 8:21am UTC](https://forum.cmascenter.org/t/there-is-a-problem-when-running-the-cb6r3m-ae7-kmtbr-mechanism-and-the-oceanfile-file-lacks-chlo-variables/1853/1 "2020-10-21T08:21:34Z")
I want to know if this mechanism is different from the Oceanfile file of other mechanisms, do I need to add variables for halogen elements? ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/1X/db21a08993d0931733cb714049df65c0e3c7b147.png) ---
**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:** [October 21, 2020, 3:54pm UTC](https://forum.cmascenter.org/t/there-is-a-problem-when-running-the-cb6r3m-ae7-kmtbr-mechanism-and-the-oceanfile-file-lacks-chlo-variables/1853/2 "2020-10-21T15:54:41Z")
Yes, you do need chlorophyll in your ocean file if you want to use the cb6r3m\_ae7\_kmtbr mechanism since this mechanism requires emissions of iodine and bromine species which are parameterized from chlorophyll-a concentrations in sea water along with other parameters. For further details, see G. Sarwar, B. Gantt, D. Schwede, K. Foley, R. Mathur, A. Saiz-Lopez, Impact of enhanced ozone deposition and halogen chemistry on tropospheric ozone over the Northern Hemisphere, Environ. Sci. Technol., 49 (15) (2015), pp. 9203-9211, 2015 and Golam Sarwar, Brett Gantt, Kristen Foley, Kathleen Fahey, Tanya L. Spero, Daiwen Kang, Rohit Mathur, Hosein Foroutan, Jia Xing, Tomás Sherwen, Alfonso Saiz-Lopez, Influence of bromine and iodine chemistry on annual, seasonal, diurnal, and background ozone: CMAQ simulations over the Northern Hemisphere, Atmospheric Environment, Volume 213, 2019, Pages 395-404, [https://doi.org/10.1016/j.atmosenv.2019.06.020](https://doi.org/10.1016/j.atmosenv.2019.06.020) My understanding is that the required chlorophyll-a values are typically obtained from MODIS, but I don’t know which tools are being used for that process. ---
**Author:** ![gsarwar](https://avatars.discourse-cdn.com/v4/letter/g/5f9b8f/32.png) [@gsarwar](https://forum.cmascenter.org/u/gsarwar)\ **Post date:** [October 21, 2020, 4:45pm UTC](https://forum.cmascenter.org/t/there-is-a-problem-when-running-the-cb6r3m-ae7-kmtbr-mechanism-and-the-oceanfile-file-lacks-chlo-variables/1853/3 "2020-10-21T16:45:43Z")
The halogen chemistry needs the variable “CHLO” in the ocean file to calculate halocarbon emissions. The model will not run without this variable. We can add “CHLO” in your ocean file if you can provide following files for your domain: “ocean file”, “GRIDDESC” and met files for one day. Thanks, Golam Sarwar ---
**Author:** ![lihongli](https://avatars.discourse-cdn.com/v4/letter/l/f17d59/32.png) [@lihongli](https://forum.cmascenter.org/u/lihongli)\ **Post date:** [October 23, 2020, 8:57am UTC](https://forum.cmascenter.org/t/there-is-a-problem-when-running-the-cb6r3m-ae7-kmtbr-mechanism-and-the-oceanfile-file-lacks-chlo-variables/1853/4 "2020-10-23T08:57:22Z")
Thank you very much for your reply, your reply is very helpful to me, I have learned a lot! 😀 ---
**Author:** ![lihongli](https://avatars.discourse-cdn.com/v4/letter/l/f17d59/32.png) [@lihongli](https://forum.cmascenter.org/u/lihongli)\ **Post date:** [October 23, 2020, 9:29am UTC](https://forum.cmascenter.org/t/there-is-a-problem-when-running-the-cb6r3m-ae7-kmtbr-mechanism-and-the-oceanfile-file-lacks-chlo-variables/1853/5 "2020-10-23T09:29:57Z")
Thank you for your reply and help! Considering that the met files of a day is also relatively large, I would like to know if all the 2D and 3D are required for the metfile of the day you need to provide. And I want to know what form I can send my file to you. ---
**Author:** ![gsarwar](https://avatars.discourse-cdn.com/v4/letter/g/5f9b8f/32.png) [@gsarwar](https://forum.cmascenter.org/u/gsarwar)\ **Post date:** [October 23, 2020, 12:13pm UTC](https://forum.cmascenter.org/t/there-is-a-problem-when-running-the-cb6r3m-ae7-kmtbr-mechanism-and-the-oceanfile-file-lacks-chlo-variables/1853/6 "2020-10-23T12:13:13Z")
We do not need all met files; we need GRIDCRO2D file for a day, current ocean file and GRIDDESC file. Yes, some files may be too large. I can set up a ftp account where you can upload the files. We can add the needed variable to the ocean file and upload it to the ftp account from which you can download it. Please contact me at [sarwar.golam@epa.gov](mailto:sarwar.golam@epa.gov) for information about the ftp account. Thanks, Golam Sarwar