CMAQ cb6r3m mechanism issues

I’m running CMAQ 5.3.2 with cb6r3m mechanism to study ozone loss yielded by halogen species. However, I encountered some issues while running the benchmark cases with cb6r3m.
It returned a failure while reading the ocean file of the test data.

I went through the source code and found out in centralized_io_mod.F where it showed that computing sea spray emission requiring DMS and CHLO data in OCEAN_1 file but not file. In this case, I need to obtain both chlorine and DMS emission inventory if i’m using cb6r3m mechanism with ocean halogen chemistry turned on.
But in several papers i referenced using halogen chemistry in CMAQ, the emission inventory didn’t include DMS or chlorine data (or perhaps i missed). So I was wondering if i could have any options to avoid this error or using the cb6r3 version with halogen chemistry adding into it?
Thank you very much, and im appreciating any suggestions!

Hi Henry,

It seems that cb6r3m needs DMS and CHLO in the OCEAN_1 file. They are DMS and chl-a concentrations in the ocean, and are used to calculate DMS and halocarbon fluxes from the ocean (I think they are not required by SSA emission calculation. See also MGEMIS.F file). You can just add them to the OCEAN_1 file and set the values to zero and the DMS and halocarbon fluxes from the ocean would be zero. Or you can get the values from climatology, parameterization, or satellite products.

Best regards,

@Zhizhua , Thank you very much for providing a response, and apologies, @Henry for not following up sooner.

We do not recommend running cb6r3m without DMS and chl-a as this is the marine chemistry version of cb6r3. Zhizhua is correct that they are required for the DMS and detailed halogen chemistry in the mechanism.

Also, while cb6r3 does not include DMS chemistry it does include a simplified version of the halogen chemistry in cb6r5m which does not rely on the chl-a data.

In the next CMAQ release (v5.4), scheduled for this fall, the CMAQ repository will include a new python tool for adding DMS and CHLO to the ocean file.