My understanding is that, to use CMAQ’s bi-directional NH3 module, you should provide NH3 emissions from fertilizer separately (as NH3_FERT) to avoid double-counting.
Then, CMAQ uses total NH3 emissions (NH3) minus NH3_FERT in the emissions module, and the soil NH4 contents estimated by EPIC (through FEST-C) will completely replace the conventional soil NH3 emissions from NEI (NH3_FERT). Is that correct?
Thanks~
Yes, that is correct. However, if you do not have NH3 emissions from fertilizer already you can specify this array in the emissions file(s) as 0.0 and estimate these emissions with the bidirectional exchange option in-line.
Take care,
Jesse
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Hy,
I am trying to run CMAQv5.4 with DDM using 2020 emissions data. The emissions dataset we have got from our collaborator does not include data for running the Ammonia Bi-directional tool in the CCTM script. My question is, can I use EQUATES ammonia bi-directional dataset for running CMAQ? My model domain is 12km and COLXROW is 442X365.
I tried to run one-month data using EQUATES data (please see the image below), but it seems CCTM crashed without giving any error. Without Ammonia tools turning on, the model runs fine.
Tanks for the post. There is not quite enough information to confirm this, but I suspect that the error is originating from the differences in your model domain from the EQUATES inputs. The EQUATES EPIC data in on a 12km 459 column by 299 row domain. Unless the inputs have been modified, there are no input data to drive bidirectional NH3 exchange in the additional 166 rows in your domain. This should be fairly easy to confirm by running the model compiled with debug flags.
FYI: EPIC/FEST-C does not have the input data for simulations in Canada or Mexico and uses look up tables in those areas so the EQUATES data could likely be used if it copied to the corresponding cells in files with the correct domain dimensions and values of 0 for the additional rows in Canada and Mexico.