How to find how much of PM10 was deposited

CMAQ
1

Hi.

I wonder if someone could provide some hint?
I want to know how much of total PM10 mass was deposited every hour. Does CMAQv5.3.1 or any tools in it, such as ‘combine’, output the deposition of PM10 (I do not mean the deposition of individual species, but I need the total mass corresponding to PM10)

Thanks.

2

This is not a standard CMAQ output but can be calculated with the ‘combine’ tool using the aerosol species written to the dry and wet deposition files.

To do that, you would want to modify the example deposition species definition file for the mechanism you are using (e.g. this file if you are using CB6R3_AE7_AQ) to add a species like ATOTIJK defined in the example concentration species definition file (e.g. this file), making sure to pull the relevant component species from both the dry and wet deposition output file and adding them. If you are interested in only the PM10 portion instead of the total I+J+K mode aerosol mass, you can include the size cutoff fractions from the APMDIAG file in the same fashion these fractions are used in the example concentration species definition file when calculating PM10.

3

Thank you very much; your replies have been always helpful. I will follow your suggestion.

4

Thank you for the hint above. A related question, though it may sound naive, is: is there a way to compute how much total mass (all chemical constituents combined) was deposited and how much emitted (emitted may be computed from the input emission files) to compute mass budget (net loss or gain). In other words, if all species that are saved in DRYDEP and WETDEP files are added together, would that equal total mass deposited (or some of the species saved in these DEP files ‘intersect’)? Does CMAQ transport species heavier than PM10, or the particles are removed (deposited) as soon as they become heavier than 10 um?
Even partial response would be helpful, anybody, please!
Thank you.

5

Hello,

You can get an approximate answer to this request using the Process Analysis features in CMAQ (CMAQ/CMAQ_UG_ch09_process_analysis.md at main · USEPA/CMAQ · GitHub). It is able to give you the production and loss of individual compounds, or user-defined families for processes that you mention. These data are processed for the model grid and are available in concentration units, not total mass gained or lost. In order to get domain-wide totals, you would need to convert the concentrations or mixing ratios to total mass, and sum across the domain.

In the next release of CMAQ, there will be an option for outputing a ‘BUDGET’ file which will include domain-wide mass gains and losses for all processes for any species or family you wish. These values will not include the spatial detail of process analysis, but will have the same hourly temporal resolution.

Best wishes,
Ben Murphy

2 Likes
6

Thank you for the hints above. I think following the suggestions from @hogrefe.christian should be easier to go: assuming the total particle mass formed is ATOTIJK, and that this quantity includes the mass of all particulate matter (of all sizes). [edit: removed a few questions as they could be confusing to people!]