Very Low Simulated PM2.5 in 36 km CMAQ Runs

CMAQ
1

Hi teachers,

I am currently using the HTAP-EDGAR emissions inventory to simulate the Asian region (including India, China, and parts of Southeast Asia) at a 36 km resolution. However, I’ve encountered an issue: the simulated PM2.5 concentrations (extracted from the merged CCTM_AELMO output file) appear to be significantly underestimated across the domain.

This is quite different from my earlier simulations over China alone (smaller domain than simulation this time), where I used a finer 27 km resolution. In that case, the model was able to capture higher PM2.5 values, especially over northeastern India, which were much closer to observed values.

I would like to ask what could be causing this underestimation and what steps would you recommend to improve the accuracy of PM2.5?

this time:

image
image954×386 69.3 KB

before, with 27km*27km:

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image638×635 160 KB

2

There is not enough information here to be sure, but the issue is probably emissions. You say you are using the same emission inventory, but how were the actual emissions inputs prepared?

3

Hi cgnolte,

Sorry, I found that different versions of this inventory have different emission values for the same year. I am currently reprocessing the emissions using the version I previously used to see if re-running it improves the results. Additionally, I want to confirm whether differences in simulation accuracy and the size of the simulated area would not cause such a significant difference in results, right?