Hello, I have a question related to the PM2.5 AQS method codes for sitecmp. From what I understand, AQS method code 88101 corresponds to PM2.5 Local Conditions, while 88502 corresponds to Acceptable PM2.5 AQI & Speciation Mass (both of which are in the daily AQS_CSN_YYYY tables from AMET). When using sitecmp, is it best to use PM25_TOT or PM25_FRM to compare model data to PM2.5 from the AQS_CSN data tables?
Our recommendation would be to use the PM25_TOT value. The PM25_FRM value was created some time ago in an attempt to account for artifacts in the PM2.5 from FRM filter measurements at CSN sites and was based on research performed quite a long time ago at this point. It was designed to replicate the artifacts in the modeled value for comparison to the measured value, since we could not simply adjust the measured value for the artifacts.
I’ve not revisited that FRM adjustment for some time, so I cannot say that the adjustments made are still fully applicable now. And there have been efforts made on the measurement side to account for those artifacts already. So, I recommend using the PM25_TOT value, which is what we use now in our comparisons. I may need to revisit the PM25_FRM value to determine whether is should be retained in the AMET workflow.
Wyat
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Thanks for your help!