# CMAQ v5.3.3 UFP concentration and number

**URL:** <https://forum.cmascenter.org/t/cmaq-v5-3-3-ufp-concentration-and-number/3317>\
**Category:** CMAQ\
**Created:** [June 10, 2022, 12:23am UTC](https://forum.cmascenter.org/t/cmaq-v5-3-3-ufp-concentration-and-number/3317 "2022-06-10T00:23:59Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![kkkghs0828](https://avatars.discourse-cdn.com/v4/letter/k/ce7236/32.png) [@kkkghs0828](https://forum.cmascenter.org/u/kkkghs0828)\
**Post date:** [June 10, 2022, 12:23am UTC](https://forum.cmascenter.org/t/cmaq-v5-3-3-ufp-concentration-and-number/3317/1 "2022-06-10T00:23:59Z")

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I am not sure my combine file for UFP (less than 0.1um) is right.  
or Are there any other ways to calculate UFP concentration and its numbers?

UFP total = ATOTI, UFP number = NUMACC[1]

 ![image](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/2X/6/6e4edad8b64081745c73f4035296d8b8df4cd333.png)

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**Author:** ![Havala.Pye](https://avatars.discourse-cdn.com/v4/letter/h/67e7ee/32.png) [@Havala.Pye](https://forum.cmascenter.org/u/Havala.Pye)\
**Post date:** [June 10, 2022, 9:38pm UTC](https://forum.cmascenter.org/t/cmaq-v5-3-3-ufp-concentration-and-number/3317/2 "2022-06-10T21:38:18Z")

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If you define ultrafine as diameter \< 0.1 um, then you would need to determine how much of the aitken (I) + accumulation (J) modes are present below 0.1 um. NUMACC is the number of accumulation mode particles and ATOTI is the aitken mode mass. The [PMDIAG output file currently computes the fraction of aitken, accumulation, and coarse modes below 1, 2.5, and 10 um](https://github.com/USEPA/CMAQ/blob/main/CCTM/src/aero/aero6/PMDIAG_DATA.F). You could add a \<0.1 cutoff as well. To implement it, take a look at aero\_driver.F and the calculation and assignment of “fPM1” quantities as well as SUBROUTINE AERO\_INLET in aero\_subs.F for a template. @Ben_Murphy may have more suggestions.