# Parameter for model in AMET\_species\_list.R (AMET)

**URL:** <https://forum.cmascenter.org/t/parameter-for-model-in-amet-species-list-r-amet/4300>\
**Category:** AMET\
**Created:** [August 11, 2023, 7:06pm UTC](https://forum.cmascenter.org/t/parameter-for-model-in-amet-species-list-r-amet/4300 "2023-08-11T19:06:19Z")\
**Posts on this 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:** [August 12, 2023, 2:31pm UTC](https://forum.cmascenter.org/t/parameter-for-model-in-amet-species-list-r-amet/4300/3 "2023-08-12T14:31:06Z")

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1. ATOTIJ is Total PM Aggregates and what are the differences between ATOTIJ and PM25\_TOT?  
Definition in combine:  
PM25\_TOT ,ug/m3 ,ATOTI[0]\*PM25AT[3]+ATOTJ[0]\*PM25AC[3]+ATOTK[0]\*PM25CO[3]

2. What is the exact meaning of PM25AT (PM25 Aitken mode species of mass?)?

3. Why do they use ATOTIJ instead of PM25\_TOT or PM25\_FRM in AMET for PM2.5 mass?

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