# Emission preparation using the Emission Modeling Platform

**URL:** https://forum.cmascenter.org/t/emission-preparation-using-the-emission-modeling-platform/5510
**Category:** SMOKE
**Tags:** emissions
**Created:** [January 13, 2025, 7:32pm UTC](https://forum.cmascenter.org/t/emission-preparation-using-the-emission-modeling-platform/5510 "2025-01-13T19:32:28Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![ychengen](https://avatars.discourse-cdn.com/v4/letter/y/ce73a5/32.png) [@ychengen](https://forum.cmascenter.org/u/ychengen)
#### Post date: [January 13, 2025, 7:32pm UTC](https://forum.cmascenter.org/t/emission-preparation-using-the-emission-modeling-platform/5510/1 "2025-01-13T19:32:28Z")

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Hi,

I have questions when preparing emission inputs for CAMx ozone source apportionment simulations. I understand this is a CMAQ-focused forum, but I expect my emissions questions to be relevant to this forum.

I am trying to generate 2023 CAMx emissions using the 2016v3 Emission Modeling Platform (EMP) for CAMx 12US2 ozone source apportionment (OSAT) simulations. I intend to tag _individual emission sectors_ (e.g., ptegu, onroad, wildfires, etc.) at four source regions/states (TN, AR, MS, all the other regions (the other US states, Mexico, Canada, offshore)). However, I am a bit confused about the emission data preparation processes:

1. The default **groupid** from EMP under the `ge_dat/sa` folder assigns 53 tags for each state/region in the 12US2 domain. I modified the **groupid** from 53 tags to only four tags based on my case. Do those numbers only affect the point emission sources but not the area sources for OSAT simulations?

2. I downloaded the pre-merged emission data from [EPA’s AWS site](https://2016v3platform.s3.amazonaws.com/index.html#2016v3platform/2023gf_emissions/). In my case, I only use four source areas rather than 53. Can I directly use these pre-merged sectoral emissions without re-running the emission preparation scripts provided in the EMP package? Or do I need to re-run all emission sectors? Or just the point emission ones? I understand I need to convert the CMAQ-ready inputs to CAMx inputs through the provided EMP scripts.

Any help and/or comments would be much appreciated.

Thank you,  
Ken