Hi，Could you please send me a tutorial of ISAM（CMAQ5.0.2），thanks

liuxin · April 20, 2021, 9:36am

I want to know what is the chemical mechanism for ISAM（CMAQ5.0.2）

lizadams · April 20, 2021, 12:50pm

The ISAM Tutorial is available here:CMAQ/CMAQ_UG_tutorial_ISAM.md at master · USEPA/CMAQ · GitHub

The User Guide chapter on ISAM:

USEPA/CMAQ/blob/master/DOCS/Users_Guide/CMAQ_UG_ch11_ISAM.md


<!-- BEGIN COMMENT -->

[<< Previous Chapter](CMAQ_UG_ch10_HDDM-3D.md) - [Home](README.md) - [Next Chapter >>](CMAQ_UG_ch12_sulfur_tracking.md)

<!-- END COMMENT -->

# 11. Integrated Source Apportionment Method (CMAQ-ISAM)
## 11.1 Introduction

The Integrated Source Apportionment Method (ISAM) calculates source attribution information for user specified ozone and particulate matter precursors within the CMAQ model.  CMAQ-ISAM has been substantially updated in the CMAQv5.3 release, and differs significantly from previous releases. The major changes to the ISAM chemistry solver are detailed in the [ISAM Chemistry Supplement](Supplement/CMAQ_ISAM_Chemistry_Supplemental_Equations.pdf). 

The CMAQ model provides users the concentration and deposition fields of many pollutant species. These species are usually combinations of different types of primary emissions and secondary formation that have been physically and chemically transformed in the model. However, sometimes it is desirable to know specific source attribution information for the model outputs. For example, how much of the ozone in an urban area was formed due to nitrogen oxides emitted from motor vehicles in a neighboring state?

Answering this type of question often requires running an air quality model twice, once with the standard emissions scenario and once with the source of interest completely removed. The difference between the two runs is then assumed to be attributed to the removed source.  While this approach is reasonably straightforward to implement, it has some drawbacks.  For example, removing a large source from the system in a highly nonlinear chemical mixture can lead to some errors. Also, calculating source attribution of many sources can be logistically and computationally prohibitive.

Alternatively, running CMAQ with ISAM enabled allows the user the ability to calculate source attribution of a large number of sources directly by the model in one simulation.

Note: While full model species list apportionment is in development, currently ISAM is limited to the following species classes in CMAQ:

This file has been truncated. show original

liuxin · April 21, 2021, 12:55am

Thanks for your reply

liuxin · April 21, 2021, 1:26am

Thanks for your reply

Topic		Replies	Views
New ISAM module in CMAQv5.3.1 CMAQ-ISAM admin , smoke	1	497	November 10, 2020
Contrasting Source Apportionment Approaches with Zero Out Testing CMAQ-ISAM research-topic	1	356	November 14, 2023
Secondary PM source apportionment by CMAQ-ISAM CMAQ-ISAM admin , cmaq	2	586	November 18, 2021
Question about differences between ISAM and Zero-out method in O3 source apportionment CMAQ-ISAM cmaq	2	20	March 2, 2025
CMAQ ISAM ozone source apportionment weird situation CMAQ-ISAM	12	938	January 20, 2021

Hi，Could you please send me a tutorial of ISAM（CMAQ5.0.2），thanks

Related topics