Hi,runISAM.txt.txt (54.9 KB)
If you are just running the benchmark case, then please try to unlimit the stacksize.
In csh/tcsh you can add the command ‘limit stacksize unlimited’ to your .cshrc.
And/or ask for a higher amount of memory in your batch queue submission.
The amount of memory required for ISAM will depend on the number of sources that you use. Please refer to this documentation that discusses the need to build the I/O API large memory version to support ISAM for a large number of sources.
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# 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 starting with the CMAQv5.3 release, and now 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). In addition, signifcant updates and multiple minor fixes were included in the subsequent releases including substantial updates to the gas-phase chemistry apportionment algorithms that improve both physical and numerical aspects of the method. Users of CMAQ-ISAM are strongly encouraged to update to the latest available release of the model.
The base 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:
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