Lightning NO parameters file for CMAQ5.3.1

I couldn’t find anywhere within the CMAQ documentation the method to generate lighning parameters file for inline NO option. My domain is spread over US and Mexico, can you suggest how to obtain such a file?


The lightning parameters for CMAQ inline lightning NO production were generated based on past lightning flash data that were only available over the contiguous US (including some northern part of Mexico). Therefore, the lightning parameters are only applicable to the US domain. It is possible to interpolate to a larger domain with additional uncertainties. I can easily make such a file based on your domain configuration if you can send me your METCRO2D file (any day).

Daiwen Kang

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Thank you. I will send you the METCRO2D file.

Dr Kang,

I wanted to check with you a few things about the Lightning NOx module in CMAQv5.3.1, given that I am interested in both present day and future (year 2050 meteorology) NOx production due to lightning flashes:

  1. My guess is that to get future lightning NOx production, I should use LTNG file in CMAQ rather than NLDN file. My argument is that NLDN file is just present day observation of hourly lightning flashes per sq. km while LTNG will help estimate the lightning NOx based on future convective rain supplied from WRF/MCIP to CMAQ. Is this thinking correct?

  2. A few months ago, there was an issue in CMAQv5.3.1 that would seek NLDN file even if I turned off NLDN file and turned on LTNG file. I was wondering if that is fixed, and how I can incorporate that into my existing CMAQv5.3.1 installation? If my thoughts in 2) above are correct, I would prefer to use LTNG file and not use NLDN file in my future PM simulations.

Thanks in advance!

Hi skunwar,

The answers to your questions:

  1. Yes, your thinking is correct. There is no way to have future observed lightning flash data, and that is the reason the parameters (associated with convective rainfall from WRF/MCIP) are created. For consistence, if you want to compare past scenarios with future ones, it would be more appropriate to run the past cases with the parameters, too, even though the observed lightning flash data are available.
  2. The bug in CMAQv5.3.1 you mentioned was fixed, and it would be released in CMAQv5.3.2; that should be available soon. However, if you can’t wait, you can contact me directly, and I can send you the specific fix for you to incorporate into your CMAQv5.3.1. But CMAQv5.3.2 will be more robust.

Thanks a lot! I will contact you for the fix to v5.3.1.