USEPA/CMAQ

MEGAN preprocessor

ramespada opened this issue · 4 comments

ramespada commented

HI,

In the Documentation (Chapter 4) when describing MEGAN input files, it mentioned a "MEGAN preprocessor", could you share where to find it?

Thanks

jeff-willison commented

The preprocessor can be downloaded from this page:

https://bai.ess.uci.edu/megan/data-and-code/megan32

The developers are still working on the documentation for it and it can be somewhat difficult to use. If you have trouble you can email me at willison.jeff@epa.gov and I can help create inputs for you.

  • ❤️1
ramespada commented

Perfect, thanks you for your quick response.

Just a coment, this preprocessor (as far as i can see in the code) doesn't use IOAPI, they just print the values of the input files like this:

prepmegan4cmaq_grwform.f90:      write(99,'(a)')"gridID,TreeFrac,CropFrac,ShrubFrac,HerbFrac"

And the CMAQ documentation says that the input file is an I/O API GRDDED3 file.

Thanks again for your time

jeff-willison commented

That's correct. The "calculator and mechanism mapper code" has a program called TXT2IOAPI that converts the csv files to IOAPI. The "Emission Factor Processor" tool also takes the growthform and ecotype files from the preprocessor and creates a new file that TXT2IOAPI converts IOAPI. The EFP tool requires setting up a python 3 environment.

In summary it's

preprocessor -> cantype, optional LAI, and optional soil csv files -> TXT2IOAPI
preprocessor -> growthform and ecotype csv files -> EFP -> TXT2IOAPI

They used to have a user guide on their site but I don't see it anymore. Hopefully they post a new one soon. Until then I'm happy to help with creating input files.

  • 👍1
ramespada commented

Aah, now it makes sense, many thanks Jeff!