Comparing BenMAP's inbuilt 'CMAQ 12km Nation' grid with CMAQ's '12US2' grid

BENMAP
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(a) BenMAP has several inbuilt 12km grids for CMAQ:

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I am trying to use 12k CMAQ PM2.5 simulations based on ‘12US2’ grid in CMAQ for health impacts calculations in BenMAP. I am not sure whether BenMAP’s inbuilt ‘CMAQ 12km Nation’ grid or the ‘CMAQ 12km Nation - Clipped’ grid defined in BenMAP are exactly based on the ‘12US2’ grid in CMAQ. The number of rows and columns (246 X 396) of gridcells are the same in BenMAP’s ‘CMAQ 12km Nation’ grid and CMAQ’s 12US2 grid, but it is still possible that gridcells are located in slightly different lat-lon positions. Could somebody verify this?

(b) On a related note, how is the BenMAP’s ‘CMAQ 12km Nation - Clipped’ population calculated? How is it different from ‘United States Census - County’ population in BenMAP? I am just trying to find the best population dataset (of the two available) in BenMAP to go with my CMAQ 12km grid.

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You can do the verification by yourself easily. Note that BenMAP provides the option to output the grid file then you can compare them.

Again, you can output these dataset for comparison. As indicated in the BenMAP, CMAQ 12km Nation means gridded population dataset which corresponds to CMAQ model grids, while the “United States Census - County” population is for County level (which generally far larger than 12km by 12km CMAQ model grids). Thus, CMAQ 12km should work much better in your case.

Before doing the follow-up calculation, please get the files output or visualize them in BenMAP then you will get to know how the data looks like.