There are some questions about the parameter synthesis of pm2.5

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tom_cruise
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There are some questions about the parameter synthesis of pm2.5

by tom_cruise » Sun Sep 10, 2023 12:31 pm America/New_York

Thank you very much for the help you have provided, I have recently encountered a new problem, the problem is this, I have downloaded the nc data from the following dataset:
MERRA-2 tavgM_2d_aer_Nx: 2d,Monthly mean,Time-averaged,Single-Level,Assimilation,Aerosol Diagnostics V5.12.4 (M2TMNXAER).
And with matlab extracted from it, dusmass25/ocsmass/bcsmass/sssmass25/so4smass, these five parameters of the tif format image, please ask me is it possible to according to the formula, with the arcgis in the raster calculator will be a month of these five parameters are added up to get the month of the pm2.5 concentration of the average value.


PM2.5 = DUSMASS25 + OCSMASS+ BCSMASS + SSSMASS25 + SO4SMASS* (132.14/96.06)
Now I calculated based on this formula above and got the monthly mean value of pm2.5 concentration, but I found in arcgis that the pixel size of the original five parameters (dusmass25/ocsmass/bcsmass/sssmass25/so4smass) is not the same as the pixel size of the monthly mean value of the pm2.5 concentration, which is confusing to me and I am not sure if this method is correct. If you have a way to synthesize the image of the monthly mean of pm2.5 concentration based on these five parameters, please let me know about it, I am very much looking forward to your help.

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Re: There are some questions about the parameter synthesis of pm2.5

by GES DISC - mgreene » Mon Sep 11, 2023 8:49 am America/New_York

Thank you for your question. A Subject Matter Expert has been notified and will respond to your question shortly.

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Re: There are some questions about the parameter synthesis of pm2.5

by GES DISC - mgreene » Mon Sep 11, 2023 11:44 am America/New_York

The equation for PM2.5 is the same as what we have posted on our FAQ page, so that is correct. (https://gmao.gsfc.nasa.gov/reanalysis/MERRA-2/FAQ/) I think this should work equally well for 1 hourly or 1 monthly calculations.

As to why “the pixel size of the original five parameters (dusmass25/ocsmass/bcsmass/sssmass25/so4smass) is not the same as the pixel size of the monthly mean value of the pm2.5 concentration” it is not quite possible for anyone here to say, as it is a function of the software and routine that the user are using to make the calculations to compute the data.

Hope this helps.

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