Earthdata Forum

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.

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

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.