Earthdata Forum

Hi,
Apologies for the dumb question.
I've downloaded Terra MODIS Monthly NDVI/EVI rasters (MOD13A3.061) for a wildlife study. I just want to make sure I'm extracting the right values for each month.
I understand the 16-day averages use the preceding 16 days, is this the same for Monthly averages?
For instance, NDVI/EVI rasters with 'doy21060' correspond to 2021-03-01. Would this raster have Vegetation Indexes that average the month of March or for the preceding month February?

Thanks!

Hi juni.rechter That is a good question, because it is not stated obviously anyplace, and it does vary with MODIS products. All MODIS products except the MCD43 BRDF/Albedo products use the first day of the composite period as the acquisition date. So, in response to your specific date, 2021060 that composite is the month of March. Just a side note, the MCD43 acquisition date given is the 9th day of the 16-day period.
Please let me know if you have any questions.
Thanks,
Brett

Hi Brett,
Amazing, thank you for the clarification!
Juni