Earthdata Forum

Dear Forum Communiy,

I wanted to assess the NPP over Sweden MOD17A3HGF.A2023001.h18v02.061.2024021044317. However, when I opened the dataset in Qgis it showed the highest NPP values possible (not correlating to the usual values of Sweden) for certain areas. https://e4ftl01.cr.usgs.gov/MOLT/MOD17A3HGF.061/2023.01.01/MOD17A3HGF.A2023001.h18v02.061.2024021044812.hdf
20.08886 67.87942
20.08577 67.80678
20.36111 67.87916
20.36249 67.806

Could the dark green area be a water body and the satellite is thinking that it has the highest NPP value (also the sea-area in the picture has the highest values possible: 3.2766) [are the dark green values error values]? For the NPP calculation of the area should I just exclude the dark green pixels?

I would really appreciate you help,
thank you for your time, best regards,
Alex

Hi Alex -- We answered your question via email but wanted to add the answer here as well, in case any other users search the forum with your question.

Hi Alexexander,
Those pixels with the high value should not be used. Please note the NPP fill values from the picture below. The value 32766 represents: Land cover assigned as perennial salt or inland fresh water. Let me know if you have any questions.


Thanks,
Brett