Earthdata Forum

Hello,

I'm trying to make a map of ocean Net Primary Productivity values for yearly or monthly at the global scale. I've found the data in HDF4 and xyz formats at http://www.science.oregonstate.edu/ocean.productivity/standard.product.php. However, when I try to convert the hdf file using MODIS Conversion Toolkit in ENVI or Nasa's HEG tool to a tif file it doesn't recognize it as a Modis HDF and therefore will not process it. Could someone point me to NPP Modis hdf file, or even a Geotiff of the NPP ocean values?

I also found tiff files of mean NPP annual at https://cdn.rawgit.com/OHI-Science/ohiprep/master/globalprep/prs_fish/v2016/prim_productivity/npp.html. But the values are very low for being in mg c/ m^2/ day. Does anyone know why these values are so low?

Thanks so much.

While derived from MODIS data, the NPP products distributed by Oregon State University are not in the format recognized ENVI or the HEG tool.  Those tools expect files in HDF-EOS.  The "-EOS" part is a convention used by the Land, Atmosphere and Cryosphere disciplines - but not the Ocean disciple (at least not since 2004...)  In fact, the OSU files differ from those produced by us (the OBPG - Ocean Biology Processing Group).  All is not lost, though :wink: 

The OSU HDF files are quite simple, and ENVI should be able to read them using its generic HDF reader.

The files are also supported (well, because they are HDF) by the SeaDAS software package we maintain.  SeaDAS can export the files as GeoTIFF, if you require that format (I'm sure ENVI could as well, but I don't use ENVI so can't really help there).

Regards,
Sean

BTW, the other link you point to seems to be someone's script for R that reads the xyz text files from OSU.  No clue what it's doing or why it's values seem low. ...definitely not an official source.
In fact, not a source at all, just a reader for the OSU data :grin:

I got it! Thanks so much for your help.