MODIS-Aqua POC data June 2014 onwards

Use this Forum to find information on, or ask a question about, NASA Earth Science data.
Post Reply
peter.strutton
Posts: 1
Joined: Tue Aug 22, 2017 10:44 am America/New_York
Answers: 0

MODIS-Aqua POC data June 2014 onwards

by peter.strutton » Tue Aug 22, 2017 4:01 pm America/New_York

There seems to be a problem with the monthly 9km POC data after May 2014, has anyone else noticed this? File sizes become much smaller and seem corrupted?

https://oceandata.sci.gsfc.nasa.gov/MODIS-Aqua/Mapped/Monthly/9km/poc/

Filters:

OB SeaDAS - dshea
Subject Matter Expert
Subject Matter Expert
Posts: 263
Joined: Thu Mar 05, 2009 10:25 am America/New_York
Answers: 0
Been thanked: 2 times

MODIS-Aqua POC data June 2014 onwards

by OB SeaDAS - dshea » Wed Aug 23, 2017 9:59 am America/New_York

The SMI files after May 2014 are produced by l3mapgen instead of smigen.  The new files are smaller since the poc data is stored as a scaled 16 bit int instead of a 32 bit float.  As you noticed, the file size is almost 3 times smaller.  From the NetCDF metadata:

  short poc(lat, lon) ;
    poc:scale_factor = 0.2f ;
    poc:add_offset = 6400.f ;
    poc:_FillValue = -32767s ;

so:
pocVal(float) = poc(short) * scale_factor + add_offset

The files look fine.  Can you point me to a file that seems corrupt?

don

Post Reply