High Resolution Land Mask

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avmehta
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High Resolution Land Mask

by avmehta » Wed Sep 16, 2020 2:57 pm America/New_York

Hello,
I have posted this question yesterday - but in another topic - so repeating here!
  In SeaDAS GUI there is a way to get 50m land mask (based on SRTM data). Is there any way to include this high-res land mask when running l2gen on a Linux machine to batch process L1 to L2 conversion for OLI images?
Thank you.
Amita

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OB.DAAC - SeanBailey
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High Resolution Land Mask

by OB.DAAC - SeanBailey » Wed Sep 16, 2020 3:11 pm America/New_York

Amita,

No. The 50m landmask in SeaDAS is a series of tiled PNG images, which is not a format that l2gen reads.  For a project the OBPG supports, we have a limited scope (the continental US) 60m resolution landmask based on the SRTM data set. That one l2gen does read.  It will be part of the next SeaDAS release, but if your interests are limited to CONUS, you can pull this file down and use it now:

https://oceandata.sci.gsfc.nasa.gov/manifest/tags/v3.1.0-rc/common/lwm_CONUS_SRTM60m_v3.1.nc

Regards,
Sean

avmehta
Posts: 148
Joined: Mon Feb 03, 2020 10:27 am America/New_York

High Resolution Land Mask

by avmehta » Wed Sep 16, 2020 10:49 pm America/New_York

Thanks a lot Sean. I have downloaded the data to my server!
Could you please help me with its usage in l2gen? I see that current land mask file is located in ocssw/share/common. I see these files:
landmask.dat  landmask_GMT15ARC.nc  landmask_dilated_25.dat  landmask_null.dat
I will add the 60m land mask to this directory. Should I specify this file name in the parameter file for l2gen?  I'd really be grateful if you can let me know  which program file  would  read this data during l2gen processing.
Regards,
Amita

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High Resolution Land Mask

by OB.DAAC - SeanBailey » Thu Sep 17, 2020 7:53 am America/New_York

Amita,

The l2gen usage statement (what you get when l2gen runs with no inputs or with only --help) lists (most) of the parameters it accepts (a few are super secret :wink:). 
The landmask is:
   land (ifile) (default=$OCDATAROOT/common/landmask_GMT15ARC.nc) = land mask file

So, in your parameter file (or on the command line), add:
  land=<path where you put it>/lwm_CONUS_SRTM60m_v3.1.nc

It can live anywhere,so lon as the <path where you put it> points to is where it is.
When we release it with SeaDAS, that'll be $OCDATAROOT/common/

Sean

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