L2 chl Flags

r.fernandes · by **r.fernandes** » Wed Feb 08, 2017 8:38 am America/New_York

Hi,

Is there any way to change the range of valid pixel expression for the chl in seadas 7? I know how to change it on each image, but i wanted to know if i'm able to change the values that seadas uses so that i dont need to do it image by image. Im using Seadas 7.3.2 with macOS sierra.

Thanks in advance!

gnwiii · by **gnwiii** » Wed Feb 08, 2017 10:05 am America/New_York

Which files are you using? Are you using the OCSSW Processing System? Level-2 NetCDF files from l2gen have:

chlor_a:valid_min = 0.001f ;
 chlor_a:valid_max = 100.f ;

These are set in the product.xml file and also appear in level-3 mapped files (either carried through or set from the product.xml file. If you generate your own level-2 files you can edit the product.xml file

Maybe you are referring to limits for the range of values used for display:

chlor_a:display_min = 0.01f ;
chlor_a:display_max = 20.f ;

These are set in l3mapgen, again using values from the product.xml file, so if you are generating the mapped files yourself you can edit the product.xml file.

If you are using files created elsewhere, there are command-line tools that can edit NetCDF attributes efficiently in batch scripts. One example is ncat NetCDF Operators package, but you can probably do it with most languages that support NetCDF files (Python, Matlab, IDL, etc.).

r.fernandes · by **r.fernandes** » Wed Feb 08, 2017 11:55 am America/New_York

I'm using L2.LAC images. Using L2bin and then L3mapgen to do the daily and 8-day average.

thanks a lot!

gnwiii · by **gnwiii** » Wed Feb 08, 2017 12:54 pm America/New_York

Sounds like you need to adjust the values in $OCSSWROOT/ocssw/data/common/product.xml. Since that file is managed by git, will want to create your own local branch. Sean recently posted an example of this for a customized script, but the same principle should apply for product.xml.