Earthdata Forum

If I have an L1A file from VIIRS-JPSS1 and it's corresponding GEO file, what commands would I use in OCSSW to process it forward to an L2 file?

(Sorry about the "newbie question", I've exclusively used MODISA data with OCSSW since the demise of SeaWIFS)

Thank you!
-Andrew L.

Hi Andrew,

Make sure you have the VIIRSJ1 bundle installed (install_ocssw.py --viirsj1) and then
do something like the following.

getanc.py V2020099121800.L1A_JPSS1.nc

l2gen ifile=V2020099121800.L1A_JPSS1.nc geofile=V2020099121800.GEO-M_JPSS1.nc ofile=V2020099121800.L2.nc l2prod=rhos_445,rhos_556,rhos_667,rhos_868,chlor_a

Those are the level-2 products I use; you may choose to use a different set.

Help pages are available here.

https://seadas.gsfc.nasa.gov/help/

Regards,
Norman

...don't forget to include par=V2020099121800.L1A_JPSS1.nc.anc ...without that, you've pulled the ancillary files but didn't tell l2gen to use them :grin:

The l2gen process is pretty much the same for all missions, with the exception of those requiring an external geolocation file (i.e. MODIS, VIIRS) requiring the additional geofile=<GEOFILE>
Unlike MODIS, VIIRS can be run through l2gen with the L1A file.  However, like MODIS,  it can also be run with the L1B file, for which there is the calibrate_viirs code to generate.

Sean

"...don't forget to include par=V2020099121800.L1A_JPSS1.nc.anc ...without that, you've pulled the ancillary files but didn't tell l2gen to use them"

Huh.  I've been doing it wrong for a couple of years now.
Thanks for the heads up.

Norman

Thank you Norman & Sean! It worked like charm!

Just in case somebody is reading this thread later it turns out you need to install with

install_ocssw.py --viirsn --viirsj1

even if you are just processing just viirsj1. --viirsn seems to get some files that are common between both instruments and not included when you use only --viirsj1