I processed OLCI-A L1B data using l2gen under SeaDAS v7.5. I used the Multi-scattering with 2-band, RH-based model selection and iterative NIR correction option for aerosol mode.
I got high peaks at 400 and 681 nm for all spectra that I compared with in-situ Rrs spectra. Why such peaks at 400 and 681 nm ? Is it due to the fluorescence at 681 nm ?
Does l2gen include any florescence correction by default ?
No, there is not fluorescence correction in l2gen.
Without seeing your data, I can't provide a comment about the 400nm peak, however the 681 is very likely due to an indexing bug in the "smile" correction code as implemented in the version of l2gen released in SeaDAS v7.5. The bug has been fixed and we anticipate an update soon.
Here attached the spectra from l2gen.
The 400 nm peak is quite similar to 681 nm bug. What is 400 nm peak reason for all spectra ?
Looks like just ASD spectra were included in the figure you attached - OLCI is not hyperspectral...
Sorry about that. I attached the right figure.
Yep, that 681 peak is the bug :grin:
There are a number of possible explanations for the 400nm peak, but the most likely is calibration. We have not implemented a vicarious calibration for OLCI yet.
Was the fixed for this bug released in any of the recent SeaDAS v7.5 minor level releases? If not, is there any work around. I tried disabling the smile correction with "rad_opt=0" option but that had no impact of the output L2.
The fix for the smile correction bug went in with v7.5.2