More on OLCI

Ernst Lobsiger

Dear All,

I only recently discovered that we still have world wide Near-Real-Time (NRT) OLCI 300m resolution data on HVS-2. These are level 2 ocean colour data S3A_OL_2_WFR_*.tar in EUMETCast channel E2H-S3A-10 and S3B_OL_2_WFR_*.tar in channel E2H-S3B-10. As with earlier distributed (level 1b) OLCI S3X_OL_1_EFR_*.tar these are 3 minute segments. That said you can adapt any of my old Sentinel3-A/B/X SatPy scripts to image these ocean colour WFR data. For this purpose you must use the "olci_l2" reader as follows:

"reader =  'olci_l2', reader_kwargs = {'engine': 'netcdf4'}"

You will have to check in ../satpy/etc/readers/olci_l2.yaml what data this reader can handle. The data is especially apt to study water quality, sedimentation and chlorophyl. You can (and will have to) invent your own composites with some of the 16 OaXX reflectance channels or use the chlorophyl channels with some colour map. As a little competition advanced users could publish their most impressive WFR composites here. I add my very first images as a proof of concept ...

Happy hacking,

P.S. As I said the S3X_OL_X_XFR_*.tar are 3 minute chunks. For unknown reasons in my PyTROLL/SatPy Kit 3.0 Sentinel3 scripts I used 2 minutes and advanced 60 seconds to the segment centers. This is another bug that I only discovered now and that you certainly want to fix. According to the documentation (and also most of such files I still found on my receivers) S3X_OL_1_EFR chunks are 3 minutes and you have to advance 90 seconds to the segment centers.

Ernst Lobsiger


here some ocean colour experiments (cloudy sky is black). It feels like SatPy painting the sea.