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Chlorophyll product FLAGS
Posted: Tue Nov 29, 2022 3:52 am America/New_York
by floriid
Hello,
I hope this question was not previously asked, but I can't find something on the subject.
I am currently reviewing the NASA OceanColor Chlorophyll products and I can't find the flags and/or masking products. I need some guidance towards documentation and download for these.
Thank you!
Re: Chlorophyll product FLAGS
Posted: Tue Nov 29, 2022 10:59 am America/New_York
by OB SeaDAS - dshea
Every Level 2 NetCDF file has a set of flags in the variable l2_flags. Here is a dump of the definition:
int l2_flags(number_of_lines, pixels_per_line) ;
l2_flags:long_name = "Level-2 Processing Flags" ;
l2_flags:valid_min = -2147483648 ;
l2_flags:valid_max = 2147483647 ;
l2_flags:flag_masks = 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304,8388608,16777216, 33554432, 67108864, 134217728, 268435456, 536870912, 1073741824, -2147483648 ;
l2_flags:flag_meanings = "ATMFAIL LAND PRODWARN HIGLINT HILT HISATZEN COASTZ SPARE STRAYLIGHT CLDICE COCCOLITH TURBIDW HISOLZEN SPARE LOWLW CHLFAIL NAVWARN ABSAER SPARE MAXAERITER MODGLINT CHLWARN ATMWARN SPARE SEAICE NAVFAIL FILTER SPARE BOWTIEDEL HIPOL PRODFAIL SPARE" ;
Level 3 files are more difficult since the data is binned. You can't really bin a bit pattern value to everyone's satisfaction. The Level 2 flags are used to decide whether a Level 2 pixel is added to the Level 3 bin or not.
Hope this helps.
don