Earthdata Forum

Hello,
I am working on a project in coastal Antarctic waters and found a large discrepancy between chlor_a and FLH. See the attached figure (January 2022). While there are some possible "science" reasons for this (e.g., adjacency effects), I wanted to verify that both of these products use the same atmospheric correction (l2gen). Do they use the same atmospheric correction? Could you please provide information about the quality flagging that is performed for each product? Is the flag list different for chlor_a versus FLH? Perhaps High-light or something else is turned "off" for FLH allowing it to retain more coastal data? Any insights would be much appreciated. In the future, could the flagging process be documented on the algorithm pages for chlor_a and FLH?
Thank you,
Jessie Turner
jturner@uconn.edu

The flags used in processing are recorded in the L3 metadata:

%ncdump -h AQUA_MODIS.20240312.L3b.DAY.CHL.NRT.nc | grep :flaguse
:flaguse = "ATMFAIL,LAND,HILT,HISATZEN,STRAYLIGHT,CLDICE,COCCOLITH,LOWLW,CHLWARN,CHLFAIL,NAVWARN,MAXAERITER,ATMWARN,HISOLZEN,NAVFAIL,FILTER,HIGLINT" ;

%ncdump -h AQUA_MODIS.20240312.L3b.DAY.FLH.NRT.nc | grep :flaguse
:flaguse = "ATMFAIL,LAND,HILT,HISATZEN,STRAYLIGHT,CLDICE,COCCOLITH,LOWLW,CHLWARN,CHLFAIL,NAVWARN,MAXAERITER,ATMWARN,HISOLZEN,NAVFAIL,FILTER,HIGLINT,PRODWARN,MODGLINT" ;

Tommy

Thank you!
-Jessie