Earthdata Forum

NASA Ocean Color Data Users:                                                                               
                                                                                                           
The Ocean Biology Processing Group is initiating a reprocessing of the                                  
ocean color products from MODIS on Aqua (MODISA), to incorporate advancements                              
in instrument and vicarious calibration.  This reprocessing will begin today (19 Dec 2017),
and it should be completed within the coming weeks.                                    
                                                                                                           
There will be no changes to product formats or product algorithms relative to                              
the current R2014.0.2 product distribution.                                                                
                                                                                                           
The purpose of this R2018.0 reprocessing for MODISA is two-fold:                                           
1) to incorporate significant advancements in instrument calibration                                       
2) to update the vicarious calibration to incorporate recent developments in                               
the MOBY instrument calibration.                                                                           
                                                                                                           
The combined impact of the MOBY update and the instrument calibration update                               
is 2%-10% changes in the global mean deep-water Rrs retrievals from MODISA,                                
largest in the blue and red, with an associated reduction in chlorophyll of                                
order 10%. While these impacts are large, they have have been found to                                     
significantly improve the validation of the satellite retrievals to in situ                                
measurements. especially Rrs in the blue.                                                                  
                                                                                                           
Full details on the reprocessing changes and impact are available here:                                    
https://oceancolor.gsfc.nasa.gov/reprocessing/r2018/aqua/

All forward stream production has been switched to the R2018.0
processing configuration.  The retrospective data for MODIS-Aqua ocean
color will cease to be accessible from our servers until such time as the data
products are regenerated with the R2018.0 processing configuration.                                                  
                                                                                                           
Best Regards,                                                                                              
Bryan Franz and the NASA Ocean Biology Processing Group

The MODIS-Aqua R2018.0 reprocessing is now complete.  All data through Level 3 Standard Mapped Images have been regenerated.
The data up through 15 Oct 2017 are considered "Refined".   The newer data will be considered "Quicklook" until we have had an
opportunity to assess the rapidly changing temporal calibration and made any necessary adjustments.  This will be done on a monthly
basis.  This is a change from our previous definition of "Refined" data, which was solely based on the availability of the necessary
ancillary data.  The previous definition allowed files to be defined as "Refined" after approximately 15 days from collection.  The new
approach means the "Quicklook" status may be retained  for up to 90 days from collection.  

The "Quicklook" designation can be determined by examining the file metadata.  The processing_version attribute will
have a "QL" appended for these data.  Please note that in the future we will also provide an indicator in the filename to make
the distinction easier to identify.

With the MODIS-Aqua reprocessing complete, we are now preparing to reprocess the SeaWiFS mission...stay tuned!

Regards,
Sean