OceanColor Aqua Processing

Since the transition of MODIS-Aqua processing to the Ocean Color Discipline Processing Group (OCDPG) at NASA/GSFC in February, much effort has been dedicated to establish a new baseline data set that the research community can use to conduct their studies with greater confidence in the data products. As presented at the recent NASA Ocean Biogeochemistry Science Team meeting in Washington, DC (April 14-16, 2004), substantial progress has been made since February and a reprocessing has been approved based on the most recent on-orbit calibrations provided by the MODIS Characterization Support Team (MCST) and corrections to the sensor polarization sensitivity tables. These modifications have greatly improved the consistency between SeaWiFS and MODIS-Aqua derived products as is shown below. There remain other refinements and corrections that need to be considered in the future such as bidirectional reflectance (BRDF), response vs. scan sensitivity, etc. These further refinements are being actively examined by the OCDPG in collaboration with the MODIS Science Team, and other interested members of the research community and will be incorporated into future reprocessings as considered appropriate by the Science Team and the algorithm working groups recently established by the NASA Biogeochemistry Program Manager, Paula Bontempi. The sequence of analyses shown below is provided to illustrate the improvements that have been realized in the data products beginning with the initial unvalidated MODIS-Aqua products currently in the GES DAAC to what will be available from this reprocessing.

The plots posted below provide a comparative time series of Ocean Color products (specifically, water-leaving radiances) for MODIS-Aqua and SeaWiFS. Briefly, multi-day (8-day or 4-day as noted) mean level-3 equal-area binned products with 9-km resolution were generated for each sensor. Common bins from a deep water subset (water depth greater than 1000 m) were averaged and compared.

CURRENT GES DAAC HOLDINGS MODAPS Collection 3 processing Launch - Dec 2003
FORMER OceanColor Web HOLDINGS Prototype configuration (Feb - Mar 2004) Updated MCST calibration (v4.3.1.0, linear-fit m1s) Updated RSMAS polarization table (aqua_1a) RADCOR corrections disabled Single vicarious gain applied (MOBY) Gothic-R BRDF correction applied OCDPG processing (MSl12 v3.5.2) Launch - Present
CURRENT OceanColor Web HOLDINGS Reprocessing configuration Updated MCST calibration (v4.3.1.5S, log-fit m1s) Corrected polarization sensitivity Updated vicarious gain (MOBY) Fresnel BRDF correction applied More conservative cloud screening Mask high glint at level-3 OCDPG processing (MSl12 v4.0.2) Launch - Present View validation results Below are four day composites, chl a, July 2003
SeaWiFS	MODIS-Aqua