Abstract:
This data set consists of merged satellite measurements of global ocean
chlorophyll data derived from the Moderate Resolution Imaging Spectroradiometer
(MODIS), in orbit on the Aqua (formerly EOS PM) platform, and the Sea-viewing
Wide Field-of-view Sensor (SeaWIFS), in orbit on the OrbView-2 (formerly
SeaStar) platform.
Aqua MODIS and SeaWiFS products are processed and distributed by the Ocean
... Biology Processing Group (OBPG). MODIS/Aqua processing details can be found at
http://oceancolor.gsfc.nasa.gov/DOCS/MODISA_processing.html . SeaWiFS
processing details can be found at
http://oceancolor.gsfc.nasa.gov/DOCS/SW_proc.html .
The Aqua MODIS and SeaWiFS Level-3 9 km merged chlorophyll products are
generated routinely for daily, 8-day, monthly, seasonal and annual time periods
once the refined products for each of the contributing missions are processed.
Increased coverage over the single mission product is realized through the
merging of the two data sets. There is a substantial improvement (> 50%) in
coverage at the daily level, decreasing with the increase in the temporal
period binned.
The MODIS/SeaWiFS merged product is generated in essentially two steps. First,
the MODIS Level-3 file is reduced in resolution from 4 to 9 km to match the
global resolution of the SeaWiFS chlorophyll product. This involves combining
the sum and sum squared field values for the (typically) four 4 km bins into
the corresponding single 9 km bin. In the second step, the reduced-resolution
MODIS file and the corresponding SeaWiFS Level-3 file are combined. Because
both input files are at the same 9 km resolution, the summing is performed
bin-by-bin. The Standard Mapped Image file that is generated from the merged
Level-3 binned file stores scaled 16 bit integer values rather than the usual 8
bit values, giving the user much greater numerical precision. The actual
images displayed on the Ocean Color website in PNG format are provided for
visual inspection only.
Browse Level 3 Standard Mapped Images (SMI) at
http://oceancolor.gsfc.nasa.gov/cgi/level3.pl
The Aqua MODIS and SeaWiFS Level 3 Merged Chlorophyll data files are available
from the FTP site at ftp://oceans.gsfc.nasa.gov/Merged/ 
