Abstract:
This data set consists of algorithm estimates of global Photosynthetically
Active Radiation (PAR) reaching the surface obtained by the Sea-viewing Wide
Field-of-view Sensor (SeaWiFS), in orbit on the OrbView-2 (formerly SeaStar)
platform. SeaWiFS data products are processed and distributed by the Ocean
Biology Processing Group (OBPG). Processing details can be found at
... http://oceancolor.gsfc.nasa.gov/DOCS/SW_proc.html
PAR is defined as the quantum energy flux from the Sun in the spectral range
400-700 nm. It is expressed in Einstein/m2/day. The PAR model uses
plane-parallel theory and assumes that the effects of clouds and clear
atmosphere can be de-coupled. The planetary atmosphere is therefore modeled as
a clear sky atmosphere positioned above a cloud layer. This approach was shown
to be valid by Dedieu et al. (1987) and Frouin and Chertock (1992). For
additional information about the algorithm see
http://oceancolor.gsfc.nasa.gov/DOCS/seawifs_par_wfigs.pdf
The SeaWiFS Level 3 standard mapped image (SMI) products are integer
representations of binned data products. This image is an 8-bit,
two-dimensional array of an Equidistant Cylindrical projection of the globe.
(The capability to produce 16-bit SMI products has been implemented by the
OBPG, and the SeaWiFS PAR products are expected to be regenerated as 16-bits
values at the next reprocessing in about 1 year.) Each SMI product contains
one image of a geophysical parameter and is stored in one physical HDF file.
The Level 3 binned products are used to generate mapped data products on 9 km
equi-rectangular projection. The products are generated for the following
binning periods: Daily, 8-Day, Monthly, Monthly Climatology, Seasonal, Seasonal
Climatology, Annual, Cumulative.
More detailed information on the Level-3 Standard Mapped Image data product
format specifications can be found in the document at
http://oceancolor.gsfc.nasa.gov/DOCS/Ocean_Level-3_SMI_Products.pdf
Browse Level 3 Standard Mapped Images (SMI) at
http://oceancolor.gsfc.nasa.gov/cgi/level3.pl
The SeaWiFS Level 3 Mapped data files are available from the FTP site at
ftp://oceans.gsfc.nasa.gov/SeaWiFS/Mapped/ 
