60 
The following levels of data processing will be 
undertaken: 
® level 0. This is the raw data stream, |.e., what 
is contained on the ground station's tapes. 
This data stream will have navigation, predict- 
ed ephemeris elements, and attitude and 
housekeeping data within It. 
Level 1. This is Level O data in a reformatted 
structure, reversible to Level O, with calibration 
and navigation information within the header. 
The data product from this level of processing 
contains the total radiances for visible and 
near-infrared bands and brightness tempera- 
tures for thermal bands. The basic block of 
data will be determined by the recording peri- 
od. That is, for 4.5-km data, the basic block of 
data will be an entire orbit. For 1.13-km data, 
the smallest block of data will be the minimum 
recording period. A minimum recording period 
of 2 minutes is recommended, with a maximum 
of 12 minutes. 
Level 2. This level of data processing repre- 
sents the geophysical data in satellite swath 
format, not gridded nor resampled, and not re- 
versible to Level 1 format. The data product is 
a product derived from Level-1 containing 
chlorophyll-a, other pigments, water-leaving 
radiances, and sea-surface temperature. 
Level 3. This level of data processing con- 
sists of the geophysical data that have been 
resampled and/or composited - not reversible 
to Level-1 format. The data products are daily 
mosaics of nine Level-2 images on an 18-km 
grid with statistics including the number of pix- 
els, number of days, and sums of squares for 
each grid element. Weekly composites will be 
made of the geophysical data. 
Browse images will be available, consisting of 
all Level-1, -2, and -3 data products recorded on 
video disks. 
NASA will process all recorded high- and low- 
resolution data to Level-3 data products. The 
processing capacity has been sized to be twice 
that of the raw data rate to allow for processing 
backlog, implementation of improved algorithms, 
and possible processing of locally recorded HRPT 
data supplied to NASA. 
Archiving and Distribution of Data 
for Research 
All data products will be archived and distrib- 
uted through NSSDC/NODS. Three months of 
Level-1 data products and all Level-3 data prod- 
ucts will be accessible on-line at any time. Data 
will be loaded into the archive at monthly inter- 
vals, 1 to 2 months following collection. Cata- 
logue listings and inventory listings for digital and 
analog data, searchable by time and location via 
SPAN or other network systems, will be maintained 
and updated using the processing data base. 
NASA/GFSC will provide data products to its 
principal investigators, Announcement-of- 
Opportunity Investigators, and other national and 
international research users through the archival 
and distribution system described above. NASA 
will not offer its stored data to commercial or op- 
erational users in the private sector nor opera- 
tional users within the government. EOSAT will 
acquire copies of the data products for its ar- 
chive to serve all commercial and operational 
users. 
The system for processing and archiving the 
research data from SeaWiFS is based on the 
CZCS global data-processing and archiving effort 
underway at GSFC in terms of hardware, soft- 
ware, and methodology. Existing algorithms and 
processing times have been assumed for deter- 
mining pigment concentration and sea-surface 
temperature. 
Figure 25 summarizes the baseline SeaWiFS 
data acquisition and dissemination plans. 
