38 
achieve. Furthermore, the instrument would al- 
ways be undergoing a tilt change somewhere in 
these latitudes, so daytime sea-surface tempera- 
ture measurements would be sporadic at the lati- 
tudes where the capability was desired. 
Since, as discussed in Section 5, the 
Landsat-6 nighttime power capacity is limited and 
nighttime data would be separated by 12 hours 
from data acquired in the visible regions, the Re- 
search Panel also favored locating the infrared 
bands in the 10.5 to 12.5 um region, preserving 
the continuity with prior AVHRR-based work. As 
a result, the baseline SeaWiFS instrument design 
contains the split long-wavelength band set. 
Band Selection Summary 
The spectral regions and band characteris- 
tics agreed upon for the baseline SeaWiFS instru- 
ment are summarized in Table 3. The SNR per- 
formance goals for the VNIR bands are chosen 
so that the error induced by the noise on the sig- 
nal approximately equals the error inherent in the 
atmospheric correction algorithms. These values 
represent minimum acceptable performance. The 
noise-equivalent temperature differences 
(NEATs) of Table 3 are sufficient to determine 
sea-surface temperatures in cloud-free areas to 
a few tenths of a Kelvin. An accuracy of 0.1K is 
the anticipated requirement for the 1990s; how- 
ever, the resulting NEAT requirement of a few 
hundredths of a Kelvin would exceed the capa- 
bility of the SeaWiFS instrument. Considering that 
the NEAT performance of the CZCS at 300K was 
0.29K, the goal for the SeaWiFS was taken as a 
NEAT of less than 0.29K at 300K. 
Spatial Resolution 
As discussed in Section 5, the Landsat orbital 
altitude of 705 km, in conjunction with the deci- 
sion to use the AVHRR High-Resolution Picture 
Transmission (HRPT) data format of six frames per 
second, fixes the sensor's spatial resolution at 
1.13 km at nadir. Both panels agreed that this 
resolution would be adequate for their local-area 
Table 3. SeaWiFS Baseline Spectral Regions and Performance Goals 
Spectral 
Region Range 
Visible 
Visible 
Visible 
Visible 
Near IR 
Near IR 
IR 
IR 
433-453 
490-510 
559-575: 1 
655-675 n 
745-785 n 
843-887 n 
1 
2 
3 
4 
5 
6 
iG 
8 
Spectral 
mM 
mM 
mM 
mM 
mM 
mM 
10.5-11.5 um 
11.5-12.5 um 
Expected Signal 
Radiance Minimum 
(mW/cm2 -sr-um) ! 
SNR/NEAT! 
1H. R. Gordon 1987: personal communication. The SNR values must be 
met at all sun angles. 
Notched between 760 and 770 to minimize interference from the 
3 oxygen absorption band. 
At 300K. 
