Ocean-color imagery also has potential com- 
mercial applications in the recreational sportfish- 
ing industry. For instance, most large gamefish, 
such as sailfish and marlin, are nearly always 
found in the blue water typical of open-ocean 
conditions. An operational map of distance and 
heading to the nearest blue water from selected 
sportfishing ports or marinas would be an attrac- 
tive commercial value-added data product. Fig- 
ure 7 is an example of such a map of the north- 
ern Gulf of Mexico derived from CZCS data. Al- 
ternatively, the availability of SeaWiFS data at a 
central site would also be extremely valuable to 
the sportfishing industry in reducing the time and 
fuel now spent searching for blue water. 
Offshore Oil and Gas Exploration 
and Production 
AVHRR sea-surface temperature data cur- 
rently are major sources of the information used 
in preparing eddy forecasts for offshore oil explo- 
ration and production (Haustein and Vastano 
1987). Temporal changes in eddy size and posi- 
Figure 7. Distance in 
nautical miles and 
heading in degrees 
(from true North) from 
selected ports to the 
nearest blue water in 
the northern Gulf of 
Mexico on 9 May 1982. 
(Courtesy of T. Leming.) 
tion and current frontal locations are used to 
produce routine summaries of their positions, 
surface-flow directions, and estimates of their 
probability, duration, and magnitude. Figure 8 
shows a typical summary. 
However, the utility of thermal-infrared sea- 
surface temperature measurements deteriorates 
seriously from the summer through fall in the Gulf 
of Mexico and in many other regions at latitudes 
between 30° South and 30° North (e.g., the 
equatorial Atlantic and Pacific Oceans and the 
Indian Ocean). First of all, during these months 
surface conditions are relatively isothermal as a 
result of strong solar heating of the surface 
layer, with temperature ranges in the narrow 
band from about 29 to 31°C. Secondly, humid 
atmospheric conditions cause a severe attenua- 
tion of some regions of the thermal-infrared sig- 
nature. The limitations due to surface heating 
are greatest when the surface is calm and solar 
intensity is high. In some instances the ocean's 
features are masked, significantly diminishing the 
usefulness of the data. 
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