Operational Applications 
Navigation and Ship Routing 
As indicated earlier, the location of eddies, 
fronts, and currents is important for maritime and 
naval applications. The importance of ocean- 
color imagery to these uses is demonstrated in. 
Figures 11 and 12, both taken 12 May 1986, sep- 
arated in time by 14 hours. The thermal image 
from the AVHRR shown in Figure 11 indicates 
there is a warm spot in the center of the image 
below Majorca, Spain (represented by dark gray 
shades). During this period, ship and aircraft sur- 
veys registered calm sea conditions and high so- 
lar heating. The upper 1 meter of the water was 
reported to be as much as 3°C warmer than the 
lower layers. Hence, in interpreting this image, 
consideration must be given to the fact that sur- 
face heating may mask the actual circulation pat- 
terns. 
In the imagery of Figure 12 there is no evi- 
dence of biological distribution patterns below 
Majorca usually associated with warm water sur- 
rounded by colder water. Since the radiance 
leaving the water emanates from a depth of ap- 
proximately one attenuation coefficient (typically 4 
to 20m, depending on turbidity), the imagery rep- 
resents the circulation patterns below the heated 
surface of the ocean. Since the ground-truth 
data indicates high solar heating that may mask 
the actual circulation patterns, it can be conclud- 
ed that the general circulation patterns of the 
ocean are better represented by biological distri- 
bution patterns than by surface thermal patterns 
under certain conditions. 
Hydrology 
The utility of satellite-acquired imagery in 
monitoring floods was also demonstrated using 
CZCS data. For example, Figure 13 is imagery 
acquired by the CZCS of the Parana River Valley 
in Argentina. The flooded area extends 700 km 
from the confluence of the Rio Parana to the Rio 
COMMERCIAL AND OPERATIONAL USERS' PANEL 
de la Plata near Buenos Aires and ranges from 
20 to 70 km in width. While data from stream 
gauges can often provide warning of impending 
flood conditions, they do not provide information 
on the extent of flooding, which may be of critical 
importance to rescue or relief operations. 
Surveying, Monitoring, and 
Managing of Inland and Coastal 
Fisheries 
Compared to conventional ground-sampling 
techniques, remotely sensed data from inland and 
coastal fishing areas are more cost-effective for 
gathering data, if the data are received in a timely 
fashion or in near real time. This is especially 
true in sparsely populated, developing countries 
where communications are poor and environ- 
mental data are not available. Welcomme (1985) 
has enumerated the surveying and monitoring 
functions that can be accomplished using satellite 
imagery. A brief summary of those functions that 
can only be accomplished using data acquired by 
a SeaWiFS-type sensor is presented below. 
The potential fishery output of rivers has 
been found to be directly related to the flooded 
area of the river, i.e., catches in flood-plain rivers 
in a particular year are correlated with the flood 
intensity of the previous year (Welcomme 1985). 
Welcomme also found that macrophytes tend to 
tie up nutrients for longer periods than phyto- 
plankton. Data from a sensor like SeaWiFS can 
be used to measure macrophyte growth, phyto- 
plankton growth, and the extent of the drawdown 
of water bodies. The seasonal turnover and 
even upwelling can also be efficiently monitored. 
The same kinds of information can be ac- 
quired on coastal waters where circulation pat- 
terns are better defined, due to the increased 
flows and often higher color-to-temperature con- 
trasts between various water masses. These 
areas are often large and remotely located and, 
therefore, best assessed through use of satellite- 
acquired data. 
