package is planned for use with Nimbus-F, scheduled for launch in 

 1974. It will be possible, at that time, to track the movement of more 

 than one hundred drifter buoys. 



Marine Remote Sensing 



Information on water color, sea surface temperature, sea surface 

 roughness, and sea and fresh-water ice can be obtained remotely by 

 means of sensors that respond to the visible, infrared, and 

 microwave portions of the electromagnetic spectrum. Since no one 

 remote-sensing technique is capable of measuring all these 

 parameters, it is necessary to use an optimum mix of remote sensors 

 with appropriate spectral and spatial resolution capabilities. 



Considerable advances have been made in the development of 

 multi-spectral visible remote sensors and their utilization on aircraft 

 and satellites. Examples of such sensors are conventional cameras 

 with different lens-filter-film combinations, television cameras with 

 a variety of filters, and multi-spectral scanning radiometers. Data 

 obtained with these remote sensors have been used to monitor ocean 

 current boundary movements, delineate upwelling regions, identify 

 regions with high bioproductivity, map contours of shallow-water 

 bottom features, monitor the dispersal of slicks associated with oil 

 spills and dumpings of acids and sewage sludge, and map coastal 

 zone features. 



The state of the art of infrared remote sensing has reached a stage 

 of development where it is being used on operational NOAA 

 satellites and NASA research and development satellites to provide 

 thermal images depicting variations in sea surface temperatures. 

 The newer remote sensors are providing sufficient spatial resolution 

 to permit observations of current eddies, convergences and 

 divergences, and water mass dynamics from satellite altitudes. 

 Airborne infrared remote sensors are being used to monitor the 

 heated water discharged by power plants into rivers and estuaries. 



At this time the remote sensing of ocean water color can be 

 accomplished only during daylight when the ocean surface is not 

 obscured by haze, fog, or clouds. Depending on the choice of spectral 

 bands, some infrared remote sensors cannot be used at night or at 

 times of adverse weather conditions. To overcome this kind of 

 operational constraint, NASA is now placing emphasis on the 

 development and testing of passive and active microwave remote 

 sensing techniques. Passive microwave remote sensors have the 

 potential to provide information on sea surface temperature and sea 

 roughness, and possibly information about ocean surface wind 

 speeds and directions. Passive microwave scanning radiometers 

 have been found to be useful in delineating the boundaries of sea ice 

 and the distributions of new ice and multi-year ice in the Arctic 

 region. These observations were made from aircraft altitudes. 



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