Gain change may suddenly cause an apparent sea surface structure to be lost or acquired 

 in the image (fig. 2, note 1, line A). Tentatively, the reflection patterns attributable to 

 the oceanic effects are as follows: 



1 . Reflections from the Sea Floor in Shallow Water Areas - Many images of the Yellow 

 Sea suggest that the video data contain reflections from the bottom in areas with depths as 

 great as 10 fathoms. Persistence of position and form over many months suggest that these 

 features may be sea floor reflections, rather than suspended sediments moving over the 

 shallows (fig. 2), but this is unverified. 



2. Reflection from Turbid Surface Waters in Deep Water Areas - Aircraft underflights 

 during the experiments off South Korea have shown turbid plumes and extensive coastal 

 turbidity along the southeast coast of the peninsula (see fig, 3). In this region the water 

 depths increase rapidly and reflections in DAPP data are obtained from the surface waters 

 in areas of 600 foot water depths. 



3. Reflection from Areas of High Sea State and Extensive Whitecapping of Waves - 

 The development of substantial amounts of white foam by strong winds and high seas, when 

 combined with cloud free skies may produce more reflective areas on the sea surface. Very 

 sharp boundaries have been seen by aircraft between whitecapped and whitecap free areas 

 associated with oceanic thermal fronts. Figure 3 appears to have a series of patterns of 

 sea state differences, but no field verifications have been accomplished to date. 



Display of Infrared Sea Surface Temperature Data (HRIR) 



The temperature range of -2 to 30°C covers more than 90 percent of the surface temp- 

 eratures around the globe (Montgomery, 1958). This 32°C range is slightly less than one 

 third of the full range, 100°K, of the system. For any particular oceanic region (i .e. 

 linear distances of tens of miles) the temperature range Is much less, more In the order of 

 a few degrees, with some regions up to ten degrees. As a result of experiments In the 

 strong gradient areas off the Korean Peninsula, the following procedure was established for 

 obtaining synoptic sea surface thermal structure from the remote-site readout vans: 



1. Infrared Data Display Brilliance Inversion Mode (Mil) - Use the 16 gray shades for 

 charting sea surface temperature patterns (fig. 12). 



2. Temperature Range Expansion (X4 setting) - The system has a calibrated temperature 

 sensitivity range of 210-310°K. There are three temperature expansion settings, 

 Xl, X2, and X4, which vary the range of temperatures over which the 16 gray 

 shades are spread. Xl covers the entire 100°K, X2 can cover any 50°K span, and 

 X4 any 25°K span of temperatures (fig. 12). 



3. Brilliance Inversion Base Temperature Setting - This value determines the warmest 

 temperature included In the gray shade scale, of a particular display, and fixes 

 the temperature range which the 16 gray shades will cover. By setting a base 

 temperature of 298°K (0°C = 273°K, 25°C = 295°K) the X4 temperature range of 

 25°C Is displayed in the range of 0-25°C, the interval of most sea surface temp- 

 eratures encountered (fig, 12). Slightly different settings of the base temperature 

 may be required to produce the highest quality images under different oceanic and 

 atmospheric conditions. By experimenting with several degree variations in base 



