Dr. Gifford C. Ewing; Evaporation gradients at the sea surface 



Dr. Ewing reviewed his basic studies on the nature of heat transfer in water. 

 Photomicrographs were shown which demonstrated convection current formation. He also 

 discussed the various programs carried out at the Scripps Institute of Oceanography which 

 involved LRT measurements, part of which have been covered in two papers (G. Ewing and 

 E. D. McAlister, Science 131, 1374-76; E, D. McAlister, Applied Optics 3, 609-612). The 

 upper 10 microns of the ocean surface is the active radiation area and this breaks down 

 as follows: 



Event Depth 



Evaporation 3 angstroms 



Reflection 5 angstroms 



Protein-mono layer 30 angstroms 



Radiation layer 1,000,000 angstroms 



A difference of 0.6°C was measured between the microsurface temperature and a depth of 

 15 cm, in one test done at night off the Scripps pier. The most rapid area of change in 

 temperature is the first mm. of the surface. Recordings from an airborne infrared scanner 

 showed convection cells and whitecaps. Foam on the surface was shown to have a pro- 

 nounced effect. 



Following Dr. Ewing's presentation there was a discussion of the probable effects of 

 sky reflection. The consensus of this discussion involving Messrs. Moser and Frank was 

 that at a level of accuracy of ±1.0°F., reflectivity should be no great problem. The effect 

 of error in absolute temperature read-out in apparent displacement of isotherms on thermal 

 maps was discussed. It was also brought out that under "average conditions" the microsur- 

 face temperature appears to be about 0.6°C. cooler than the immediate subsurface. Mr. 

 Clark mentioned that the average annual difference shown by the Sandy Hook work was 

 about 1.0°F. Correction for the difference in temperature of this film of water at the sur- 

 face is a major problem with IRT survey of surface temperature. It was noted that the 

 surface film tends to maintain itself and requires considerable force to rupture it. It is 

 restored to its original condition (relative to the temperature gradient across the micro- 

 surface) in about 20 seconds after the breaking of a wave. The wind has to be blowing quite 

 hard in order to produce whitecaps with sufficient frequency to effect this rupture and there- 

 fore to significantly affect the gradient across the microsui-face when averaged over a fairly 

 large area. 



Robert A. Peloquin, John C. Wilkerson, George L. Hanssen : Use of Barnes Model 

 14-320 Airborne Radiation Thermometer in Aerial Survey Over the North Atlantic 



The nominal accuracy of the Barnes 14-320 Airborne Radiation Thermometer (ART) 

 is ±0.2°C. Calibration is conducted with a temperature-controlled bath and usually holds 

 good for up to three weeks. A number of tests have been performed to determine the 



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