shown to be both positive and negative depending upon a variety of environmental influences. 

 Factors involved in the variation between skin temperature and immediate subsurface 

 temperature were given as follows: radiation, sensible heat transfer, latent heat transfer, 

 precipitation, and wind mixing. It was suggested that to reduce problems due to sky re- 

 flection, instruments should be calibrated outside of shelter under the sky. The IRT 

 instrument was mounted in the bow of the ship about 40 feet from the surface of the water 

 in such a way that the instrument itself was protected, being mounted above and behind a 

 viewing port in the bow. This was a Barnes instrument with a 2° cone. The thermistor was 

 towed at about 1 meter depth behind the ship. Calibration was the greatest problem in this 

 work; this was done against an immersion thermometer using a bucket of water. A certain 

 amount of variation was shown to exist in instrument accuracy by the bucket checks; this 

 varied up to ±1°C. Under average conditions the microsurface temperature was about 

 0.6°C. In discussion Dr. Franceschini said that he considered that differences to be as- 

 sociated with cloud cover may be appreciable, especially if the IRT is calibrated with a 

 blackbody cavity. For clear sky conditions the difference could be as great as 1.0°C, In 

 situ calibrations minimize or eliminate this variation. Calibration was done with the water 

 in the bucket under strong agitation. The resulting roughened surface approximates more 

 closely the natural sea surface and destroys surface layering. It was not possible to relate 

 the tefnperature of the rain to the microsurface temperature because no data were available 

 on rain temperature. In dead calm weather the differences between microsurface and 

 immediate subsurface temperature did not increase very much. It was pointed out that 

 reflectivity from the instrument itself may be minimized if the angle of view during calibra- 

 tion is near to but not vertical. 



Paul M. Moser: Airborne Infrared Oceanic Mapping 



Mr. Moser reported on his experience in using a highly sensitive radiometer which 

 could be calibrated as an LRT, in conjunction with an airborne infrared mapping device 

 which records thermal pictures of the sea surface on photographic film such that cool areas 

 appear dark and warm areas appear light. The scanner permits an area of view of one 

 nautical mile for each 1100 feet of altitude with a scanning angle of 140°. He described the 

 network pattern of cool-edged polygonal spots associated with convection cells at night 

 (about 100 feet in diameter) as well as oil slicks, wind streaks, and sun glare (stressing 

 that sun glare operates at all wave lengths). Meteorological conditions affecting IRT 

 readings were also discussed. White caps were seen to show up typically as cold spots at 

 night. By use of the scanner, both small-and large-scale water motion could be deduced. 

 Mr. Moser concluded that "bucket depth" temperatures should be calculable to within 0.1°C. 

 from nighttime vertical IRT measurement provided air temperature, wind force, and 

 humidity are known. Nighttime IRT records would give absolute definition of temperature 

 fields of greater accuracy than daytime records when thermal stinicture is more stable. 



In discussion Mr. Moser stated that the IRT sensor was located within the airplane 

 just far enough inside to avoid the slipstream. An air diverter was installed just ahead of 

 the opening so as to provide a gentle air outflow. Mr. Moser qualified the remark made in 

 his preconference notes (which were distributed to those in attendance) by stating that many 

 of the phenomena listed therein can be recorded only if the measuring device has a 



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