as have resulted therefrom. However, fog patches and light rain appeared not to affect 

 our readings significantly under the sea and air temperature conditions encountered. 



FACTORS AFFECTING SURFACE TEMPERATURE DETERMINATION 



Temperature measurement of the micro-surface of the sea with temperature-calibra- 

 ted infrared detectors is a well established technique. Doubts about the accuracy of the 

 infrared thermometer for this purpose are related to an apparent confusion over exactly what 

 is being measured at the sea/air surface. Since our objective is primarily to estimate the 

 temperature of the upper meter of the sea, our concern is with our ability to make these 

 estimates. We have collected data which bear on the accuracy of the estimating procedure. 



A repeatability test consisting of a two-aircraft simultaneous comparison was carried 

 out as a cooperative venture between the Sandy Hook Marine Laboratory and the U. S. Naval 

 Oceanographic Office. A special flight with our IRT (Barnes IT-1) was set up following our 

 regular survey flight track (within an expected maximum error of ±2 miles) . This track was 

 followed by a second aircraft, a Navy Constellation using a Barnes 14-320 # ART. The flight 

 paths could not be made to coincide exactly because the two planes could not fly side-by-side, 

 the minimum speed of the Constellation being 40 mph greater than that of the UF2G (See 

 Figure 1). However, the two aircraft were close enough together for most of the operation 

 to give useful comparisons because the area was typified by gradual change and isotherms 

 about normal to the direction of flight. 



In using the portable IT-1 with a tripod-mounted sensor head directed through the 

 open side hatch of the UF2G aircraft, we are able to re-position the head easily for frequent 

 calibration checks against a known reference target, (a water-bath). No corrections were 

 required for the IT-1 on this flight as it read within our ±0.5° F. operation limit at all times. 

 Checks were made against lightship bucket temperatures where possible with results as shown 

 in Table 1. That micro-surface temperature averages about 1.0 °F, lower than bucket tem- 

 perature is to be expected for the beginning of the cooling season, in early Autumn. 



Table 1. Lightship and IRT Temperature Comparisons On 

 Sandy Hook/Navy Comparative Flight 



Date/Time 



Lightship 



Position 



9/30 -0900 



-1330 

 -0902 

 10/1 - 0910 

 - 1215 



Scotland 



Scotland 

 Ambrose 

 Bamegat 

 Delaware 



5 mi. E. Sandy Hook 



10 mi. E. Sandy Hook 



7 mi. E. Bamegat inlet 

 25 mi. E. Cape Henlopen 



-137- 



