u. 



o 



a. 



3 

 t- 

 < 



ID 



a. 



S 



78.0 



77.0 



76.0 



75.0 



0800 



1200 



1600 

 TIME (LOCAL) 



2000 



Fig. 9. AET sea surface temperature comparison tests at AEGUS ISLAND, 27 June 1962. 



Data from the 23 June test are shown in 

 Figs. 10 and 11. Temperatures were recorded by 

 "both the ship and the aircraft. Sharp spikes 

 appeared in the ART trace each time the heli- 

 copter crossed the ship's wake. Although the 

 temperatures generally agree, an exact comparison 

 is difficult because of the variability in sur- 

 face thermal conditions shown by the traces. 

 Meteorological conditions offer a possible explan- 

 ation for the surface conditions ; surface winds 

 were light and variable and skies were clear. 



On the second day, light winds were present 

 at the surface, the water appeared to be more 

 thoroughly mixed and the thermistor trace was 

 steady. ART temperatures were lower than ther- 

 mistor temperatures (Fig. ll) . Analysis of the 

 data shows a probable ART deviation of *0.31°C 

 from the reference sea surface temperature. 



WV-2 Flights 



The ART was shock mounted in the baggage 

 compartment of a WV-2 aircraft. It views the 

 water surface through an opening in the fuselage 

 bottom. The aircraft is normally pressurized to 

 allow air to exhaust around the sensing unit. 

 This was found necessary to prevent instrument 

 noise resulting from excessive turbulence around 

 the lens . The recorder is separated from the 

 console and mounted at one of the radiomen's 

 stations. Continuous temperature records are 

 manually noted at one minute intervals. During 

 normal operations the aircraft was flown at an 

 altitude of 1,500 feet at 190 knots. All flights 

 to date have been conducted during daylight 

 hours j however, night flights are being scheduled. 

 Flight tracks do not usually exceed 1,1|00 miles ; 

 average flight duration is usually 6 to 8 hours. 



Aircraft surveillance with the ART provides 

 a quick method of obtaining sea surface tempera- 

 tures over large areas . Accumulated data aid 

 in the construction of sea surface temperature 



charts . A sample of surface isotherms for 

 2 October I962 is shown in Fig. 12. The data 

 were collected off the North Carolina coast in 

 connection with sea surface temperature studies 

 in the Gulf Stream. During the flights skies 

 were clear, the sea was calm and the air tem- 

 perature was 23 °C (73°F). 



A series of flights was completed between 

 15 and 25 July 1962 over a triangular track 

 centered at 39°N 70TJ. The exercise was designed 

 to determine time-space variability or persis- 

 tency of sea surface temperature patterns. The 

 aircraft was flown at an altitude of 1, 500 feet 

 at 190 knots. The range of the observed tempera- 

 tures was 18 to 27°C. Temperatures compared 

 over 2, k8 and 72-hour periods are shown in 

 Figs. 13, 1^ and 15 respectively. 



CONCLUSIONS 



The ART is becoming a valuable means of 

 obtaining sea surface temperatures. Aircraft 

 surveillance with the ART makes possible the col- 

 lection of large quantities of data in relatively 

 short periods over broad areas. When first put 

 into operation, the instrument was subject to 

 frequent failure of electronic components; 

 however, this problem has been resolved and the 

 instrument now has good operational reliability. 



Instrument accuracy of 0.2°C has been shown 

 in the laboratory. The ability of the instru- 

 ment to detect horizontal temperature gradients 

 at the surface has been of particular value. In 

 field use the ART has not produced results com- 

 parable to those obtained in the laboratory. On 

 several occasions ART temperatures have concurred 

 with immersion temperatures; on other occasions 

 significant differences have occurred. At pre- 

 sent, these differences remain unexplained. 

 Future temperature measurements with the ART are 

 expected to increase in accuracy and become a 

 valuable source of information. 



68 



