The inverter was powered by the aircraft 28 

 Vdc system, and a rheostat was provided to 

 control the inverter input voltage. The ART 

 electronic circuitry was modified by adding 

 capacitance to the output circuit to reduce ex- 

 cessive fluctuations in the temperature record. 

 An opening was made in the instrument case to 

 provide access to the electronic circuitry for the 

 purpose of making in-flight calibration adjust- 

 ments. In addition to the fixed electronic equip- 

 ment, accessory items including an insulated 

 water container and standard mercury thermo- 

 meter were carried for use in calibration of the 

 ART. 



The ART detector head was adjusted to view 

 the sea surface through the open lower half of 

 the port double-door hatch, at an angle of ap- 

 proximately 15° to 20° from the vertical. This 

 angle was within angular viewing limits of the 

 instrument for accurate sea surface tempera- 

 ture measurements (Frank, 1964) and allowed 

 positioning of the detector head within the air- 

 craft where air tubulence was minimal, yet 

 where the detector had an unobstructed view 

 of the ocean surface. The detector head was 

 mounted on a rubber shockmount attached to a 

 screw clamp and bracket. The screw clamp was 

 fastened to a vertical handhold and the detector 

 head was partially suspended by rubber tubing 

 to provide a fully shock-dampened mounting. 

 A plywood panel was fitted into the lower half 

 of the port hatch, filling approximately three- 

 quarters of the opening, to reduce the amount 

 of air turbulence within the aircraft cabin. 



OPERATIONAL PROCEDURES 



U.S. Coast Guard Air Stations at San Diego 

 and San Francisco, Calif., and Port Angeles, 

 Wash., made available Grumman HU-16E 

 "Albatross" twin-engined amphibious aircraft 

 (frontispiece) for each monthly flight. A total 

 of 179 flights was made involving over 1,100 

 hours flight time, serving the dual purpose of 

 providing an aircraft for oceanographic studies 

 and for low-altitude training for Coast Guard 

 pilots and crew. A 152-meter (500-ft) cruising 

 altitude was selected as a compromise between 

 low elevation to reduce the effect of haze on the 

 ART reading and minumum altitude for safety 

 in case of an engine failure. 



Survey flight tracks extended to about 45 

 nautical miles offshore in the northern and 



central areas and about 85 miles offshore in the 

 southern area (figs. 3-5) . The flight track lines 

 in the northern and central survey areas were 

 not changed during the 5-year period. On num- 

 erous occasions survey aircraft in the southern 

 area were not allowed to enter or were diverted 

 out of the area south of the Santa Barbara 

 Channel Islands and south of Point Arguello. 

 These areas were military missile firing areas 

 under the jurisdiction of the U.S. Navy, Pacific 

 Missile Range, and military operations in these 

 areas were at times hazardous to aircraft. In 

 January 1968, the flight track was adjusted to 

 eliminate entry into these firing areas by ex- 

 tending it farther offshore to Cortez Bank, 

 farther offshore from 60-mile Bank, and farther 

 south to near Todos Santos Island, Mexico, 

 (dashed lines on fig. 3). 



Prior to the start of a survey flight, power 

 checks were made on the output of the aircraft 

 electrical system and output of the ART inverter 

 power supply. The ART electronic console unit 

 was placed on line and the detector was allowed 

 to reach operating temperature. After takeoff 

 the detector head was adjusted to view the 

 water, the recorder placed in operation, and 

 survey flight track started. The optical field of 

 view of the infrared detector used was 3°. The 

 normal groundspeed of the ART viewing sys- 

 tem was 250 km/hr (135 kts., 69.4 m/sec.) 

 Temperature data from all surveys were rec- 

 orded on a strip chart recorder at a chart speed 

 of 1 inch per minute. Information marked on 

 the strip chart included start times, beginning 

 and ending of legs, geographical points, and any 

 other data that would be useful in correlating 

 the recorder chart with the flight track. 



ART Calibration 



In the laboratory, the ART unit was cali- 

 brated by scribing a readout grid for the analog 

 recorder while the unit was exposed to a tem- 

 perature-controlled water bath. The water bath 

 was well mixed by a magnetic stirrer and dur- 

 ing the calibration procedure was stabilized at 

 each 1 F° interval (0.66 C°) as determined by 

 a standardized mercury thermometer. The read- 

 out grid was made for the temperature range 

 normally expected to be encountered during the 

 survey flights. 



In-flight calibration checks were made at 

 intervals during the survey, comparing the ART 



4 



