on the distribution of fish populations. As a 

 direct application of this technique to fisheries, 

 the Commonwealth of Australia began experi- 

 mentt with an ART in 1964 and since 1966 has 

 produced sea surface temperature charts for 

 the southern bluefin tuna (Thunnus thynnus 

 maccoyii) fishing fleet off New South Wales 

 (Hynd, 1968). The Australian ART survey 

 charts indicated the flight path, surface iso- 

 therms (°C), fish sightings, and locations of 

 temperature fronts. Areas having favorable 

 conditions for bluefin tuna were noted and re- 

 ported to the fishing fleet, and subsequently 

 catches were made in these areas. 



The temperature of the surface layer of the 

 ocean and the water mass below is affected 

 mainly by radiation absorbed from sun and 

 sky, radiation from the sea into space, evapora- 

 tion from the sea surface, and conductive ex- 

 changes between sea and atmosphere. The 

 shallow surface layers tend to become mixed 

 through wind action and convection, and in 

 certain nearshore areas there is considerable 

 mixing resulting from tidal action. The effect 

 of subsurface phenomena on the surface layers 

 as observed with infrared equipment has been 

 studied by McAllister and McLeish (1965). 

 They described variations in small scale hori- 

 zontal sea surface temperatui-e structures as- 

 sociated with such physically observed phenom- 

 ena as fronts, eddies, and surface slicks. Tully 

 (1961) described in detail some of the reasons 

 for sea surface temperature fluctuations, as 

 reflected in the ART record, and the possible 

 relation of these fluctuations to transient 

 thermoclines. 



The oceanographic measurement of sea sur- 

 face temperature has been described by Sver- 

 drup, Johnson, and Fleming (1942) as a tem- 

 perature measurement taken of a sample of 

 water from within 1 meter of the surface. The 

 ART measures the temperature of the micro- 

 surface of the sea and consequently the read- 

 ings taken from the ART equipment may vary 

 from readings taken by a conventional bucket 

 thermometer. Comparative temperatures deter- 

 mined by a bucket thermometer or near-surface 

 thermistor and the ART indicate differences on 

 the order of ±0.2 C° (Peloquin, Wilkerson, and 

 Hanssen,1964), ±1.0 C° (Tully, 1964), ±1.0 C° 

 (Clark and Stone, 1964), ±1.0 F° (Squire, 

 1964), ±0.5 C° (Reintjes, 1964). Pickett 



(1966) found ART readouts to be 0.3 to 1.8 C° 

 lower. Hynd (1968) in his work off Australia 

 reports comparative observations which indi- 

 cated a mean difference of ±0.5 C°. 



METHODS AND EQUIPMENT 



In October 1962, the Tiburon Marine Labora- 

 tory began experiments with an ART, testing 

 its reaction to atmospheric attenuation of the 

 incoming infrared signal due to the effects of 

 altitude and moisture (haze) and measuring 

 the instrument's repeatability over ranges of 

 sea surface temperature. Continuous surveys 

 of near-shore surface temperatures were made 

 from the Mexican border to Cape Flattery, 

 Wash. Surveys were also made of north San 

 Francisco Bay, Sacramento River, Santa Bar- 

 bara Channel, and of several warm sea water 

 discharges from coastal steam-electric gener- 

 ating plants (Squire, 1967). Operational ex- 

 perience gained in the conduct of these surveys 

 made it possible to initiate a coastal survey 

 program in cooperation with the U.S. Coast 

 Guard. 



Infrared equipment used in coastal surveys 

 was manufactured by the Barnes Engineering 

 Co., Stamford, Conn. Models 14-312, IT-1, and 

 IT-2 were used. Temperature information from 

 these units was continuously recorded by a 

 Model (J-14 analog strip chart recorder manu- 

 factured by Varian Associates, Palo Alto, Calif. 

 The problems of mounting and operating infra- 

 red equipment of laboratory grade in an en- 

 vironment of high noise and vibration of an 

 aircraft have been discussed by Fames (1964), 

 Squire (1964), Peloquin, et al. (1964), and 

 Clark and Stone (1964). Stabihty of the air- 

 craft power supply, physical and sonic vibration 

 resulting from propeller or engine noise, and 

 air turbulence were the principal problems en- 

 countered in airborne operations. 



Each ART unit (ART electronics, recorder, 

 power supply, and metering equipment) was 

 mounted on a wooden panel (fig. 2), which was 

 secured in the aircraft by mounting the panel 

 across the armrests of a standard aircraft 

 double seat. The power supply unit consisted 

 of an inverter (28 Vdc to 115 Vac, 60 Hz), a 

 frequency meter, a switch panel with two volt- 

 meters (18-36 Vdc, 0-150 Vac), and a polarity 

 selector switch for the direct current voltmeter. 



