well established program. Sea surface tempera- 

 ture data were obtained monthly along more than 

 6,800 kilometers (3,670 nmi) of transects cover- 

 ing approximately 130,000 square kilometers 

 (37,700 nmi^) of Atlantic shelf and Slope Waters 

 (fig. 1). The mailing list for the monthly surface 

 isotherm charts had grown to 750, including gov- 

 errmient agencies, universities, private marine 

 institutions, newspapers, journals, and commer- 

 cial and sport fishermen. 



Approximately 2,400 drift bottles and sea bed 

 drifters were released each month for the Woods 

 Hole Oceanographic Institution as part of their 

 drifter program to study the circulation of the At- 

 lantic shelf region. 



Because of limited funds in FY69, the BSF felt 

 that the ART survey could no longer operate 

 within its research budget. The BSF and the 

 Committee for the Scientific Exploration of the 

 Atlantic Shelf (SEAS) considered the east coast 

 ART survey too valuable to the oceanographic 

 community to be discontinued. In July of 1969, 

 the Coast Guard was asked to assume full respon- 

 sibility for all aspects of the program. This report 

 presents the scientific results of the ART program 

 in its first year of operation by the Coast Guard 

 Oceanographic Unit (CG OCEANOU). 



INFRARED RADIOMETRY 



Much work has been done in the field of air- 

 borne infrared radiometry. A good description of 

 the past and present background in infrared 

 radiometry is summarized in a report by J. L. 

 Squire, Jr. (1971). Briefly, an infrared thermome- 

 ter detects and measures the infrared radiation 

 naturally emitted by objects. The intensity and 

 spectral distribution of the energy emitted are 

 functions of the radiometric temperature of the 

 object and the nature of its surface (emissivity). 

 Infrared energy (heat) emitted from the sea sur- 

 face is transmitted through the atmosphere in the 

 form of electromagnetic waves within the 

 wavelength region between visible red light and 



microwaves (.7 to 10"'/Ltm). The infrared energy 

 emitted by distant objects can be reflected by 

 conventional optical systems and directed toward 

 an infrared detector which senses and measures 

 the energy. Infrared radiation from the sea must 

 pass through the atmosphere which contains 

 gases and particulate matter that absorb and scat- 

 ter the emitted radiation. To reduce these at- 

 tenuating effects of the atmosphere, the detected 

 radiation is usually limited by filters to the region 

 between 8 to 14 ^m. It is in this region or "win- 

 dow" that the atmospheric attenuation is at a 

 minimum. 



METHODS AND EQUIPMENT 



Portable ART instrument packages were de- 

 signed to cope with the logistic problems encoun- 

 tered by CG OCEANOU survey teams. 

 Aluminum was used to construct the instrument 

 package. The packages are extremely rugged, yet 

 light in weight. A package includes four principal 

 components: • Infrai^ed thermometer with sensor 

 head • Strip chart recorder • Regulated power 

 inverter • Control panel (fig. 2). 



The Barnes Engineering Company, Precision 

 Radiation Thermometer (PRT-5) used to measure 

 the sea surface temperature data presented in this 

 report (A Barnes Engineering Company IT-3 was 

 used on a few early surveys.) consists of a radiation 

 sensing unit and an electronic processing unit. 

 Naturally emitted radiation from the sea surface 

 passes through an objective lens (10 mm, 

 IRTRAN-2, F/2.8, [2° field of view] manufactured 

 by Eastman Kodak Company) and a spectral filter 

 which limits the radiation to the 9.5 to 11.5 fim 

 atmospheric window, all located in a temperature 

 controlled reference cavity. Through optical 

 chopping the detector (a hyperimmersed thermis- 

 tor bolometer) continuously compares emitted 

 radiation levels from the sea surface with that 

 einitted by the internal, controlled, reference en- 

 vironment. The detector now produces an electri- 

 cal output signal proportional to their difference. 



