Sensors 



Airborne Radiation Thermometer : The aircraft is equipped 

 with a Barnes Model 14-320 airborne radiation thermometer which meas- 

 ures sea surface temperature "by recording the intensity of infrared 

 radiation from the ocean surface in the 7*3- to 13.5-micron band. 

 This nadir-directed instrument is normally flown at low altitudes to 

 reduce atmospheric interference. The infrared signal is averaged over 

 a 6-meter square spot at a 300-meter altitude. Surface temperature 

 is measured by comparing the intensity of incoming infrared radiation 

 with that from a temperature-controlled cavity contained in the instru- 

 ment. Measurement accuracies of 40.2°C have been achieved in the lab- 

 oratory (Peloquin and Weiss, 19637, anci field accuracies are j-0.5°C 

 95 percent of the time for daytime flights in the altitude range 

 of 60 to 550 meters after correction for atmospheric effects (Pickett, 

 1966). 



Radar Wave Profilers : The aircraft is also equipped with a 

 radar wave profiler. This sensor is an FM-CW radar device operating 

 at a center frequency of 4.3 GHz with frequency modulations of +12.5 

 MH Z . The wave meter, normally flown at an altitude of 150 meters 

 illuminates a spot on the sea surface 5 meters in diameter (Radcom- 

 Emertron, 1963)* Waves 100 feet or more in wavelength (greater than 

 3-second periods) can be recorded. The output is a profile of the 

 sea surface along the flight path. 



Meteorological Sensors 



A. AN/aMQ-17 Aerograph . The AN/AMQ-17 simultaneously 

 measures flight-level air temperature, relative humidity, and pressure. 

 Air temperature is measured with a platinum wire resistor over the 

 range of -50° to 49°C. A carbon-coated resistor is used to measure 

 relative humidity between and 90 percent; a mechanical bellows 

 linked to a potentiometer measures atmospheric pressure between 50 



and 1,050 mb. The recorder has both analog and digital outputs. 



B. Infrared Hygrometer . The infrared hygrometer meas- 

 ures absolute humidity from to 35 gm/m3. Two infrared beams of dif- 

 ferent wavelengths are alternately passed through a one-meter path of 

 atmosphere. One wavelength (1.37m) ^ s attenuated by water vapor, and 

 the other (1.3^/x) is unaffected by water vapor. The difference in 

 energy of the two beams received by a detector is proportional to the 

 absolute humidity. 



ARGUS ISLAND Tower 



Background 



ARGUS ISLAND tower (figure 3) was selected for the test site 

 because of available sensors and its proximity to deep water. ARGUS 

 ISLAND was built during the summer of 1959 under the direction of the 

 Office of Naval Research. Through the cooperation of that Office, 

 the tower has been used by NAV0CEAN0 since 1961 as an experimental 

 platform. 



