Bay flights are made at an altitude of 600 feet (higher near populated areas) in a 

 Cessna 172 aircraft. The sensing head is mounted in the luggage compartment and views 

 the sea-surface through an observation hole in the deck. Air temperature is measured be- 

 fore and after each survey and sea state is estimated along the flight track. 



The IRT has been foimd to be particularly well-suited for airborne surveys of large 

 estuarine systems. As temperature changes in such restricted, shallow waters are often 

 great and rapid at certain periods of the year, virtually synoptic coverage over a wide area 

 by the IRT has several distinct advantages to both the physical oceanographer and biologist 

 over conventional ships surveys even though only one parameter can be measured. 



Longitudinal gradients in the estuaries are often readily apparent, and shoal-channel 

 boundaries have been sharply defined in transverse sections taken during certain periods 

 of the year. 



Tidal influences at times cause interesting patterns at estuary mouths, and these may, 

 with careful studies in the future, be delineated throughout an estuarine system by IRT 

 techniques. 



An expanded program for study of all Chesapeake Bay waters is planned. Of special 

 interest will be rates of change over short periods and attempts to correlate changing 

 temperature patterns with measured tidal currents. 



Ship and Stationary Platform Studies 



In addition to airborne surveys, the IRT has been used to study the thermal pattern 

 and mixing characteristics of an effluent at the Virginia Electric and Power Company plant 

 on the lower York River. With the sensir^ head mounted on the antenna staff of a motor 

 launch, a series of traverses across the area yielded a detailed pitcure of thermal condi- 

 tions. Further studies over several tidal cycles are in the planning stage. 



In order to record surface temperature changes through time at a fixed point and to 

 study the effects of weather conditions (i.e. rain, fog, etc.) on accuracy of measurements of 

 the IRT, the instrument was mounted for one week on the tender's house of the York River 

 Bridge at Yorktown. Readings were compared with those taken with an Induction Conduc- 

 tivity Temperature Indicator (ICTI) mounted in the support caisson below the tender's house. 

 Further checks were achieved by bucket sampling of surface water. Bath3^hermograph 

 lowerings delineated the subsurface thermal structure and a current meter measured tidal 

 flow. Surface winds and relative humidit}' were recorded and wave height was estimated. 



INST RUME NT ATION 



The Institute has employed a Barnes Model IT-1 infrared thermometer in investiga- 

 tions. In February 1964 the company loaned a Model IT-2 for evaluation, but little actual 

 surveying was accomplished due to equipment malfimctions. 



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