THERMAL AND SOUND VELOCITY MICROSTRUCTURE DATA 

 TAKEN WITH AN UNMANNED RESEARCH VEHICLE 



by 



S. R. Murphy and G. E. Lord 

 Applied Physics Laboratory, University of Washington 



ABSTRACT 



For the past several years the Applied Physics Laboratory, University 

 of Washington, has operated torpedo-like research vehicles in a series of 

 investigations of thermal microstructure. Readings have been taken with 

 thermistor probes and a sound velocimeter for isobaric trajectories of 6 

 to 20 nautical miles in length. The depth of the measurements range from 

 50 m down to 2500 m. Cruises have been to areas several hundred miles 

 west of San Diego and near Oahu, Hawaii. 



These data have been subjected to several statistical treatments. The 

 root-mean- square deviation from the mean, autocorrelation and cross- 

 correlation functions for temperature and sound velocity, and power spec- 

 tra have all been computed. Digital filtering has been employed to enhance 

 portions of the spectra. It has been essential for the interpretation of the 

 results of these analyses to determine carefully the control characteristics 

 of the vehicle and the limitations of the data system in order to determine 

 the "noise" level of the measurements. Preliminary results show temper- 

 ature deviations of the order of 0. 3° C at 50 m falling to 0. 02° C at 1500 m 

 with correlation lengths of several thousand feet. Likewise, horizontal 

 gradients are of the order of 0. 1° C /nautical mile near the surface and 

 0.001° C /nautical mile at 2000 m. 



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