1. Under conditions of vertical stability indicated by a negative 

 thermal gradient, the passage of short-term internal disturbances 

 resembling solitary waves is quite common. 



2. These temperature wave forms or signatures occur irregularly 

 in identifiable groups of one to four temperature humps (density 

 troughs) moving onshore at a speed of approximately one knot. 



3. The conspicuous onshore (normal to depth contours) orientation 

 of the signatures as well as the reasonable agreement of travel speeds 

 with shallow water internal wave theory verifies the direct association 

 of signatures with long internal waves originating offshore from the 

 measuring station. 



4. Measured ocean currents are predominantly rotary clockwise; 

 average speeds are about one-fourth those of the internal temperature 

 signatures. This combination seems to account for most of the spread 

 in signature velocities. 



5. The design of future field experiments should include provisions 

 for simultaneous and continuous measurement of temperature, salinity, 

 and current velocity to a frequency resolution better than 10 seconds. 

 A greater number of sensing units should be placed vertically at each 

 measuring station. Additional observations should be made at positions 

 up to several miles away from the main station to determine the 

 horizontal uniformity of the water medium. 



6. To establish the probability for predicting internal variations of 

 the type discussed in this report, more detailed long-term descriptive 

 and diagnostic field studies will be required in several different 

 oceanic regions. 



VII. ACKNOWLEDGEMENTS 



Cooperation between the U. S. Navy Hydrographic Office and the 

 Agricultural and Mechanical College of Texas has made possible the 

 support and information exchange necessary for this work which was 

 begun at the former and concluded at the latter. Among the many 

 members of the oceanographic staff at the Hydrographic Office who 

 have contributed to this study, particular note is due Mr. R. B. Elder 

 for his major part in field operations and data analysis; Mr. H. V. 

 French was a constant source of encouragement; and the field work of 

 Mr. W. A. Garth is gratefully acknowledged. 



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