SECTION 2.0 



INTRODUCTION 



The Bathythermograph has provided the Navy and the Oceanographic Institutions 

 with close to a half-million Bathythermograms. These Bathythermograms, taken over a 

 period of ten years, indicating temperature versus depth structures in the oceans of the 

 vi'orld, have been of immeasurable value in accumulating scientific data and thus further- 

 ing the general knowledge of oceanography. 



The initial use of the Bathythermograph was in the qualitative studies of the tem- 

 perature depth relationships. However, the advent of World War II created a definite ap- 

 plication for the Bathythermograph as a military instrument. It was during this period that 

 a large number of these data were continuously collected. Following the war, the Bathy- 

 thermograph program was continued with the idea of collecting data which would be avail- 

 able for analysis at a later date. 



Emphasis has gradually shifted from the qualitative contributions of the Bathyther- 

 mograph to a more precise and more exacting quantitative requirement. Quantitative ap- 

 plications imply that a certain accuracy of measurement is expected from the BT. It is 

 quite evident, therefore, that the extent to which the existing mass of data can be utilized 

 depends largely upon the reliability of the information contained therein. This reliability 

 is a function of many factors, such as the manufacture of the instrument itself, its calibra- 

 tion, state of maintenance, operation, and the methods of correcting, processing and cor- 

 relating the data. 



The National Scientific Laboratories for the past year have been concerned with a compre- 

 hensive study to determine the possible sources of errors which may exist in the Bathythermo- 

 graph data. This study has included, (1) intensive investigations of several anchor stations, 

 i.e., data taken on a ship while in a fixed position; and (2) a comprehensive conference pro- 

 gram withmembers of various Oceanographic Institutions to analyze their needs, methods and 

 processes. The result has led to a classification of possible sources of errors involved in obtain- 

 ing Bathythermograph information and several techniques and suggestions for handling the 

 Bathythermograph data in order to recognize and minimize these errors. 



In this report these errors are classified wherever possible in accordance with standard 

 mathematical nomenclature and practices. These errors are grouped together according to 

 error source, i.e., instrument limitation, calibration technique, operation technique and data 

 processing. Correlation methods are also discussed and proposed techniques for minimizing 

 error through correlation studies are suggested. 



The National Scientific Laboratories wishes to extend to the Oceanographic Fellowship its 

 sincere gratitude for the generous and helpful assistance which many of its members so gra- 

 ciously extended to us. 



