to determine maximum possible errors. It 1» apparent that a properly used 

 BT yields sufficiently accurate results for many research projects. The 

 average sea surface temperature error is .U^F. 



It has generally been accepted that a BT has an Instrument bias that 

 is constant with depth. Paired BT observations indicate that the bias is 

 not constant but varies with depth, being as much as l.QOF and averaging 

 about 0.5°F. Complete compensation for this bias appears to be impossible. 

 An accurate reference temperature could be used for partial compensation. 

 A ship's injection thermometer is not as accurate as the average BT and 

 should not be used to determine instrument bias. Bucket thermometer obser- 

 vations do not significantly improve the accuracy of BT data. 



The reference temperature should not be measured at the sea siirface 

 owing to possible existence of a near surface temi)erature gradient. A 

 reference depth of at least 3 feet appears to give satisfactory results. 

 An accurate temperature probe placed in the injection pipe also should 

 give acceptable results while the vessel is underway. Further temperature 

 sensor research is indicated, such as was performed in reference 6. 



Errors related to digitized BT data are quite large and therefore can 

 be screened out by a computer program. Variations between individual read- 

 ings of identical BT prints will average less than .1°F and are considered 

 to be insignificant. 



REFERENCES 



1. U.S. Naval Oceanographic Office. Statistical Analysis of the Thermal 

 Structure at Ocean Weather Station ECHO, by J, B. Hazelworth. ASWEPS 

 Report No. 8. H.O. Technical Report No. Ik6, July 196k 



2. Bralove, A. L. and E. I. Williams, Jr. A Study of the Errors of the 

 Bathythermograph. National Scientific Laboratories, Inc. June 1962. 51 P. 



3. U.S. Naval Oceanographic Office. Test and Evaluation of the Mechanical 

 Bathythermograph, by R. L. Stewart. Informal Manuscript Report No. 

 1-1-63 (Unpublished Manuscript). June I963. 33 p. 



4. National Oceanographic Data Center. A Progress Report on Some Problems 

 in Determining the Reference Temperature for Bathythermograph Obseirva- 

 tions, by Thomas Winterfeld. Unpublished Manuscript. July I963. 10 p. 



5. Saur, J. F, T. A Study of the Quality of Sea Water Temperatures Report 

 in Logs of Ships' Weather Observations. In Journal of Applied Meteor- 

 ology, Vol. 2, No. 3. June I963. p. lH7-^25. 



6. U.S. Naval Oceanographic Office. Sea Stirface Temperature System (SURTEMS), 

 by R. J. Farland and J. A. Kuhn. Informal Manuscript Report No. I-2-63 

 (Unpublished Manuscript). May I963. 79 P. 



7. - — . — , Instruction Manual for Oceanographic Observations. H.O. Pub 

 No. 607. 2nd Edition, 1955. 210 p. 



