Expendable Bathythermograph Observations From 

 the NMFS/MARAD Ship of Opportunity Program 



for 1975 



STEVEN K. COOK.' BARCLAY P. COLLINS,^ CHRISTINE S. CARTY' 



ABSTRACT 



This report is designed to show the results of the fifth year of operation of the NMFS/MARAD Ship of 

 Opportunity Program (SOOP). The data are presented in the form of vertical distributions of temperature 

 and horizontal distributions of sea surface temperture and salinity. Operational and data management 

 procedures are discussed, and a descriptive analysis of the most dynamic transects showing the Yucatan, 

 Loop. Florida, and Gulf Stream current systems is presented. The annual development and subsequent 

 degradation of the cold cell off the Middle Atlantic Bight is also discussed. 



INTRODUCTION 



In midyear of 1970, a cooperative expendable 

 bathythermograph (XBT) program was initiated 

 between the National Marine Fisheries Service (NMFS) 

 and the Maritime Administration (MARAD) of the U.S. 

 Department of Commerce. The objective of the 

 cooperative program was to identify and describe 

 seasonal and year-to-year variations of temperature and 

 circulation in the major current regimes of the western 

 tropical Atlantic, Caribbean Sea, Gulf of Mexico, and 

 western North Atlantic, utilizing various ships as 

 relatively inexpensive platforms for the collection of 

 data. 



Annual reports encompassing the calendar year SOOP 

 efforts have been published for 1971 through 1974 (Cook 

 1973, 1975, 1976; Cook and Hausknecht 1977). With the 

 completion of this 1975 SOOP report the National 

 Oceanographic Data Center (NODC) will publish all 

 future SOOP data, beginning with January 1976, as a 

 Data Availability Notice. The Data Availability Notice 

 will show the monthly transect location of all SOOP runs 

 along with an NODC access number that will allow in- 

 terested users easier access to the SOOP data. 



The program, conducted in support of the Marine 

 Resources Monitoring Assessment and Prediction Pro- 

 gram (MARMAP) of NMFS, involved the use of 

 maritime cadets from the Kings Point Maritime 

 Academy to collect XBT data on board merchant ships 

 operating along the east and Gulf coasts of the United 

 States. Since 1970 the SOOP program has expanded to 

 include U.S. Coast Guard cutters and university research 

 vessels in addition to regular merchant ships. 



Atlantic Environmental Group. National Marine Fisheries Service. 

 NOAA. R.R. 7A. Box 522-A. Narragansett. Kl 02882. 



Gulf Research and Development Co.. Houston Technical Service 

 Center. Box :)6.i()6. Houston. TX 77036. 



'I'.S. Dep, Cummer.. NOAA. Environ. Kes. Lab., Room 408. 6:i2 West 

 6th Ave.. Anchorage. AK 99501. 



Ship routes were selected to obtain regular sampling in 

 the most dynamic areas of the Gulf of Mexico and 

 western North Atlantic. The features of principal in- 

 terest were the Yucatan Current, Loop Current, Florida 

 Current, Gulf Stream, shelf water-slope water front, and 

 a cold-water cell in the Middle Atlantic Bight. 



METHODS 



The SOOP effort for 1975 consisted of a total of 65 

 cruises: 20 merchant vessels sailing from New York, 15 

 merchant vessels from New Orleans, 19 Coast Guard 

 cruises from various ports, 7 ferryboat cruises across the 

 Gulf of Maine, and 4 cruises utilizing university research 

 vessels. Ninety-eight transects of subsurface 

 temperature observations £ind associated surface data 

 were obtained. A total of 1,619 XBTs were launched; of 

 these, 1,426 (88'^c) were considered of sufficient quality to 

 be archived. Approximately 241 XBT drops and as- 

 sociated surface data are not included in this repwrt 

 because the observations were too widely separated in 

 time and space to be formed into useful transects. All 

 data collected were archived by the NODC and are 

 available at the NODC, Washmgton, DC 20235. 



Subsurface temperature data were obtained by use of 

 Sippican XBT systems. At the same time, surface water 

 samples were collected with bucket thermometer units 

 for later analysis to determine salinity. The surface water 

 samples were analyzed on shore using an inductive 

 salinometer calibrated with standard seawater at least 

 once every 30 samples. 



The XBT traces were submitted to NODC where they 

 were digitized, key punched, and quality controlled. 

 Finally, these processed data were listed in printout form 

 and machine plotted. The plots produced by NODC were 

 essentially camera ready and needed little hand cor- 

 recting. The few corrections necessary were caused by 

 anomalous XBT observations that could not be sup- 

 ported by other associated data such as sea surface 



