Table 7.— Gulf Stream eddies transected by SOOP vessels in 1974. 







Location 



Approximate 



Maximum 







Appendix 



of 



surface 



observed 



Direction 



Eddv 



figure/ 



center 



diameter 



depth 



of 



number 



Date 



(lat., long.) 



nm (km) 



(m) 



rotation 



1 



19 

 5 May 



32°N, 75°W 



165 

 (306) 



650 



Cyclonic 



2 



21 

 5-6 May 



36°N, 68°W 



145 

 (269) 



500 



Cyclonic 



3 



33 

 20 Oct. 



37°N, 74°W 



90 

 (167) 



450 



Anticyclonic 



4 



35 

 7-8 Dec. 



32°N, 73°30'W 



150 

 (278) 



660 



Cyclonic 



Figure 10. — Gulf Stream eddies surveyed during 1974. 



of The Gulf Stream Monthly Summary showed a 

 cyclonic eddy with a width of about 80 nautical miles 

 (148 km) centered at a position of lat. 36°30'N, long. 

 68°00W, which corresponded closely to the position of 

 Eddy #2. No correlation could be made with the NESS 

 N-69 charts of 4-7 May 1974 because of heavy cloud 

 cover in the study area. However, the 14 May 1974 N-69 

 charts showed a cold-water intrusion in this area. Com- 

 parison of SOOP original XBT traces with other traces 

 shown in The Gulf Stream Monthly Summary revealed 

 reasonable similarity; it was concluded that Eddy #2 was 

 the same eddy depicted in the May summary. 



Appendix Figure 21 also showed another unusual 

 feature. An unusually strong thermal gradient (surface 

 temperatures changed from 23° to 20°C over a distance 

 of 15 nautical miles or 28 km) was present between 

 stations 3 and 4. Similar fronts in the Sargasso Sea have 

 been described by Katz (1969), Voorhis (1969), and Voor- 

 his and Hersey (1964). 



Eddy #3 (Appendix Fig. 33) was located by USCGC 

 Ingham on 20 October 1974. This anticyclonic eddy was 

 centered near lat. 37°N, long. 74°W with the charac- 

 teristic downwarping of the isotherms being detectable 

 between stations 3 and 7. An intrusion of warm water 

 shown on the 23-28 October and 31 October-3 November 

 N-69 charts could have been the result of this warm eddy 

 moving into this region. However, no eddy was shown at 

 this location in the October or November issues of The 

 Gulf Stream Monthly Summary. 



Eddy #4 (Appendix Fig. 35), a cold core, cyclonic eddy, 

 was crossed by Santa Cruz on 7-8 December 1974. The 

 maximum depth observed by XBT was 660 m, while the 

 eddy center was located around lat. 32°00'N, long. 

 73°30'W (station 14). Sea surface temperatures were as 

 much as 3°C lower than adjacent Gulf Stream waters, 

 but no signature was detectable in the surface salinities. 

 This eddy was apparently the same one that was 

 monitored with neutrally buoyant floats by the U.S. 

 Naval Oceanographic Office and surveyed on 11 Decem- 

 ber 1974 by P. L. Richardson aboard RV Trident (Gem- 

 mill 1974; Anonymous 1975; Gemmill and Cheney 1975). 



Shelf Water-Slope Water front.— SOOP transects 

 crossed the Shelf Water-Slope Water front five times 

 during 1974. Determinations of frontal crossings were 

 made primarily on the basis of subsurface temperature 

 gradients shown on the vertical sections with additional 

 supporting evidence being drawn from surface tem- 

 perature and salinity gradients. A summary of these 

 crossings is given in Table 8 and in Figures 6-9. 



In order to provide a means of verification of the posi- 

 tion of the front as determined from SOOP sections, 

 comparisons have been made with NESS N-69 charts. 

 After the position of the front was determined on the 



Table 8. 



-Shelf Water-Slope Water front crossings by SOOP vessels 

 in 1974. 



Appendix 







Frontal position 



figure 



Ship 



Date 



(lat., long.) 



23 



Santa Cruz 



11-12 June 



38°N, 71°48'W 



25 



Mormac Rigel 



14 Aug. 



39°42'N, 73°W 



27 



Santa Cruz 



3-4 Sept. 



38°N, 74°W 



28 



USCGC Taney 



29-30 Sept. 



37°N, 75°W 



31 



Santa Cruz 



9-10 Oct. 



SanSTVI, 73°54'W 



