Cruise D37 also showed a salinity and tem- 

 perature maximum on 7 out of 40 stations, but 

 this time at about 800 meters. The temperature 

 and salinity were much higher than D32 or any 

 of the other stations (Table 4). No Subarctic 

 Intermediate water was present on D37 to mask 

 the Mediterranean intrusion. There may be 

 some question as to whether this was actually 

 Mediterranean water since the average sigma-t 

 value was only 27.52. 



Cruises D26 and D27 did not indicate any 

 Mediterranean intrusion. Cruise D32 showed in- 

 trusions on some stations. Cruise D37 showed 

 intrusions on 7 out of 40 stations. Since these 

 were all STD stations on D26, D27, D32, and 

 D37 it is obvious that Mediterranean water is 

 not continuous on OS DELTA. 



Labrador Sea Water 



There is much confusion in the nomenclature 

 for the water mass referred to as Labrador Sea 

 water (LS). The definition of LS used here is 

 that definition given it by Worthington and 

 Metcalf (1961). They refer to it as a pro- 

 nounced salinity minimum at 3.5 °C. They be- 

 lieve it is the most recently produced deep water 

 in the North Atlantic, forming in the Labrador 

 basin. 



The T-S curves of the deep casts (greater 

 than 1500 meters) were plotted (fig. 19). The 

 characteristic temperature and salinity for LS, 

 Northwest Atlantic Bottom water (NWAB), 

 Northeast Atlantic Deep water (NEAD), and 

 the potential temperature-salinity curve for 

 North Atlantic Deep water (NAD) are plotted 

 along with each deep T-S curve on OS DELTA. 



The salinity minimum on each cast at about 

 1500-2000 meters indicates water of Labrador 

 Sea origin. It seemed to be present year-round. 

 Unfortunately the majority of the Nansen and 

 STD casts were only taken to 1500 meters, thus 

 just missing LS. 



On station D23-10 the LS minimum occurred 

 at 1447 and 1863 meters, and on stations D34-5, 

 16, and 19 it occurred at 1978, 2062, and 1425 

 meters respectively. The bottle spacing for 

 Nansen casts placed a bottle at 1500 and 2000 

 meters. It would be easy for the 1500 meter 



bottle to be too shallow to sample LS or for the 

 2000 meter bottle to be too deep. Station D23-10 

 could therefore indicate that the LS influence 

 could be as thick as 400 meters since LS was 

 present at both 1447 and 1863 meters. 



Mixture of Labrador Sea water with North- 

 east Atlantic Deep Water 



Below the depth of influence of LS, the salin- 

 ity increased for all the deep casts (fig. 19), 

 except station D24— 10. If a line is drawn from 

 LS to Northeast Atlantic Deep water (NEAD), 

 this salinity increase falls directly on the line. 

 Computing the percentages of LS and NEAD 

 it was determined that this water contained 

 60±4% LS and 40zt4% NEAD. NEAD has 

 been described by Lee and Ellett (1967) as 

 Scotland-Iceland overflow from the Norwegian 

 Sea. 



North Atlantic Deep Water 



North Atlantic Deep water (NAD) is a mix- 

 ture of NEAD and Northwest Atlantic Bottom 

 Water (NABW). This is the theory of Lee and 

 Ellett (1967) where NABW is described as 

 Iceland-Greenland overflow and NEAD as 

 Scotland- Iceland overflow. 



The deep T-S curves (fig. 19), using Lee and 

 Ellett's criteria and the NAD curve of Worth- 

 ington and Metcalf (1961), clearly indicate the 

 presence of NAD. 



CONCLUSIONS 



The physical oceanography of OS DELTA is 

 quite complex. Although the water column con- 

 sists generally of North Atlantic Central water, 

 OS DELTA is subject to intrusions from numer- 

 ous water masses and is frequently influenced by 

 the North Atlantic Current. Since it is such a 

 complicated area it is often difficult to determine 

 exactly what is going on on OS DELTA, based 

 exclusively on OS DELTA data. However, 

 thanks to oceanography conducted around OS 

 DELTA and to scientists who have published 

 numerous papers on the various water masses 

 and the Gulf Stream System, a fairly good pic- 

 ture can be developed from the data taken at the 

 single point (OS DELTA). 



