Table 11. 



-Shelf water-slope water front crossinKs in the Middle Atlantic 

 Bight by SOOP vessels in 1975. 



The April crossing (App. Fig. 49) was masked by the 

 low sea surface temperatures and salinities. The vertical 

 structure of the water column near the 100-m isobath was 

 probably an artifact of contouring due to the large sta- 

 tion separation between stations 1 and 2. 



In May (App. Fig. 51) the SSF appeared separated. 

 There was a strong surface gradient between stations 14 

 and 15 associated with low salinities and cooler water, 

 but also between stations 16 and 17 there was a frontal 

 structure near the 100-m isobath which is more usually 

 associated with the SSF. The subsurface frontal struc- 

 ture was a good example of the early shape and extent of 

 the cold cell. 



In June (App. Fig. 52) the SSF crossing was reflected 

 in a steep increase in both sea surface temperature and 

 salinity. Once again a strong surface expression of the 

 front was overlying a strong subsurface front and cold 

 cell. 



In June (App. Fig. 52) the SSF appeared at two dif- 

 ferent positions (between stations 18 and 19 and again 

 between 20 and 21). This double crossing of the front 

 probably reflected a small meander in the front. 



In July (App. Fig. 55) the SSF surface temperature ex- 

 pression was weak, as is expected in the summer, and the 

 front was better reflected in the subsurface temperature 

 structure surrounding the cold cell. 



In October (App. Fig. 62) the SSF was considerably 

 stronger (l'^C/9 n.mi. (16.7 km)) than the earlier cross- 

 ing in October, probably because of increased surface 

 cooling of the shelf waters. 



The final October crossing of the SSF (App. Fig. 64) 

 again showed the front was weak, but was detected by 

 the steep increase in surface salinity and the large in- 

 crease in sea surface temperature. 



On 5 December (App. Fig. 65) the front had increased 

 in strength (l°C/4 n.mi. (7.4 km)) and also was easily 



discernible from the large increase in both sea surface 

 temperature and salinity. 



On 10 December (App. Fig. 66) the SSF was still 

 strong (l°C/5.7 n.mi. (10.6 km)) and easily evident from 

 the sea surface temperature and salinity plots. 



On 12 December (App. Fig. 67) the SSF temperature 

 structure was not as strong as previous crossings and the 

 front was more easily determined by the strong salinity 

 gradient. 



The final December crossing of the SSF was made on 

 28 December (App. Fig. 68). The front was particularly 

 strong (l°C/3.5 n.mi. (6.5 km)) and was readily discerni- 

 ble by the large increase in sea surface temperature and 

 salinity. 



Low salinity surface water. — As previously dis- 

 cussed in the Cape Hatteras section, the utilization of 

 the 34.5%o surface isohaline as the salinity boundary of 

 the shelf water-slope water has worked well in the past, 

 corresponding closely with the temperature increase 

 usually associated with the slope water. 



In 1975 SOOP vessels transected coastal water of 

 <34.5%= in the Middle Atlantic Bight on 19 occasions 

 (see Table 12 and App. Figs. 47 through 57, 59, and 62 

 through 68). The data were used in conjunction with sea 

 surface temperature data and sometimes independently 

 to determine the exact position of the SSF. 



Eddies. — Analysis of the vertical sections contained in 

 this section show five crossings of Gulf Stream eddies 

 within the Middle Atlantic Bight during 1975 (see Table 

 13 and App. Figs. 52, 60 through 62, and 64). Unfor- 

 tunately the five crossmgs were of only two different ed- 

 dies. Eddy number 1 (App. Fig. 52) was an anticyclonic 

 eddy crossed on 10 June and was centered along this 

 transect between stations 16 and 17 (lat. 39°0rN, long. 



