the wind veered to the south and increased to greater than 9 m/sec. 

 and (2) stratus clouds developed. The vertical temperature profile 

 changed so that two basic layers became evident; a cold (8°C) layer 

 near the surface separated by a strong positive gradient (O.T^C in 

 10 meters) from a warmer (9°C) layer near the bottom. 



Changes in the vertical salinity profile were similar to changes 

 in the temperature profile. Minimum salinity (31.23°/oo) occurred 

 during reoccupation of Station 1 simultaneously with a strong posi- 

 tive salinity gradient (0,86°/qo in 5 meters) in the surface layer. 

 Positive salinity gradients observed below the surface layer coin- 

 cided with positive temperature gradients. 



The T-S diagram shows a negative temperature gradient to a depth 

 of 8 meters during the initial occupation of Station 7 without a cor- 

 responding salinity gradient, implying that surface heating was the 

 cause of the negative temperature gradient. The change in the ver- 

 tical water structure during the interval between occupations may 

 have resulted from (1) gradual decay of the mixed layer formed dur- 

 ing the frontal passage of 8 March and/or (2) replacement of surface 

 water driven seaward by wind-induced currents by an intrusion of 

 oceanic water along the bottom in agreement with classical theories 

 of upwelling. 



Sound velocity computed from observed values of temperature and 

 salinity at each station showed that negative sound gradients coin- 

 cide with negative temperature gradients during the initial occupa- 

 tion. Negative gradients were underlain by positive gradients to the 

 bottom, creating a weak sound channel. In no case was the sound chan- 

 nel axis deeper than 12,5 meters. 



Development of prediction techniques appropriate to the sur- 

 vey area requires knowledge of the nature of external processes and 

 their interaction with local oceanographic conditions. During the 

 present survey, three external processes were observed to affect the 

 local regime: (1) intrusion of warm water into the area from the Gulf 

 Stream, (2) discharge of Chesapeake Bay water, and (3) heat exchange 

 across the air-sea interface, A fourth process, mass transport into 

 the area by coastal currents, was not observed. 



Warm water in the southeastern quadrant of the survey area 

 probably: (1) originated from the Gulf Stream, possibly as a mean- 

 der, (2) intruded into coastal water as a tongue, (3) became an 

 eddy, and (H) was absorbed into coastal water through mixing. North- 

 ward movement of this warm water could be expected to result from 

 momentum imparted by the Gulf Stream and/or northeasterly movement 

 of coastal water entrained by the Gulf Stream, Since the life 

 cycle of such a system would be expected to proceed in an orderly 

 process, prediction should be possible once the frequency and scale 



