water along the shelf as described by Bigelov was noted. This is iu 

 opposition to the February-March survey when bottom wanning, probably 

 due to wind-induced upwelling, was observed. Southerly winds observed 

 during the present survey were of the same magnitude and duration as 

 winds during the winter survey. However, the strong thersial stratifi- 

 cation observed during the present survey would require stronger winds 

 to induce upwelllng than are required in winter, when little stratifi- 

 cation occurs. 



The sound transalsslon characteristics in the two water regimes 

 studied are considerably different, as shown in figure 17. A rela- 

 tively large change in submarine detection would occur within a few 

 minutes «rhile transiting between the two regimes. This illusCrates 

 the need for improvement of prediction techniques and an increase in 

 oceanographic data.. It also illustrates the importance of consider- 

 able data collection and Interpretation by fleet units operating 

 within any given area. 



Development of analysis and prediction techniques suitable for 

 such areas as considered in this study require a reasonable input 

 of synoptic oceaoographlc data and a knowledge of environaental pro- 

 cesses both within Che area and in adjacent areas. During Che present 

 surrey, three ezteraal processes were observed to affect Che local reglae: 

 (1) incmsion of warm, saline water from Che Gulf Scream, (2) advection 

 of cold shelf water ky Che coastal current, and (3) emergy exchange across 

 Che air-sea interface. A fourth external process, aeetfliulation of cold 

 runoff over Che shelf, continued to affect Che local area. 



A process whereby Gulf Stream water would intrude into coastal water 

 was discussed previously. A relatively dense network of synoptic 

 oceanographic observations over short periods between Cape Fear and the 

 Virginia Capes is required to verify this postulatlon. Upon deCerminaCion 

 of Che life cycle of Che warm inCrusion, regular observaCion would be 

 required Co deCecC newly formed systems. Once detected, the system may 

 be tracked and predicted by means of a moderate increase of sea surface 

 temperature (CTEM) reports and bathythermograph (BATHY) reports. 



The amount of shelf water advected into the survey area by southwest- 

 erly flowing coastal currents could be predicted if (1) CTEM and w^tpv 

 reports are sufficient to define the temperature field end (2) comput4>ii 

 wind drift currents and estimated geostrophic currents are sufficient ^c 

 define the current field. However, the assumption that shelf water is 

 present unless replaced by an Intrusion of denser oceanic water would 

 eliminate the need for current data. In inshore areas, however, the sur- 

 face layer may be greatly modified by low-density effluent from rivers 

 and estuaries. 



