stability criteria requires that V < Ax/At, which limits the maximum 

 current in this model to about 92 cm/sec before the solutions become 

 unstable. 



Several problems were immediately apparent in this model. The 

 fixed outflow alon^ the eastern boundary was so restrictive that waves 

 could not move across the boundary, therefore instabilities eventually 

 developed. To eliminate this problem, the eastern boundary was extra- 

 polated eastward to SO'V. Also, the Gulf Stream was noted to widen with 

 time owing, in part, to a nonlinear effect created by the unreal cross- 

 stream current profile. 



The prediction model was run for short prediction periods (up to 

 10 days). A sample prediction and verification is shown in figure 7. 



C. CONCLUSION 



None of these methods is entirely satisfactory for Gulf Stream pre- 

 diction, since each method requires rather simplified assumptions about 

 the ocean. However, each method attempted to isolate a particular physical 

 relation as a predictor for Gulf Stream positions. 



The first two prediction methods, (1) application of a river meander 

 theory to Gulf Stream meanders, and (2) the relation of Gulf Stream 

 meanders to paths of constant potential vorticity in a barotropic flow, 

 were not adequate for simulating observed paths of the Gulf Stream. The 

 remaining two methods, the harmonic and barotropic prediction models, appear 

 adequate for short-term (less than 10 days) prediction. Either of the 

 latter methods can be Implemented to aid in the analysis of synoptic oceano- 

 graphic charts. Present methods of analysis give an uncertain position of 

 the northern edge of the Gulf Stream unless airborne data are available for 

 establishing its location. Thus, the above methods could be used for esti- 

 mating the position of the stream between aircraft flights. 



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