very high. The two basic types could be separated for the selection of typical profiles; 

 however, the key to the advance prediction of the occurrence of either type is not 

 apparent from this analysis. 



Fall — This season again indicates the presence of the three profile types observed 

 during the spring. However, Type I has a deeper surface layer extending to 50 m or more 

 and a correspondingly thinner thermocline layer. The occurrence of deep surface layers 

 results in the classification of 92 percent of the profiles as positive gradient. The winter- 

 type positive gradient profiles are observed only during late November and December. 

 Based on the sound speed gradient statistics, more than one-half of the fall profiles 

 extending past 50 m have an overall negative gradient when measured from the surface. 

 This is caused by the predominantly negative gradient observed below 50 m. The separa- 

 tion of profile types and the selection of typical profiles for the fall is difficult because 

 the distinction between the types is less clear than during the summer. 



74 



