occurrence presentation"-. Although MILOC 65 was in the 

 heating season (July) , the strong winds that prevailed 

 should have caused strong mixing and, hence, nearly 

 isothermal water. We certainly expected a lot of data 

 to yield a sound- velocity gradient indicative of 

 isothermal water (the points on the right of Fig. S) > 

 but we did not expect so much data to be indicative of 

 non-isothermal water (the rest of the points) . We are 

 forced to conclude — for this location, in this season — 

 that the variability of gradients is higher than expected 

 and that the ranges of hull-mounted sonars — particularly 

 those with high range capability — are very sensitive to 

 the sound velocity gradient, always assuming that the 

 underlying model for the propagation of sound in water is 

 correct. 



The MILOC 66 data have not yet been thought about 

 enough for us to be able to deliver any conclusions. 

 One of the interesting differences between MILOC 64 and 

 MILOC 66 is that the traverse of two ships side-by-side 

 from KILO to JULIET was repeated, but not at a constant 

 lateral separation; the ships started 1.5 n. miles apart 

 and gradually increased their separation. We are now 

 looking at the data to discover if a horizontal coherence 

 length exists for layer depth and layer gradient. 

 We know from MILOC 64 that 12 n. miles is greater than the 

 coherence length of layer depth and less than the 

 coherence length of SST. We hope to find these coherence 

 lengths more exactly with this new approach. Perhaps the 

 presence of internal waves makes the hope for coherence a 

 sma 1 1 h op e-" " . 



MILOC 67 was held in the Baltic Sea and was the start 

 of our present air-sea interaction efforts. The cruise 

 was organized by the Germans and the Danes and we have 

 not yet seen any reduction of the general data. Our own 

 meteorological experiments have been processed and 

 reported LRef. 5]} a somewhat dishearting result [Fig. 6] 

 was that the wind profile measured on the ship and that 

 measured simultaneously 100 m away on a buoy were not in 

 good agreement. It is entirely possible that the air we 



No report on this work has been released. 



Note added in press: Preliminary analysis of these 

 data indicates that 1 n.mile is greater than the 

 coherence length for individual layer depth measure- 

 ments, but that the mean values of layer depth at two 

 points are coherent over much larger distances, 

 e.g. 15 n. miles. 



66 



