The preparation of other oceanographic products is as in- 

 timately related to the atmosphere as is the sea surface tempera- 

 ture analysis. 



Sea state, surf, tide and current predictions are invaluable 

 to many naval operations, such as amphibious landings, replenish- 

 ment at sea, carrier operations, or just moving ships from one part 

 of the ocean to another. However, our interest in the past few 

 years has been directed more and more to underwater operations, both 

 defensive and offensive (Fig. 2l). The rapid growth of the Soviet 

 submarine fleet has forced upon us the necessity of being able to 

 detect, track, and if need be, destroy these boats. We have made an 

 intensive effort to become proficient at forecasting underwater 

 sound propagation, and to adapting our forecasts to the existing de- 

 fensive vehicles and their sound gear. As you know, the Wavy uses 

 the greatest possible mix of search vehicles in order to exploit the 

 peculiar advantages of each--ships, fixed wing aircraft, helicopters, 

 and submarines all of which carry a variety of sound sensors. 



To provide Fleet units with unending volumes of sea surface 

 temperature, layer depth predictions, temperature profiles, and sea 

 states is to miss the mark slightly. These parameters are important 

 not in themselves, but to the extent that they influence or affect 

 the sound ray path and propagation loss. Fleet operators really are 

 only concerned with the question, "At what range will my sonar sys- 

 tem acquire a target in my immediate area today? " So, the Naval 

 Weather Service has devised a system for providing forecast detec- 

 tion ranges for each of the several sonar systems now in use. The 

 approach is to combine a full array of oceanographic analysis field 

 into composite propagation loss profiles for a series of point loca- 

 tions which are representative of predetermined acoustical regimes. 

 Each regime is an area reasonably homogenous as to water mass, bathy- 

 metry, and bottom boixnce acoustical loss. Both power-limited (Fig. 22) 

 and ray path-limited ranges are predicted; the selection depends up- 

 on the spatial relationship of the transducer and target, whether 

 they are in the same layer, lie across a layer boundary or are both 

 in a duct. Range variability which might be expected with each 

 regime is also calculated. The system is adaptable to both active 

 and passive detection systems. 



To present the acoustic ranges in the most useable form, we have 

 divided our system into two parts (Fig. 23). Acoustic Sensor Range 

 Prediction (ASRAP) is for the support of fixed wing aircraft, the 

 P2/P3/S2 squadrons. Ship Helicopter Acoustic Range Prediction Sys- 

 tem (sharps) is for the support of other Fleet users. Both ASRAP 

 and SHARPS are simple to use. The user knows what sonar ranges are 

 possible in the area in whish he is operating, or in which he is 

 about to go. The operator is freed of most computational work. He 

 knows the range variability for his area. For the first time bottom 



22 



