eT DRAFT eee. waters are most stratified (i.e., density gradients aie greatest) at depths of 50 to 175 meters, being shoalest in the southeastern part of the area, deepest in the northwestern portion, and of intermediate depth at Bikini. Water masses in the area Pectin ob” are primarily Equatorial Pacific, North Pacific Intermediate, and west North Pacific Central. Underwater sound propagation conditions at depths ebove the thermocline are good, but will become less favorable as summer progresses. Fropagation in the deep water is bottom limited where depths are less than 1000 fathoms. The axis of the deep sound channel is found at 800 to 1200 meters (1.3 te 1.5 times as deep as off the U. S. West Coast). Tre physical hydrography of Bikini Lagoon is simllar to that obtained at CHOSSROALUS, r Surface waters move dewnwind, and deep waters flow in the ovposite direction to complete a cellular circulation. at the upwind end the deep waters are diverted both north and south into two sevcndary horizontal celis. During moderate to strong trades, water flows into the lagoon along the windward reefs and fiows-out througa Enyu flows oufChannel and.at the leeward reefs and cnannels. With southerly and southeasterly winds most of the inflow occurs ‘through tnyu channel. Speed of the surface current was measured to be about 1.6% of the wind speed instead of 3% as previously found. The ageep flow wes apnarently more variable in direction and of considerably less speed than that obtained during previous inves*1lgations, As ‘the trade winds materially decrease, the surface COPIED/DOE LANL RG” OTT Re - meea mega . ETE S RYer wee 5 pre reepee