POLYNOMIAL EXPRESSIONS FOR THE COEFFICIENT OF NONLINEARITY-BETA AND BETA/(PC(5))(1/2) FOR FRESH-WATER AND SEAWATER

In this Letter, polynomial expressions are presented for the coefficient of nonlinearity beta for both seawater and fresh water. The seawater relations are for salinities of 30-40 ppt, temperatures of 0-40-degrees-C, and pressures of 1-800 bars absolute. The fresh water relations are for temperatures of 0-90-degrees-C and pressures of 1-1000 bars absolute. Also presented are polynomial expressions for the term LAMBDA = beta/(rhoc5)1/2, which arises in nonlinear geometrical acoustics. The precision of the fits of the polynomials to the underlying data is better than 1 ppt in all cases. However, the uncertainty in the seawater beta relation is +/-3% for realistic ocean temperatures and pressures. An uncertainty estimate was not obtained for the fresh water beta relation.