Walter H. Munk
IGPP, Univ. of California, San Diego, La Jolla, CA 92903-0225
Spiesberger et al. [J. Acoust. Soc. Am. (to be published)] has demonstrated the feasibility of phase-coherent processing of 250-Hz coded acoustic signals transmitted from Hawaii to the West Coast over ranges of 3000 to 4000 km. The Heard Island Test [W. Munk et al., J. Acoust. Soc. Am. (to be published)] extended the range for 57-Hz transmission to antipodal distances. Such low-frequency long-range acoustics transmissions are well suited for monitoring ocean climate variability. The acoustic travel time between two fixed points are a measure of the average temperature of the intervening ocean. Basin scale averages suppress the intense mesocale eddies (order 100 km) that would otherwise dominate over the climatic variations. Propagation problems that are peculiar to global-scale transmissions will be discussed. Acoustic thermometry of ocean climate (ATOC) is scheduled for the North, Central, and South Pacific starting 1994 as a beginning of a global network. [Work supported by ONR, ARPA, NOA, NSF, and DOE.]