Acoustical absorption in the atmosphere at high altitudes.

Abstract

Before 1978, acoustical absorption in the atmosphere was modeled semiempirically based on numerous experimental studies, especially those of Harris and Tempest. In 1969, this author presented a semiempirical model to explain the divergence of the absorption data from theoretical values predicted from classical absorption and molecular relaxation of just moist oxygen. Joe Piercy published a correction of my error in neglecting molecular relaxation of moist nitrogen. This activity stimulated formation of an ANSI working group on atmospheric absorption chaired by Joe Piercy and included the late Henry Bass and myself as members. The result was ANSI Std. S1.25‐1978 (1995) which was stated as being valid only up to 20 km. Later, I had the distinct honor to collaborate with Bass in a paper [J. Acoust. Soc. Am. 115 (2004)] which provided a computational model for atmospheric acoustical absorption up to 160 km. Unique elements of this high altitude atmospheric absorption model are reviewed, including the molecular relaxation loss from carbon dioxide. This high altitude atmospheric absorption model was possible only with the key role played by Bass in its development. The Society has lost a true scientist, scholar, and gentleman of the highest caliber.