ASA 125th Meeting Ottawa 1993 May

5aPA2. Micrometeorologically forced intermittency in atmospherically propagated signals.

Scott D. Hansen

Grad. Prog. in Acoust., Penn State Univ., Appl. Sci. Bldg., University Park, PA 16804

Dennis W. Thomson

Penn State Univ., University Park, PA 16802

Line of sight, continuous acoustic signal propagation experiments were conducted as a part of the Joint acoustic Propagation experiment (JAPE) performed during July and August of 1991 at White Sands Missile Range. One of the purposes of JAPE was to examine the effects of the micrometerological phenomena on low-frequency sound. During one experiment, pure tones of 80, 200, and 500-Hz were propagated simultaneously for a period of 1 h over distances up to 1000 m. Tower-based measurements included both microphones and turbulence sensors spaced logarithmically to a height of 32 m. Frequency, height-, and range-dependent statistics of the recorded acoustic transmission loss (TL) are interpreted in terms of the ambient surface and boundry layer micrometeorological processes. In addition, nonlinear attractor-based parameterizations of signal variability are evaluated.