Acoustic Sounder for Probing of the Lower Atmosphere

Abstract

The technique for probing the lower troposphere by acoustic sounding is described. Short pulses of acoustic energy (peak power, 6 W; pulse duration, 10 msec; carrier frequencies, 1000-2000 Hz; and repetition rate, 3 sec) are beamed vertically upwards with a beam divergence of 20° from a cross-array of loudspeakers. The back-scattered echoes are received by a dynamic microphone placed at the focus of a large paraboloid bowl and are displayed on a cathode ray oscilloscope fitted with a camera to photograph the displayed trace. The results indicate that with this set-up definite back-scattered echoes are obtained during night-time from temperature fluctuation boundaries located at a distance of 200 m.