The Principles of Acoustic Radar

Acoustic radar is employed to probe the temperature and wind field structures of the lower atmosphere. It operates by directionally transmitting intense acoustic pulses at a specific frequency and subsequently receiving the scattered acoustic echoes. By analyzing the intensity of these scattered echoes, one can determine the atmosphere's thermal structure-such as the strength and height of convection, as well as the presence of inversion layers-and assess turbulence conditions. Furthermore, by comparing the frequency difference between the transmitted acoustic waves and the scattered echoes, it is possible to calculate how wind direction and speed vary with both time and altitude. However, because acoustic waves undergo significant attenuation as they propagate through the atmosphere, the detection range of acoustic radar is limited, typically extending only to an altitude of approximately one kilometer.

The speed of sound is intrinsically linked to atmospheric temperature and wind velocity; consequently, when the distribution of atmospheric temperature and wind speed is non-uniform (i.e., exhibits fluctuations), it causes the acoustic waves to scatter. Notably, the scattering efficiency of acoustic waves is approximately one million times greater than that of radio waves or light waves. As a result, acoustic waves serve as an exceptionally sensitive medium for measuring fluctuations in atmospheric temperature and wind.