Investigation of vertical microphysical characteristics of precipitation under the action of low-frequency acoustic waves

Abstract

As a potentially effective technology for particle removal, acoustic agglomeration technology has been tested for airport defogging and weather modification. Small-scale experiments and simulation studies have shown that acoustic waves can accelerate agglomeration of droplets and aerosol particles, but this has not been confirmed by large-scale field experiments and observations. In this study, field experiments were conducted in a high-altitude and non-interference environment to investigate cloud and precipitation interference by low-frequency acoustic waves. Field tests were carried out in the source region of the Yellow River (SRYR) from July 21, 2019 to November 20, 2019. Macro- and micro- physical characteristics of cloud and precipitation in stratiform and convective–mixed precipitation systems were monitored by disdrometer, micro rain radar, and microwave radiometer. The results showed sensitivity of microphysical parameters of rain rate (R), radar reflectivity factor (Z), liquid water content (Lwc) and height of cloud base (Hc) to acoustic operation. Of these, values of R, Z, and Lwc became larger under the action of acoustic waves, and Hc values became lower with acoustic operation. Spectral parameters λ against μ, Z against R, and Lwc against R at different sampling altitudes and for different precipitation systems follow a quadratic function, power function, and linear function, respectively. The results of this study should be instructive for further efforts to investigate and develop atmospheric interference technology with low-frequency strong acoustic waves.