Influences of environmental factors on low frequency abnormal sound transmission through sea-air interface

Abstract

In view of low frequency abnormal sound transmission of sound source in the sea at the sea-air interface, according to the two-layer medium sound transmission model, we analyze the relationships of the sound speed and the density of the atmosphere with the atmospheric pressure, the air temperature, the humidity; we also analyze the relationships of the sound velocity and the density of seawater with the sea surface temperature (SST) and salinity; we investigate the low-frequency abnormal sound transmissions influenced by temperature, pressure, salinity, humidity and other environmental factors; we analyze the influences of various factors on the sound transmission. The obtained results are as follows. 1) the sound power in the air, obtained by the sound transmission of sound source in the shallow sea, is negatively correlated with atmospheric temperature and humidity, and positively correlated with the SST, salinity, and atmosphere pressure. 2) The sound power that is radiated into the sea by the monopole and horizontal dipole source at the sea, is negatively correlated with SST and salinity, while the sound power that is radiated into the sea by the vertical dipole sound source, is positively related to SST and salinity. 3) The sound transmission directivity is positively related to SST and negatively correlated with atmospheric temperature. 4) The air temperature and SST have the greatest influence on low-frequency abnormal sound transmission, while the effects of air pressure and humidity on them are smaller than that of salinity. The effect of temperature on the low frequency abnormal sound transmission of vertical dipole sound is greater than those of the horizontal dipole and a monopole sound source.