摘要
本文计算表明速度场湍流对逾量衰减的作用比温度场湍流的大5倍.在有限宽度声束条件下,引入有效湍流外尺度Le后,计算表明在大多数情况下逾量衰减系数难以忽略.当波束有张角时,同样的大气湍流状态下逾量衰减系数值随离声源距离增大而增大.过量衰减系数与声波波长关系近似为Ke∝λ^(-2).提供了考虑通量衰减作用的计算C_T^2的简单方法并给了几个计算实例.
In the condition of finite width of sound beam the excess attenuation coefficients depend on CT2, Cv2,λ, T and L, the effective turbulent outer scale. The coefficients increase with the distance from the source and follow a-2 dependence with the acoustic wave length. Calculation shows that the effect of Cv2 on the excess attenuation is times larger than that of CT2. In most cases the excess attenuation can not be ignored in quantitative measurements of sodar echo, especially at convective unstable condition. A simple method can be used to estimate the CT2 when excess attenuation is taken into accunt.
出处
《大气科学》
CSCD
北大核心
1991年第4期116-122,共7页
Chinese Journal of Atmospheric Sciences
关键词
大气
声波
湍流
散射
yu量衰减
Turbulence scattering
Finite-width sound beam
Excess attenuation.
