由声雷达回波反演湍流场结构系数

RETRIEVAL OF TURBULENT STRUCTURE COEFFI CIENTS FROM SODAR ECHO

定量测量声雷达回波强度可以导出大气温度结构系数（Ｃ２ｔ）和速度结构系数（Ｃ２ｖ）．文章简要回顾和评述了过去的工作，并讨论了逾量衰减、风和湍流等因素对该测量的影响．研究表明：逾量衰减主要是由速度场的不均匀性所造成．其次，风场也有不可忽视的衰减作用，在风速达１０ｍ／ｓ时，引起的衰减达５０％以上．最后给出了改进后的声雷达方程和反演Ｃ２ｔ和Ｃ２ｖ的方法．初步的试验结果对理论的应用是支持的．

Temperature structure coefficient ( C 2 t) and velocity structure coefficient (C 2 v) can be deduced from the sodar return intensity. The past researches are reviewed briefly. The impacts of these physical factors, such as excess attenuation, wind and turbulence etc on the echo measurements are discussed. The results show that the excess attenuation of acoustic wave is mainly caused by the velocity fluctuation. On the other hand, the wind also causes some echo attenuation. When wind speed reaches 10 m/s, the received energy at antenna will reduce about half. At the end, a modified sodar equation and the retrieval method of C 2 t and C 2 v are given. The primary tests indicate a qualitative agreement with the theory presented here.