从光闪烁频谱反演大气湍流谱:原理与数值模拟

RETRIEVAL OF TURBULENCE SPECTRUM FROM TEMPORAL SPECTRUM OF A LIGHT WAVE PROPAGATING THROUGH ATMOSPHERE: PRINCIPLE AND SIMULATIONS

建立了一种数值算法,从光波在湍流大气中传播的闪烁时间频谱的高频特征反演大气光学湍流谱.此算法具有两点优越性:（1）反演出的湍流谱直接表征大气折射率的起伏而非大气温度场的起伏;（2）可以获得高空间波数、大部分位于耗散区的湍流谱,而用其它方法不易获得此区域的湍流谱.对Hill湍流谱以及一种复杂的湍流谱进行了大量数值模拟来检验此种算法,结果表明:如果知道大气风速与湍流内尺度就可以相当有效地获得湍流谱.

A numerical algorithm is set up for the retrieval of optical turbulence spectrum from high-frequency temporal spectra of a light wave propagating through a turbulent atmosphere. This technique has two advantages. First, the retrieved spectrum is directly related to the refractive index fluctuation rather than temperature fluctuation. Second, the turbulence spectrum at rather high spatial wavenumber, most in the dissipation range, can be retrieved. We test the retrieval procedure through carrying out a lot of simulations with Hill turbulence model and a composed model. It is found that if the wind velocity and the turbulence inner scale are known correctly the turbulence spectrum can be achieved effectively.