Bogucki Darek J, Domaradzki Julian A, von Allmen Paul
Opt Express. 2018 Mar 19;26(6):6806-6816. doi: 10.1364/OE.26.006806.
Lidar is one of few remote sensing methods available to researchers to sense below the oceanic air-surface. We present polarimetric lidar measurements of turbulence in a laboratory generated turbulent flow. We found that the nearforward light depolarization characterized by the depolarization rate γ(z), varies with the turbulent flow parameter: χ(z)∊(z), where χ(z) and ∊(z) are the respective depth dependent, temperature variance, and turbulent kinetic energy dissipation rates. The presence of particles in the flow modifies the values of γ in such a way that the ratio γ(z)/α(z) becomes independent of the particle concentration and depends only on χ(z)∊(z). We posit that the mechanism of light depolarization in turbulent flow with particles is forward scattered light interaction between turbulent refractive index inhomogeneities and flow particles. Such interactions result so that the observed depolarization rate, γ(z), is much larger than expected from 'pure' turbulent flow. Our observations open up the fascinating possibility of using lidar for turbulence measurements of aquatic flows.
激光雷达是研究人员可用于探测海洋空气表面以下情况的少数遥感方法之一。我们展示了在实验室生成的湍流中进行的偏振激光雷达湍流测量。我们发现，以去偏振率γ(z)表征的近前向光去偏振随湍流参数而变化：χ(z)∊(z)，其中χ(z)和∊(z)分别是与深度相关的温度方差和湍流动能耗散率。流中颗粒的存在以这样一种方式改变了γ的值，即γ(z)/α(z)的比值变得与颗粒浓度无关，仅取决于χ(z)∊(z)。我们假定，含颗粒湍流中光去偏振的机制是湍流折射率不均匀性与流中颗粒之间的前向散射光相互作用。这种相互作用导致观测到的去偏振率γ(z)比“纯”湍流预期的要大得多。我们的观测结果开启了利用激光雷达进行水流湍流测量的迷人可能性。
