Lilley Marc, Lovejoy Shaun, Strawbridge Kevin, Schertzer Daniel
Department of Physics, McGill University, 3600 University Street, Montreal, Quebec, Canada.
Phys Rev E Stat Nonlin Soft Matter Phys. 2004 Sep;70(3 Pt 2):036307. doi: 10.1103/PhysRevE.70.036307. Epub 2004 Sep 16.
In buoyancy-driven flows, another dimensional quantity appears in addition to the energy flux. Classically, this leads to the prediction that at large scales, isotropic Bolgiano-Obukhov (BO) scaling can dominate isotropic Kolmogorov scaling. We investigate this in the atmosphere by using state-of-the-art high-powered lidar data. We examine simultaneous horizontal and vertical sections of passive scalar surrogates over the ranges 100 m to 120 km and 3 m to 4.5 km , respectively. Overall, this spans the crucial "mesoscale" and involves nearly 1000 times more data than the largest relevant experiments to date. Rather than a transition from one isotropic regime to another, we find that the two regimes always coexist in an anisotropic Corrsin-Obukhov law with the Kolmogorov holding in the horizontal, and the BO holding in the vertical. The stratification is quantified by an elliptical dimension D(el) found to be equal to 2.55+/-0.02 . This anisotropic scaling is very close to that predicted by the 23/9 dimensional unified scaling model of the atmosphere and is consistent with observations of the horizontal wind.
在浮力驱动流中，除了能量通量外还会出现另一个维度量。传统上，这导致了一种预测，即在大尺度上，各向同性的博尔贾诺 - 奥布霍夫（BO）标度可以主导各向同性的柯尔莫哥洛夫标度。我们通过使用最先进的高功率激光雷达数据在大气中对此进行研究。我们分别检查了在100米至120千米以及3米至4.5千米范围内被动标量替代物的水平和垂直同步剖面。总体而言，这涵盖了关键的“中尺度”，并且涉及的数据量比迄今为止最大的相关实验多出近1000倍。我们发现，并非从一种各向同性状态转变为另一种，而是这两种状态总是在一种各向异性的科尔辛 - 奥布霍夫定律中共存，其中柯尔莫哥洛夫标度在水平方向成立，而BO标度在垂直方向成立。分层由一个椭圆维度D(el)量化，发现其等于2.55±0.02。这种各向异性标度非常接近大气的23/9维度统一标度模型所预测的结果，并且与水平风的观测结果一致。
