Structure and dynamics of convective mixing in Lake Onego under ice-covered conditions
Structure and dynamics of convective mixing in Lake Onego under ice-covered conditions
复制标题
冰覆盖条件下奥涅戈湖对流混合的结构和动力学
作者：
S. Bogdanov;G. Zdorovennova;S. Volkov;R. Zdorovennov;N. Palshin;T. Efremova;A. Terzhevik;D. Bouffard
摘要2016年3月和2017年3月在冰封条件下在奥涅戈湖的彼得罗扎沃茨克湾进行的水文物理研究检测到辐射驱动的对流，并揭示了对流混合层（CML）的特定结构和动力学参数。时间序列，谱能量分布和垂直速度剖面的分析表明，存在的平均电流，假潮和对流运动。由于其相似的空间和时间尺度，这些过程进行了研究，使用渐进矢量图（PVDs）。尽管低水的速度，CML的流体动力学制度仍然接近充分发展的湍流，并在一系列不同尺度的对流细胞的预期。信号分辨率限制了仅对最大细胞的检测。我们调查了CML的水平结构，使用单独的和合并的意见，从3个声速剖面位于半径几十米。这种新的设置收集的数据表明，CML的大规模水平流结构由一个连续的准确定性细胞。从PVD和速矢曲线推导出了用于估算湍流传递所需的单元参数。
ABSTRACT Hydrophysical studies conducted in Petrozavodsk Bay of Lake Onego under ice-covered conditions in March 2016 and 2017 detected radiatively driven convection and revealed specific structural and dynamic parameters for the convectively mixed layer (CML). Analysis of time series, spectral energy distribution, and vertical velocity profiles indicated the presence of a mean current, seiches, and convective motion. Because of their similar spatial and temporal scales, these processes were investigated using progressive-vector diagrams (PVDs). Despite low water velocities, the CML hydrodynamic regime remained close to that of fully developed turbulence, and convective cells at a range of different scales were expected. Signal resolution constraints limited detection to only the largest cells. We investigated the horizontal structure of the CML using individual and combined observations from 3 acoustic velocity profilers located within a radius of a few tens of meters. This novel setup collected data indicating that the CML’s large-scale horizontal flow structure consists of a continuum of quasi-deterministic cells. Cell parameters necessary for estimating turbulent transfer were derived from PVD and hodograph curves.