Interface structure and flux laws in a natural double-diffusive layering
Interface structure and flux laws in a natural double-diffusive layering
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自然双扩散分层中的界面结构和通量定律
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
A. Wüest
中科院分区：
文献类型：
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作者：
T. Sommer;T. Sommer;J. Carpenter;M. Schmid;R. Lueck;M. Schurter;A. Wüest
双扩散对流的扩散状态产生了夹在对流混合层之间的由薄的高梯度界面组成的阶梯。从基伍湖的楼梯上同时测量温度和电导率的微观结构，用于测试通量定律和双重扩散的理论模型。基伍湖的密度比在1到10之间，混合层的平均厚度为0.7米。温度的界面厚度（平均9 cm）大于溶解物质（6 cm），证实了界面的边界层结构。我们的观察表明，边界层断裂不能用单一临界边界层瑞利数来表征，而是发生在O（10(2)）到O（10(4)）的范围内。对假设努塞尔数随瑞利数Ra呈幂律增长的热通量参数化的指数进行了检验。与标准估计值=1/3相反，我们发现密度比在2和6之间=0.200.03。因此，我们建议对基于=1/3的热通量估计进行修正。修正量的大小取决于感兴趣系统中的Ra。对于基伍湖（平均热通量0.10 W m(-2)）， Ra= 0(10(8))，校正是微不足道的。然而，在Ra= 0（10(8)）至0（10(12)）的北冰洋，热通量可能被高估四倍。
The diffusive regime of double-diffusive convection generates staircases consisting of thin high-gradient interfaces sandwiched between convectively mixed layers. Simultaneous microstructure measurements of both temperature and conductivity from the staircases in Lake Kivu are used to test flux laws and theoretical models for double diffusion. Density ratios in Lake Kivu are between one and ten and mixed layer thicknesses on average 0.7 m. The larger interface thickness of temperature (average 9 cm) compared to dissolved substances (6 cm) confirms the boundary-layer structure of the interface. Our observations suggest that the boundary-layer break-off cannot be characterized by a single critical boundary-layer Rayleigh number, but occurs within a range of O(10(2)) to O(10(4)). Heat flux parameterizations which assume that the Nusselt number follows a power law increase with the Rayleigh number Ra are tested for their exponent . In contrast to the standard estimate =1/3, we found =0.200.03 for density ratios between two and six. Therefore, we suggest a correction of heat flux estimates which are based on =1/3. The magnitude of the correction depends on Ra in the system of interest. For Lake Kivu (average heat flux 0.10 W m(-2)) with Ra=O(10(8)), corrections are marginal. In the Arctic Ocean with Ra=O(10(8)) to O(10(12)), however, heat fluxes can be overestimated by a factor of four.
影响因子：
3.7
作者：
Boehrer;S. Dietz;C. von Rohden;U. Kiwel;K. D. Jöhnk;S. Naujoks;J. Ilmberger;D. Lessmann
通讯作者：
D. Lessmann