极地冰脊表面几何形态和形拖曳系数研究

In-situ measurement, mathematical modelling and parameter identification are combined to study the surface morphology and form drag coefficient of polar pressure ridges. The measured space probability distributions of pressure ridges are considered to establish the optimal identification model on the cutoff height, the corresponding algorithm is also presented for the seperation of pressure ridges from the undulations of the sea ice surface. An clustering algorithm based on optimization is designed, with the consideration of the impact of ice age, geographical location and pressure ridge type on the surface morphology. The morphology parameters such as height,spacing, slope angle and area of pressure ridges are analyzed. The key parameters affecting the surface morphology of pressure ridges are found out. By analyzing the correlation between the heights of the local roughness of the upper and lower sea ice surfaces and that between the heights of the upper and lower pressure ridge surfaces, the correlation between the heights of the upper and lower sea ice surfaces is studied, and the morphology of the lower sea ice surface and the total thickness of sea ice are retrived by the morphology of the upper sea ice surface. Based on the empirical formulas, the form drag coefficient of presure ridges are estimated and analyzed, and the deviation with its reasons between the form drag coefficients of the upper and lower pressure ridge surfaces are quested, and the correlation between them is also studied. It will be helpful for the improvement and perfection of the parameterization of air-ice and ice-water drag coefficients.

将现场观测与数学建模、参数辨识等数学研究方法相结合对极地冰脊表面几何形态和形拖曳系数进行研究。基于冰脊的实测空间概率分布，建立关于切断高度的优化辨识模型，并构造确定该参数的优化算法，使从海冰表面起伏中分离出的冰脊尽可能符合实际情况。完善冰脊分类优化算法，进而深入分析冰脊高度、间距、倾角、横截面面积等表面几何形态参数与冰龄、地理位置和冰脊类型的关系，找出影响冰脊表面几何形态的关键参数。分析海冰上下表面局部粗糙单元高度的相关性、冰脊上下表面高度的相关性，进而研究海冰上下表面高度的相关性，实现海冰上表面形态对下表面形态和总厚度的高精度反演。基于已有的经验公式，估算冰脊形拖曳系数，并分析冰脊表面几何形态对冰脊形拖曳系数的影响，探索冰脊上下表面形拖曳系数的差异以及引起差异的原因，并进行相关性分析，为冰-气、冰-水拖曳系数参数化方案的改进和完善提供依据。

项目将现场观测、数学建模和参数辨识等研究方法有机结合对极地冰脊表面几何形态和形拖曳系数进行了研究，目标是建立关于冰脊切断高度的优化辨识模型，为海冰表面冰脊的合理分离提供有效方法，并结合极地自然环境因素改进完善冰脊分类方法，在此基础上，研究冰脊上下表面相关性，并找出冰脊上下表面形拖曳系数之间的关系。主要工作如下：(1)基于冰脊高度和间距的实测概率分布，建立了关于切断高度的优化辨识模型，并构造了确定该参数的优化算法；(2)结合地理位置、生长环境和海冰年龄等因素完善了冰脊分类优化算法，分析了冰脊高度、间距、横截面面积等表面几何形态参数与冰龄、地理位置和冰脊类型的关系；(3)建立了冰脊上下表面高度的相关关系，并对海冰总厚度进行了初步估算；(4)估算了冰脊形拖曳系数，并分析了冰脊表面几何形态对冰脊形拖曳系数的影响，探索了冰脊上下表面形拖曳系数的差异以及引起差异的原因，并进行了相关性分析，为冰-气、冰-水拖曳系数参数化方案的改进和完善提供了依据。以上研究不仅能够使我们深入理解冰脊表面几何形态及冰脊形拖曳系数，而且可以为海冰现场观测和模式研究提供理论依据。