侧向融化物理过程及其对北极夏季海冰分布和快速变化的影响机制研究

The impacts of lateral melt on size distribution and rapid change of Arctic sea ice in summer have attracted many attentions of people, but the knowledge on the physical mechanism inside the process and the quantitative degree of the impact is still far from enough. In this proposal, aiming at the physical processes of lateral melt, field observations on the system of sea ice-open leads-ocean beneath ice are planned to carried out, combining with physical modeling of the melting of sea ice and monitoring on the micro process in laboratory experiments, influences on the rate of lateral melt from metrological and hydraulic factors, and ice physical properties will be investigated. Variations of sea ice size distribution with lateral melt are also studied through analyzing the historical sea ice imagery during Arctic expeditions and high-resolution satellite remote sensing data. The results will serve to improve the parameterization of sea ice lateral melt, and to setup the physical mechanism and quantitative relationship for the interactions between lateral melt rate and size distribution function. Through applications in sea ice thermodynamic modelling, the mathematical descriptions on the energy and mass exchange among sea ice, open leads, and ocean beneath ice will be improved. Further, the relative amount of melt on ice surface, lateral area, and bottom can be estimated, together with their impacts on the ice thickness, ice concentration and ice volume, to finally explore the role of lateral melt on the change of Arctic sea ice. This study will provide solid theoretical supports to the improvement of the capability of numerical modeling on the rapid decline of Arctic sea ice.

海冰侧向融化对北极夏季海冰尺寸分布和快速变化的影响已经受到关注，但对其内在物理机制和定量程度仍缺乏足够认识。本项目以海冰侧向融化的物理过程为切入点，通过在现场调查中开展海冰-冰间水道-冰下海洋的系统观测，结合实验室冰试样侧面融化的物理模拟和微观过程监测，探讨不同气象、水文要素及冰物理性质对侧向融化速率的影响规律。同时，通过对北极考察历史影像资料和高分辨率卫星遥感数据的分析，获得海冰尺寸分布随侧向融化的变化规律。在此基础上，完善海冰侧向融化的参数化方案，明确侧向融化速率与海冰尺寸分布函数之间相互影响的物理机制和定量关系。通过在热力学模式中应用，改进对海冰-冰间水道-冰下海洋之间能量和质量交换过程的数学描述，进而评估夏季海冰表面、侧面和底面等不同融化过程的相对大小，及其对冰厚、密集度和冰体积的影响，揭示侧向融化在海冰快速变化中的贡献，为提高数值模拟对北极海冰快速变化的模拟能力提供重要理论支持。

通过冰体侧向融化过程的现场调查和室内物理模型试验，探究了气象、水文要素及冰物理性质对海冰侧向融化速率的影响。结合历史资料和卫星遥感数据分析了浮冰尺寸分布和侧向融化之间的响应关系。结果揭示了气温、风速和水温等因素对侧向融化物理机制的影响；依据物理分析和数学描述建立了气温、水温等不同参数与侧向融化速率之间的参数化方程并定量得到了表面、侧面和底面的融化速率差异；发现了侧向融化剖面的非均匀性特征以及造成侧向融化速率存在深度差异的原因；利用图像处理技术结合北极单冰体侧向融化过程和区域多浮冰尺寸得到了侧向融化对北极浮冰尺寸分布的影响及演变规律；依据研究结果加强了对于侧向融化物理机制的了解，建立了热力学参数化方程，将侧向融化的定性认识提高到了定量认识。明确了从单冰体侧向融化过程到浮冰尺寸分布演变，再到北极海冰快速变化之间的反馈关系，为未来改进北极海冰快速变化数值模型提供了理论支持和参考。