北极海冰输出区海冰热力学和运动学过程研究

Ice-based buoy arrays has been or will be deployed in the central Arctic Ocean, and used to monitor sea-ice thermal and kinematic processes in the Arctic outflow region during the floes drift from the central Arctic to the Fram Strait. Measurements of sea-ice mass balance and temperature profiles will be used to estimate the conductive heat flux within the ice cover and the oceanic heat flux under the ice. Seasonal and spatial changes in the fluxes and critical influences on their changes will be explored. Position data collected by the buoy arrays will be used to analyze the temporal and spatial changes in the ice kinematic parameters and the deformation of ice field, and their responses to the atmospheric forces. The effects of ice drift and deformations on the oceanic heat flux, and sequentially on the ice mass balance also will be assessed. Combined with historical data collected by the International Arctic Buoy Program, the long-term changes in the sea-ice thermal and kinematic characteristics in the Arctic outflow region will be ascertained. The relationship between Arctic sea-ice outflow and the sea-ice conditions in the regions of Arctic Northeast Passage will be analyzed. Based on the data of sea-ice concentration, thickness and drift derived from remote sensing and/or buoys, the changes in the volume of Arctic sea-ice outflow through the Fram Strait will be quantified. Using the high-resolution sea-ice thermodynamic model and the validation data measured by the buoys, the applicability of different versions of the atmospheric reanalysis data and the parameterizations of sea-ice thermal parameters will be tested. Results derived from this project, will effectively improve the full picture of sea-ice thermal and kinematic regimes in the Arctic outflow region, and give some supports for the developments of climate model in the Polar Regions.

在北极中心区布放冰基浮标阵列，对北极输出区海冰热力学和运动学过程进行观测。基于观测数据计算冰内热传导通量和冰底海洋热通量，量化其时空变化特征，分析影响通量变化的主要因素。利用浮标阵列GPS观测数据，分析海冰运动和冰场形变特征参数的时空变化，及其对风强迫的响应规律，分析海冰运动对冰底海洋热通量，乃至冰底物质平衡的影响。结合国际北极浮标计划共享的观测数据，量化海冰热力学和运动学特征参数的长期变化趋势及其影响因素，评价北极海冰输出对东北航道区域冰情的影响。结合海冰运动、厚度和密集度遥感或浮标观测数据，量化弗拉姆海峡冰量输出的变化趋势。海冰物质平衡观测数据作为验证数据，利用高分辨率海冰热力学模式评价大气再分析数据和海冰热力学关键参数参数化方案的合理性。基于研究成果提高对北极输出区海冰热力学和运动学机理的全景性认识，支持极区气候模式的发展。

本项目围绕北极输出区的海冰热力学和运动学过程开展了一系列现场观测和机理研究。分析了中国第3-6次北极考察在北极中心区域布放的海冰物质平衡浮标和海冰漂移浮标观测数据。在第7-9次北极考察中以浮标阵列的方式在北极中心区域布放了冰基浮标，发展了“海-冰-气无人冰站观测系统”，并在第9次北极考察中实现了成功布放。利用浮标观测数据，刻画了北极输出区的海冰运动特征参数的季节和长期变化，证实2005年以来北极偶极子正位相导致海冰输出有增强的趋势，促进了北极海冰的减退。海冰物质平衡浮标的观测表明2010年夏季北极发生穿极融化现象导致上层海洋吸收更多的短波辐射，使得海冰生长滞后，而2013年夏季，大气环流不利于北极海冰向北欧海输出，穿极流减弱，海冰滞留于北极中心区域，从动力学和热力学角度均不利于海冰融化。结合卫星遥感和船基的观测结果，分析了北极东北航道适航性的季节和长期变化，揭示冬季穿极流加强有利于海冰从俄罗斯沿岸向北输送，形成冰间湖，促进东北航道的开通。结合卫星遥感和现场观测数据，刻画了西北极海冰反照率的季节和长期变化，阐明了北极偶极子和穿极流强弱对西北极海冰和反照率变化的影响。基于上述研究成果，在JGR_Oceans等国际期刊上发表了SCI检索论文5篇。项目负责人受邀参加了第23届IAHR-冰科学国际研讨会和2017年中国极地科学年会，以大会报告的方式展示了本项目的研究成果；2017年获得了国家优秀青年基金资助。研究成果支持了国家重点研发计划“高分辨海冰模式的研发”的立项，本项目提出了基于冰类型的海冰反照率参数化方案将应用到高分辨海冰模式的研发中，支持我国地球系统模式的发展，从而提高对北极海冰的预测能力。本项目的研究成果得到了国际同行的关注，课题组受邀参加了MOSAiC国际漂流冰站计划积雪-海冰工作组的工作方案编写；东北航道适航期的研究工作得到了芬兰图尔库大学航运经济学者的关注，为其开展东北航道经济潜力评估提供了依据。在学生培养方面，支持了2名博士生学位论文的研究工作。