南极普里兹湾海冰/雪面能量收支

A series of research results were achieved under the grant of ongoing NSFC Youth Science Foundation: On the platform of Antarctic Zhongshan station, the albedo measurements over the sea ice/snow surface of Prydz Bay sea ice was continuously conducted from 2010 to 2012, which is the longest records among all the Antarctic sea ice albedo observation; Based on above observational data, the variation and key affecting factors of the surface albedo were analyzed. To represent the daily variation of the albedo over the snow and ice surface, two experimental formulas were proposed, which could be easily applied over other Antarctic costal sites in spring and early summer. Surface albedos are calculated using seven different snow/ice albedo parameterizations and are evaluated against the in situ observations. A new parameterization of surface albedo which takes the snowfall and cloud effects into consideration was developed and has been evaluated with a much better performance than that before. If the new NSFC proposal is agreed, the surface albedo and radiation will be continuously observed. Meanwhile, the sensible heat flux, latent heat flux, the conductive heat flux from the ice/snow and the ice/snow melting flux will be also quantitatively measured. Thus the energy budget conceptual model during the melting and non-melting period can be established, and the influences of surface heat flux on the ice growth and melting can be quantified. The parameterization schemes that are more in line with the actual observations will be developed and incorporated into the numerical models to evaluate their impacts on the Antarctic sea ice modeling. The long-term observation data of surface albedo and surface energy budget would be an important baseline data set for the international Antarctic sea ice research, the parameterization and numerical modeling results will also provide an important reference to the improvements of ice-ocean coupled models and climate models.

正在进行的青年基金取得了重要成果：依托中山站持续开展了2010～2012年越冬观测，获取了目前国际上最长的南极海冰/雪面反照率观测数据；分析研究了反照率的变化特征及影响因子，提出了一组表述不同海冰/雪面反照率日变化的经验公式；对7种国际上常用的参数化方案进行评估，并独立发展了一个考虑降雪和云量影响的参数化方案，显著改进了反照率计算。拟在基金连续资助下，连续开展南极普里兹湾海冰/雪面反照率和辐射观测，并通过增加表面感热、潜热、冰/雪传导和融化（冻结）热通量的直接或间接测量，建立融化期和非融化期冰/雪面能量收支的概念模型，定量能量变化对海冰和积雪生消过程的影响程度。进而发展更符合实际观测的反照率和湍流通量参数化方案，并结合数值模式分析其对南极海冰数值模拟的影响。本项目获取的反照率和能量收支长期观测数据集将成为国际上南极海冰研究的重要基准数据，参数化和数值模拟成果也将为海冰模式改进提供重要参考。

本项目于2014-2017年度在南极中山站海冰区持续开展了冰雪面辐射、湍流通量、冰雪厚度等的连续观测，获取了目前国际上最长的海冰面辐射、反照率、光谱反照率、感热通量、潜热通量的观测数据集。分析研究了冰雪表面光谱反照率的天气尺度和季节尺度变化特征及影响因子，重点分析了降雪天气对光谱反照率的影响，评估了国际上气候模式常用的海冰反照率参数化方案，并进行了改进。基于小波分析、经验模态分解等方法研究了2010年以来连续5年的春季中山站海冰表面短波和长波辐射变化率，特别分析了短波、长波辐射的周期特征以及其环流原因。分析研究了中山站冰雪表面和陆雪表面的气象要素、辐射、湍流通量和表面能量平衡的日变化和季节变化特征，分析评估了国际上常用的湍流通量参数化方案，给出了更加符合南极局地特点的热力粗糙度长度和动力粗糙度长度计算方法。针对涡动观测设备超声探头发生碰撞、出现轻微形变的情况，为恢复宝贵的南极冰雪面通量观测数据，首次研发出了针对性的湍流通量数据修复算法和软件，并已完成2014和2015年湍流通量数据修复工作。基于海冰物质平衡浮标（SIMBA）观测的气-雪-冰-水垂直温度廓线，首次研发了可以自动解析SIMBA数据的算法和软件。本项目还基于一维高分辨雪冰热力学模式（HIGHTSI）开展了不同组合的南极中山站海冰热力学模拟试验，评估了不同反照率等参数化方案对南极中山站海冰模拟的影响；设计了不同初始雪厚的敏感性试验，研究了积雪厚度对南极中山站海冰生长和消融过程的影响机制，并定量分析了雪冰、叠加冰和冻结冰在一年冰和多年冰生消演变中的贡献；模拟了南极中山站当年冰的底部生长和次年冰的底部融化过程，量化了表面能量收支和冰底海洋热通量对冰厚变化的贡献。