Regional response of winter snow cover over the Northern Eurasia to late autumn Arctic sea ice and associated mechanism
Regional response of winter snow cover over the Northern Eurasia to late autumn Arctic sea ice and associated mechanism
复制标题
DOI：
10.1016/j.atmosres.2019.02.010
复制
发表时间：
2019-07
影响因子：
5.5
通讯作者：
Bei Xu;Haishan Chen;Chujie Gao;Botao Zhou;Shanlei Sun;Siguang Zhu
中科院分区：
文献类型：
--
作者：
Bei Xu;Haishan Chen;Chujie Gao;Botao Zhou;Shanlei Sun;Siguang Zhu
海冰的变化会对大气环流、温度和降水产生重大影响，导致积雪等异常的地表条件。本研究通过基于多源雪深数据的观测分析和数值敏感性实验，探讨了北极晚秋海冰异常对欧亚大陆冬季积雪深度的可能影响，特别是积雪对海冰异常的区域响应机制。结果表明，随着巴伦支海和喀拉海（BKS）地区海冰的减少，积雪深度表现出明显的区域响应，其特点是欧亚大陆北部雪深减少，而中欧地区雪深增加。进一步分析表明，北极涛动（AO）是BKS海冰与冬季异常积雪深度之间的重要联系，影响着欧亚大陆冬季的气温和降水。区域差异主要来源于区域大气环流异常的显着差异以及影响降雪形成的各种控制因素。在欧亚大陆北部，水汽对冬季降雪的形成和进一步冬季雪深起着决定性作用。正（负）BKS海冰异常一般会诱发正（负）AO模式，可以增强（减弱）纬向风，增加（减少）向欧亚大陆北部的水汽输送，导致冬季积雪深度增加（减少）。相比之下，在欧洲，温度是影响降雪形成和雪深的主导因素。正（负）AO 模式增强（减弱）温暖潮湿的平流，从而导致欧洲气温升高（降低），从而导致冬季雪深减少（增加）。
Variations of sea ice can exert significant impacts on the atmospheric general circulation, temperature and precipitation, resulting in anomalous land surface conditions such as snow cover. In this study, we explored the possible impacts of the abnormal late autumn Arctic sea ice on winter snow depth over the Eurasia, especially the mechanism responsible for regional response of the snow cover to the sea ice anomalies through both observational analysis based on multi-source snow depth data and numerical sensitivity experiments. Results show that with decreasing sea ice in the Barents and Kara Seas (BKS) region, the snow depth exhibits evident regional responses, which are featured by decreased snow depth in the North Eurasia but increased in central Europe. Further analysis suggests that the Arctic Oscillation (AO) is an important connection between the BKS sea ice and anomalous winter snow depth, which affect both the temperature and the precipitation in winter over the Eurasia. The regional difference mainly comes from significant differences in regional atmospheric general circulation anomalies as well as the various controlling factors affecting the formation of the snowfall. In North Eurasia, water vapor plays a decisive role in the formation of the winter snowfall and further the winter snow depth. Positive (negative) BKS sea ice anomaly generally induces positive (negative) AO pattern, which can enhance (weaken) the zonal wind and increase (decrease) water vapor transportation to the North Eurasia, causing increased (decreased) winter snow depth. In contrast, in Europe, temperature is the dominant factor affecting the formation of the snowfall and the snow depth. Positive (negative) AO pattern, enhances (weakens) the warm moist advection and thus leads to increased (decreased) temperatures in the Europe, consequently resulting in reduced (increased) winter snow depth.