Evolution of summer Arctic sea ice albedo in CCSM4 simulations: Episodic summer snowfall and frozen summers
Evolution of summer Arctic sea ice albedo in CCSM4 simulations: Episodic summer snowfall and frozen summers
复制标题
CCSM4 模拟中夏季北极海冰反照率的演变：夏季偶发降雪和夏季冰冻
DOI：
--
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
M. Holland
中科院分区：
文献类型：
--
作者：
B. Light;S. Dickinson;D. Perovich;M. Holland
利用20世纪世纪共同体气候系统模式第4版（CCSM 4）的夏季模拟结果，计算了北极海冰的年变化。这是比较经验记录的基础上的概括性意见的夏季冰进行沿着与融化的起始日期从遥感。仅分析了冰、雪和池塘对冰的贡献;在本评估中不考虑冰面积。决定夏季降水演变的关键因素是积水和积雪的时间和程度。CCSM 4夏季海冰平均下降幅度小于经验记录或CANA-SAL卫星记录。模拟的冰温并不像经验记录那样低，夏季的低温也不像经验记录那样长。在该模型中，发现某些夏季会将雪保留在海冰上，从而抑制冰面融化和融化池的形成或保留。这些“冰冻”的夏天通常不是春季积雪最多的夏天，而是在6月或7月至少有微量降雪的夏天。当这些冰冻的夏天从比较中省略时，模型和经验记录的一致性要好得多。这表明夏季北极降雪事件和/或其对海冰条件的影响的代表性并没有很好地体现在CCSM 4集成，为未来的模型开发工作提供了一个目标。
The albedo of Arctic sea ice is calculated from summertime output of twentieth century Community Climate System Model v.4 (CCSM4) simulations. This is compared with an empirical record based on the generalized observations of the summer albedo progression along with melt onset dates determined from remote sensing. Only the contributions to albedo from ice, snow, and ponds are analyzed; fractional ice area is not considered in this assessment. Key factors dictating summer albedo evolution are the timing and extent of ponding and accumulation of snow. The CCSM4 summer sea ice albedo decline was found, on average, to be less pronounced than either the empirical record or the CLARA-SAL satellite record. The modeled ice albedo does not go as low as the empirical record, nor does the low summer albedo last as long. In the model, certain summers were found to retain snow on sea ice, thus inhibiting ice surface melt and the formation or retention of melt ponds. These “frozen” summers were generally not the summers with the largest spring snow accumulation, but were instead summers that received at least trace snowfall in June or July. When these frozen summers are omitted from the comparison, the model and empirical records are in much better agreement. This suggests that the representation of summer Arctic snowfall events and/or their influence on the sea ice conditions are not well represented in CCSM4 integrations, providing a target for future model development work.