Snow on Arctic Sea Ice in a Warming Climate as Simulated in CESM.
Snow on Arctic Sea Ice in a Warming Climate as Simulated in CESM.
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DOI：
10.1029/2020jc016308
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发表时间：
2021-01
期刊：
影响因子：
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通讯作者：
Bailey DA
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文献类型：
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作者：
Webster MA;DuVivier AK;Holland MM;Bailey DA
地球系统模型是了解北极冰雪系统及其反馈如何应对气候变暖的宝贵工具。在这项分析中，我们调查了北极海冰上的雪，以更好地了解在不同的强迫情景下，雪的条件可能会如何变化。首先，我们使用现场，空中和卫星观测来评估社区地球系统模型（CESM）在北极海冰上模拟雪的现实性。对CESM版本1和版本2进行了评估，其中V1是大型密闭实验（CESM 1-LE），V2配置有低顶和高顶大气组件。评估结果表明，CESM 2低估了积雪深度，产生了过于均匀的积雪分布，而CESM 1-LE产生了高度可变的、过厚的积雪。观测表明，CESM 2中的雪在秋季积累得太慢，在冬春季节积累得太快，在春末融化得太快。1950-2050年的年平均雪深趋势在CESM 2（-0.8 cm decade-1）中明显小于CESM 1-LE（-3.6 cm decade-1），这是因为CESM 2的总体降雪量较少。常年厚厚的海冰覆盖、凉爽的夏季和过量的夏季降雪促进了CESM 1-LE更厚、更持久的积雪。在SSP 5 - 8.5强迫情景下，CESM 2表明，与目前相比，北极海冰上的雪将：（1）经历增强的，更早的春季融化，（2）在夏秋季节积累较少，（3）升华更多，（4）促进略微更多的冰雪形成。CESM 2还表明，无雪冰的夏季可能比无冰的北极中部早30-60年出现，这可能会促进海冰更快融化。1950-2050年北极海冰年平均雪深趋势在CESM 2和CESM 1-LE中分别为− 0. 8和− 3. 6 cm十年−1，CESM 2显示出更早的融雪，更少的积雪，更多的升华，以及未来几十年的冰雪形成。
Earth system models are valuable tools for understanding how the Arctic snow‐ice system and the feedbacks therein may respond to a warming climate. In this analysis, we investigate snow on Arctic sea ice to better understand how snow conditions may change under different forcing scenarios. First, we use in situ, airborne, and satellite observations to assess the realism of the Community Earth System Model (CESM) in simulating snow on Arctic sea ice. CESM versions one and two are evaluated, with V1 being the Large Ensemble experiment (CESM1‐LE) and V2 being configured with low‐ and high‐top atmospheric components. The assessment shows CESM2 underestimates snow depth and produces overly uniform snow distributions, whereas CESM1‐LE produces a highly variable, excessively‐thick snow cover. Observations indicate that snow in CESM2 accumulates too slowly in autumn, too quickly in winter‐spring, and melts too soon and rapidly in late spring. The 1950–2050 trends in annual mean snow depths are markedly smaller in CESM2 (−0.8 cm decade−1) than in CESM1‐LE (−3.6 cm decade−1) due to CESM2 having less snow overall. A perennial, thick sea‐ice cover, cool summers, and excessive summer snowfall facilitate a thicker, longer‐lasting snow cover in CESM1‐LE. Under the SSP5‐8.5 forcing scenario, CESM2 shows that, compared to present‐day, snow on Arctic sea ice will: (1) undergo enhanced, earlier spring melt, (2) accumulate less in summer‐autumn, (3) sublimate more, and (4) facilitate marginally more snow‐ice formation. CESM2 also reveals that summers with snow‐free ice can occur ∼30–60 years before an ice‐free central Arctic, which may promote faster sea‐ice melt. CESM2 (CESM1‐LE) snow depths on Arctic sea ice are thinner (thicker) than observed depths The 1950–2050 trends in annual mean snow depth on Arctic sea ice are −0.8 and −3.6 cm decade−1 in CESM2 and CESM1‐LE, respectively CESM2 shows enhanced earlier snowmelt, less snow accumulation, more sublimation, and slightly more snow‐ice formation in future decades