Seasonality and timing of sea ice mass balance and heat fluxes in the Arctic transpolar drift during 2019–2020
Seasonality and timing of sea ice mass balance and heat fluxes in the Arctic transpolar drift during 2019–2020
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DOI：
10.1525/elementa.2021.000089
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发表时间：
2022
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通讯作者：
R. Lei;B. Cheng;M. Hoppmann;Fanyi Zhang;Guangyu Zuo;J. Hutchings;Long Lin;Musheng Lan;Hangzhou Wang;J. Regnery;T. Krumpen;J. Haapala;B. Rabe;D. Perovich;M. Nicolaus
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作者：
R. Lei;B. Cheng;M. Hoppmann;Fanyi Zhang;Guangyu Zuo;J. Hutchings;Long Lin;Musheng Lan;Hangzhou Wang;J. Regnery;T. Krumpen;J. Haapala;B. Rabe;D. Perovich;M. Nicolaus
海冰的生长和消解是北极气候系统的关键过程，但综合观测结果非常稀少。我们分析了 2019-2020 年北极气候研究多学科漂流观测站 (MOSAiC) 考察期间部署的 23 个海冰质量平衡浮标 (IMB) 的数据，以研究北极跨极漂移中海冰热力学质量平衡的季节性和时间。数据揭示了冰季的四个阶段：（一）冰基结冰开始，10月中旬至11月； (II) 冰快速增长，12月至3月； (III) 冰生长缓慢，4 月至 5 月； (IV) 六月以后开始融化。冰底生长范围为 0.64 至 1.38 m，速率为 0.004-0.006 m d-1，主要取决于初始冰厚度。与 2012 年 9 月部署在 MOSAiC 设置地点附近的浮标相比，由于 MOSAiC 地点的初始冰厚度相对较薄，冰的总增长量大约是原来的两倍。在两个地点观察到冰从顶部生长，这是由地表洪水和随后的雪冰形成引起的，可能与动态过程有关。到2020年5月2日，积雪的最大深度达到0.25±0.08m，并于2020年6月25日完全融化。2019年6月7日（±10天）冰底融化相对较早，部分原因是MOSAiC浮冰向弗拉姆海峡异常快速的平流。根据冰底热平衡计算，12月至4月海洋热通量为2.8±1.1Wm–2，从5月起逐渐增加，到2020年6月中旬达到10.0±2.6Wm–2。随后，随着冰渗透性的增加，大部分地点形成了冰下融化池。我们的分析为未来与 MOSAiC 及其他相关的研究提供了有关北极海冰质量平衡的重要信息。
Sea ice growth and decay are critical processes in the Arctic climate system, but comprehensive observations are very sparse. We analyzed data from 23 sea ice mass balance buoys (IMBs) deployed during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in 2019–2020 to investigate the seasonality and timing of sea ice thermodynamic mass balance in the Arctic Transpolar Drift. The data reveal four stages of the ice season: (I) onset of ice basal freezing, mid-October to November; (II) rapid ice growth, December–March; (III) slow ice growth, April–May; and (IV) melting, June onward. Ice basal growth ranged from 0.64 to 1.38 m at a rate of 0.004–0.006 m d–1, depending mainly on initial ice thickness. Compared to a buoy deployed close to the MOSAiC setup site in September 2012, total ice growth was about twice as high, due to the relatively thin initial ice thickness at the MOSAiC sites. Ice growth from the top, caused by surface flooding and subsequent snow-ice formation, was observed at two sites and likely linked to dynamic processes. Snow reached a maximum depth of 0.25 ± 0.08 m by May 2, 2020, and had melted completely by June 25, 2020. The relatively early onset of ice basal melt on June 7 (±10 d), 2019, can be partly attributed to the unusually rapid advection of the MOSAiC floes towards Fram Strait. The oceanic heat flux, calculated based on the heat balance at the ice bottom, was 2.8 ± 1.1 W m–2 in December–April, and increased gradually from May onward, reaching 10.0 ± 2.6 W m–2 by mid-June 2020. Subsequently, under-ice melt ponds formed at most sites in connection with increasing ice permeability. Our analysis provides crucial information on the Arctic sea ice mass balance for future studies related to MOSAiC and beyond.