The Energetics of Extensive Melt Water Flooding of Level Arctic Sea Ice

During the spring-to-summer transition, the snow cover on Arctic sea ice melts and meltwater pools on the surface to form melt ponds; however, the timing and extent of the ponding varies between years. In Dease Strait (Nunavut), this transition was particularly dramatic in 2014 when on 18 June meltwater had flooded >95% of the surface. In this study, continuous surface energy balance measurements throughout the transition highlight how the timing of transient weather events influenced seasonal shifts in distinct ice melt stages. The keys to the extensive flooding were 1) the level ice cover, 2) a strong low-pressure system on 24 May that deposited ~10 cm of snow, and 3) freeze-thaw cycling and a subsequent return to sub-zero air temperatures on 30 May that led to superimposed and interposed ice formation. Without these, melt ponds would have likely developed within days from an initial melt onset on 28 May. After a 2-week delay, snow-melt resumed and lead to near-complete flooding of the surface for four days. The albedo of the flooded ice remained high (0.35-0.40), as a result of the bubble-laden superimposed ice layer. Once this layer eroded, the albedo over melt ponds decreased to a more typical level (~0.20). Our observations suggest that the formation of superimposed and interposed ice prevented the vertical drainage of meltwater to the ocean. Future challenges remain to measure the presence of these layers and understand their effect on sea ice permeability and pond evolution while sea ice temperatures are near the melting point.

We present a time series of the full surface energy budget of the landfast sea ice cover in Dease Strait, Nunavut (Canada), over the spring to summer transition in 2014.

Time-series of hourly means of vertical temperature in the snow, sea ice, and seawater. This is the metadata template associated with the data files. Contains site locations for atmospheric, ice, snow and seawater data.

在春末夏初的转换期间，北极海冰上的积雪融化，融水在表面积聚形成融水池塘；然而，这种积聚的时间与程度在不同年份中存在差异。在戴斯海峡（努纳武特地区），2014年的这一转换过程尤为显著，6月18日，融水已覆盖超过95%的表面。在本研究中，对整个转换过程中的连续表面能量平衡测量突显了瞬时天气事件的时间如何影响了季节性变化的特定冰融阶段。导致广泛洪水的原因包括：1）冰层水平，2）5月24日的一次强烈低压系统，该系统沉积了约10厘米的雪，3）5月30日出现的冻融循环以及随后的气温降至零下，这导致了叠加和交错冰的形成。如果没有这些因素，融水池塘可能从5月28日的最初融化开始几天内就形成了。经过两周的延迟后，雪融重新开始，并在接下来的四天内导致表面几乎完全被洪水淹没。洪水冰面的反照率保持较高（0.35-0.40），这是由于充满气泡的叠加冰层所致。一旦这一层被侵蚀，融水池塘上的反照率降至更为典型的水平（约0.20）。我们的观察结果表明，叠加和交错冰的形成阻止了融水向海洋的垂直排水。在冰温接近融点时，未来仍需测量这些层的存在，并了解它们对海冰渗透性和池塘演化的影响。

我们呈现了2014年春末夏初期间，加拿大努纳武特地区戴斯海峡（Dease Strait）固定海冰覆盖全表面能量预算的时间序列。

雪、海冰和海水垂直温度的小时均值时间序列。这是与数据文件关联的元数据模板，包含大气、冰、雪和海水数据的位置。