Estimated heat budget fluxes during summer melt of Arctic first year sea ice offshore of Utqiagvik (formerly Barrow), Alaska, 2001-2018

Melt ponds on summer Arctic sea ice control surface albedo, governing energy and mass balance of the ice. The date ponds first form has been connected to interannual variations in ice retreat. Here we evaluate the surface energy balance that governs this critical pond formation date. A three-dimensional sea ice model with resolved melt ponds is used to diagnose pond onset date at a coastal site across years with observed surface fluxes but incomplete pond observations. Results show that the combined sensible and latent heat flux is the best predictor of pond formation date. This finding supports the hypothesis that synoptic weather events transporting warm, moist air into the Arctic are key to initiating pond formation, triggering albedo feedbacks, and, by extension, ice retreat. Changes in timing and frequency of spring warm air incursions may have significant implications on the ice cover and provide predictive power over seasonal ice retreat. This analysis is presented in Skyllingstad and Polashenski (2018) with data contained in this archive.

北极夏季海冰表面的融池（melt ponds）调控地表反照率（surface albedo），进而决定海冰的能量与质量平衡。融池首次形成的时间，与海冰消退的年际变率紧密相关。本研究针对支配这一关键融池形成时间的地表能量平衡（surface energy balance）开展评估。我们采用一款可解析融池过程的三维海冰模式（three-dimensional sea ice model），针对某沿岸站点，在拥有观测地表通量（surface fluxes）但融池观测资料不完备的多年时段内，诊断融池的起始形成时间。研究结果显示，感热通量与潜热通量的总和是融池形成时间的最优预测因子。这一发现支持了如下假说：将暖湿空气输送至北极的天气尺度天气事件（synoptic weather events），是启动融池形成、触发反照率反馈（albedo feedbacks），并进而推动海冰消退的核心驱动因素。春季暖空气侵入事件（spring warm air incursions）的发生时间与频率变化，可能对海冰覆盖（ice cover）产生显著影响，并可为季节性海冰消退提供预测依据。本分析成果已发表于Skyllingstad与Polashenski（2018），相关数据集收录于本档案库中。