Abstract In the stratified water column inside the Ilulissat ice fjord, oceanic mixing processes can promote an upward transport of heat and salt from the subsurface to the surface mixed layer. Our objective was to map the temporal variation of vertical mixing inside the fjord by estimating the diapycnal mixing rates derived from oceanographic data collected during summer research cruises between 2009 and 2017. We applied the Thorpe scale method based on local density inversions. We found enhanced mixing in the deep water at 400 m sill depth inside the fjord, with diapycnal diffusivity reaching a maximum value of 1× 10–3.5 m2 s−1. The strongest mixing rates in 2013, and the weakest during 2016, were mainly due to the Glacier's melting conditions and melange. The highest values of diapycnal diffusivity values occurred during years when low melange concentrations inside the ice fjord increased ventilation, which favored the intrusion of Polar and Irminger waters that perturbed the water structure. These years were also associated with a decrease in diffusive convection processes. Our results give insight into how the intrusion of waters from Disko Bay to the Ilulissat ice fjord may affect the stability of the Jakobshavn Isbrae Glacier.

中文翻译：

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格陵兰伊卢利萨特冰峡湾的年际夏季混合过程

摘要 在伊卢利萨特冰峡湾内的分层水柱中，海洋混合过程可以促进热量和盐分从地下向上输送到地表混合层。我们的目标是通过估计源自 2009 年至 2017 年夏季研究巡航期间收集的海洋学数据的渗透混合率来绘制峡湾内垂直混合的时间变化图。我们应用了基于局部密度反演的索普尺度方法。我们发现峡湾内 400 m 基坑深度的深水中混合增强，渗透率达到最大值 1×10–3.5 m2 s-1。2013 年混合速率最强，2016 年最弱，主要是由于冰川的融化条件和混杂。当冰峡湾内的低混杂物浓度增加通风，有利于扰动水结构的极地和 Irminger 水域的入侵时，渗流扩散率值的最高值出现在年份。这些年也与扩散对流过程的减少有关。我们的研究结果深入了解了从迪斯科湾到伊卢利萨特冰峡湾的海水入侵可能如何影响雅各布港伊斯布雷冰川的稳定性。