Investigating the impact of glacial meltwater plumes in Greenland's Fjords

全球气候变化将不成比例地影响极地地区。大气和海洋温度变暖将增加极地地区的冰融化，这将导致全球海平面上升。格陵兰冰盖在格陵兰湾与海洋相遇，在那里温暖的海水可以融化终止海洋的冰川(潮水冰川)的前部。为了更准确地预测未来海平面上升的速度和数量，我们需要了解海洋性质如何影响格陵兰冰盖的冰流失速度和数量。理解格陵兰峡湾的冰海相互作用也很重要，因为当来自冰川的新鲜、漂浮的融化水进入海洋时，它会改变周围水的温度和盐度。这种新鲜浮水的注入将影响格陵兰峡湾的海洋循环，以及从峡湾输出到大陆架的水的物理性质。理解融化水引起的海洋环流变化很重要，因为海洋环流是一个全球过程，调节着更广泛的气候。当前全球气候模型的局限性之一是，它们假设峡湾海洋的物理性质与大陆架上的海洋相同。然而，观察表明，情况并非如此。这个项目旨在提高我们对格陵兰冰盖在冰下融水羽流中输出的融水如何影响格陵兰峡湾实际海洋性质的理解，方法是：(1)核对格陵兰范围内对峡湾水性质的观测与邻近陆架水性质的对比；(2)对一个成熟的羽流模型进行实验，以了解冰川融化水羽对格陵兰峡湾海水性质的影响程度；(3)利用最先进的全球环流模式MITgCM研究这些羽流的影响如何在整个融化季节和沿峡湾的距离发生变化。

Global climate change will disproportionately affect the polar regions. Warmer atmospheric and ocean temperatures will increase ice melt from polar regions, which will contribute to global sea level rise. The Greenland Ice Sheet meets the ocean in Greenland's fjords, where warm ocean water can melt the front of marine-terminating glaciers ('tidewater glaciers'). To predict the rate and volume of future sea level rise more accurately, we need to understand how ocean properties affect the rate and volume of ice loss from the Greenland Ice Sheet. Ice-ocean interactions in Greenland's fjords are also important to understand because when fresh, buoyant meltwater from the glaciers enters the ocean it changes the temperature and salinity of the surrounding water. This injection of fresh buoyant water will affect ocean circulation in Greenland's Fjords, and the physical properties of water exported onto the shelf from the fjords. Meltwater-induced changes in ocean circulation are important to understand, as ocean circulation is a global process that regulates the wider climate. One of the limitations of current global climate models is that they assume that the physical properties of the ocean in fjords are the same as on the shelf. However, observations show that this is not the case. This project aims to improve our understanding of how meltwater exported from the Greenland Ice sheet in subglacial meltwater plumes affects the physical ocean properties in Greenland's fjords by: (i) collating Greenland-wide observations of fjord water properties vs adjacent shelf water properties; (ii) running experiments on a well-developed plume model to understand the degree to which glacial meltwater plumes are responsible for the modification of ocean water properties in fjords across Greenland; (iii) studying how the effect of these plumes varies throughout the melt season and with distance along the fjord using MITgcm, a state-of-the-art global circulation model.