The influence of ocean circulation on local biogeochemistry and melting tidewater glaciers in northern Baffin Bay

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"NERC : Emma Louise White : NE/S007512/1"Climate change has disproportionately affected the Arctic, and the recent Sixth Assessment Report from the IPCC states that the Arctic is highly likely to continue warming at twice the average global rate. Outside of Greenland and Antarctica, the melting of glacial ice in the Canadian Arctic Archipelago has made the largest contribution to recent sea-level rise. This makes the Canadian Arctic Archipelago a critical region to understand, yet it remains understudied due to its remoteness. There are over 300 tidewater glaciers in the Canadian Arctic Archipelago which are in contact with the ocean. To understand the recent melting and ice mass loss from these glaciers, it is highly important to understand how the ocean influences them. This work will focus on an area of the Canadian Arctic Archipelago called northern Baffin Bay, which is an important area to understand due to the presence of the two fastest retreating tidewater glaciers in the region. The North Water Polynya is also present in northern Baffin Bay, which is a large area of open water which remains free of sea ice. There is very high primary productivity in this area, and it sustains a large diversity of marine life which has led to it being classified as an Ecologically and Biologically Significant Area by Fisheries and Oceans Canada. The aim of this work is to improve understanding of ocean circulation in northern Baffin Bay, and the influence that ocean circulation has on melting tidewater glaciers in the region as well as local nutrient distributions.This study will use data from an ocean circulation model, along with a software called ARIANE, to release modelled particles in the vicinity of tidewater glaciers in northern Baffin Bay. These modelled virtual particles will be traced backwards in time, providing information on the origin of the particles and pathways that water follows as it enters the region. Once we have identified these pathways, we will then consider the temperature of water travelling along these pathways, and where warmer water is able to access. In particular, we will assess if warmer, deeper water originating from the Atlantic Ocean is able to reach the tidewater glaciers in the region. This is important to understand, as warmer water is able to drive more melting of glaciers, so it is crucial to understand if warmer Atlantic Water is in contact with tidewater glaciers. We will also consider the nutrients that are supplied to the region by the ocean circulation pathways identified. Phytoplankton are photosynthetic organisms that form the base of many marine food chains, similar to plants. They are found in the surface ocean where there is light availability, and they also require nutrients to grow. Ocean circulation pathways can provide these nutrients to the surface ocean, and it is therefore an important control on primary productivity. Tidewater glaciers can influence the supply of nutrients to the surface ocean because where the glaciers are in contact with the ocean, the freshwater buoyancy input from them can lead to upwelling of deeper, nutrient rich waters towards the surface, where these nutrients can stimulate phytoplankton growth. In summary, the main aims of this work will be to 1) identify pathways of water transport to northern Baffin Bay to improve understanding of ocean circulation in the region; 2) assess the influence of ocean circulation and pathways of warmer water on melting tidewater glaciers; and 3) assess the impact that ocean circulation has on nutrient distributions, and therefore primary productivity.