My science research centers on ocean circulation in the seas around Greenland and the role these currents have in regulating our planet’s climate. The Nordic seas to the east of Greenland are a unique confluence or waters that have travelled over vast distances; Warm salty tropic waters flow in to the ocean from the south, some of this continues on into the Arctic and the rest circulates in the Northern basins; Cold fresh meltwater streams out of the Arctic, spreading out into the nordic seas and progressing on down in to the North Atlantic; Dense water is also formed through intense cooling from Atlantic storms and exits at depth through channels in the ridge connecting Scotland with Greenland, cascading 100s of meters down in to the deep ocean to return towards the equator. In undertaking these movements, these waters transport huge amounts of heat from the Equator towards the pole and help regulate the climate of our planet.
My research is about looking at the particular branches of this global system and asking how they work locally. How do the waters entering the Nordic Seas interact with one another? where do they flow and why? how do winds act to drive them around the planet? and how might they be influencing and be influenced by a changing climate? I work mainly with in-situ observational data and I’m motivated by how much there is to find out in this historically data sparse region. Here are a few highlights of my work, see also my publications.
Denmark Strait Overflow
I work with data from upstream of theDenmark Strait Overflow – a major cascade of dense water out of the nordic seas through the channel between Greenland and Iceland. Here, I investigate the sources of the water that enters the overflow, how this is partitioned and what this means for how stable the overflow might be in the future.
As part of the project I was involved in the deployment and collection of this data aboard two WHOI expeditions in the summers of 2011 and 2012. I also documented both trips in video, one set of which was recently published in the book “To the Denmark Strait”.
Project Collaborators: Bob Pickart, Andreas Macrander, Kjetil Vage, Svein Osthose, Steingrimmur Jonsson, Hedinn Valdermissen, Laura de Steur, Lisbeth Havik.
East Greenland Coastal Current
The cold, fresh polar water that is ejected from the Arctic due to sea ice melt flows southward towards the Atlantic along the east coast of Greenland. We need to know how much water flows southward in order to understand how much of the warm water can flow northward and in order to appreciate how an increase in fresh water production could affect dense water formation. Doing so is difficult though; much of the Greenland shelf is ice choked and we have no real indication of how representative snap-shot boat measurements are of the current.
I am trying to improve our understanding of the variability in this current by analyzing some of the first time series data from the inner Greenland shelf underneath the sea ice. The data shows how the current changes its character over the course of four years. It looks like winds are an important driver of this variability as well as eddies and meanders in the current. If we can understand how this current moves we can better pin down its role in the climate stability of the Northern Oceans.
Project Collaborators: Fiamma Straneo, Dave Sutherland.
Greenland Fjord Circulation
I am working with a data set from Upernavik Fjord in northwest Greenland. Like many of Greenland’s outlet glacial fjords, Upernavik is full of warm Atlantic water thats hidden below the icy-cold surface layer. We think that this water might aid the melting of the Greenland glaciers that pour into the fjords. This could potentially destabilize the icecap and provide a mechanism in which a warming Atlantic ocean could melt the Greenland Icecap. We don’t know much about these waters though so I’m taking a look at the first hydrographic data to be collected from this remote fjord.
Project collaborators: Fiamma Straneo, Camilla Andreson
East Greenland Spill Jet
Dense water makes it through the Denmark Strait and flows into the main overflow plume that descends rapidly and transports huge amounts of water towards the equator. Recent studies, though have found that some dense water passes through the Denmark Strait on the shelf and spill off down stream to form a new branch of the overturning circulation. Using data from the shelf edge we were able to show that this is happen year round and is forced by a combination of fast moving eddies at the shelfbreak and through the driving of strong wind events which flush the shelf through downwelling and the excitation of coastally trapped waves
Project collaborators: Bob Pickart, Ian Renfrew
Greenland Barrier winds
Greenland is massive. Towering 3000 m above sea level it is a major obstacle to atmospheric flow in the North Atlantic and produces a range of topographically enhanced wind jets that make the sea around Greenland some of the stormiest on the planet. Barrier winds are one type of event produced when air is forced towards the southeast coast of Greenland. The air is unable to climb the immense barrier and as a result it is channeled along the coast in intense wind jets that are a weekly feature in the winter time. I undertook my PhD studying these winds, how they form and what their impact is on the ocean. We were able to show that these wind events occur at a range of locations, forced by large synoptic storms and can have a significant impact on the ocean, both in driving heat fluxes and inputing momentum to coastal currents.
Project collaborators: Ian Renfrew, Nina Petersen, Kent Moore