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About Me

I am an oceanographer and climate scientist. My research is concerned with understanding how climate-relevant tracers, such as heat and carbon dioxide, are taken up by, stored within, and transported around the ocean. The uptake, transport and storage of these tracers is achieved by a combination of atmosphere-ocean exchange processes, the large-scale ocean circulation, turbulent ocean dynamics, and biogeochemical processes. I use a host of tools in my research, including large-scale numerical simulations, process models, theoretical ideas, trajectory analysis, and ocean observations. I did my PhD in the Department of Earth Sciences at the University of Oxford, where I worked with Helen Johnson and David Marshall. In September 2018 I started as a post-doc at Princeton University, working with Jorge Sarmiento and Steve Griffies as part of the SOCCOM project.



Research

ventilation location of north atlantic deep water

Ocean ventilation

Ventilation is the process by which water from the surface ocean is moved into and around its interior. It is a primary mechanism by which tracers such as carbon dioxide are taken out of contact with the atmosphere. I have focussed in particular on showing the difference between ventilation and dense water formation; processes that are often conflated. See MacGilchrist et al. (2020) JClim, MacGilchrist et al. (2019) Science Advances, and Naveira Garabato et al. (2018) Phil. Trans. Roy. Soc.

polar southern ocean carbon schematic

Carbon cycling in the high-latitude oceans

The high-latitude oceans play a disproportionately important role in the uptake and deep-ocean sequestration of carbon dioxide. I have conducted observation-based budget analyses of the carbon system in the Artic Ocean and the subpolar Southern Ocean. See MacGilchrist et al. (2019) Science Advances, Naveira Garabato et al. (2018) Phil. Trans. Roy. Soc., and MacGilchrist et al. (2014) DSR

chaotic ventilation pathways

Dynamical systems in oceanography

The turbulent ocean circulation bears many similarities to nonlinear dynamical systems. Analogies and ideas from this discipline has fostered understanding of many nonlinear ocean processes. I have used such understanding to investigate the role of turbulence in setting the distribution of tracers in the ocean interior. See MacGilchrist et al. (2017) JGR

phytoplankton carbon and temperature in ESM4

Watermass transformation

Conceiving of the ocean as distinct regions defined by certain properties (commonly temperature, salinity and/or density), we can transform the circulation and biogeochemical dynamics into a coordinate system that is (a) easier to constrain, and (b) arguably more aligned with its fundamental properties of the system (compared to traditional latitude-longitude-depth coordinates). I am exploring the capacity of this framework to lend insight into fundamental questions in biogeochemical dynamics and ocean circulation .

Publications

Pre-publication

Yan, K. et al. (in prep) Rapid onset of labour productivity reduction due to heat stress in the 21st century, intended submission to Nature Communications.

MacGilchrist, G.A. et al. (in prep) Evaluating the biological carbon pump in a watermass transformation framework, intended submission to Global Biogeochemical Cycles.

MacGilchrist, G.A. et al. (in prep) Decadal variability of the Southern Ocean overturning circulation, intended submission to Science Advances.

2020

MacGilchrist, G.A. et al. (2020) Locations and mechanisms of ocean ventilation in the high-latitude North Atlantic in an eddy-permitting ocean model, in press at Journal of Climate.

2019

MacGilchrist, G.A. et al. (2019) Reframing the carbon cycle of the subpolar Southern Ocean, Science Advances, 5(8), eaav6410. URL

2018

van Sebille, E. et al. (2018) Lagrangian ocean analysis: Fundamentals and practices, Ocean Modelling, 121: 49-75. PDF

2017

Naveira Garabato, A.C., MacGilchrist, G.A. et al. (2017) High latitude ocean ventilation and its role in Earth’s climate transitions, Philosophical Transactions of the Royal Society A, 375: 20160324. PDF

MacGilchrist, G.A. et al. (2017) Characterizing the chaotic nature of ocean ventilation. Journal of Geophysical Research: Oceans, 122: 7577-7594. PDF

2014

MacGilchrist, G.A. et al. (2014) Effect of enhanced pCO2 levels on the production of dissolved inorganic carbon and transparent exopolymer particles in short term bioassay experiments. Biogeosciences, 11: 3695-3706. PDF

MacGilchrist, G.A. et al. (2014) The Arctic Ocean carbon sink. Deep Sea Research I, 86: 39-55. PDF

Contact Me

Atmospheric and Oceanic Sciences

Princeton University

Princeton, NJ, U.S.A.

graemem@princeton.edu