The focus of my PhD was developing a numerical coupled general circulation model to test the importance of ocean basin geometry on ocean circulation and climate. In other words, with the help of some brilliant people, I modified a computer program that models the physics of the ocean and sea-ice, made some custom coastline shapes, and tacked it onto another computer program that models the physics of the atmosphere and the land. We made different continents to try to better understand how certain features - like the narrow width of the Atlantic compared to the Pacific, the curve of the Eastern North American seaboard, the horn of Africa - change the way the ocean moves water, heat, salt, and other nutrients around the world. We learned that widening the Atlantic ocean can result in a stronger circulation in an ocean-only model. However, when we added in a dynamic atmosphere, the model placed deep water formation in the North Pacific Ocean, when in the real world, these physics occur in the North Atlantic. Then, when we moved the northern boundary of the Pacific Ocean farther south, the deep sinking switched over to the Atlantic. We also explored ways in which heat is more effectively transported by the ocean when there are continents that extend farther towards the poles compared to when there are no continents or when they are more concentrated in the low latitudes. Additionally, we see that the heat transport in the atmosphere is almost all accomplished by evaporation and subsequent condensation of water. If you’d like to read more, my dissertation is linked here.

If you’re interested, feel free to take a look at my academic CV.

Laguë, M. M., Quetin, G. R., Ragen, S., & Boos, W. R. (2023). Continental configuration controls the base-state water vapor greenhouse effect: lessons from half-land, half-water planets. Climate Dynamics. Link. PDF

Fajber, R., Donohoe, A., Ragen, S., Armour, K. C., & Kushner, P. J. (2023). Atmospheric heat transport is governed by meridional gradients in surface evaporation in modern-day earth-like climates. PNAS, 120(25). Link. PDF

Roach, L. A., Blanchard‐Wrigglesworth, E., Ragen, S., Cheng, W., Armour, K. C., & Bitz, C. M. (2022). The impact of winds on AMOC in a fully‐coupled climate model. Geophysical Research Letters, e2022GL101203. Link. PDF

Ragen, S., Armour, K. C., Thompson, L., Shao, A., & Darr, D. (2022). The Role of Atlantic Basin Geometry in Meridional Overturning Circulation. Journal of Physical Oceanography, 52, 475-492. Link. PDF

Laguë, M. M., Pietschnig, M., Ragen, S., Smith, T. A., & Battisti, D. S. (2020). Terrestrial evaporation and global climate: lessons from Northland, a planet with a hemispheric continent. Journal of Climate, 1-64. Link. PDF

Ragen, S., Pradal, M. A., & Gnanadesikan, A. (2020). The Impact of Parameterized Lateral Mixing on the Antarctic Circumpolar Current in a Coupled Climate Model. Journal of Physical Oceanography, 50(4), 965-982. Link. PDF