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Marginal Ice Zone dynamics and wave-ice interactions

As the polar regions experience increasingly warmer surface temperatures and stronger winds, the Marginal Ice Zone (MIZ) has emerged as a critical region of interest. The MIZ refers to the mosaic of loosely consolidated sea ice separating the open ocean from the thick, relatively homogenous pack ice. The MIZ is strongly influenced by surface ocean waves, which can fracture sea ice floes and accelerate melting. However, most climate models treat sea ice as a quasi-continuous medium with no representation of floe-scale dynamics.

Our group is engaged in several observations-based projects that seek to improve our understanding of MIZ dynamics. In collaboration with the Stanford Radio Glaciology group, we are developing new methods to monitor floe-scale dynamics in the Southern Ocean using synthetic aperture radar. Additionally, our group (led by graduate student Lexi Arlen) has deployed surface wave buoys in the Chukchi Sea to quantify wave attenuation in the Arctic MIZ.

idealized channel model

Subpolar gyres and overturning circulation in the Southern Ocean

The Southern Ocean is arguably the central cog in the global ocean overturning circulation. In addition to connecting all the major ocean basins, the Southern Ocean facilitates the upwelling of carbon-rich waters from intermediate depths and the production of the dense bottom water that occupies most of the abyssal ocean. The Antarctic subpolar gyres bridge the regions of deep water upwelling, which mainly occurs within the Antarctic Circumpolar Current (ACC), and bottom water formation, which is formed exclusively along the continental margins of Antarctica. We aim to further our understanding of the dynamical coupling between the ACC, subpolar gyres, and the Antarctic margin.

map of sea surface temperature anomaly

Marine heatwaves and climate variability in the Southern Ocean

We seek to understand processes that modulate Southern Ocean surface temperature and sea ice cover over various time scales. We have a particular interest in the mechanisms that can lead to abrupt and extreme surface warming and the impacts these events have on local ecosystems

 

weddell sea polynya

Open-ocean polynyas and sea ice-ocean feedbacks

A key feature of the sea-ice-covered Southern Ocean is the vertical arrangement of cold, fresh surface water above warmer, saltier deep water. Under certain conditions, warm deep water may get vented to the surface and melt the overlying sea ice cover, creating what is known as an open-ocean polynya. Open-ocean polynyas can support deep convection that releases heat and carbon from the usually sequestered ocean interior. We aim to better characterize the conditions that lead to these events and diagnose their potential to occur in future climates.

glacier-cross-section

Subglacial discharge and seawater intrusions

Marine-terminating glaciers, such as those along the coastline of Greenland, often release meltwater into the ocean via subglacial discharge plumes. The conditions surrounding the genesis of these plumes remain poorly constrained, and little is known about the geometry of subglacial outlets and the extent to which seawater may intrude into them. We are interested in developing theories and models that describe the dynamics of subglacial seawater intrusions and their impact on ice-sheet stability.