The ice-covered Southern Ocean around Antarctica is a dynamic region that plays a key role in global climate. It is characterized by substantial spatial and temporal variability in heat, salt, and biogeochemical fluxes.

My research focuses on several processes within this region: air-ice-ocean interactions, offshore polynyas, and ventilation of deep waters (i.e. heat and gas exchange). The primary tools I have used in my research are under-ice hydrographic measurements, remote sensing, and atmospheric reanalysis.

Offshore polynyas in the Weddell Sea

2017 Weddell polynya (credit: NASA Worldview)

  • The periodic appearance of large sea ice openings, known as polynyas, offshore of the Antarctic coast has been an enduring mystery in polar oceanography. In Campbell et al. (2019) in Nature (see also Swart et al. 2018 in BAMS), we try to explain why polynyas form near the Maud Rise seamount in the Weddell Sea in some years but not others. Two SOCCOM Project biogeochemical profiling floats were present during the unexpected 2016 and 2017 polynya events and collected measurements that suggest reduced haline stratification preconditioned the appearance of the polynyas, which were sustained by deep overturning. Note that these are the first in situ observations of this phenomenon in an offshore polynya. Using these and a variety of other data sources, we show that storms were the proximal trigger of the recent openings. Both increased storminess and reduced upper-ocean stability in the eastern Weddell Sea region are favored by positive fluctuations in the Southern Annular Mode (SAM), which we identify as a common factor in the 2016-2017 events as well as past polynyas near Maud Rise. The long-term increasing trend in SAM raises questions of whether this effect will win out over the simultaneous trend toward a more stratified Southern Ocean, which would tend to limit polynya occurrences.

  • The Weddell Sea is more susceptible to destabilization and polynya formation than other sectors of the Southern Ocean. In Wilson et al. (2019) in JPO, we highlight the regional variability in ice–ocean feedbacks within the seasonal ice zone, which affect the growth of sea ice and release of heat during winter. Idealized 1-D model simulations show that, to a large extent, ice–ocean feedbacks also determine the sensitivity of the upper ocean–sea ice system to strong wind-mixing events.

Ongoing and future work

The following are several projects that I have been actively working on (or just thinking about!). Of course, not all of these will be completed in the next few years of my PhD. Contact me if any of these sound interesting or if you are engaged in similar research. I would be excited to collaborate!

  • Reconstruction of Antarctic sea ice formation and melt from ocean salinity
  • Impact of storms on the upper ocean under sea ice
  • Effects of Taylor column dynamics on mixing, deep ventilation, and biogeochemistry
  • Changes in Southern Hemisphere subpolar gyre strength under anthropogenic forcing
  • Pathways of Antarctic Bottom Water formation during glacial climates
  • Influence of offshore deep convection on records from Ocean Drilling Project (ODP) Sites 689 and 690 at Maud Rise