2024 Investiture Information

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PhD Thesis Proposal: Ian Raphael



10:00am - 12:00pm ET

Rm 232, Cummings Hall (Jackson Conf Rm)/Online

Optional ZOOM LINK

"How’s it growing? Tools for observing snow and sea ice in a changing Arctic Ocean"


September Arctic sea ice extent has decreased by roughly 50% percent in the 45 years since satellite observations began. The Arctic Ocean may experience ice-free summers within the next decade, with implications for ecological habitat, resource extraction, geopolitics, and local and global climate change, among many other issues. In order to predict Arctic sea ice change in the future, we need to understand its behavior in the present. In situ sea ice mass balance measurements (snow depth, ice growth, surface melt, and bottom melt) are essential for understanding the processes driving rapid changes in the ice pack, and for validating remote sensing measurements and climate models.

In this proposal, I will share sea ice mass balance results from the 2019–2020 MOSAiC expedition in the central Arctic, and highlight significant changes in sea ice growth and melt processes over the past several decades. These results indicate that snow depth and its heterogeneity are increasingly powerful controls on winter ice growth in this younger, thinner ice pack. Yet, we lack the precise, spatially dense measurements of snow depth necessary to fully understand and model the role of snow in the Arctic sea ice system. I will share the development of a low-cost, autonomous snow observation system that meets this need, and propose work to improve the system for community distribution. While this system is a leap forward in low-cost, widespread snow observation, budget and resource constraints continue to limit the scope of autonomous and crewed snow sampling efforts. I will propose work towards determining the optimal arrangement of sampling locations that minimizes sampling cost while achieving adequate results.

Thesis Committee

  • Professor Don Perovich (chair)
  • Professor Chris Polashenski (Thayer/USACE-CRREL)
  • Professor Robert Hawley (Earth Sciences)
  • Dr. Marcel Nicolaus (Alfred Wegener Institute, Bremerhaven, Germany)


For more information, contact Thayer Registrar at thayer.registrar@dartmouth.edu.