Breaking up is hard to do – Simulating Arctic sea ice break-up in neXtSIM

Jonathan Winfield Rheinlænder (Sea Ice Modelling)
Seminar Date: 
20. October 2020 - 11:15 - 11:45
Lecture room, Ground Floor, NERSC

In the last decade, the thickness of Arctic sea ice has declined dramatically with thicker multi-year ice being replaced by thinner first-year ice. As the sea ice thins it becomes more mobile and less dy­namically stable, thereby making the Arctic ice cover increasingly vulnerable to oceanic and atmo­spheric forcing (such as Arctic storms). As a consequence, extreme sea ice break-up events have become more frequent in the last 5-7 years, particularly in the Beaufort Sea region. One of the largest break-up events ever recorded occurred in the 2013 winter season off the northern coast of Alaska, which was likely due to a combination of in­tense winds and anomalously thin sea ice following the 2012 record sea ice minimum.

Meanwhile, the ability to simulate such events is lacking in the current generation of climate mod­els, and as a result little is known about how and why they occur as well as their impact on the long-term evolution of Arctic sea ice volume.

In this seminar talk, I will present some early results from the neXtSIM model where we attempt to simulate the 2013 break-up event in the Beaufort Sea. Using this as a case study, we will be investigating the main drivers of sea ice fracturing and lead formation through a series of sensitivity experiments. In particular, we will focus on the dependency of ice fracturing on (1) the initial thickness distribution, (2) oceanic forcing and (3) atmospheric resolution and its effect on storm intensity. Finally, we will evaluate the impact of sea ice break-up on ocean-atmosphere heat fluxes and implications for the large-scale Arctic sea ice mass budget.