Speaker: Peter Sutherland (IFREMER)
Title: Surface waves and sea ice in the Arctic; changing dynamics in a changing ocean.
The Arctic is changing: since the beginning of the satellite record, summer sea ice extent has decreased by approximately 3 million square kilometers. New "seasonal seas" are now present nearly every summer, and the Arctic Ocean is transitioning from a quiescent ice-covered basin to a more energetic ocean dominated by free-surface phenomena. One of the more visible aspects of this transition is the emerging presence of surface waves. Waves are a key control on the exchanges of energy, momentum, and mass between the atmosphere and the ocean. Additionally, in high latitudes, waves are known to break up ice over large areas and have important effects on ice formation. Consequently, the emergence of surface waves in the Arctic has the potential to create feedback mechanisms that could either increase the rate of ice melt or help stabilize the ice pack. However, our current understanding of the interactions between waves and sea ice is rather limited, the largest obstacle being the general lack of observations against which theories and models can be tested. This seminar will discuss recent work designed to understand these processes using field and remote sensing observations. These efforts have spanned a range of scales and techniques, from small-scale in-situ process studies in the St. Lawrence Estuary, to airborne remote sensing in the Arctic Ocean, to satellite-borne synthetic aperture radar measurements. Two main areas will be discussed: 1) The modification of waves by the presence of sea ice; this will focus on the mechanisms of wave attenuation and their dependence on ice conditions - notably ice thickness and ice floe size. 2) The modification of ice by waves, specifically a mechanism by which wave stress can set ice thickness. The general applicability of the results, their implications, and planned future work will be discussed.