TRR 181 Special Colloquium "New aspects of waves in ice – observations and idealized modeling"

The TRR 181 special colloquium is held by Johannes Gemmrich (University of Victoria) on June 28, 2 pm at Universität Hamburg, Bundesstr. 53, room 22/23.

Abstract

The reduction of arctic summer ice coverage has prompted a renewed interest in the physics of wave-ice interactions. Progress has been made on the observational, theoretical and modeling aspects of waves in the presence of ice.
This presentation will address our recent observational and theoretical studies of spectral wave properties in the marginal ice zone, in ice covered seas, and the open water Arctic. I present data from high-resolution inverted echosounders in the Arctic. In particular, the shape of the high frequency part of the spectrum and the group structure will be discussed.
Theoretical studies showed that a two-layer fluid supports so-called “class 3” three-wave resonant interaction between surface waves and interfacial waves, all propagating in the same direction. I use a numerical spectral model to map out the parameter range of idealized but realistic oceanic conditions of these three-wave interactions, and track the evolution of the surface and interfacial wave spectra. I find the most prominent effects are the steepening of short surface waves, which results in an increased energy dissipation due to wave breaking, and the generation and growth of interfacial waves, which might contribute to interfacial mixing. This process is likely to be relevant to the evolution of the surface wave field in the increasingly ice-free Arctic where an often shallow, cold and fresh surface layer overlays a saltier and warmer layer, and the generated interfacial waves could contribute to warming of the surface waters.