A study of wave refraction in a marginal ice zone: Frazil-pancake ice

Abstract

Theoretical estimates based on both offline calculation and an online model are made to study the wavenumber variations during wave refraction in a marginal ice zone (MIZ). Analysis of in situ observations from the MIZ of the Arctic Ocean confirms the conclusion drawn based on theoretical estimates as well as the simulation ability of our new model to describe wave evolution in the MIZ. In wave refraction, variation of wavenumber in magnitude is determined by the incident wavenumber and the ice mass. A larger incident wavenumber or a larger ice mass leads to a larger variation of wavenumber in magnitude, though during refraction, the variation of wavenumber in magnitude is more sensitive to the incident wavenumber because it is proportional to the cube of the incident wavenumber, while it is linearly proportional to the ice mass. On the other hand, both the angle of refraction and the deflection are determined by the angle of incidence, the incident wavenumber and the ice mass. A larger angle of incidence, a shorter wave or larger ice mass results in a larger angle of refraction and a larger deflection. All these conclusions are supported by offline calculations, an online model and in situ observations. The online model also suggests that the instrument should be kept at a distance from the ice edge to obtain more general information of the open ocean.