Scale-dependent air-sea exchange in the polar oceans: floe-floe and
floe-flow coupling in the generation of ice-ocean boundary layer
turbulence
Abstract
Sea ice is a heterogeneous, evolving mosaic comprised of many individual
floes, which vary in spatial scales from meters to tens of kilometers.
Both the internal dynamics of the floe mosaic (floe-floe interactions),
and the evolution of floes under ocean and atmospheric forcing
(floe-flow interactions), determine the exchange of heat, momentum, and
tracers between the lower atmosphere and upper polar oceans. Climate
models do not represent either of these highly variable interactions. We
use a novel, high-resolution, discrete element modelling framework to
examine the production of ice-ocean boundary layer (IOBL) turbulence
within a domain approximately the size of a climate model grid. We show
floe-scale effects cause a marked increase in IOBL turbulent production
relative to continuum model approaches, and provide a method of
representing that turbulence using bulk parameters related to the
spatial variance of the ice and ocean: the floe size distribution and
the ocean kinetic energy spectrum.