Modeling ocean dynamics in ice-shelf rifts.
Abstract
Ice-shelf break-up is thought to be driven by a combination of various
environmental factors that can be classified as oceanographic,
glaciological and atmospheric. These contribute to different phases of
the ice damaging process. However, physical processes driving ice-shelf
collapse and rift propagation are still poorly understood. A few studies
have suggested that ice-shelf rifting can be highly influenced by the
rift’s infill. In particular, ice melange, a heterogeneous mixture of
sea ice, marine ice, and trapped icebergs, is thought to stabilize rift
evolution, potentially slowing or halting rift growth. In this study, we
investigate ocean dynamics associated with rifts in ice-shelves using
the Massachusetts Institute of Technology ocean general circulation
model. Our goal is to estimate the effects of rifts on ice-shelf melting
and freezing processes and in turn on sub-ice shelf circulation.
Enhanced (reduced) melting/freezing rates induced by ice-shelf rifts
affect the physical properties of the volume confined between rift’s
flanks. Here, we examine key hydrographic conditions on sensitivities to
the cracked ice-shelf basal environment in an idealized set-up. We find
that basal fractures modify the thermohaline circulation by accumulation
of cold and fresh water in the rift’s open volume, which potentially is
a prerequisite for ice melange formation. An improved representation of
ice-ocean interactions below a fractured ice-shelf is a step toward a
better understanding of rifting processes and, on a larger scale, of
ice-shelves collapse. To further study this, we use a more realistic
regional set-up of Larsen C in the Antarctic Peninsula.