In:
Geoscientific Model Development, Copernicus GmbH, Vol. 11, No. 4 ( 2018-04-10), p. 1257-1292
Kurzfassung:
Abstract. An increasing number of Southern Ocean models now include Antarctic ice-shelf
cavities, and simulate thermodynamics at the ice-shelf/ocean interface. This
adds another level of complexity to Southern Ocean simulations, as ice
shelves interact directly with the ocean and indirectly with sea ice. Here,
we present the first model intercomparison and evaluation of present-day
ocean/sea-ice/ice-shelf interactions, as simulated by two models: a
circumpolar Antarctic configuration of MetROMS (ROMS: Regional Ocean
Modelling System coupled to CICE: Community Ice CodE) and the global model
FESOM (Finite Element Sea-ice Ocean Model), where the latter is run at two
different levels of horizontal resolution. From a circumpolar Antarctic
perspective, we compare and evaluate simulated ice-shelf basal melting and
sub-ice-shelf circulation, as well as sea-ice properties and Southern Ocean
water mass characteristics as they influence the sub-ice-shelf processes.
Despite their differing numerical methods, the two models produce broadly
similar results and share similar biases in many cases. Both models reproduce
many key features of observations but struggle to reproduce others, such as
the high melt rates observed in the small warm-cavity ice shelves of the
Amundsen and Bellingshausen seas. Several
differences in model design show a particular influence on the simulations.
For example, FESOM's greater topographic smoothing can alter the geometry of
some ice-shelf cavities enough to affect their melt rates; this improves at
higher resolution, since less smoothing is required. In the interior Southern
Ocean, the vertical coordinate system affects the degree of water mass
erosion due to spurious diapycnal mixing, with MetROMS' terrain-following
coordinate leading to more erosion than FESOM's z coordinate. Finally,
increased horizontal resolution in FESOM leads to higher basal melt rates for
small ice shelves, through a combination of stronger circulation and
small-scale intrusions of warm water from offshore.
Materialart:
Online-Ressource
ISSN:
1991-9603
DOI:
10.5194/gmd-11-1257-2018
Sprache:
Englisch
Verlag:
Copernicus GmbH
Publikationsdatum:
2018
ZDB Id:
2456725-5
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