The Whole Antarctic Ocean Model (WAOM v1.0): Development and Evaluation

Abstract

Abstract. The Regional Ocean Modeling System (ROMS), including an ice shelf component, has been applied on a circum-Antarctic domain to derive estimates of ice shelf basal melting. Significant improvements made compared to previous models of this scale are the inclusion of tides and a horizontal spatial resolution of 2 km, which is sufficient to resolve onshelf heat transport by bathymetric troughs and eddy scale circulation. We run the model with ocean-atmosphere-sea ice conditions from the year 2007, to represent nominal present day climate. We force the ocean surface with buoyancy fluxes derived from sea ice concentration observations and wind stress from ERA-Interim atmospheric reanalysis. At the northern boundaries ocean conditions are derived from the ECCO2 reanalysis and tides are incorporated as sea surface height and barotropic currents. The accuracy of tidal height signals close to the coast is comparable to those simulated from widely-used barotropic tide models, while off-shelf hydrography agrees well with the Southern Ocean State Estimate (SOSE) model. On the shelf, most details of ice shelf-ocean interaction are consistent with results from regional modelling and observational studies, although a paucity of observational data (particularly taken during 2007) prohibits a full verification. We conclude that our improved model is well suited to derive a new estimate of present day Antarctic ice shelf melting at high resolution and is able to quantify its sensitivity to tides.

Antarctic Ice Shelves Lose Most of Their Mass From Shallow Depths

“…-3-non-peer reviewed preprint A cold bias under some of the warm water ice shelves has been previously reported (Richter et al, 2020). Affected ice shelves are, e.g.…”

“…We analyse a prediction of Antarctic ice shelf melting during 2007 derived with the Whole Antarctic Ocean Model (WAOM v1.0). The simulation and its evaluation is described in detail elsewhere (Richter et al, 2020), here we outline only the technical details relevant for this study. Major improvements of WAOM compared to previous largescale models are the inclusion of tides and an eddy resolving resolution.…”

“…A new estimate of Antarctic-wide ice shelf melting at high resolution has recently been derived from an ocean model with improved representations of important physics (Richter et al, 2020). Here we analyse these model results as well as a comparable estimate from satellite studies to quantify the mass loss distribution from different depth ranges and provide Antarctic-wide context for the role of surface water driven melting.…”

Dynamics of Large Pelagic Ice Crystals in an Antarctic Ice Shelf Water Plume Flowing Beneath Land-Fast Sea Ice

“…At the 60 larger regional to global scale the challenges lie more with sea ice production and water mass formation as coupled models seek to combine the ocean, atmosphere and ice structure (e.g. Roach et al, 2018;Richter et al, 2020;Moorman et al, 2020). Uniformly these studies identify the need for more observations both at the process, and monitoring, scales.…”

“…Following this water north, a number of studies have concluded that the ice shelf water from the Ross/McMurdo system persists for a hundred or more km northward (Hughes et al, 2014;Robinson et al, 2014). Richter et al (2020) state that ice shelf-sea ice-ocean connections remain the major outstanding challenge in models operating at the continental and global scale. Injection of the range of processes 425 described here into modelling approaches that typically resolve scales around 2 km will be a challenge.…”