Iceberg trajectory modeling and meltwater injection in the Southern Ocean

Abstract

Abstract. This is the first large-scale modeling study of iceberg trajectories and melt rates in the Southern Ocean. An iceberg model was seeded with climatological iceberg calving rates based on a calculation of the net surface accumulation from each snow catchment area on the Antarctic continent. In most areas, modeled trajectories show good agreement with observed patterns of iceberg motion, though discrepencies in the Weddell Sea have highlighted problems in the ocean general circulation model output used to force the iceberg model. The Coriolis force is found to be important in keeping bergs entrained in the coastal current around Antarctica, and topographic features are important in causing bergs to depart from the coastal regions. The modeled geographic distribution of iceberg meltwater joining the ocean has been calculated and is found in many near-coastal regions to be comparable in magnitude to the excess of precipitation over evaporation (P-E).

Sensitivity of the glacial ocean to Heinrich events from different iceberg sources, as modeled by a coupled atmosphere‐iceberg‐ocean model

“…Also the meltwater pattern does not reproduce a minimum in the Indian Ocean sector of the Southern Ocean. We attribute this to the relatively coarse resolution of our model grid in the Southern Ocean as this is better represented by higher-resolution standalone (uncoupled) iceberg model simulations by Gladstone et al [2001]. In the Northern Hemisphere the greatest impact of the PD icebergs is the melt delivery to Baffin Bay, while there is also significant impact around the whole Greenland coast.…”

“…A similar coupling has recently been performed independently by Jongma et al [2008], who focus on the PD period. The dynamic and thermodynamic iceberg model we use was first introduced by Bigg et al [1997] and modified by Gladstone et al [2001]. It has been used to calculate iceberg trajectories and meltwater fields that are forced by off-line ocean and atmospheric fields of momentum and temperature from GCMs.…”

“…[28] For the Southern Hemisphere we have used climatological iceberg fluxes from Gladstone et al [2001] that are based on PD mass balance calculations for the Antarctic ice sheet. Even though the Antarctic ice sheet has decreased in volume since the LGM, there is evidence from cores taken at various latitudes in the South Atlantic that IRD delivery is at a minimum at periods surrounding the LGM and during the Holocene [e.g., Kanfoush et al, 2000].…”

“…The inclusion of a realistic iceberg model is likely to have a different impact on the MOC response to Heinrich events than the direct release of freshwater at iceberg source locations, as the iceberg trajectories will determine whether the meltwater is gradually released in, or upstream of, the deep convection regions. Icebergs are likely to have an impact on the temperature and freshwater distribution in the ocean, even during a steady state climate, as has been shown to be the case in the present-day (PD) Southern Ocean by Gladstone et al [2001].…”

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

“…Icebergs tend to be formed in large numbers at a limited number of locations and are advected by the prevailing currents in those regions (e.g., Gladstone et al, 2001). Icebergs melt during their movements, imparting fresh waters locally (e.g., K.L.…”