Iceberg meltwater estimates for the Southern Ocean including giant icebergs

Thomas.Rackow [ at ]


Poster Code: Fri_214_OS-4_1872 Iceberg calving is an important component of the mass balance of the Antarctic Ice Sheet, with recent estimates of ∼1300 Gt/year being on the same level as ice shelf basal melting. The iceberg mass is usually assumed to be evenly divided between giant icebergs (length >10km) and smaller ones, with some estimates even preferring giant icebergs (as high as 89%). However, it is still unclear what the best way is to include giant icebergs into model estimates of the Southern Ocean freshwater cycle. Here, we estimate the iceberg meltwater input from a simulation of present-day Antarctic icebergs and compare it to the balance between precipitation and evaporation (P-E) and sea-ice production rates. For the first time, an iceberg model is initialized with a set of nearly 7000 satellite-observed iceberg positions and sizes. It reproduces typical drift patterns for a large spectrum of size classes, including typical routes taken by giant icebergs. The associated meltwater input is generally on the order of 5–20% of the P-E balance in large areas of the Southern Ocean, especially around the coast, with local maxima even exceeding P-E. Furthermore, the freshwater flux from melting icebergs is on the order of 5–20% of coastal sea ice production rates and, thus, partly compensates the effect of brine rejection in the annual mean. Iceberg melting is also the largest vector of freshwater input from frozen ice along (and northward of) the sea-ice edge.

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POLAR2018 Open Science Conference OSC, 19 Jun 2018 - 23 Jun 2018, Davos, Switzerland.
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Rackow, T. , Wesche, C. , Timmermann, R. , Hellmer, H. , Juricke, S. and Jung, T. (2018): Iceberg meltwater estimates for the Southern Ocean including giant icebergs , POLAR2018 Open Science Conference OSC, Davos, Switzerland, 19 June 2018 - 23 June 2018 .

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