On the Modified Warm Deep Water flow toward the Filchner Ronne Ice Shelf: Observations and Model Results

• Main Authors: Ryan, Svenja, Schröder, Michael, Timmermann, Ralph, Hattermann, Tore, Kanzow, Torsten
• Format: Conference Object
• Language: unknown
• Published: 2018
• Subjects: Antarc*; Antarctic; Filchner Ronne Ice Shelf; Filchner-Ronne Ice Shelf; Ice Shelf; Ronne Ice Shelf; Sea ice; Weddell Sea
• Online Access: https://epic.awi.de/id/eprint/46815/; https://epic.awi.de/id/eprint/46815/1/HE41A_Svenja_Ryan.pdf; https://hdl.handle.net/10013/epic.c6d056de-3a02-4a3c-9031-fbd7b6c4a831

The Filchner Ronne Ice Shelf (FRIS), located in the southern Weddell Sea, plays a key role in the dense water formation, which is a precursor of AABW in the world ocean. Today, the ice shelf is protected by a large cold continental shelf. Model studies, however, have suggested the potential for an increased flow of Modified Warm Deep Water (MWDW) toward and under FRIS via the Filchner Trough, causing a substantial increase in basal melt rates by the end of this century. Historic data in the region suffer from a strong summer bias. New two-year long mooring time series from 2014 to 2016 reveal a distinct seasonal cycle in hydrography along the eastern flank of the Filchner Trough, with a southward flow of MWDW only in summer, connected to a seasonal shoaling of the Antarctic Slope Front (ASF). With the goal of analysing the seasonal and interannual variability of this warm inflow, we set up a new global configuration for the Finite Element Sea-ice Ocean Model (FESOM) with increased resolution over the Weddell Sea and eddy-permitting resolution over the continental shelves. We find a strong sensitivity of the on-shelf flow of MWDW to the representation of the general Weddell Gyre circulation and in particular the ASF properties upstream of the Filchner Trough. Both improve significantly with the new high-resolution grid. In order to ensure a correct representation of the water masses encountering the Filchner Trough, which is necessary to study the inflow dynamics and variability, we perform an experiment with restoring the upstream temperature and salinity field over the continental slope. For this, a monthly climatology at17°W compiled from historic data was incorporated into the World Ocean Data Atlas.