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SUMMARY:From Models to Observations: A Case Study for the Filchner-Ronne I
 ce Shelf -  Hartmut Hellmer (Alfred Wegener Institute)
DTSTART:20210505T130000Z
DTEND:20210505T140000Z
UID:TALK156292@talks.cam.ac.uk
CONTACT:Dr. Shenjie Zhou
DESCRIPTION:Warm water of open ocean origin on the continental shelf of Am
 undsen and Bellingshausen Seas drives the highest basal melt rates reporte
 d for Antarctic ice shelves. This has severe consequences for ice shelf/ic
 e sheet dynamics and the mass balance of the Antarctic Ice Sheet. Ice shel
 ves fringing the broad continental shelf in Weddell and Ross Seas melt at 
 rates orders of magnitude smaller. However\, simulations using coupled ice
 –ocean models forced with the atmospheric output of the HadCM3 SRES-A1B 
 scenario run indicate that the circulation in the southern Weddell Sea mig
 ht change during the 21st century. As elaborated by additional sensitivity
  studies\, certain environmental settings support the flow of Circumpolar 
 Deep Water derivatives southward underneath the Filchner–Ronne Ice Shelf
 \, warming the cavity and intensifying basal melting. The results also ide
 ntify a tipping point in the southern Weddell Sea: a positive melt water f
 eedback enhances the shelf circulation and the onshore transport of open o
 cean heat. Motivated by the model results\, the Alfred Wegener Institute i
 n collaboration with the British Antarctic Survey and Norwegian Research C
 entre participated in two projects (FISP and FISS) focused on the investig
 ation of the Filchner-Ronne Ice Shelf (FRIS) cavity and the southern Wedde
 ll Sea continental shelf. Here\, I combine the results from data of four m
 oorings operating beneath FRIS with the most recent survey (PS111-2018) al
 ong the FRIS front and across the Filchner Trough\, complemented by moorin
 g data recovered during the PS124-2021 COSMUS cruise. It turns out that wi
 de-ranging atmospheric teleconnections influence sea ice and thus dense wa
 ter formation in the southern Weddell Sea on interannual time scales. The 
 shelf process (a) controls the cavity circulation\, (b) causes mode shifts
  underneath the northern Filchner Ice Shelf\, and (c) determines the stren
 gth of the density barrier at the continental shelf break\, thereby affect
 ing the onshore flow of warmer waters. This suggests that keeping an eye o
 n the large-scale atmospheric conditions in the Southern Ocean might be on
 e (easy) way to infer changes in the northern Filchner Trough.
LOCATION:British Antarctic Survey\, Zoom
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