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SUMMARY:Antarctic sea ice sensitivity to the orographic gravity wave drag 
 in a fully coupled climate model - Maria Vittoria Guarino (International C
 entre for Theoretical Physics)
DTSTART:20240830T100000Z
DTEND:20240830T110000Z
UID:TALK218680@talks.cam.ac.uk
CONTACT:Thomas Caton Harrison
DESCRIPTION:Low-level winds over Antarctica are overwhelmingly controlled 
 by the local orography. They\, in turn\, exert a large control on sea ice 
 formation and transport.\n\nIn this work\, we investigate the relationship
  between Antarctic sea ice and the parameterized Orographic Gravity Wave D
 rag (OGWD) in the UK Earth System Model (UKESM). We present results from s
 ensitivity tests performed using the UKESM-CMIP6 historical runs.\n\nIn th
 ese simulations\, the partition between the “flow-blocking” component 
 and the “gravity wave” component of the OGWD parameterization was alte
 red to simulate “flow-over” and “flow-blocking” regimes. These exp
 eriments show that sea ice strongly responds to changes in the orographic 
 gravity wave drag. The strong sea ice decline simulated by the control run
  from 1980 to 2015 is delayed by 15-20 years (across the ensemble members)
  in our flow-blocking regime simulation. Conversely\, in the flow-over reg
 ime simulation\, sea ice begins declining about 10 years earlier than in t
 he control run.\n\nThe systematic response of the coupled system suggests 
 the existence of a dynamical relationship between sea ice and OGWD. To exp
 lain this\, we investigate changes in surface circulation and total ocean 
 surface stress across the different flow regimes. 
LOCATION:BAS Cambridge Seminar Room 1 and Zoom
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