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SUMMARY:Shenjie Zhou (British Antarctic Survey)
DTSTART:20210210T140000Z
DTEND:20210210T150000Z
DTSTAMP:20260423T021417Z
UID:BAS-PO/10
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/BAS-PO/10/">
 Ocean’s response to the stochastic atmospheric forcing</a>\nby Shenjie Z
 hou (British Antarctic Survey) as part of BAS Polar Oceans Seminar\n\n\nAb
 stract\nThe ocean is forced by the atmosphere on a range of spatial and te
 mporal scales. In ocean and climate models the resolution of the atmospher
 ic forcing sets a limit on the scales that are represented. For typical cl
 imate models this means mesoscale (< 400 km) atmospheric forcing is absent
 . Previous studies have demonstrated that mesoscale forcing significantly 
 affects key ocean circulation systems such as the North Atlantic Subpolar 
 gyre and the Atlantic Meridional Overturning Circulation (AMOC). However\,
  the approach of these studies has either been ad hoc or limited in resolu
 tion. Here we present ocean model simulations with and without realistic m
 esoscale atmospheric forcing that represents scales down to 10 km. We use 
 a novel stochastic parameterization – based on a cellular automaton algo
 rithm that is common in weather forecasting ensemble prediction systems 
 – to represent spatially coherent weather systems over a range of scales
 \, including down to the smallest resolvable by the ocean grid. The parame
 terization is calibrated spatially and temporally using marine wind observ
 ations. The addition of mesoscale atmospheric forcing leads to coherent pa
 tterns of change in the sea surface temperature and mixed-layer depth. It 
 also leads to non-negligible changes in the volume transport in the North 
 Atlantic subtropical gyre (STG) and subpolar gyre (SPG) and in the AMOC. A
  non-systematic basin-scale circulation response to the mesoscale wind per
 turbation emerges – an in-phase oscillation in northward heat transport 
 across the gyre boundary\, partly driven by the constantly enhanced STG\, 
 correspoding to an oscillatory behaviour in SPG and AMOC indices with a ty
 pical time scale of 5-year\, revealing the importance of ocean dynamics in
  generating non-local ocean response to the stochastic mesoscale atmospher
 ic forcing. Atmospheric convection-permitting regional climate simulations
  predict changes in the intensity and frequency of mesoscale weather syste
 ms this century\, so representing these systems in coupled climate models 
 could bring higher fidelity in future climate projections.\n
LOCATION:https://researchseminars.org/talk/BAS-PO/10/
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