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Internal and external variability of MOC in the Kiel Climate Model (ECHAM5/NEMO) Wonsun Park (Mojib Latif group) Leibniz Institute of Marine Sciences, Kiel. Contents: Model Internal MOC variability (5000 yr control) Multidecadal to Multicentennial variability
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Internal and external variability of MOC in the Kiel Climate Model (ECHAM5/NEMO)Wonsun Park (Mojib Latif group)Leibniz Institute of Marine Sciences, Kiel • Contents: • Model • Internal MOC variability (5000 yr control) • Multidecadal to Multicentennial variability • External variability (solar forced exp.) • Outlook THOR WP1 Meeting, Bergen, 1-2 October 2009
The Kiel Climate Model (KCM)ECHAM5 (T31L19), NEMO (0.5-2°) Park et al. 2009 J. Clim.
Atlantic MOC(ctrl, 4000a) Park and Latif 2008 GRL
SH icevs. MOC Sea ice response to MOC
Freshwater and Sea ice threshold Park et al. in preparation
Summary (1/2) • Multidecadal variability is originated in the North Atlantic, whereas multicentennial variability is driven in the Southern Ocean. • Multicentennial Southern Ocean variability is related to the convective activities associated with sea ice capping threshold. • SO multicentennial signal is advected the North Atlantic, and provides stabilization (salinity) effect on MOC.
1000 years 4W/m2 Millennial solar forcing experiments • Solar forcing integration (4200a) : periodic (P=1000a, ±2W/m2) • ECHAM5/MLO simulation (2000a)
Northern Hemisphere temperatureresponse to external solar forcing Jones and Mann (2004) Jones and Mann (2004) reconstruction Latif et al. 2009 Met. Zeit.
Northern Hemisphere SAT IPCC 2007 IPCC 2007
Summary (2/2) • Both internal variability and external (solar) forcing may explain the Northern Hemisphere SAT during the last millennium. • The MOC is strongly phase-locked to the solar forcing, and provides a strong negative feedback on the NH-SAT.
Outlook • Idealized solar forced experiments • ±2W/m2,±1W/m2 (1000yr cycle) • New integrations (T42/ORCA2) • Preindustrial: 2000yr • Last millennium simulations: all forcings (solar, GHG) without carbon cycle (planned)