ORCALIM experiments with the interannual Large

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ORCA-LIM experiments with the interannual Large
Yeager forcing

• Claus Böning, Arne Biastoch, Ulf Schweckendiek,
• Sabine Hüttl, Joke Lübbecke
• (IFM-GEOMAR, Kiel)
• with special thanks to our
• French colleagues
• collaborating in the
• DRAKKAR
• project

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Examples of interannual-decadal
variability in ORCA2
and ORCA05

• Tropical oceans EUC and STC-transports, SST
• ACC (Drake Passage) transport
• Atlantic MOC transport
• Sea ice coverage

Question effect of long-term drifts in the
CNYF-runs ?

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Tropical circulation examples of spin-up
behaviors (CORE-1)
EUC transports
Sv
GFDL
Pacific
ORCA2
years
ORCA2
Atlantic
ORCA05
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Pacific SST anomalies
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CORE-2 Pacific SST variability
(Nino3) ORCA05 , ORCA2
vs. Data
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SST variability (Nino3-region) in ORCA05 vs.
SOI index
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Pacific Subtropical-Tropical overturning Cells
(STCs)Equatorward transports across 10N/10S
Sv
ORCA05 ORCA2

• robust
• trend !
• (-14 Sv)

shown here Deviations from long-term means 59
Sv (ORCA2), 67 Sv (ORCA05)
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euc205ia -- EUC 155W ORCA05 (red), ORCA2 (blue)
black ORCA2 with climatol.winds
EUC transport anomalies (Pacific, 155W)
ORCA05 (red), ORCA2 (blue) black
climatological winds
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Atlantic SST anomalies after 50 yrs spin-up
(CORE-1)
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Atlantic EUC transport spin-up under CNYF
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SST variability (ATL4-region) ORCA05 vs.
Reynolds
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Atlantic STC-index (8N/8S) ORCA05 ORCA05
ORCA2 FLAME(1/3)
- trend robust (2 Sv) -
year-to-year var. differing -
decadal variab. (gt 5 yrs)
fairly robust
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ORCA2 and MICOM
(W.Hazeleger, KNMI)
Annual cycle of the EUC at 23W (after 50-yr
spin-up)
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ORCA2 - MICOM - ORCA05
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EUC (23W) ORCA2 MICOM - ORCA05 - FLAME1/12
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Regarding simulations of tropical variability

• CORE-II experiments help to identify where
  models are
• robust and where results are sensitive to
  model choices
• - (inter-)decadal transport changes are
  very robust
• - seasonal-interannual variability differs
  between realizations

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Drake Passage transport (two ORCA05-cases)
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Drake Passage transport anomalies(deviations
from the climatological reference runs)
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Atlantic MOC (45N)
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MOC anomalies(deviations from the climatological
reference runs)
ORCA05 3 realizations
FLAME-1/3
ORCA2
ORCA05
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