1. 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

2. 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 ?

3. Tropical circulation: examples of spin-up behaviors (CORE-1)
EUC transports Sv
GFDL
Pacific
ORCA2
years
ORCA2
Atlantic
ORCA05

4. Pacific SST anomalies

5. CORE-2: Pacific SST variability (Nino3): ORCA05 , ORCA2 vs. Data

6. SST variability (Nino3-region) in ORCA05 vs. SOI index

7. Pacific Subtropical-Tropical overturning Cells (STCs): Equatorward transports across 10°N/10°SSv
ORCA05
ORCA2
robust
trend !
(-14 Sv)
shown here:
Deviations from long-term means: 59 Sv (ORCA2), 67 Sv (ORCA05)

8. Atlantic: SST anomalies after 50 yrs spin-up (CORE-1)

9. SST variability (ATL4-region): ORCA05 vs. Reynolds

10. Atlantic STC-index (8°N/8°S) ORCA05 – ORCA05 – ORCA2 – FLAME(1/3)
- trend:
robust (+2 Sv)
- year-to-year var.:
differing
- decadal variab.
(> 5 yrs):
fairly robust

11. ORCA2 and MICOM (W.Hazeleger, KNMI)
Annual cycle of the EUC at 23°W (after 50-yr spin-up)
ORCA and MICOM (W.Hazeleger, KNMI)

12. ORCA2 - MICOM - ORCA05

13. EUC (23°W) ORCA2 – MICOM - ORCA05 - FLAME1/12

14. 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

15. Drake Passage transport (two ORCA05-cases)

16. Drake Passage transport anomalies (deviations from the climatological reference runs)

17. Atlantic MOC (45°N)

18. MOC anomalies (deviations from the climatological reference runs)
ORCA05 – 3 realizations
FLAME-1/3°
ORCA2
ORCA05