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New transient runs for GCEP

New transient runs for GCEP. Alan project meeting 18/11/08. Summary of runs. Flux corrected transient runs 1860 – present, 4-member IC ( δ SST) ensemble.

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New transient runs for GCEP

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  1. New transient runs for GCEP Alan project meeting 18/11/08

  2. Summary of runs • Flux corrected transient runs 1860 – present,4-member IC (δSST) ensemble. • Previous transient runs may have contained “control drifts” due to ICs – this time start from end of 500-year control (in turn started from near end of HC’s 1000-year run). • Some drifts remain in control despite long spin-up. These are small (typical change per century: 0.005 PSU, -0.05K), even though at depth they exceed any faster variability.

  3. Global mean surface temperature

  4. Southern Hemisphere ice volume

  5. North America snow covered area

  6. OLR

  7. NAO index (not normalised)

  8. MOC from transient runs: 25N

  9. MOC from transient runs: 35N

  10. MOC from transient runs: 45N

  11. Atlantic heat transport (45N)

  12. Atlantic upper ocean heat content >45N

  13. Is the ~1915-1945 MOC decrease internal variability? • Compare MOC power spectrum with control run • Have lost control run on gorgon, but still have similar 500-year control run done for COAPEC • (currently messy to diagnose, as the netCDF files lack correct metadata to drive diagnostics package) • Obtain 3 x 146-year timeseries • can’t treat as IC ensemble (ICs differ by more than δ) • but can treat as 3 samples of control power spectrum, compare with spectra of transient ensemble members

  14. MOC 45N, power spectrum: transient

  15. MOC 45N, power spectrum: control

  16. MOC 45N, power spectrum: transient (black) and control (blue)

  17. Global upper-ocean temperature,surface to fixed depth (220m)

  18. Global upper-ocean temperature,surface to isotherm (14C)

  19. Pacific Decadal Oscillation First EOF of monthly SST (detrended, deseasonalised) 1900-1992 in box shownPlotted here: SST regressed on first PC, showing some correlated signals elsewhere

  20. PDO principal component

  21. PDO continued • Have EOF pattern that we can project other SST timeseries onto (e.g. other runs, or outside EOF analysis period) – should I incorporate into diagnostics package? • ‘bullseye’ in EOF pattern near Japan not seen in other studies but seems to be consistent area of high variability in these UM runs. (Why?) • Can we relate PDO timeseries to upper ocean heat content? (Keith to explain?)

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