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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 Alan project meeting 18/11/08
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.
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
MOC 45N, power spectrum: transient (black) and control (blue)
Global upper-ocean temperature,surface to fixed depth (220m)
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
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?)