New transient runs for gcep
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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

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New transient runs for gcep

New transient runs for GCEP


project meeting 18/11/08

Summary of runs

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.

Global mean surface temperature

Global mean surface temperature

Southern hemisphere ice volume

Southern Hemisphere ice volume

North america snow covered area

North America snow covered area

New transient runs for gcep


Nao index not normalised

NAO index (not normalised)

Moc from transient runs 25n

MOC from transient runs: 25N

Moc from transient runs 35n

MOC from transient runs: 35N

Moc from transient runs 45n

MOC from transient runs: 45N

Atlantic heat transport 45n

Atlantic heat transport (45N)

Atlantic upper ocean heat content 45n

Atlantic upper ocean heat content >45N

Is the 1915 1945 moc decrease internal 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

MOC 45N, power spectrum: transient

Moc 45n power spectrum control

MOC 45N, power spectrum: control

Moc 45n power spectrum transient black and control blue

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

Global upper ocean temperature surface to fixed depth 220m

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

Global upper ocean temperature surface to isotherm 14c

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

Pacific decadal oscillation

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 principal component

PDO principal component

Pdo continued

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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