GECCO SSH Changes"

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GECCO SSH Changes"

• Armin Koehl and
• Detlef Stammer
• Universität Hamburg

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SSH Drift

• Changes in SSH on inter-decadal time scale have
  been observed. Unclear is what is causing them.
  In fact, the data base is hardly sufficient to
  infer global and regional inter-decadal sea level
  trends with any statistical significance.
• We can use again the results from the 50-year
  long ocean state estimation performed in Germany
  as part of the ECCO project (GECCO) to
  investigate changes in SSH for the period 1952
  through 2001 and infer dynamical causes.

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Heat Content Changes in 50 yr GECCO Estimates.
ECCO looses heat in the top 500 m during the
70th, mainly In the tropics.
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GECCO and Willis et al. upper 700 m steric
estimate.
GECCO gains salt problems with freshwater
cycle in southern ocean.
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GECCO and Willis et al. upper 700 m steric.
Data sampling
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Conclusions

• Much of the recent rise can be explainable by
  increases in the thermosteric component.
• The thermosteric component has substantial
  decadal and regional variability. Model
  reproduce the data satisfactorily in various
  aspect, but sampling is important, as are details
  of the assimilation.
• 1/3 of the global sea level trend is caused by
  eustatic effects, 2/3 by the (thermo-)steric
  effect(s). But also dependent on approach.
• The thermosteric sea level rise stems from all
  layers. About 1/2 the contribution comes from
  below 512m depth.
• In some results the halosteric contribution from
  different layers compensate to a small residual,
  indicating a redistribution of salt from the top
  layers to depth. In other results the halosteric
  part is of the same size as the thermosteric in
  many places. It partly compensates the
  thermosteric, especially at the deeper layers

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Thank you

• for your attention