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| Titel |
Spectral analysis of sealevel during the altimetry era, and evidence for GIA and glacial melting fingerprints |
| VerfasserIn |
Giorgio Spada, Gaia Galassi |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126842
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| Publikation (Nr.) |
 EGU/EGU2016-6628.pdf |
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| Zusammenfassung |
| We study the spatial patterns of the mass and steric components of sea-level change during
the “altimetry era” (1992-today), and we characterize them at different scales by
the orthonormal functions method. The spectrum of the altimetry-derived rate of
sea-level rise is red and decays with increasing wavenumber nearly following a power
law with exponent ≈ 10. By analyzing the degree correlation and the admittance
function, we find that the altimetric rate of sea-level change is coherent with the total
steric field in the whole range of wavelengths considered (down to 1000 km),
but particularly for wavelengths exceeding 2000 km. Thermosteric and halosteric
components are moderately anti-correlated within the range of wavelengths 1000-4000
km. Their power spectrum varies significantly with the wavelength and, for 2000
km, it is equally partitioned between the two components. The power of regional
sea-level variations driven by Glacial Isostatic Adjustment (GIA) and the melting of
continental ice sheets is small compared to that held by the steric component, which
explains most of the regional variability shown by the altimetry record. This causes the
elusiveness of the “static” sea-level fingerprints, which at present are hidden in the
pattern of the residual sea-level (i.e., the altimetry-derived sea-level minus the steric
component). However, we find that at harmonic degree 2, mainly associated with
rotational variations, the power of glacial melting is significant and it will progressively
increase during next century in response to global warming. We also estimate that at
the end of the Mid-Holocene the strength of the GIA fingerprints was ≈ 10 times
larger than today, well above the long-wavelength component of residual sea-level. |
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