Interannual fluctuations of the global mean sea level during the altimetry era
Abstract
The detrended global mean sea level (GMSL) displays significant year-to-year fluctuations of 2-3 mm amplitude, as revealed by satellite altimetry over the past 2 decades. In particular, the detrended GMSL shows positive anomalies during El Nino and negative anomalies during La Nina. Previous studies (Llovel et al, 2011, Boening et al., 2012, Cazenave et al., 2012) have shown that these ENSO-related anomalies are mostly caused by ocean mass variations linked to changes of the global water cycle, with precipitation excess (deficit ) over the oceans (land) during El Nino, and inversely during La Nina. Here, we study the respective contributions of the mass and steric contributions to the interannual GMSL fluctuations over the whole altimetry period (since 1993); We find that over this time span, interannual GMSL fluctuations are in general poorly correlated to the steric component while ocean mass variations explain most of the observed year to year oscillations, even apart from ENSO events . These ocean mass oscillations appear inversely correlated to the total land water storage oscillation. However over the oceanic domain, interannual mass changes are not uniformly distributed but mostly confined in the tropical Pacific and Indian oceans. We also find that at some periods (in particular during the 2010/2011 La Nina event), the steric sea level contribution has to be accounted for, in addition to the mass term, to fully explain the observed GMSL anomaly.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.G41A0879D
- Keywords:
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- 1222 GEODESY AND GRAVITY / Ocean monitoring with geodetic techniques;
- 1223 GEODESY AND GRAVITY / Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions;
- 1225 GEODESY AND GRAVITY / Global change from geodesy;
- 1641 GLOBAL CHANGE / Sea level change