Hausse du niveau de la mer et impact du changement climatique global

William Llovel 1
1 GOHS
LEGOS - Laboratoire d'études en Géophysique et océanographie spatiales
Abstract : Tide gauge records suggest a rise in sea level rise of ~1.8 mm/yr over the 20st century. More recently, satellite altimetry data reveal a global mean sea level rise of 3.3 mm/yr over 1993-2010. This rise is attributed to Earth's global warming observed since several decades. In this thesis, we analyze observed global mean sea level and its causes over the entire altimetry era (since 1993). Over the recent years (2002-2009), we estimate the effects of ocean thermal expansion and salinity (called steric effects) on sea level, as well as ocean mass change due to land ice and land waters, using Argo and GRACE space gravimetry data. We discuss the regional variability by comparing several datasets for thermal expansion and ocean mass signal. In another study, we investigate terrestrial land water storage variability of the 33 largest river basins worldwide, using GRACE space gravimetry data. We analyze this contribution to the observed global mean sea level inferred by satellite altimetry. In an extension of this study, we analyze the interannual variability of terrestrial land water storage and its impact on sea level variations over the altimetry era and tide gauge era. Finally, we conclude this chapter by studying the sea level budget over the entire altimetry era and the recent years. In a second part, we study the regional patterns in sea level trends. First, we discuss causes of regional variability, mainly non-uniform ocean warming. We then interpret the residual signal (i.e., observed sea level corrected for thermal effects) for the altimetry era. Thereafter, we analyze regional patterns of past sea level over the last decades (1950-2003). The purpose of this study is to provide 2-D regional past sea level reconstruction and obtain some insight on spatial trend patterns and their dominant modes of variability. The ultimate goal is to constrain coupled climate models used by the IPCC (Intergovernment Panel on Climate Change) to predict sea level rise over the 21st century. Moreover, this study highlights a long term signal detected in the reconstructed sea level. This signal is also observed in in situ data and in coupled climate models.
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William Llovel. Hausse du niveau de la mer et impact du changement climatique global. Planète et Univers [physics]. Université Paul Sabatier - Toulouse III, 2010. Français. ⟨tel-00558287⟩

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