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In this study, we have estimated the different sea level components (observed sea level from satellite altimetry, steric sea
level from in situ hydrography—including Argo profiling floats, and ocean mass from Gravity Recovery and Climate Experiment;
GRACE), in terms of regional and interannual variability, over 2002–2009. We compute the steric sea level using different
temperature (and salinity) data sets processed by different groups (SCRIPPS, CLS, IPRC, and NOAA) and first focus on the regional
variability in steric and altimetry-based sea level. In addition to El Nino–La Nina signatures, the observed and steric sea
level data show clear impact of three successive Indian Ocean Dipoles in 2006, 2007, and 2008 in the Indian Ocean. We next
study the spatial trend patterns in ocean mass signal by comparing GRACE observations over the oceans with observed minus
steric sea level. While in some regions, reasonably good agreement is observed, discrepancy is noticed in some others due
to still large regional trend errors in Argo and GRACE data, as well as to a possible (unknown) deep ocean contribution. In
terms of global mean, interannual variability in altimetry-based minus steric sea level and GRACE-based ocean mass appear
significantly correlated. However, large differences are reported when short-term trends are estimated (using both GRACE and
Argo data). This prevents us to draw any clear conclusion on the sea level budget over the recent years from the comparison
between altimetry-based, steric sea level, and GRACE-based ocean mass trends, nor does it not allow us to constrain the Glacial
Isostatic Adjustment correction to apply to GRACE-based ocean mass term using this observational approach. 相似文献
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Alix Lombard Anny Cazenave Pierre Yves Le Traon Stephanie Guinehut Cécile Cabanes 《Ocean Dynamics》2006,56(5-6):445-451
In this paper, we first discuss the controversial result of the work by Cabanes et al. (Science 294:840–842, 2001), who suggested that the rate of past century sea level rise may have been overestimated, considering the limited and heterogeneous
location of historical tide gauges and the high regional variability of thermal expansion which was supposed to dominate the
observed sea level. If correct, this conclusion would have solved the problem raised by the IPCC third assessment report [Church
et al, Cambridge University Press, Cambridge, pp 881, 2001], namely, the factor two difference between the 20th century observed sea level rise and the computed climatic contributions.
However, recent investigations based on new ocean temperature data sets indicate that thermal expansion only explains part
(about 0.4 mm/year) of the 1.8 mm/year observed sea level rise of the past few decades. In fact, the Cabanes et al.’s conclusion
was incorrect due to a contamination of abnormally high ocean temperature data in the Gulf Stream area that led to an overestimate
of thermal expansion in this region. In this paper, we also estimate thermal expansion over the last decade (1993–2003), using
a new ocean temperature and salinity database. We compare our result with three other estimates, two being based on global
gridded data sets, and one based on an approach similar to that developed here. It is found that the mean rate of thermosteric
sea level rise over the past decade is 1.5±0.3 mm/year, i.e. 50% of the observed 3 mm/year by satellite altimetry. For both
time spans, past few decades and last decade, a contribution of 1.4 mm/year is not explained by thermal expansion, thus needs
to be of water mass origin. Direct estimates of land ice melt for the recent years account for about 1 mm/year sea level rise.
Thus, at least for the last decade, we have moved closer to explaining the observed rate of sea level rise than the IPCC third
assessment report. 相似文献
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A. Cazenave K. Dominh S. Guinehut E. Berthier W. Llovel G. Ramillien M. Ablain G. Larnicol 《Global and Planetary Change》2009,65(1-2):83-88
From the IPCC 4th Assessment Report published in 2007, ocean thermal expansion contributed by ～ 50% to the 3.1 mm/yr observed global mean sea level rise during the 1993–2003 decade, the remaining rate of rise being essentially explained by shrinking of land ice. Recently published results suggest that since about 2003, ocean thermal expansion change, based on the newly deployed Argo system, is showing a plateau while sea level is still rising, although at a reduced rate (～ 2.5 mm/yr). Using space gravimetry observations from GRACE, we show that recent years sea level rise can be mostly explained by an increase of the mass of the oceans. Estimating GRACE-based ice sheet mass balance and using published estimates for glaciers melting, we further show that ocean mass increase since 2003 results by about half from an enhanced contribution of the polar ice sheets – compared to the previous decade – and half from mountain glaciers melting. Taking also into account the small GRACE-based contribution from continental waters (< 0.2 mm/yr), we find a total ocean mass contribution of ～ 2 mm/yr over 2003–2008. Such a value represents ～ 80% of the altimetry-based rate of sea level rise over that period. We next estimate the steric sea level (i.e., ocean thermal expansion plus salinity effects) contribution from: (1) the difference between altimetry-based sea level and ocean mass change and (2) Argo data. Inferred steric sea level rate from (1) (～ 0.3 mm/yr over 2003–2008) agrees well with the Argo-based value also estimated here (0.37 mm/yr over 2004–2008). Furthermore, the sea level budget approach presented in this study allows us to constrain independent estimates of the Glacial Isostatic Adjustment (GIA) correction applied to GRACE-based ocean and ice sheet mass changes, as well as of glaciers melting. Values for the GIA correction and glacier contribution needed to close the sea level budget and explain GRACE-based mass estimates over the recent years agree well with totally independent determinations. 相似文献
4.
Toyoda Takahiro Fujii Yosuke Kuragano Tsurane Kosugi Naohiro Sasano Daisuke Kamachi Masafumi Ishikawa Yoichi Masuda Shuhei Sato Kanako Awaji Toshiyuki Hernandez Fabrice Ferry Nicolas Guinehut Stéphanie Martin Matthew Andrew Peterson K. Good Simon A. Valdivieso Maria Haines Keith Storto Andrea Masina Simona Köhl Armin Yin Yonghong Shi Li Alves Oscar Smith Gregory Chang You-Soon Vernieres Guillaume Wang Xiaochun Forget Gael Heimbach Patrick Wang Ou Fukumori Ichiro Lee Tong Zuo Hao Balmaseda Magdalena 《Climate Dynamics》2017,49(3):891-907
Climate Dynamics - The interannual-decadal variability of the wintertime mixed layer depths (MLDs) over the North Pacific is investigated from an empirical orthogonal function (EOF) analysis of an... 相似文献
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