Daily Archives: July 3, 2015

Deep Ocean Contribution to the “Global Warming” Hiatus is negligible

H. B. Dieng , A. Cazenave , K. von Schuckmann , M. Ablain , and B. Meyssignac  Sea level budget over 2005–2013: missing contributions and data errors  Ocean Sci. Discuss., 12, 701–734, 2015

Based on the sea level budget closure approach, this study investigates the residuals between observed global mean sea level (GMSL) and the sum of components (steric sea level and ocean mass) for the period January 2005 to December 2013. The objective is to identify the impact of errors in one or several components of the sea level budget on the residual time series. This is a key issue if we want to constrain missing contributions such as the contribution to sea level rise from the deep ocean (> 2000 m). For that purpose, we use several data sets as processed by different groups: six altimetry products for the GMSL, four Argo products plus the ORAS4 ocean reanalysis for the 10 steric sea level and three GRACE-based ocean mass products. We find that over the study time span, the observed trend differences in the residuals of the sea level budget can be as large as ∼ 0.55 mm yr−1 . These trend differences essentially result from the processing of the altimetry data (e.g., choice the geophysical corrections and method of averaging the along-track altimetry data). At short time scale (from sub-seasonal 15 to multi-annual), residual anomalies are significantly correlated with ocean mass and steric sea level anomalies (depending on the time span), indicating that the residual anomalies are related to errors in both GRACE-based ocean mass and Argo-based steric data. Efforts are needed to reduce these various sources of errors before using the sea level budget approach to estimate missing contributions such as the deep 20 ocean heat content.

Additional discussion of this study is here.