Abstract
Recent studies have shown significant sea surface salinity (SSS) changes at scales ranging from regional to global. In this study, we estimate global salinity means and trends using historical (1950–2014) SSS data from the UK Met Office Hadley Centre objectively analyzed monthly fields and recent data from the SMOS satellite (2010–2014). We separate the different components (regimes) of the global surface salinity by fitting a Gaussian Mixture Model to the data and using expectation–maximization to distinguish the means and trends of the data. The procedure uses a non-subjective method (Bayesian information criterion) to extract the optimal number of means and trends. The results show the presence of three separate regimes: Regime A (1950–1990) is characterized by small trend magnitudes; Regime B (1990–2009) exhibited enhanced trends; and Regime C (2009–2014) with significantly larger trend magnitudes. The salinity differences between regime means were around 0.01. The trend acceleration could be related to an enhanced global hydrological cycle or to a change in the sampling methodology. Understanding past SSS changes can provide insight into future climate evolution by complementing the knowledge acquired in recent decades from long-term temperature record analyses.
Highlights
Global sea surface salinity (SSS) is changing at scales ranging from regional to global [1,2]
After we have found the number of components, nc, component distributions, G(μk, αk, Σk), and their respective likelihoods, τk, we can conduct an empirical orthogonal function (EOF) analysis on the Σk
We have analyzed global salinity datasets to identify a series of regimes characterized by fluctuations around a changing average and temporal tendency
Summary
Global sea surface salinity (SSS) is changing at scales ranging from regional to global [1,2]. The intensification of the global water cycle is expected to be occurring at a rate of 8% ◦−1 of surface warming [4] or around 20% considering the projected 2–3◦ of temperature increase over the century. The mechanisms controlling the intensification of the water cycle have recently been evaluated [5,6]. Antonov et al [1] and Boyer et al [2] described a general change pattern with surface subtropical areas becoming saltier and high-latitude regions becoming fresher. Curry et al [7] found increased salinity in the subtropical evaporation-dominated regions between 25◦ S and 35◦ N when they compared the time periods 1955–1969 and 1985–1999 for the entire Atlantic basin. Cravatte et al [8] described a large freshening in the Pacific warm pool over the 1955–2003 period
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
