Vertical redistribution of salt and layered changes in global ocean salinity

Abstract

Salinity is an essential proxy for estimating the global net freshwater input into the ocean. Due to the limited spatial and temporal coverage of the existing salinity measurements, previous studies of global salinity changes focused mostly on the surface and upper oceans. Here, we examine global ocean salinity changes and ocean vertical salt fluxes over the full depth in a dynamically consistent and data-constrained ocean state estimate. The changes of the horizontally averaged salinity display a vertically layered structure, consistent with the profiles of the ocean vertical salt fluxes. For salinity changes in the relatively well-observed upper ocean, the contribution of vertical exchange of salt can be on the same order of the net surface freshwater input. The vertical redistribution of salt thus should be considered in inferring changes in global ocean salinity and the hydrological cycle from the surface and upper ocean measurements.

Water‐Mass Properties and Circulation in the Deep and Abyssal Philippine Sea

“…When comparing with previous studies, a reduced warming trend post‐2000 compared with pre‐2000 in the open Pacific was also suggested (Desbruyeres et al., 2016), whereas this result is based on no more than five occupations in each WHP section. As for salinity, the trend is exactly opposite the freshening/salinification pre‐2005/post‐2005 at the depth between 2,000 m and 4,500 m applying ECCO simulation (Liu et al., 2019), although this conclusion depends on the phenomenon that globally average of salinity anomaly changed sign at 2005. Note that the change in sign around the middle of the examined period (1993–2014) only reflects the presence of a linear trend.…”

“…The freshening may be influenced by that of the AABW near the Southern Ocean (Purkey & Johnson, 2013; Purkey et al., 2019; Rintoul, 2007) and the negative S differences below 2,000 m at 24.25°N, 135°E−137°E (Kouketsu et al., 2009). Also, salinification under 2,000 m was suggested before because of downward salt flux at 2,000 m in the Pacific based on the global assimilation model of Estimating the Circulation and Climate of the Ocean (ECCO) (Liu et al., 2019).…”

The Arctic Subpolar Gyre sTate Estimate: Description and Assessment of a Data‐Constrained, Dynamically Consistent Ocean‐Sea Ice Estimate for 2002–2017

“…Among the publicly available ECCO state estimates is ECCO Version 4 Release 3 (ECCOv4r3, Forget, Campin et al., 2015; Fukumori, Heimbach et al., 2018), which has been constrained to satellite and in situ data (including Argo and elephant seal data) outside of the Arctic, ITP data in the Arctic, and other mooring data at important Arctic gateways. The ECCOv4 releases have been widely used, with applications including investigation of global vertical heat and salt redistribution (Liang et al., 2017; Liu et al., 2019), heat budgets in the North Atlantic (Buckley et al., 2014, 2015; Foukal & Lozier, 2018; Piecuch et al., 2017) and the Nordic Seas (Asbjørnsen et al., 2019), high‐latitude freshwater budgets (Tesdal & Haine, 2020), and sea level change (Piecuch & Ponte, 2013).…”

The Arctic Subpolar gyre sTate Estimate (ASTE): Description and assessment of a data-constrained, dynamically consistent ocean-sea ice estimate for 2002-2017

“…Among the publicly available ECCO state estimates is ECCO Version 4 Release 3 (ECCOv4r3, Forget, Campin et al, 2015;, which has been constrained to satellite and in situ data (including Argo and elephant seal data) outside of the Arctic, ITP data in the Arctic, and other mooring data at important Arctic gateways. The ECCOv4 releases have been widely used, with applications including investigation of global vertical heat and salt redistribution (Liang et al, 2017;Liu et al, 2019), heat budgets in the North Atlantic (Buckley et al, 2014(Buckley et al, , 2015Foukal & Lozier, 2018;Piecuch et al, 2017) and the Nordic Seas (Asbjørnsen et al, 2019), high-latitude freshwater budgets (Tesdal & Haine, 2020), and sea level change (Piecuch & Ponte, 2013).…”