What governs the North Atlantic salinity maximum in a global GCM?

Abstract

[1] Taking advantage of the rapid advance in ocean modeling, this study investigates the sea surface salinity maximum in the North Atlantic, using results from a model of the Consortium for Estimating the Circulation and Climate of the Ocean (ECCO). Salinity budget terms were computed at the model's integration time step and archived as monthly averages. The simulated mixed layer salinity budget provides the first quantitative evidence for the ocean's role in governing the sea surface salinity maximum in the North Atlantic. Our analysis reveals that ocean dynamics explains about half of the sea surface salinity variance, being of equal importance as surface forcing. The sea surface salinity maximum varies both seasonally and interannually, as a consequence of interplay among surface flux, advection, and vertical entrainment. Contribution from eddies and small-scale processes is relatively weak but not negligible. These results may provide useful hints for the design and interpretation of future observations in the region.

Sea Surface Salinity and Temperature Budgets in the North Atlantic Subtropical Gyre during SPURS Experiment: August 2012-August 2013

“…As mentioned before, SSS maximum is located a few degrees to the north of the E-P maxima (Figure 8) which shows the importance of the ocean dynamics in this region (Qu et al, 2011), indicating in particular a contribution of Ekman advection, and suggesting a large scale balance between sea surface forcing, advection and mixing processes. In winter 2012-2013 (especially in December) a rain band was found in the middle of the region which resulted in two local maxima on Figure 8B.…”

“…Thus, the ocean dynamics needs to be accurately assessed to link E-P field's variability with change in SSS (Yu, 2011). At meso-scale, recent work in the North Atlantic subtropical gyre (Qu et al, 2011;Busecke et al, 2014;Gordon and Giulivi, 2014;Farrar et al, 2015) shows a significant contribution of horizontal advection in governing surface salinity, with roughly half of the salinity variation being explained by ocean meso-scale dynamics. In the South Pacific, the compensation of fresh water loss is also made by vertical turbulent mixing and horizontal salinity advection (Hasson et al, 2013;Kolodziejczyk and Gaillard, 2013).…”

Mixed-layer salinity budget in the tropical Indian Ocean: seasonal cycle based only on observations

“…These terms may significantly contribute to the seasonal SSS balance, as was shown in other basins of the Pacific and the Atlantic oceans (Vialard and Delecluse 1998;Vialard et al 2002;Qu et al 2011;Vinogradova and Ponte 2013;Hasson et al 2013;Kolodziejczyk and Gaillard 2013;Da-Allada et al 2013, 2014b.…”

Interannual sea surface salinity variations observed in the tropical North Pacific Ocean

“…[8] We then perform a budget analysis using conservation equation of the mixed layer salinity [Qu et al, 2011],…”