Global Patterns of Submesoscale Surface Salinity Variability

Type Article
Date 2019-07
Language English
Author(s) Drushka Kyla1, Asher William E.1, Sprintall Janet2, Gille Sarah T.2, Hoang Clifford2
Affiliation(s) 1 : Univ Washington, Appl Phys Lab, Seattle, WA 98195 USA.
2 : Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA.
Source Journal Of Physical Oceanography (0022-3670) (Amer Meteorological Soc), 2019-07 , Vol. 49 , N. 7 , P. 1669-1685
DOI 10.1175/JPO-D-19-0018.1
WOS© Times Cited 7
Keyword(s) Small scale processes, Freshwater, Fronts, Sea surface temperature, Oceanic variability
Abstract

Surface salinity variability on O(1-10) km lateral scales (the submesoscale) generates density variability and thus has implications for submesoscale dynamics. Satellite salinity measurements represent a spatial average over horizontal scales of approximately 40-100 km but are compared to point measurements for validation, so submesoscale salinity variability also complicates validation of satellite salinities. Here, we combine several databases of historical thermosalinograph (TSG) measurements made from ships to globally characterize surface submesoscale salinity, temperature, and density variability. In river plumes; regions affected by ice melt or upwelling; and the Gulf Stream, South Atlantic, and Agulhas Currents, submesoscale surface salinity variability is large. In these regions, horizontal salinity variability appears to explain some of the differences between surface salinities from the Aquarius and SMOS satellites and salinities measured with Argo floats. In other words, apparent satellite errors in highly variable regions in fact arise because Argo point measurements do not represent spatially averaged satellite data. Salinity dominates over temperature in generating submesoscale surface density variability throughout the tropical rainbands, in river plumes, and in polar regions. Horizontal density fronts on 10-km scales tend to be compensated (salinity and temperature have opposing effects on density) throughout most of the global oceans, with the exception of the south Indian and southwest Pacific Oceans between 20 degrees and 30 degrees S, where fronts tend to be anticompensated.

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