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Freshwater Variability and Transport in the Labrador Sea From In Situ and Satellite Observations
Author(s) -
Majumder Sudip,
Castelao Renato M.,
Amos Caitlin M.
Publication year - 2021
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2020jc016751
Subject(s) - oceanography , downwelling , stratification (seeds) , geostrophic wind , salinity , water column , climatology , geology , meltwater , upwelling , ocean current , water mass , temperature salinity diagrams , halocline , glacier , seed dormancy , paleontology , botany , germination , dormancy , biology
The Greenland ice sheet is melting at increasing rates. Changes in freshwater input to the Labrador Sea can influence coastal circulation and biological processes, stratification, and potentially winter convection. Many recent studies have investigated freshwater variability in the region based on model simulations or observations with limited spatial/temporal coverage. Here, we use in situ (1990–2019) and satellite (2011–2017) observations of surface salinity to characterize freshwater content and to identify transport pathways in the Labrador Sea over multiple years. Large freshening is observed in coastal waters off southwest Greenland from July to November. Interannual variability in freshening near the coast seems to be at least partially related to variability in meltwater input, although the sparseness of in situ data precludes a quantitative assessment. The seasonal westward transport of freshwater is enhanced between 60°–62°N and especially between 63°–64.8°N from August to October, with the low‐salinity waters circumnavigating the basin following the 1,000–2,000 m isobaths. That pathway coincides with intensifications in the component of the surface geostrophic flow that is directed offshore, highlighting the role played by the large‐scale circulation on the westward transport of the freshwater. Low‐salinity water can be transported toward the central Labrador Sea at synoptic scales, however, where it can potentially influence stratification. Consistent with previous modeling studies, offshore freshening is reduced in years with persistent downwelling‐favorable wind conditions. Despite limitations under cold water conditions, satellite observations of surface salinity compare well with in situ data suggesting that they can be useful for monitoring freshwater content in high latitudes.