Sea Surface Salinity Distribution in the Southern Ocean as Observed From Space

Abstract

Large‐scale spatial and temporal variabilities of sea surface salinity (SSS) in the Southern Ocean from 2011 to 2017 were studied using products derived from microwave sensors on board Aquarius, Soil Moisture and Ocean Salinity (SMOS), and Soil Moisture Active and Passive (SMAP) satellites. Four products, three from Aquarius and one from SMOS, were evaluated and shown to be generally consistent within 0.3 to 0.6 psu and agree favorably with in situ measurements. However, although the Aquarius products show consistent seasonality of SSS with high values of 34.45 psu in October and low values of 33.40 psu in May, the SMOS and SMAP products lack such seasonal variations. This may be caused by larger uncertainties in the SMOS and SMAP data due in part to the lack of concurrent scatterometer measurements that is used to correct for roughness effects. The four products provide similar spatial distributions of SSS with root‐mean‐square difference from 0.25 to 0.58 psu. Differences among Aquarius products are mainly due to varying salinity retrieval algorithms, smoothing, and masking of sea ice, while the SMOS product showed the highest SSS deviation that is likely due to the bias‐adjustment done on the data set. Our analyses show that SSS in the Southern Ocean region has significant meridional variations with the lowest SSS near the ice edge and highest at lower latitudes. The SSS is also lowest in summer indicating the predominant influence of sea ice and glacial melt, but it stays low near ice edges even during the growth season.

Statistical Assessment of Sea-Surface Salinity from SMAP: Arabian Sea, Bay of Bengal and a Promising Red Sea Application

“…and histograms were calculated for each SMAP product for the collocated datasets to assess SMAP performance in the North Indian Ocean in both the spatial and temporal domains. These statistics are generally used in studies evaluating satellite salinity observations [1,3,8,9,12,13,[16][17][18]21,61].…”

Simulation Framework and Case Studies for the Design of Sea Surface Salinity Remote Sensing Missions

“…Accurate study of the connections between ocean salinity and ice melt in cold water systems such as the Arctic and Southern oceans will also become more important as warming continues to impact these regions. It will be imperative for future remote sensing missions to accurately characterize seasonal trends in these regions, and there is evidence to suggest that even considerable time-averages of current spacecraft products are not capable of such characterization [51]. From our case studies, we conclude that wideband and targeted revisit systems are capable of meeting these challenges and broadly improving the state of the art in SSS remote measurement.…”

“…Due to the lower sensitivity of satellite salinity measurements over colder waters, identification of front boundaries from such measurements is limited to averages over long periods of time. Additionally, different satellite products demonstrate different local and seasonal trends [51]. We consider here the challenge of accurately measuring SSS over the Southern Ocean so that the locations of front boundaries are clearly visible.…”

Documenting the impacts of increasing salinity in freshwater and coastal ecosystems: Introduction to the special issue

“…We conclude that the need to better understand lake and coastal salinization impacts on plankton communities will intensify with global climate change in most parts of the world (Jeppesen et al 2015), and impacts will vary regionally. For example, in regions receiving large freshwater inputs from melting glaciers, salinity will decrease (Garcia-Eidell et al 2019). In the search for solutions to FSS impacts, effective management practices that adjust for regional variability (e.g., calcium levels, additional contaminant pressures, changing climate and precipitation patterns) in ecosystem and community responses will help prevent costly impacts.…”