Sea Surface Salinity as a Proxy for Arctic Ocean Freshwater Changes

Fournier, Séverine; Lee, Tong; Wang, Xiaochun; Armitage, Thomas; Wang, Ou; Fukumori, Ichiro; Kwok, R.

doi:10.1029/2020jc016110

Cited by 28 publications

(22 citation statements)

References 60 publications

(80 reference statements)

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“…Arctic Ocean salinity is a key element of seasonal and interannual variability [1]. In this paper, we provide a comparison regarding modeled, remotely sensed, and directly observed salinity in the Arctic Ocean.…”

Section: Introductionmentioning

confidence: 99%

Intercomparison of Salinity Products in the Beaufort Gyre and Arctic Ocean

2021

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Salinity is the primary determinant of the Arctic Ocean’s density structure. Freshwater accumulation and distribution in the Arctic Ocean have varied significantly in recent decades and certainly in the Beaufort Gyre (BG). In this study, we analyze salinity variations in the BG region between 2012 and 2017. We use in situ salinity observations from the Seasonal Ice Zone Reconnaissance Surveys (SIZRS), CTD casts from the Beaufort Gyre Exploration Project (BGP), and the EN4 data to validate and compare with satellite observations from Soil Moisture Active Passive (SMAP), Soil Moisture and Ocean Salinity (SMOS), and Aquarius Optimally Interpolated Sea Surface Salinity (OISSS), and Arctic Ocean models: ECCO, MIZMAS, HYCOM, ORAS5, and GLORYS12. Overall, satellite observations are restricted to ice-free regions in the BG area, and models tend to overestimate sea surface salinity (SSS). Freshwater Content (FWC), an important component of the BG, is computed for EN4 and most models. ORAS5 provides the strongest positive SSS correlation coefficient (0.612) and lowest bias to in situ observations compared to the other products. ORAS5 subsurface salinity and FWC compare well with the EN4 data. Discrepancies between models and SIZRS data are highest in GLORYS12 and ECCO. These comparisons identify dissimilarities between salinity products and extend challenges to observations applicable to other areas of the Arctic Ocean.

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Section: Introductionmentioning

confidence: 99%

Intercomparison of Salinity Products in the Beaufort Gyre and Arctic Ocean

2021

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“…The development of this CCI L4 version 2 algorithm focused on low to mid latitudes regions where satellite SSS datasets were the most mature. Recent products (Brucker et al., 2014; Olmedo et al., 2018; Supply, Boutin, Vergely et al., 2020; Tang et al., 2018) are nevertheless achieving a useful accuracy for detecting Arctic Ocean freshwater changes (Fournier et al., 2020), changes in river plumes extent (Vazquez‐Cuervo et al., 2021) and their relations to wind atmospheric forcing (Tarasenko et al., 2021). Hence keeping the best potentialities demonstrated with the existing datasets associated with the three satellite missions at high latitudes will be another remaining main challenge for the future research and developments of CCI + SSS merging algorithms.…”

Section: Discussion and Perspectivesmentioning

confidence: 99%

Satellite‐Based Sea Surface Salinity Designed for Ocean and Climate Studies

et al. 2021

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Sea Surface Salinity (SSS) is an increasingly used Essential Ocean and Climate Variable. The Soil Moisture and Ocean Salinity (SMOS), Aquarius, and Soil Moisture Active Passive (SMAP) satellite missions all provide SSS measurements, with very different instrumental features leading to specific measurement characteristics. The Climate Change Initiative Salinity project (CCI + SSS) aims to produce a SSS Climate Data Record (CDR) that addresses well‐established user needs based on those satellite measurements. To generate a homogeneous CDR, instrumental differences are carefully adjusted based on in‐depth analysis of the measurements themselves, together with some limited use of independent reference data. An optimal interpolation in the time domain without temporal relaxation to reference data or spatial smoothing is applied. This allows preserving the original datasets variability. SSS CCI fields are well suited for monitoring weekly to interannual signals, at spatial scales ranging from 50 km to the basin scale. They display large year‐to‐year seasonal variations over the 2010–2019 decade, sometimes by more than ±0.4 over large regions. The robust standard deviation of the monthly CCI SSS minus in situ Argo salinities is 0.15 globally, while it is at least 0.20 with individual satellite SSS fields. r2 is 0.97, similar or better than with original datasets. The correlation with independent ship thermosalinographs SSS further highlights the CCI data set excellent performance, especially near land areas. During the SMOS‐Aquarius period, when the representativity uncertainties are the largest, r2 is 0.84 with CCI while it is 0.48 with the Aquarius original data set. SSS CCI data are freely available and will be updated and extended as more satellite data become available.

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“…According to [26][27][28], the root-mean-square difference (RMSD) between SSS satellite data and in situ observation is about 1 PSS-78 [29] north of 50 • N, which is much larger than the overall RMSD of 0.2 PSS-78 between 40 • S and 40 • N. Despite the uncertainties, remote sensing salinity was found to capture successfully the large salinity changes in the Arctic [30][31][32]. SSS averaged over the Arctic basin usually obtain encouraging results and the basin mean SSS displayed consistent annual and interannual variability with in situ products [32,33]. In addition, satellite salinity was also combined with ocean color data to quantify the river plume and infer a different freshwater source in the Arctic Ocean [34,35].…”

Section: Introductionmentioning

confidence: 99%

Sea Surface Salinity Variability in the Bering Sea in 2015–2020

et al. 2022

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Salinity in the Bering Sea is vital for the physical environment that is tied to the productive ecosystem and the properties of Pacific waters transported to the Arctic Ocean. Its salinity variability reflects many fundamental processes, including sea ice formation/melting and river runoff, but its spatial and temporal characteristics require better documentation. This study utilizes remote sensing products and in situ observations collected by saildrone missions to investigate Sea Surface Salinity (SSS) variability. All Satellite products resolve the large-scale pattern set up by the relatively salty deep basin and the fresh coastal region, but they can be inaccurate near the ice edge and near land. The SSS annual cycle exhibits seasonal maxima in winter to spring, and minima in summer to fall. The amplitude and timing of the seasonal cycle are variable, especially on the eastern Bering Sea shelf. SSS variability recorded by both saildrone, and satellite instruments provide unprecedented insights into short-term oceanic processes including sea ice melting, wind-driven currents during weather events, and river plumes etc. In particular, the Soil Moisture Active Passive (SMAP) satellite demonstrates encouraging skills in capturing the freshening signals induced by spring sea ice melting. The Yukon River plume is another source of intense SSS variability. Surface wind forcing plays an essential role in controlling the horizontal movement of plume water and thereby shaping the SSS seasonal cycle in local regions.

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Sea Surface Salinity as a Proxy for Arctic Ocean Freshwater Changes

Cited by 28 publications

References 60 publications

Intercomparison of Salinity Products in the Beaufort Gyre and Arctic Ocean

Intercomparison of Salinity Products in the Beaufort Gyre and Arctic Ocean

Satellite‐Based Sea Surface Salinity Designed for Ocean and Climate Studies

Sea Surface Salinity Variability in the Bering Sea in 2015–2020

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