Signature of mesoscale eddies in satellite sea surface salinity data

Melnichenko, Oleg; Amores, Ángel; Maximenko, Nikolai; Hacker, Peter; Potemra, James T.

doi:10.1002/2016jc012420

Cited by 57 publications

(66 citation statements)

References 33 publications

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“…Notable in this regard are the key contributions of the SSS data sets issued from the Soil Moisture and Ocean Salinity (SMOS; 2010 and ongoing), Aquarius (2011–2015), and Soil Moisture Active Passive (2015 and ongoing) satellite missions (Kerr et al, ; Lagerloef et al, ; Reul et al, ; Tang et al, ). Based on these satellite data sets, the signature of mesoscale variability and eddies on SSS has been documented in various regions, in particular, in the North Atlantic subtropical gyre, in the Gulf Stream region, in the Gulf of Mexico, in the Bay of Bengal, in the southern Indian Ocean, and in line with the occurrence of tropical instability waves in the Atlantic and Pacific Oceans (Fournier et al, , ; Kolodziejczyk et al, ; Lee et al, , ; Melnichenko et al, ; Reul et al, ; Yin et al, ). Despite these few studies, little is known about the eddy‐induced SSS changes, especially in tropical regions where the influence of mesoscale eddies on SSS remain poorly documented in the literature compared to the influence of the large‐scale circulation, climate modes, and long‐term trends.…”

Section: Introductionmentioning

confidence: 99%

Eddy‐Induced Salinity Changes in the Tropical Pacific

et al. 2019

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The signature of westward propagating mesoscale eddies in sea surface salinity (SSS) is analyzed for the tropical Pacific by collocating 7 years (2010)(2011)(2012)(2013)(2014)(2015)(2016) of Soil Moisture and Ocean Salinity SSS satellite data with coherent mesoscale eddies automatically identified and tracked from altimetry-derived sea level anomalies. First, the main characteristics of the long-lived coherent eddies are inferred from sea level anomalies maps. Then, the mean signature of the mesoscale eddies on SSS is depicted for the whole tropical Pacific before focusing in regions centered around the central and eastern parts of the tropical North Pacific. In these areas, composite analyses based on thousands of eddies reveal regionally dependent eddy impacts with opposite SSS anomalies for cyclonic and anticyclonic eddies. In the central region, where the largest meridional SSS large-scale gradients and smallest eddy amplitudes are observed, results show dipole-like SSS changes with maximum anomalies on the leading edge of the composite eddy. In contrast, in the eastern region, where the largest near-surface vertical salinity gradients and largest eddy amplitudes are observed, the composite eddy shows monopole-like SSS changes with maximum anomalies near the composite eddy center. These distinct dipole/monopole SSS patterns suggest the dominant role of horizontal advection and vertical processes in the central and eastern regions, respectively. Other possible explanations, notably one involving the contrasted eddy amplitudes of the two regions, are discussed.Plain Language Summary Sea surface salinity (SSS) is an Essential Climate Variable needed to improve our knowledge of the Earth's water cycle and climate. SSS has proven to be valuable for improving estimates of evaporation minus precipitation (E − P) budgets, describing and understanding climate variability at seasonal to decadal time scales, testing physical processes, assessing numerical model skills, quantifying the role of salinity on sea level change, improving El Nino prediction lead time, and quantifying the ocean-atmosphere CO 2 exchanges. Very few studies have, however, focused on what we call small-scale (that is mainly eddies of the order of 50-to 300-km radius) SSS changes in the open ocean, mainly due to the lack of high-resolution measurements. Relying on unprecedented satellite measurements of SSS, the present study shows how eddies in the tropical Pacific can modify the spatial distribution of SSS. We suggest that these modifications are likely due (i) to the rotational sense of the eddies, which move SSS horizontally, and (ii) to their capability to move or mix waters up and down while rotating.

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Section: Introductionmentioning

confidence: 99%

Eddy‐Induced Salinity Changes in the Tropical Pacific

et al. 2019

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“…Satellite missions have revealed that SSS anomalies associated with eddies can be monitored for months near river outflows (Fournier, Vandemark, et al, ; Fournier, Vialard, et al, ) and large anomalies can be seen in the tropical Pacific Ocean following El Niño and La Niña events (Hasson et al, , ). Studies have also shown that remotely sensed SSS in the tropical Pacific Ocean be used to trace mesoscale features such as tropical instability waves (Lee et al, ; Melnichenko et al, ; Yin et al, ) and heavy rainfall associated with large convective cells in the ITCZ (Supply et al, ).…”

Section: Introductionmentioning

confidence: 99%

Intraseasonal Variability of Surface Salinity in the Eastern Tropical Pacific Associated With Mesoscale Eddies

et al. 2019

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Strong variability in sea surface salinity (SSS) in the Eastern Tropical Pacific (ETPac) on intraseasonal to interannual timescales was studied using data from the Soil Moisture and Ocean Salinity, Soil Moisture Active Passive, and Aquarius satellite missions. A zonal wave number‐frequency spectral analysis of SSS reveals a dominant timescale of 50–180 days and spatial scale of 8°–20° of longitude with a distinct seasonal cycle and interannual variability. This intraseasonal SSS signal is detailed in the study of 19 individual ETPac eddies over 2010–2016 identified by their sea level anomalies, propagating westward at a speed of about 17 cm/s. ETPac eddies trap and advect water in their core westward up to 40° of longitude away from the coast. The SSS signatures of these eddies, with an average anomaly of 0.5‐pss magnitude difference from ambient values, enable the study of their dynamics and the mixing of their core waters with the surroundings. Three categories of eddies were identified according to the location where they were first tracked: (1) in the Gulf of Tehuantepec, (2) in the Gulf of Papagayo, and (3) in the open ocean near 100°W–12°N. They all traveled westward near 10°N latitude. Category 3 is of particular interest, as eddies seeded in the Gulf of Tehuantepec grew substantially in the vicinity of the Clipperton Fracture Zone rise and in a region where the mean zonal currents have anticyclonic shear. The evolution of the SSS signature associated with the eddies indicates the importance of mixing to their dissipation.

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“…Some research reveals the SSS signals that were not captured by the in situ data. For example, Aquarius SSS data captures many fine scale ocean structures, including the salinity fronts in the tropical Pacific [3], tropical instability waves in both the Pacific and Atlantic [4], the haline wake over the Amazon plume after the passage of hurricanes [5], and salinity anomalies and fluxes associated with the ocean eddy field [6].…”

Section: Introductionmentioning

confidence: 99%

Assessment of Aquarius Sea Surface Salinity

et al. 2018

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Abstract:Aquarius was the first NASA satellite to observe the sea surface salinity (SSS) over the global ocean. The mission successfully collected data from 25 August 2011 to 7 June 2015. The Aquarius project released its final version (Version-5) of the SSS data product in December 2017. The purpose of this paper is to summarize the validation results from the Aquarius Validation Data System (AVDS) and other statistical methods, and to provide a general view of the Aquarius SSS quality to the users. The results demonstrate that Aquarius has met the mission target measurement accuracy requirement of 0.2 psu on monthly averages on 150 km scale. From the triple point analysis using Aquarius, in situ field and Hybrid Coordinate Ocean Model (HYCOM) products, the root mean square errors of Aquarius Level-2 and Level-3 data are estimated to be 0.17 psu and 0.13 psu, respectively. It is important that caution should be exercised when using Aquarius salinity data in areas with high radio frequency interference (RFI) and heavy rainfall, close to the coast lines where leakage of land signals may significantly affect the quality of the SSS data, and at high-latitude oceans where the L-band radiometer has poor sensitivity to SSS.

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Signature of mesoscale eddies in satellite sea surface salinity data

Cited by 57 publications

References 33 publications

Eddy‐Induced Salinity Changes in the Tropical Pacific

Eddy‐Induced Salinity Changes in the Tropical Pacific

Intraseasonal Variability of Surface Salinity in the Eastern Tropical Pacific Associated With Mesoscale Eddies

Assessment of Aquarius Sea Surface Salinity

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