New SMOS Sea Surface Salinity with reduced systematic errors and improved variability

Boutin, Jacqueline; Vergely, Jean‐Luc; Marchand, Stéphane; D'Amico, Francesco; Hasson, Audrey; Kolodziejczyk, Nicolas; Reul, Nicolás; Reverdin, Gilles; Vialard, Jérôme

doi:10.1016/j.rse.2018.05.022

Cited by 149 publications

(128 citation statements)

References 45 publications

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“…The SMOS data pre‐processing described by Boutin et al . () includes a latitudinal and seasonal adjustment separately for ascending and descending orbits on a monthly basis. These adjustments neglect interannual effects that could result from variations in Sun activity which was particularly strong in 2014 (see for example Clette et al, ) and so is likely to be the cause of this larger Northern Hemisphere negative bias in the descending SMOS data (Boutin, personal communication, May 2018).…”

Section: Resultsmentioning

confidence: 99%

“…The SMOS data processing carried out by LOCEAN (Boutin et al, ) involves taking the L2 data from ESA, carrying out various steps to address uncertainties in the data, including a method to remove the long‐term climatological difference between the satellite data and in situ estimates from a global analysis of Argo data, In Situ Analysis System (ISAS‐13: Gaillard et al ., ), before averaging onto a 25 km grid. Separate ascending and descending files are used on each day.…”

Section: Input Observations and Pre‐processingmentioning

confidence: 99%

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Assimilating satellite sea‐surface salinity data from SMOS, Aquarius and SMAP into a global ocean forecasting system

Martin

King

While

et al. 2019

Quart J Royal Meteoro Soc

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Funding informationESA.Measuring Sea-Surface Salinity (SSS) from space is a relatively recent technique that relies on L-band radiometry that has evolved to a point where useful information is provided every few days. The impact of assimilating satellite SSS data is investigated using the global FOAM ocean forecasting system. This system assimilates daily satellite SSS products from the ESA Soil Moisture and Ocean Salinity (SMOS), NASA Aquarius and Soil Moisture Active Passive (SMAP) missions equatorward of 40 • N/S, in addition to other observing systems. The data are assimilated using a 3D-Var scheme that includes an observation bias correction scheme to estimate spatially and temporally varying bias estimates for each SSS satellite. The SSS assimilation is tested over 2 years and 3 months covering the 2015/2016 El Niño with assessment focussed on the tropical regions, particularly in the Pacific. Consistent reductions in root-mean-square errors are found in all tropical regions from each of the satellite SSS datasets. The largest improvements of up to about 8% are found in the tropical Pacific from assimilating both the SMOS and SMAP datasets together. The largest impact is in the intertropical convergence zone (ITCZ) in the central Pacific during 2015 and early 2016 where the surface salinity is reduced by about 0.03 pss on average, correcting for too little precipitation. A smaller magnitude, large-scale reduction in the SSS is also seen in the tropical Pacific that increases the modelled surface stratification and leads to reduced vertical mixing. Changes to the SSS in the ITCZ lead to changes in the meridional gradients of SSS that affects the sea surface height and surface currents, both of which are improved in the SMOS assimilation experiment compared to externally produced observation-based datasets. The results suggest that assimilation of SMOS and SMAP satellite data is now of an appropriate quality for operational implementation. 1Ocean Assimilation Model (FOAM) system (Blockley et al., 2014) produces daily analyses and 7-day forecasts of the three-dimensional ocean and sea-ice state, including temperature, salinity and velocity. The same system is also used to produce reanalyses over the satellite altimeter era in order to calibrate seasonal forecasts (MacLachlan et al., 2015).The observing systems routinely assimilated in FOAM include in situ and satellite sea-surface temperature (SST) This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.

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Section: Resultsmentioning

confidence: 99%

Section: Input Observations and Pre‐processingmentioning

confidence: 99%

Assimilating satellite sea‐surface salinity data from SMOS, Aquarius and SMAP into a global ocean forecasting system

Martin

King

While

et al. 2019

Quart J Royal Meteoro Soc

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“…These maps are available every 4 days. This product features a methodology for the removal of coastal and latitudinal SSS biases based on an update of Kolodziejczyk et al (2016) and further described by Boutin et al (2018).…”

Section: Data Setsmentioning

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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“…The ESA's Soil Moisture and Ocean Salinity (SMOS) SSS product used is the LOCEAN level 3 V3 9-day composite maps produced by LOCEAN/ACRI-ST, obtained from the Centre Aval de Traitement des Données SMOS from 4 January 2010 to present at 25-km resolution. This debiased version 3 product improves upon the previous version 2 product with better adjustment for land-sea bias close to the coast and high latitudinal biases (Boutin, Vergely, & Khvorostyanov, 2018;Boutin, Vergely, Marchand, et al, 2018). The monthly averages of both SMAP and SMOS SSS data sets were computed for this study.…”

Section: Methodsmentioning

confidence: 99%

Loop Current and Eddy‐Driven Salinity Variability in the Gulf of Mexico

Brokaw

Subrahmanyam

Morey

2019

Geophysical Research Letters

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The Loop Current System, involving the Loop Current and Loop Current Eddies, is the principal circulation feature in the Gulf of Mexico, which exhibits salinity gradients due to Mississippi River system freshwater discharge and large salinity variability on seasonal timescales. This research uses satellite‐derived sea surface salinity from NASA's Soil Moisture Active Passive and ESA's Soil Moisture and Ocean Salinity missions with altimetric sea surface height data to observe and quantify the redistribution of low‐salinity water by Loop Current System interaction. Freshwater flux in this region during summer months is modulated by Loop Current System configuration as classified by three states. An extended Loop Current transports low‐salinity water southward to the Florida Straits. A Loop Current eddy near the Louisiana‐Texas shelf recirculates low‐salinity water within the central Gulf. During a retracted Loop Current, no interaction occurs and low‐salinity water remains close to the coast in the northern Gulf.

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New SMOS Sea Surface Salinity with reduced systematic errors and improved variability

Cited by 149 publications

References 45 publications

Assimilating satellite sea‐surface salinity data from SMOS, Aquarius and SMAP into a global ocean forecasting system

Assimilating satellite sea‐surface salinity data from SMOS, Aquarius and SMAP into a global ocean forecasting system

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

Loop Current and Eddy‐Driven Salinity Variability in the Gulf of Mexico

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