SMOS and La Niña signature.... Analyzing the 2010-2011 La Niña signature in the tropical Pacific sea surface salinity using in situ data, SMOS observations and a numerical simulation Audrey Hasson(1, *), Thierry Delcroix(1), Jacqueline Boutin(2), Raphael Dussin(3), Joaquim Ballabrera-Poy(4) The tropical Pacific Ocean remained in a La Niña phase from mid 2010 to mid-2012. The near-surface...

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A SSS trip from the surface to the thermocline... By Christophe Maes Retrievals of the Sea Surface Salinity from space-borne mission like SMOS or Aquarius SAC-D provide for the first time an essential variable in the determination of ocean mass. If the field will reveal a lot of new signal at the surface its influence on the ocean dynamics is even more important at depths where it participates to the stratification...

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SMOS Level3 Catch Up data available! All SMOS L3 soil moisture products and SMOS L3 brightness temperature products from January 2010 to December 2013 have just been reprocessed and are available as usual on the CATDS FTP server (NB for new users,  please contact support@catds.fr. to gain access) This catch up processing harmonizes the whole data set to the version currently running on the operational...

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SMOS and Hurricane tracking! Nicolas Reul and his team have been busy finding ways to better track, monitor, tropical storms and hurricane (high wind speed) from SMOS data as depicted in several previous posts on this very blog. Following this, in the framework of the ESA STSE- SMOS+STORM Evolution project a more exhaustive study was initiated as shown on their page. Just to whet your appetite...

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Great News! SMOS Extension in good shape As you might well be aware SMOS was intended to be operated for five years and, this coming November, the 5 year period will be finished. So both the Centre National d'Etudes Spatiales (CNES) through the REDEM process and the European Space Agency analysed possibility to extend SMOS mission. The CNES’ SMOS extension review took place on 14 April 2014, reviewing the...

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SMOS and « La Niña » signature….

Category : CATDS, L2, Model, Ocean, Satellite

Analyzing the 2010-2011 La Niña signature in the tropical Pacific sea surface salinity using in situ data, SMOS observations and a numerical simulation

Audrey Hasson(1, *), Thierry Delcroix(1), Jacqueline Boutin(2),

Raphael Dussin(3), Joaquim Ballabrera-Poy(4)

The tropical Pacific Ocean remained in a La Niña phase from mid 2010 to mid-2012. The near-surface salinity signature of this cold El Niño-Southern Oscillation (ENSO) phase is shown in the figure below and analysed in Hasson et. al (2014) using a combination of numerical model output, in situ data and SMOS satellite salinity products.

boutin-la nina

Figure: Sea Surface Salinity anomalies relative to each product 2010-2011 monthly climatology (pss) in July 2010 (left panels) and July 2011 (right panels) for (a, d) ISAS in situ product (b, e) SMOS and (c, f) the model. Blue lines represent the Voluntary Observing Ship routes and the 170°E-180° hatched areas computation zones. (Figure from Hasson et al., 2014)

Comparisons of all salinity products show a good agreement between them, with a RMS error of 0.2-0.3 between the thermosalinograph (TSG) and SMOS data and between the TSG and model data. The last 6 months of 2010 (La Niña) are characterized by an unusually strong tri-polar anomaly captured by the three salinity products in the western half of the tropical Pacific. A positive SSS anomaly sits north of 10ºS (>0.5), a negative tilted anomaly lies between 10ºS and 20ºS and a positive one south of 20ºS. In 2011, anomalies shift south and amplify up to 0.8, except for the one south of 20ºS. Equatorial SSS changes are mainly the result of anomalous zonal advection, resulting in negative anomalies during El Niño (early 2010), and positive ones thereafter during La Niña. The mean seasonal and interannual poleward drift then exports those anomalies toward the south in the southern hemisphere, resulting in the aforementioned tripolar anomaly. The vertical salinity flux at the bottom of the mixed layer tends to resist the surface salinity changes. The observed basin-scale La Niña SSS signal is then compared in Hasson et al. (2014) with the historical 1998-1999 La Niña event using both observations and modelling.

for more details see Hasson, A., T. Delcroix, J. Boutin, R. Dussin, and J. Ballabrera-Poy (2014), Analyzing the 2010–2011 La Niña signature in the tropical Pacific sea surface salinity using in situ data, SMOS observations, and a numerical simulation, Journal of Geophysical Research: Oceans, 119(6), 3855-3867, doi:10.1002/2013JC009388.

(1) LEGOS, UMR 5566, CNES, CNRS, IRD, Université de Toulouse 14 avenue Edouard Belin, 31400 Toulouse, France

(2) LOCEAN, UMR7159, CNRS, UPMC, IRD, MNHN, Paris, France

(3) LEGI, Grenoble, France

(4) ICM/CSIC, Barcelona, Spain

(*) Corresponding author,Audrey.Hasson@legos.obs-mip.fr. Currently at the Jet Propulsion Laboratory,California Institute of Technology, Pasadena, California, USA

A SSS trip from the surface to the thermocline…

Category : L2, Non classé, Ocean

By Christophe Maes

Retrievals of the Sea Surface Salinity from space-borne mission like SMOS or Aquarius SAC-D provide for the first time an essential variable in the determination of ocean mass. If the field will reveal a lot of new signal at the surface its influence on the ocean dynamics is even more important at depths where it participates to the stratification of the water column. Concomitant with temperature profiles, reliable in situ observations of salinity at depth are now available at the global ocean scales. Above the main pycnocline (50-250m in the Tropics), Maes and O’Kane (2014) have recently shown that the stabilizing effect due to salinity could be isolated from its thermal counterpart by separating its role in the computation of the buoyancy frequency. In addition, relationships between such salinity stratification at depths and the SSS are shown to be well defined and quasi-linear in the tropics (see figure), providing some indication that in the future, analyses that consider both satellite surface salinity measurements at the surface and vertical profiles at depth will result in a better determination of the role of the salinity stratification in climate prediction systems.

maes

Maes, C., and T. J. O’Kane (2014), Seasonal variations of the upper ocean salinity stratification in the Tropics, J. Geophys. Res. Oceans, 119, 1706–1722, doi:10.1002/2013JC009366.

SMOS Level3 Catch Up data available!

Category : CATDS, L3

All SMOS L3 soil moisture products and SMOS L3 brightness temperature products from January 2010 to December 2013 have just been reprocessed and are available as usual on the CATDS FTP server (NB for new users,  please contact support@catds.fr. to gain access)

This catch up processing harmonizes the whole data set to the version currently running on the operational processor. It corresponds to the ESA level1/ 2 V600
NOTE :
- All the soil moisture products are elaborated using the Mironov model
- All the reprocessed products use the EASE grid. (NB Note the slight discrepancy, the operational products, after January 2014, use the EASE2 grid)
- The reprocessed products are tagged RE02
- The reprocessed Ocean Salinity products are not yet available. They will be at the end of the summer.

DATA POLICY : The CATDS data are freely distributed. However, when using these data in a publication, we request that the following acknowledgement be given :
« These data were obtained from the « Centre Aval de Traitement des Données SMOS » (CATDS), operated for the « Centre National d’Etudes Spatiales » (CNES, France) by IFREMER (Brest, France) »

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SMOS and Hurricane tracking!

Category : CATDS, L2, Ocean

Nicolas Reul and his team have been busy finding ways to better track, monitor, tropical storms and hurricane (high wind speed) from SMOS data as depicted in several previous posts on this very blog.

Following this, in the framework of the ESA STSE- SMOS+STORM Evolution project a more exhaustive study was initiated as shown on their page.

Just to whet your appetite here is a lengthy but interesting animation showing the wind speed retrievals (click on the picture to get it started) over the Pacific ocean

2012_Pacirfic_Hurricane_Season_animationSMOS