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Large scale SSS contrasts detected by SMOS and in situ SSS analysis in the tropical Pacific and Indian Oceans

6 mars 2013

Recent results from LOCEAN  team

Variability in the tropical Pacific and Indian Oceans between 2010 and 2011 is very large linked to the ending 2009-2010 El Nino, 2010 strong La Niña and 2011 weak La Niña events, and to negative Indian Ocean Dipole (IOD) in 2010 (see Figure below).

imageJB

figure1 Time series of SST anomalies in the four Niño regions from http://www.cpc.ncep.noaa.gov/data/indices/sstoi.indices in 2010-2011 and corresponding Indian Ocean Dipole (IOD) Index (SST difference between eastern and western equatorial Indian Ocean) from the Australian bureau of Meteorology.

animIOD20112010

Large scale SSS variability is very consistently observed on SMOS SSS maps (1) compared with ISAS SSS maps (2) derived from in situ (ARGO floats and ship data) measurements, as seen on the film. SMOS anomalies are often more contrasted than ISAS anomalies due to fresher SMOS SSS in fresh regions associated with rain (Boutin et al., 2013). Signal is much noisier from January to May due to worse SMOS SSS quality during commissioning phase in January-May 2010, but nevertheless spatial structures of anomalies remain very consistent with ISAS maps.

(1) SMOS SSS maps are generated using ESA reprocessing version 5 as described in J. Boutin, N. Martin, G. Reverdin, X. Yin and F. Gaillard, Sea surface freshening inferred from
SMOS and ARGO salinity: Impact of rain, Ocean Sci., 9, 183-192, doi:10.5194/os-9-183-2013, 2013.

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Posté dans CATDS, Cal/Val, L2, Ocean

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UPDATE on the SMOS products versions

26 avril 2012
As indicated earlier the New reprocessed SMOS data is available. It is the so called version 5
The different readme files are available on the ESA web site
ALL the LEVEL 1, 2SM and 2 OS have been reprocessed from January 2010 to the end of 2011 and the  processor (operational) is also running with the very same version so from January 2010 to April 2012 all the data has been processed uniformly and is available from ESA
For soil moisture a  new version of the Level 2 Soil Moisture processor (V5.51) has been deployed in the operational chain on 24 April 2012. The first data set generated with the new processor has the start acquisition time of 23 April 2012 08:35 UTC.

The main difference between V5.51 and previous V5.00 is the change of the dielectric constant model used in the retrieval algorithm. Processor version V5.51 uses the Mironov formulation instead of the Dobson Model. This change improves the soil moisture estimates, increases the number of successful retrievals over dry and warm surfaces and reduces extreme values of soil moisture.

The processor improvements and other associated information are summarised in the Level 2 SM read-me-first note.

Soil Moisture data users are strongly encouraged to consult the above mentioned Level 2 SM read-me-first n

Except for very arid areas we do not expect drastic changes  we will not reprocess the whole data just now.

FEED BACK is most welcome as usual

The SMOS TEAM

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Posté dans Cal/Val, Data, L1, L2, Non classé

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SMOS and Altimetry join forces to monitor horizontal advection of the Amazon Freshwater Plume

27 juin 2011

Horizontal advection of the Amazon Freshwater Plume at the surface of the North Western Tropical Atlantic as detected in 2010 by SMOS and Altimetry

By Nicolas Reul and Joe Tenerelli
See more on Ifremer website

Legend: animation showing the daily SSS in the North western Tropical Atlantic computed by averaging SMOS retrievals over a +/- 5-days running window. Superimposed are the AVISO surface currents (black arrows) derived  from merged altimeter data.The solid thick gray contours represent the vorticity for anticyclonic eddies (clockwise rotation or negative vorticity)  and the dashed one represent the vorticity for cyclonic eddies.
As illustrated, a very good visual consistency is found between the altimetric surface current patterns and the SMOS SSS spatio-temporal distribution along the year.
At the begining of june, the freshwater input at the mouth of the Amazon river is seen to be transported more than 2000 km north westward at the ocean surface and seems to travel as a passive tracer meandering in between  a succession of antycylonic/cyclonic eddy pairs, acting as a gear cluster for this large scale oceanic freshwater pump.

freshwaterpass_jun1

Legend: schematic view of the northwestward transport of freshwater from the Amazone river mouth to the subtropical gyre advected in surface current convergence zones  through a succession of pairs of cyclonic (C) and anti-cyclonic (A) eddies.

Go to the Ifremer Web page indicated above to have all the relevant info!

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Posté dans CATDS, Ocean

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Soil Moisture or Ocean Salinity? You can have them Both !

8 octobre 2010

François Cabot and Nicolas Reul, in the framework of CATDS joined forces to produce this first ever global map of sea surface salinity and Soil moisture all produced with the same instrument: SMOS!

SM_SSS

SMOS data used to obtain this level 3 were acquired over the month of August 2010.

Some imperfections are still visible but the Level 1 and level 2 teams are working hard on solving them!

Stay tuned!

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Posté dans CATDS, Data, L3

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