Happy Birthday SMOS!

Category : CATDS, Data, L3

Yes SMOS has been orbiting the Earth for over 5 years now!

And SMOS has been granted an extension which should take us for another 5 years.

To Celebrate just look at this animation prepared by Ahmad Albitar based on the SMOS median soil moisture retrievals. Just  click, look and you will see many features…. The red bars in the bottom indicate the months of the pictures . It is a 3 months running window.


Or, in term of brightness temperatures, (still done by Ahmad)  but in percentiles with also many features to be seen!


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
- 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) »

Your feed back is more than welcome!


Wet or very wet?

Category : CATDS, L3

Last winter was rather warm and very wet in western Europe while in the US and Canada it was cold or rather very cold!

We looked at the SMOS data collected over Europe as obtained from CATDS and Arnaud extracted the wettest value over ten day periods (here ascending orbits) as shown on the animation below ( to see the animation click on it)

animation-max_ascFig1: maximum soil moisture (around 6 am) over successive ten day periods from January 1 to February 10 2014 as measured by SMOS.

One can see that in Ireland, SW England , W France and SW France soil moisture saturates (value at or above field capacity) indicating sodden soils with heaving pounding. If we look at the product proving minimum value fro the descending orbits we see that even at the driest if was not always completely dry.

animation-min_dscFig2: minimum soil moisture (around 6 pm) over successive ten day periods from January 1 to February 10 2014 as measured by SMOS.

Even in the driest state, note that in some areas the soils are still quite wet.

These picture show how we can track saturated to flooded areas with SMOS. Also note the impact of RFI in some areas , giving rather dry soils when / where not expected.

Using SMOS to analyze the variability of the South Pacific Sea Surface Salinity maximum

Category : L3, Ocean

By Jacqueline BOUTIN

Understanding the variability of high-salinity surface waters, as shown in Fig. 1 for the south-eastern tropical Pacific, is important to improve our interpretation of climate and hydrological cycle changes at different time scales. SMOS CATDS-CEC LOCEAN SSS products have been used , in complement to Voluntary Observing Ships (VOS) thermo-salinograph data obtained from the French SSS Observation Service, to validate and understand the seasonal variability of the South Pacific Sea Surface Salinity maximum simulated by an ocean general circulation model with no direct SSS relaxation.


Fig. 1. Mean 1990-2011 modelled mixed-layer salinity. The blue lines represent the Matisse Ship routes of 2010 and 2011.

All products reveal a consistent seasonal cycle of the displacement of the 36-isohaline barycenter (Fig. 2; about +/-400 km in longitude) in response to changes in the South Pacific Convergence Zone location and Easterly winds intensity respectively associated with changes in precipitation and evaporation.


Fig.2. Location of isohaline 36 (simulated) and of its barycentre (dots: model; stars: SMOS) for various months (colors).

The SSS from 8 VOS transects compare remarkably well with collocated SMOS SSS averaged over 100km, 18 days (std difference=0.2), as exemplified in Fig. 3 along a shipping track running from New Zealand to Panama ; the comparison with simulated SSS is slightly degraded due to a few degrees latitudinal shift of the simulated SSS maximum (std difference=0.26).


Fig. 3. Example of comparison between SMOS (dots), VOS (straight line), and simulated (dashed line) SSS as a function of latitude.

Model results and in situ measurements further indicate a low frequency westward shift of the 36-isohaline barycenter (about 1400 km since 1992) that could not be linked to ENSO and may reflect the signature of decadal changes and/or global warming.

Details can be found in: Hasson, A., T. Delcroix, and J. Boutin (2013), Formation and variability of the South Pacific Sea Surface Salinity maximum in recent decades, J. Geophys. Res. Oceans, 118, doi:10.1002/jgrc.20367.