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.

A new tool for accessing SMOS level 3 data is available (CATDS)

Category : CATDS, L3, L4

You can now access the data from the CATDS production center with our new tool : the Sipad.

The Sipad is a web-based interactive tool which allows sub settings (geographical or by groups of parameters) and temporal aggregation.
The Sipad is available at www.catds.fr/sipad/
A registration is required. The login/password used for FTP access do not work.

New version of the level 3 product is now available

Category : CATDS, L3

Dear  SMOS L3 user,

Since June 24, 2013 (Day of the Year 175), the new version 2.60 of the level 3 processor has been implemented.

It is an important step as the MIRONOV dielectric model is used instead of the Dobson’s one. For those who are familiar with the level 2 data, it is aligned with the V6.0 level 2 processor.

Be careful as you may observe a change in the derived soil moisture as a consequence. A complete reprocessing will be done later this year to have a homogeneous time series. In the mean time be aware of the discrepancy between the two versions and , keep in mind this comment.

To summarize

*) for the new algorithm use products with  « 260 » in the name (referring to the processor used)

e.g., SM_OPER_MIR_CLF31A_20130624T000000_20130624T235959_260_001_7.tgz

*) All lower versions (typically 2.5, 2.4) use the Dobson’s model and are thus prone to be « dryer »

the L3 team