End of of the SMOS fortnight at ESAC !!

Category : CATDS, Tools, Training

A very busy two weeks at ESAC have just finished.

First a training course took place at ESAC during one week (May 18-22). It was the third SMOS training course but this time ESA took care (very efficiently!) of the logistics and provided us with very nice facilities (thank you Antonio!!)

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(all photos courtesy of Ali Mahmoodi)

This training course was aimed at newcomers wanting to learn how to use SMOS. With lectures intersped with practicals the students (18) were intitated into the different SMOS levels. The course also included a visit of the ESAC facilities together with a fine « BBQ ».

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Some of the students stayed on to take advantage of the SMOS Conference which was also a success . The presentations covered all the SMOS aspects together with presentations and posters of equivalent missions (Aquarius and SMAP) recent results and synergisms. Evening were busy with spontaneous picnics and a gorgeous banquet

The presentations will be made available by ESA on its SMOS conference site.

Towards a Flood risk alert system with SMOS?

Category : CATDS, L3, L4

SMOS gives almost real time information on soil moisture. At CESBIO / CATDS we had the idea to investigate with Capgemini how such a piece of crucial information could be used to anticipate flood risks. Using the Capgemini « Rodger » platform, we merged SMOS historical records of Soil Moisture, SMOS actual surface soil moisture information and rainfall forecasts to build a flood risk indicator.

Even though our approach is still in infancy and there are still a number of open issues to sort out (not mentioning when the extreme rainfall forecast are inadequate) we score  several successes during the past months and most notably during the recent floods in Morocco which occurred a few days ago.

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flood risks as obtained on November 22nd, 2014

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Same for November 25, 2014

So some work is still to be done but we are getting there!

Stay tuned!

Ahmad, Audrey, Julien, Sat and Yann

LEWIS is on the move! Part One

Category : Cal/Val, Data, ground measurements

Back in 2002 we had a high quality ground based radiometer built by ONERA (Jean Claude Poussière and François Lemaître) with CNES funding (TOSCA) (see Lemaitre et al, IEEE). This radiometer was installed in a fallow field south of Toulouse together with classical equipment to monitor the various meteorological and soil variables (see de Rosnay et al, 2006). In 2011 a COSMOS probe was added to the set up  (for more info see here).

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LEWIS during tests before implementation (2002)

From January 2003 to last year the set up worked almost continuously (there was one big maintenance though) providing a wealth of measurements in all possible conditions (wet years, dry years, snow, freezing soils, storms etc….) with L band dual polarised data acquired at angles from 20 to 60° on both bare soil and fallow land.  Moreover, on several occasion we did specific campaigns  for instance to alter roughness over a large range of values etc). This gave way to a number of publications and helped improving LMEB and the L2 retrieval algorithm sub models…

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Lewis in operation at the SMOS REX site near Toulouse

The data set is available for other research purposes. Just ask if you need part of the data set (yann.kerr@cesbio.cnes.fr). During this whole period, with only one maintenance stop, the instrument worked extremely well with a remarkable stability and accuracy. It even went through a bush fire unscathed!

But after 9 years in operation we decided it might be useful to go to other places and, in collaboration with ONERA (F Lemaître), INRA ISPA (Jean Pierre Wigneron as always since start !) and LTHE (Thierry Pellarin) we looked for, and found, an adequate location close to …

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The idea was to find a site where we could have more occurrences of snow and cold weather but mainly a set up offering a capacity to have well characterized mixed footprints.

Finally Arnaud and Thierry found a place satisfying all criteria close to Grenoble and we started the move … The first step was to refurbish LEWIS and replace the filters (to reduce RFI risks) this was promptly done in 2012. More complicated was setting up the site as it is located in altitude and we had to have a platform overhanging the valley built, we had to have energy brought to the site and to develop the mechanisms to point the antenna.

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Testing the controllers in a warmer (!??) and safer place than on top of the cliff!

This was done during this last winter but we then had to wait for the of the winter and snow melt before we coudl transport and finally implement our equipment on site …

This will be described in part two together with the first plots

SMOS dielectric constant product and its uses during the last cold spell in Europe

Category : CATDS, L2, L4

SMOS delivers one « strange » or rather unusual product which is an estimate of the surface dielectric constant (see ATBD!). A example of it’s potential use is shown below with the fields of dielectric constant estimated over Europe for two periods corresponding to the arrival of a cold front over Western Europe. The first picture corresponds to the period going from January 28 to 31 2012. The cold spell is arriving but not quite there yet. The second picture shows the dielectric constant for the period going from February 2nd to 5th, 2012. As one might remember, it was quiet cold and soil was often frozen while snow was widely spread over Europe (and quite dry as it was cold). The dielectric constant consequently dropped significantly. This can been seen on the pictures with the dielectric constant dropping from values equivalent to wet soils (typically 15) to values for very dry or frozen soils (1 to 3) which gives this more blueish shade.

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January 28 to 31:  western Europe is grayish white hence high dielectric constant values …

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February 2-5, 2012. Western Europe is under snow or frozen, … much lower values of the dielectric constant.

Al Bitar and al, CESBIO

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