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).


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…


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 …


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.

radiomètre lewis

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

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