SMOS, Soil Moisture and Sea Surface Salinity with Yann Kerr (CESBIO, France)

SMOS, a L Band radiometer using aperture synthesis to achieve a good spatial resolution, was successfully launched on November 2, 2009. It was the first instrument to operate operationally at L band – the first instrument thus to deliver direct estimates of surface soil moisture and sea surface salinity – and the first interferometer flown in space. A true game changer! SMOS carries a single payload, an L band 2D interferometric, radiometer in the 1400-1427 MHz protected band. This wavelength penetrates well through the vegetation and the atmosphere is almost transparent enabling to infer both soil moisture and vegetation water content, the so called L-VOD. SMOS achieves an unprecedented spatial resolution of 50 km at L-band maximum (43 km on average) with multi angular-dual polarized (or fully polarized) brightness temperatures over the globe and with a revisit time smaller than 3 days. SMOS has been now acquiring data for almost 12 years. The data quality exceeds what was expected, showing exceptional sensitivity and stability. The data is however impaired by man-made emission in the protected band, leading to degraded measurements in several areas including parts of Europe and China. Many different international teams are now addressing data use in various fields. We have now acquired data over a number of significant “extreme events” such as droughts and floods giving useful information of potential applications and are now working on the coupling with other models and or disaggregation to address soil moisture distribution over watersheds. Furthermore, we are also concentrating efforts on water budget and regional impacts. From all those studies, it is now possible to express the “lessons learned” and derive a possible way forward. This seminar thus gives an opportunity to present the achievements of the SMOS mission, a description of its main elements, and a taste of the results including performances at brightness temperature as well as at geophysical parameters level and how they are being put in good use in many domains.

Yann Kerr’s fields of interest include the theory and techniques for microwave and thermal infra-red remote sensing of the Earth, with emphasis on hydrology, water resources management and vegetation monitoring. He is involved in many space missions from conception to launch, and post-launch validation as well as to derivation of applications including EOS principal investigator of interdisciplinary investigations from 1990-1999 and PI of the precursor of the use of Scatterometer (SCAT – on board of the European Remote Sensing (ERS) satellite) data over land, Co-investigator on Interface Region Imaging Spectrograph (IRIS), Optical Spectrograph and Infra-red Imager System (OSIRIS), and Hydrosphere State (Hydros) Satellite Mission for NASA. Yann Kerr was science advisor for Multifrequency Imaging Microwave Radiometer (MIMR) and Land Surface Temperature Mission (LSTM) and Co-I on Advanced Microwave Scanning Radiometer (AMSR). In 1990, he developed interferometric concepts applied to passive microwave Earth observation and was subsequently the science lead on the Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) project for European Space Agency (ESA) with Matra Marconi Space (MMS) and Observatoire Midi-Pyrénées (OMP). In 1997, he first proposed the development of the SMOS Mission that was eventually selected by CNES and ESA in 1999 and launched in 2009 with the incumbent as the SMOS mission Lead-Investigator and Chair of the Science Advisory Group. Yann Kerr also leads SMOS science activities coordination in France and organised all the first SMOS Science workshops and is a member of the Soil Moisture Active Passive (SMAP) Science team. Yann Kerr was deputy director of LERTS and CESBIO and Director of CESBIO. 


Seminar was recorded on February 11, 2021