Soil Moisture and Ocean Salinity

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Global soil moisture and ocean salinity measurements are needed to better understand Earth’s water cycle and climate. Currently, there is no thorough dataset on soil moisture or ocean salinity. Current satellites operated by NASA have provided information to global modeling projects, like GEWEX. Soil moisture content is used routinely in forecasting models. In addition soil moisture accuracy may help better to understand crop yields over a wider region[1] Such projects have determined that soil moisture was one precondition to the Great Flood of 1993 (Upper Mississippi, Lower Missuouri, and Upper Red rivers).[2]

The SMOS mission has been designed to provide, from space, more detailed data on soil moisture and ocean salinity.[3][4] The Soil Moisture and Ocean Salinity Satellite (SMOS) is a part of ESA's Living Planet Programme.[5] In addition to provide better extreme weather forecasting SMOS is designed to monitor snow and ice accumulation. The mission uses new and more sensitive instruments in hopes of gathering precise information.

The project was proposed by CESBIO to Earth Explore Opportunity Missions in November 1998. In 2004 the project passed ESA-phase "C/D".[6] After several delays of the launch the launch is scheduled 2nd of November 2009 01:50 UTC from Plesetsk Cosmodrome on a Rockot launch vehicle.[7]

Importance and Design

Soil moisture is an important aspect of climate, and therefore forecasting. Plants, like trees transpire water from depths lower than 1 meter in many places. Satellites like SMOS can only provide moisture content down to a few centimeters, but using repeated measurements in a day the satellite can extrapolate soil moisture. These calculations are based on the difference in soil moisture from dawn to dusk.[3][4] The SMOS team of ESA hope to work with farmers around the world, including the USDA scientist in the US Midwest to use as ground based calibration for models determining soil moisture.[1] The goal of the SMOS mission is to monitor surface soil moisture with an accuracy of 4% (at 35–50 km spatial resolution).[6] This aspect is managed by the HYDROS project. Project Aquarius will attempt to monitor sea surface salinity with an accuracy of 0.1 psu (10-30 day average and a spatial resolution of 200 km x 200 km).[6][8]


The SMOS unit will carry an instrument capable of observing both soil moisture and ocean salinity. A new instrument called MIRAS has been developed for this satellite.[8] The instrument creates images of radiation emitted in the microwave L-band (1.4 GHz). MIRAS is a form of 2-D interferometric radiometer.[5][9] It will primarily measure brightness temperature fields from which 3 to 5 cm soil moisture[10] and sea surface salinity will be derived as level 2 products.[clarification needed]

Platform and Ride

Rockot, the SMOS's ride

The SMOS satellite as of 2005 will be carried on the Proteus (CNES-Alcatel Space industries). A small platform (1 m3}, the Proteus has become a 'spacecraft bus' for many missions. The satellite will be carried to an orbit of 763 km above the earth on “Rockot”, a modified Russian Intercontinental Ballistic Missile (ICBM) SS-19 launched from a decommissioned SS-19 launcher from Northern Russia's Plesetsk Cosmodrome.[3] SMOS may share its ride with Proba-2 a technology demonstration satellite.[11]

Operations and Ground Segment

The CNES Satellite Operations Ground Segment (Toulouse, France) will operate the spacecraft with telecommuncations from ESA S-band facility (Kiruna, Sweden). The Data Processing Ground Segment (CDTI, Villafranca, Spain) will process SMOS data (X-band). Higher level processing of information will be done by scientist globally.[3]


  1. ^ a b How Dry We Are: European Space Agency To Test Earth's Soil Moisture Via Satellite-Science News, Science Daily
  2. ^ GEWEX Phase I Overview GEWEX, WCRP
  3. ^ a b c d SMOS Project Team, The Soil Moisture and Ocean Salinity (SMOS) Mission European Space Agency
  4. ^ a b SMOS Special Issue of ESA Bulletin ESA Bulletin Special Issue 137, February 2009
  5. ^ a b ESA's water mission SMOS European Space Agency
  6. ^ a b c The Living Planet Program Soil Moisture and Ocean Salinity (MIRAS on RAMSES) Mission SMOS at Centre d'Etudes Spatailes de la BIOsphere (CESBIO)
  7. ^ "SMOS launch nearing: Media Day at ESA/ESRIN". ESA. 2009-10-09. Retrieved 2009-10-11.
  8. ^ a b Mecklenburg S, Kerr Y, Font J and Hahne A. The Soil Moisture and Ocean Salinity (SMOS) Mission - An overview. Geophysical Research Abstracts, Vol. 10, 2008,
  9. ^ MIRAS is Microwave Imaging Radiometer with Aperture Synthesis)
  10. ^ Kerr, Y.H. (2001). "Soil moisture retrieval from space: the Soil Moisture and Ocean Salinity (SMOS) mission". Geoscience and Remote Sensing, IEEE Transactions on. 39 (8): 1729–1735. doi:10.1109/36.942551. Unknown parameter |month= ignored (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  11. ^ ESA's SMOS Mission to be launched in July 2009 from Plesetsk The Rockot Missions. Eurolaunch Launch Service Provider

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