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Humidité de surface des sols de permafrost par télédétection

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Message  Arnaud Mialon Ven 3 Mai - 15:23

Due to above-average rising temperatures a large amount of the frozen carbon sinks in the higher northern latitudes might be released, possibly causing a significant positive feedback on global warming. Thus, there is a strong need to monitor hydrologic processes, and given the hindered accessibility of these hostile environments,
satellite observations constitute an essential tool.

The Soil Moisture and Ocean Salinity (SMOS) mission carries the first space-borne passive L-band microwave (1.4 GHz) radiometer operating at the preferred frequency for surface soil moisture retrieval (~0-5cm depth). SMOS soil moisture products are available every 2-3 days on a grid of about 15 km spacing and with a spatial resolution of approximately 40-50 km. The soil moisture retrieval is achieved by minimizing the difference between brightness
temperatures (TB) acquired by SMOS and modeled TBs by means of a radiative transfer model. The empirically-based model uses several land cover-dependent tuning parameters, which exclusively stem from study sites in dry and temperate climate zones. In order to improve our understanding of microwave L-band surface
emissions in high-latitude environments and thus, supporting the
enhancement of SMOS soil moisture product quality over these regions, the research project SMOSHiLat has been evoked in the framework of the European Space Agency’s (ESA) Changing Earth Science Network (led by the Centre d'Etudes Spatiales de la Biosphère, CESBIO). A database is created from data collected at the Sodankylä site of the Finish Meteorological Institute (FMI) in Northern Finland, including modeled as well as observed L-band radiative properties and state parameters. Using this information, an adapted emission model is developed and tested in the SMOS soil moisture prototype retrieval
algorithm. The newly derived SMOS soil moisture products will be validated over different regions, including Canada, Scandinavia and Siberia. Though, this project is focusing on unfrozen ground conditions, there is strong collaboration with the ESA SMOS+ Permafrost project (led by FMI) dealing with the detection and monitoring of soil freezing/thawing processes using SMOS data.

Arnaud Mialon

Messages : 1
Date d'inscription : 02/05/2013
Localisation : CESBIO Toulouse

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