The SMOS Mission: New Tool for Monitoring Key Elements ofthe Global Water Cycle

Kerr, Yann H.; Waldteufel, Philippe; Wigneron, Jean‐Pierre; Delwart, Steven; Cabot, François; Boutin, Jacqueline; Escorihuela, María José; Font, Jordi; Reul, Nicolás; Gruhier, Claire; Juglea, Silvia Enache; Drinkwater, Mark R.; Hahne, A.; Martín-Neira, Manuel; Mecklenburg, Susanne

doi:10.1109/jproc.2010.2043032

Cited by 1,660 publications

(1,053 citation statements)

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“…Passive microwave data are also widely used in assimilation schemes to constrain atmospheric analyses for which the surface emissivity is an issue, particularly over Antarctica (Guedj et al, 2010). These radiometers, however, have a coarse spatial resolution, typically 10-60 km depending on the frequency and the antenna size of the radiometer (Colton and Poe, 1999;Kerr et al, 2010). In Antarctic coastal and mountainous regions, the heterogeneity within the radiometer footprint is significant because of the topography.…”

Section: Introductionmentioning

confidence: 99%

Influence of meter-scale wind-formed features on the variability of the microwave brightness temperature around Dome C in Antarctica

et al. 2014

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Abstract. Space-borne passive microwave radiometers are widely used to retrieve information in snowy regions by exploiting the high sensitivity of microwave emission to snow properties. For the Antarctic Plateau, many studies presenting retrieval algorithms or numerical simulations have assumed, explicitly or not, that the subpixel-scale heterogeneity is negligible and that the retrieved properties were representative of whole pixels. In this paper, we investigate the spatial variations of brightness temperature over a range of a few kilometers in the Dome C area. Using ground-based radiometers towed by a vehicle, we collected brightness temperature at 11, 19 and 37 GHz at horizontal and vertical polarizations along transects with meter resolution. The most remarkable observation was a series of regular undulations of the signal with a significant amplitude reaching 10 K at 37 GHz and a quasi-period of 30-50 m. In contrast, the variability at longer length scales seemed to be weak in the investigated area, and the mean brightness temperature was close to SSM/I and WindSat satellite observations for all the frequencies and polarizations. To establish a link between the snow characteristics and the microwave emission undulations, we collected detailed snow grain size and density profiles at two points where opposite extrema of brightness temperature were observed. Numerical simulations with the DMRT-ML microwave emission model revealed that the difference in density in the upper first meter explained most of the brightness temperature variations. In addition, we found that these variations of density near the surface were linked to snow hardness. Patches of hard snow -probably formed by wind compaction -were clearly visible and covered as much as 39 % of the investigated area. Their brightness temperature was higher than in normal areas. This result implies that the microwave emission measured by satellites over Dome C is more complex than expected and very likely depends on the year-to-year areal proportion of the two different types of snow.

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Section: Introductionmentioning

confidence: 99%

Influence of meter-scale wind-formed features on the variability of the microwave brightness temperature around Dome C in Antarctica

et al. 2014

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“…Some other large scale measurement missions have recently started, with the SMOS (Soil Moisture and Ocean Salinity) satellite of the ESA, in orbit since 2009, that measures soil moisture with a spatial resolution of 35-50 km, with an accuracy of 4%, and a revisit time of one to three days. The satellite uses a Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) working in the L band (1.4 GHz) [61,62]. In the USA, NASA is preparing the SMAP (Soil Moisture Active Passive) mission, with a satellite launch for 2014, carrying a radiometer and synthetic aperture radar (SAR) in the L band as well (1.20-1.41 GHz), with the same accuracy and revisit time as SMOS but an improved resolution of 10 km [63].…”

Section: Satellite Productsmentioning

confidence: 99%

Soil Moisture & Snow Properties Determination with GNSS in Alpine Environments: Challenges, Status, and Perspectives

et al. 2013

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Moisture content in the soil and snow in the alpine environment is an important factor, not only for environmentally oriented research, but also for decision making in agriculture and hazard management. Current observation techniques quantifying soil moisture or characterizing a snow pack often require dedicated instrumentation that measures either at point scale or at very large (satellite pixel) scale. Given the heterogeneity of both snow cover and soil moisture in alpine terrain, observations of the spatial distribution of moisture and snow-cover are lacking at spatial scales relevant for alpine hydrometeorology. This paper provides an overview of the challenges and status of the determination of soil moisture and snow properties in alpine environments. Current measurement techniques and newly proposed ones, based on the reception of reflected Global Navigation Satellite Signals (i.e., GNSS Reflectometry or GNSS-R), or the use of laser scanning are reviewed, and the perspectives offered by these new techniques to fill the current gap in the instrumentation level are discussed. Some key enabling technologies OPEN ACCESSRemote Sens. 2013, 5 3517 including the availability of modernized GNSS signals and GNSS array beamforming techniques are also considered and discussed.

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“…Thus far, three innovative space missions with passive L-band (1-2 GHz corresponding to vacuum wavelengths of 30-15 cm) microwave instruments aboard have been launched, with the objective to provide frequent-revisit global mapping of surface soil moisture. The European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) satellite launched in 2009 was the first L-band radiometer mission [6], followed by the U.S. National Aeronautics and Space Administration (NASA) and Argentinean Space Agency (CONAE) Aquarius/Satélite de Aplicaciones Científicas (SAC)-D mission in 2011 (and stopped in 2015) [7], and the NASA Soil Moisture Active Passive (SMAP) satellite launched in 2015 [8].…”

Section: Introductionmentioning

confidence: 99%

Passive L-Band Microwave Remote Sensing of Organic Soil Surface Layers: A Tower-Based Experiment

et al. 2018

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Organic soils play a key role in global warming because they store large amount of soil carbon which might be degraded with changing soil temperatures or soil water contents. There is thus a strong need to monitor these soils and, in particular, their hydrological characteristics using, for instance, space-borne L-band brightness temperature observations. However, there are still open issues with respect to soil moisture retrieval techniques over organic soils. In view of this, organic soil blocks with their vegetation cover were collected from a heathland in the Skjern River catchment in western Denmark and then transported to a remote sensing field laboratory in Germany where their structure was reconstituted. The controlled conditions at this field laboratory made it possible to perform tower-based L-band radiometer measurements of the soils over a period of two months. Brightness temperature data were inverted using a radiative transfer (RT) model for estimating the time variations in the soil dielectric permittivity and the vegetation optical depth. In addition, the effective vegetation scattering albedo parameter of the RT model was retrieved based on a two-step inversion approach. The remote estimations of the dielectric permittivity were compared to in situ measurements. The results indicated that the radiometer-derived dielectric permittivities were significantly correlated with the in situ measurements, but their values were systematically lower compared to the in situ ones. This could be explained by the difference between the operating frequency of the L-band radiometer (1.4 GHz) and that of the in situ sensors (70 MHz). The effective vegetation scattering albedo parameter was found to be polarization dependent. While the scattering effect within the vegetation could be neglected at horizontal polarization, it was found to be important at vertical polarization. The vegetation optical depth estimated values over time oscillated between 0.10 and 0.19 with a mean value of 0.13. This study provides further insights into the characterization of the L-band brightness temperature signatures of organic soil surface layers and, in particular, into the parametrization of the RT model for these specific soils. Therefore, the results of this study are expected to improve the performance of space-borne remote sensing soil moisture products over areas dominated by organic soils.

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The SMOS Mission: New Tool for Monitoring Key Elements ofthe Global Water Cycle

Abstract: This satellite mission will use new algorithms to try to forecast weather and estimate climate change from satellite measurements of the Earth's surface.

Cited by 1,660 publications

References 77 publications

Influence of meter-scale wind-formed features on the variability of the microwave brightness temperature around Dome C in Antarctica

Influence of meter-scale wind-formed features on the variability of the microwave brightness temperature around Dome C in Antarctica

Soil Moisture & Snow Properties Determination with GNSS in Alpine Environments: Challenges, Status, and Perspectives

Passive L-Band Microwave Remote Sensing of Organic Soil Surface Layers: A Tower-Based Experiment

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