Remote sensing of soil moisture by a 21-cm passive radiometer

Eagleman, J. R.; Lin, Wen‐Chieh

doi:10.1029/jc081i021p03660

Cited by 84 publications

(53 citation statements)

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“…Moreover, L-band is the optimal wavelength range to observe soil moisture as higher frequencies are more significantly affected by perturbing factors such as atmospheric effects and vegetation cover (Schumugge, 1983;Kerr et al, 2001). Apart from a few days of L-band radiometric observations on Skylab from June 1973 to January 1974 (Eagleman et al, 1976;Jackson et al, 2004), spaceborne microwave radiometers have been operating at frequencies above 5 GHz because the satellite antenna size is directly proportional to the squared wavelength (Ulaby et al, 1982). Recent technological and scientific achievements permitted to develop the Soil Moisture and Ocean Salinity (SMOS) mission (Kerr et al, 2001 launched in November 2009.…”

Section: Introductionmentioning

confidence: 99%

Comparing soil moisture retrievals from SMOS and ASCAT over France

Parrens

Zakharova

Lafont

et al. 2012

Hydrol. Earth Syst. Sci.

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Abstract. The first products derived over France in 2010 from the L-band brightness temperatures (T b ) measured by the SMOS (Soil Moisture and Ocean Salinity) satellite, launched in November 2009, were compared with the surface soil moisture (SSM) estimates produced by the C-band Advanced Scatterometer, ASCAT, launched in 2006 on board METOP-A. SMOS and ASCAT SSM products were compared with the simulations of the ISBA-A-gs model and with in situ measurements from the SMOSMANIA network, including 21 stations located in southern France. ASCAT tended to correlate better than SMOS with ISBA-A-gs. The significant anomaly correlation coefficients between in situ observations and the SMOS (ASCAT) product ranged from 0.23 to 0.48 (0.35 to 0.96). However, in wet conditions, similar results between the two satellite products were found. An attempt was made to derive SSM from regressed empirical logarithmic equations using a combination of SMOS T b at different incidence angles and different polarizations, and the Leaf Area Index (LAI) modeled by ISBA-A-gs. The analysis of the intercept coefficient of the regression showed an impact of topography. A similar analysis applied to ASCAT and SMOS SSM values showed a more limited impact of topography on the intercept coefficient of the SMOS SSM product, while fewer residual geographic patterns were found for the ASCAT SSM.

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Section: Introductionmentioning

confidence: 99%

Comparing soil moisture retrievals from SMOS and ASCAT over France

Parrens

Zakharova

Lafont

et al. 2012

Hydrol. Earth Syst. Sci.

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“…This change in emissivity for a soil has been observed by truck mounted radiometers in field experiments (Poe et al, 1971;Blinn and Quade, 1972;Schanda et al, 1978;Newton, 1977) and by radiometers in aircraft (Schmugge, 1974;Burke et a11978;Choudhury, et al, 1979) and satellites (Eagleman and Lin, 1976;Schmugge et al, 1977). In no case were emissivities as low as 0.6 observed for real surfaces.…”

Section: Microwave Methodsmentioning

confidence: 88%

“…These results are encouraging for the use of long wavelength radiometric approaches. Eagleman and Lin (1976) To understand the effects of incidence angle and surface roughness consider the plots of 00 versus angle presented in Figure 12 for five fields with essentially the same moisture content but with considerably different surface roughness. At the longest wavelength (1.1 Oz, Figure 12a), ao for the smoother fields is very sensitive to incidence angle near nadir, while for the roiAgh field cc is almost independent of angle.…”

Section: Microwave Methodsmentioning

confidence: 99%

Survey of methods for soil moisture determination

Schmugge¹,

Jackson²,

Mckim³

1980

Water Resources Research

349

141

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With increased interest in soil moisture information for applice.tions in stch disciplines as hydrology, meteorology and agriculture, an overview is needed of both existing and proposed methods for soil moisture determination. This paper discusses the methods of in-situ soil moisture determination including gravimetric, nuclear, and electromagnetic techniques; remote sensing approaches that use the reflected solar, thermal infrared, and microwave portions of the electromagnetic spectrum; and soil physics models that track the behaviour of water in the soil in response to meteorological inputs (precipitation) and demands (evapotranspiration). The capacities of use approaches to satisfy various user needs for soil moisture information varies from application to application, but a conceptual scheme for merging these approaches into integrated systems to provide soil moisture information is proposed that has the potential for meeting various application requirements.

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“…Traditional satellite techniques for soil moisture monitoring exploit the microwave data advantages, since at these frequencies: i) electro-magnetic radiation leaving the Earth's surface is practically not affected by clouds (in the absence of rain), allowing an "all-weather" capability; ii) the microwave signal is available both during the day and night assuring an "all-time" capability of observing the Earth's surface conditions; iii) thanks to the large contrast between dielectric properties of water and dry soil, microwaves are highly sensitive to the water content in the soil (Eagleman and Lin, 1976;Jackson et al, 1981).…”

Section: Introductionmentioning

confidence: 99%

Monitoring soil wetness variations by means of satellite passive microwave observations: the HYDROPTIMET study cases

Lacava

Greco

Leo

et al. 2005

Nat. Hazards Earth Syst. Sci.

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Abstract. Soil moisture is an important component of the hydrological cycle. In the framework of modern flood warning systems, the knowledge of soil moisture is crucial, due to the influence on the soil response in terms of infiltrationrunoff. Precipitation-runoff processes, in fact, are related to catchment's hydrological conditions before the precipitation. Thus, an estimation of these conditions is of significant importance to improve the reliability of flood warning systems. Combining such information with other weatherrelated satellite products (i.e. rain rate estimation) might represent a useful exercise in order to improve our capability to handle (and possibly mitigate or prevent) hydro-geological hazards.Remote sensing, in the last few years, has supported several techniques for soil moisture/wetness monitoring. Most of the satellite-based techniques use microwave data, thanks to the all-weather and all-time capability of these data, as well as to their high sensitivity to water content in the soil. On the other hand, microwave data are unfortunately highly affected by the presence of surface roughness or vegetation coverage within the instantaneous satellite field of view (IFOV). Those problems, consequently, strongly limit the efficiency and the reliability of traditional satellite techniques.Recently, using data coming from AMSU (Advanced Microwave Sounding Unit), flying aboard NOAA (National Oceanic and Atmospheric Administration) satellites, a new methodology for soil wetness estimation has been proposed. The proposed index, called Soil Wetness Variation Index (SWVI), developed by a multi-temporal analysis of AMSU records, seems able to reduce the problems related to vegetation and/or roughness effects. Such an approach has been tested, with promising results, on the analysis of some flooding events which occurred in Europe in the past.Correspondence to: N. Pergola (pergola@imaa.cnr.it)In this study, results achieved for the HYDROPTIMET test cases will be analysed and discussed in detail. This analysis allows us to evaluate the reliability and the efficiency of the proposed technique in identifying different amounts of soil wetness variations in different observational conditions. In particular, the proposed indicator was able to document the actual effects of meteorological events, in terms of space-time evolution of soil wetness changes, for all the analysed HYDROPTIMET test cases. Moreover, in some circumstances, the SWVI was able to identify the presence of a sort of "early" signal in terms of soil wetness variations, which may be regarded as a timely indication of an anomalous value of soil water content. This evidence suggests the opportunity to use such an index in the pre-operational phases of the modern flood warning systems, in order to improve their forecast capabilities and their reliability.

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Remote sensing of soil moisture by a 21-cm passive radiometer

Cited by 84 publications

References 4 publications

Comparing soil moisture retrievals from SMOS and ASCAT over France

Comparing soil moisture retrievals from SMOS and ASCAT over France

Survey of methods for soil moisture determination

Monitoring soil wetness variations by means of satellite passive microwave observations: the HYDROPTIMET study cases

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