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Spatial sampling uncertainty in SMEX04 soil moisture fields: a data-based resampling experiment / M. Gebremichael in Remote sensing of environment, vol 112 n° 2 (15/02/2008)

Public [article]  inRemote sensing of environment > vol 112 n° 2 (15/02/2008) . - pp 326 - 336 Titre : Spatial sampling uncertainty in SMEX04 soil moisture fields: a data-based resampling experiment Type de document : Article/Communication Auteurs : M. Gebremichael, Auteur ; E.R. Vivoni, Auteur Année de publication : 2008 Article en page(s) : pp 326 - 336 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] échantillonnage d'image [Termes descripteurs IGN] humidité du sol [Termes descripteurs IGN] image aérienne [Termes descripteurs IGN] image PSR [Termes descripteurs IGN] image radar [Termes descripteurs IGN] incertitude des données [Termes descripteurs IGN] Mexico (Mexique) [Termes descripteurs IGN] SOIL MOISTURE EXPERIMENT Résumé : (Auteur) A data-based resampling experiment is performed to estimate sampling errors of area-averaged soil moisture estimates due to spatial sampling by ground-based sensors. The data consists of high-resolution soil moisture images derived from the Polarimetric Scanning Radiometer (PSR/CX) sensor flown on an aircraft as part of the summer field experiment (SMEX04 — Soil Moisture Experiment 2004) in the monsoon region of Sonora, Mexico. The sampling characteristics are investigated by accounting for random networks and evenly spaced networks. For random network designs, we develop a simple model that can be used to estimate the sampling uncertainty (expressed as standard deviation of sampling error as a percentage of the areal mean soil moisture) as a function of the number of sensors, mean soil moisture content and averaging area. This model is valid for five or more sensors. The model should prove useful to those wishing to assess the area-averaged performance of a soil moisture network. Furthermore, the method of analysis is applicable to other study regions (Oklahoma, Iowa, Alabama, Georgia, and Arizona) where soil moisture fields have been mapped at high resolution using airborne passive microwave remote sensors. Copyright Elsevier Numéro de notice : A2008-035 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29030 [article]

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Soil moisture mapping and AMSR-E validation using the PSR in SMEX02 / R. Bindlish in Remote sensing of environment, vol 103 n° 2 (30/07/2006)

Public [article]  inRemote sensing of environment > vol 103 n° 2 (30/07/2006) . - pp 127 - 139 Titre : Soil moisture mapping and AMSR-E validation using the PSR in SMEX02 Type de document : Article/Communication Auteurs : R. Bindlish, Auteur ; Thomas J. Jackson, Auteur ; A.J. Gasiewski, Auteur ; et al., Auteur Année de publication : 2006 Article en page(s) : pp 127 - 139 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] bande C [Termes descripteurs IGN] bande X [Termes descripteurs IGN] biomasse [Termes descripteurs IGN] carte thématique [Termes descripteurs IGN] Glycine max [Termes descripteurs IGN] humidité du sol [Termes descripteurs IGN] image Aqua-AMSR [Termes descripteurs IGN] image PSR [Termes descripteurs IGN] Iowa (Etats-Unis) [Termes descripteurs IGN] maïs (céréale) [Termes descripteurs IGN] télédétection en hyperfréquence [Termes descripteurs IGN] température de luminance Résumé : (Auteur) Field experiments (SMEX02) were conducted to evaluate the effects of dense agricultural crop conditions on soil moisture retrieval using passive microwave remote sensing. Aircraft observations were collected using a new version of the Polarimetric Scanning Radiometer (PSR) that provided four C band and four X band frequencies. Observations were also available from the Aqua satellite Advanced Microwave Scanning Radiometer (AMSR-E) at these same frequencies. SMEX02 was conducted over a three-week period during the summer near Ames, Iowa. Corn and soybeans dominate the region. During the study period the corn was approaching its peak water content state and the soybeans were at the mid point of the growth cycle. Aircraft observations are compared to ground observations. Subsequently models are developed to describe the effects of corn and soybeans on soil moisture retrieval. Multiple altitude aircraft brightness temperatures were compared to AMSR-E observations to understand brightness temperature scaling and provide validation. The X-band observations from the two sensors were in reasonable agreement. The AMSR-E C-band observations were contaminated with anthropogenic RFI, which made comparison to the PSR invalid. Aircraft data along with ancillary data were used in a retrieval algorithm to map soil moisture. The PSR estimated soil moisture retrievals on a field-by-field comparison had a standard error of estimate (SEE) of 5.5%. The error reduced when high altitude soil moisture estimates were aggregated to 25 km resolution (same as AMSR-E EASE grid product resolution) (SEE not, vert, similar 2.85%). These soil moisture products provide a validation of the AMSR retrievals. PSR/CX soil moisture images show spatial and temporal patterns consistent with meteorological and soil conditions. The dynamic range of the PSR/CX observations indicates that reasonable soil moisture estimates can be obtained from AMSR, even in areas of high vegetation biomass content (not, vert, similar 4–8 kg/m2). Copyright Elsevier Numéro de notice : A2006-319 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28043 [article]

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