HAL (Le Centre pour la Communication Scientifique Directe), Jul 14, 2012
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
International audienceThe SMOS mission was launched in November 2009 and allows for measuring of ... more International audienceThe SMOS mission was launched in November 2009 and allows for measuring of the surface soil moisture and vegetation optical depth over continental land areas, covering the entire globe every 3 days. The ESA’s DPGS (European Space Agency’s Data Processing Ground Segment) has been delivering the so called Level 2 products, consisting in ½ orbits data. The CNES (Centre National d’Etudes Spatiales) has developed the CATDS (Centre Aval de Traitement des Données SMOS) ground segment that now provides spatial and temporal synthesis products (referred to as Level 3 products) of soil moisture, vegetation optical depth, ocean salinity and brightness temperature, which now cover the whole SMOS operation period, from January 2010 onwards. After developing the level 3 products over land and oceans, a wealth of new science applications started to appear and are being put into the level 4 scheme after validation. These products are currently in their validation stage, with so...
After the successful acquisition by a coarse L-band radiometer on board Skylab in the early seven... more After the successful acquisition by a coarse L-band radiometer on board Skylab in the early seventies, the potential of L-band radiometry was made clear in spite of a strict limitation linked to minimum antenna dimensions required for appropriate spatial resolution. More than 20 years later new antenna concepts emerged to mitigate this physical constraint. The first to emerge, in 1997, and to become a reality, was the Soil Moisture and Ocean Salinity (SMOS) mission (Kerr, 1997, Kerr, 1998). It is European Space Agency’s (ESA’s) second Earth Explorer Opportunity mission (Kerr et al., 2001), launched in November 2009. It is a joint program between ESA, CNES (Centre National d’Etudes Spatiales), and CDTI (Centro para el Desarrollo Tecnologico Industrial). SMOS carries a single payload, an L-band 2D interferometric radiometer in the 1400–1427 MHz protected band. This wavelength penetrates well through the atmosphere, and hence, the instrument probes the Earth surface emissivity from space. Surface emissivity can be related to the moisture content in the first few centimeters of soil, and after some surface roughness and temperature corrections, to the sea surface salinity over ocean.Soil moisture retrieval from SMOS observations with a required accuracy of 0.04 m3/m3 is challenging and involves many steps. The retrieval algorithms are developed and implemented in the ground segment, which processes level 1 and level 2 data. Level 1 consists mainly of directional brightness temperatures, while level 2 consists of geophysical products in swath mode, i.e., for successive imaging snapshots acquired by the sensor during a half orbit from pole to pole. Level 3 consists in composites of brightness temperatures, or geophysical products over time and space, i.e., global maps over given temporal periods from 1 day to 1 month. In this context, a group of institutes prepared the soil moisture and ocean salinity Algorithm Theoretical Basis Documents (ATBD), used to in operational soil moisture and sea salinity retrieval algorithms (Kerr et al., 2010a).The principle of the level 2 soil moisture retrieval algorithm is based on an iterative approach, which aims at minimizing a cost function. The main component of the cost function is given by the sum of the squared weighted differences between measured and modeled brightness temperature (TB) at horizontal and vertical polarizations, for a variety of incidence angles. The algorithm finds the best set of parameters, e.g., soil moisture (SM) and vegetation characteristics, which drive the TB model and minimizes the cost function. From this algorithm, a more sophisticated one was developed to take into account multiorbit retrievals (i.e., level 3). Subsequently, after several years of data acquisition and algorithm improvements, a neural network approach was developed so as to be able to infer soil moisture fields in near-real time. In parallel, several simplified algorithms were tested, the goal being to achieve a seamless transition with other sensors, along with other studies targeted on specific targets such as dense forests, organic rich soils, or frozen and snow-covered grounds. Finally, it may be noted that most of these approaches deliver not only the surface soil moisture but also other quantities of interest such as vegetation optical depth, surface roughness, and surface dielectric constant. The goal of this article is to give an overview of these different approaches and corresponding results and adequate references for those wishing to go further. Sea surface salinity is not covered in this article, while the focus is SMOS data.
Ring-capacitor sensors are used widely for real-time estimation of volumetric soil water content ... more Ring-capacitor sensors are used widely for real-time estimation of volumetric soil water content u from measured resonant frequency f r, which is directly affected by the bulk soil permittivity e. However,the relationship f r(e) requires improved quantification. We conducted laboratory experiments to characterize the response of the Sentek EnviroSMART sensor system for a full range of e values from air to water and a range of temperatures. Water–dioxane mixtures were placed into a solvent-resistant container equipped with custom tools for heating and mixing the fluid, removing air bubbles from sensitive surfaces, measuring permittivity in situ, and creating an axisymmetric metal disturbance to the electric field. Total capacitance C was measured using a vector network analyzer (VNA) connected to one sensor, while four other sensors provided replicated fr readings. The measured temperature response of free water permittivity was linear with a negative slope, which is
In this presentation, the SMOSHiLat project will be presented with special focus on the SML2PP st... more In this presentation, the SMOSHiLat project will be presented with special focus on the SML2PP studies
La misión de SMOS (Soil Moisture and Ocean Salinity) se lanzó el 2 de Noviembre de 2009 con el ob... more La misión de SMOS (Soil Moisture and Ocean Salinity) se lanzó el 2 de Noviembre de 2009 con el objetivo de proporcionar datos de humedad del suelo y salinidad del mar. La principal actividad de la conocida como Valencia Anchor Station (VAS) es asistir en la validación a largo plazo de productos de suelo de SMOS. El presente estudio se centra en una validación de datos de nivel 3 de SMOS en la VAS con medidas in situ tomadas en el periodo 2010-2012. El radiómetro Elbara-II está situado dentro de los confines de la VAS, observando un campo de viñedos que se considera representativo de una gran proporción de un área de 50×50 km, suficiente para cubrir un footprint de SMOS. Las temperaturas de brillo (TB) adquiridas por ELBARA-II se compararon con las observadas por SMOS en las mismas fechas y horas. También se utilizó la inversión del modelo L-MEB con el fin de obtener humedades de suelo (SM) que, posteriormente, se compararon con datos de nivel 3 de SMOS. Se ha encontrado una buena co...
International audienceThe Valencia Anchor Station (VAS) is a validation site of SMOS (Soil Moistu... more International audienceThe Valencia Anchor Station (VAS) is a validation site of SMOS (Soil Moisture and Ocean Salinity) since 2010. For this purpose, different in situ measurements are performed there. This paper will focus on the parameterization of roughness, a key topic for the SMOS and SMAP (Soil Moisture Active Passive) missions. The area covered by the VAS is quite homogeneous, a surface of 50 x 50 km2 mainly composed by vineyards (65%) and other Mediterranean vegetation (30%), which is very stable along the year. The vegetative period of the vineyards lasts approximately from April to October. MELBEX-III is a station inside the area of the VAS, where among other equipments (meteorological station, thermistors, etc.), there is an ELBARA-II Lband radiometer performing multi-angular measurements over a vineyard. There are also two Delta-T ML2x soil moisture probes, one measuring between two rows of vines and the other one next to a vine stump. In the year 2013, measurements of r...
Energy and matter fluxes between the atmosphere and the land surface are affected by hydrological... more Energy and matter fluxes between the atmosphere and the land surface are affected by hydrological states of the terrestrial land surface . We must increase our knowledge of these transfer processes to improve research on climate change. To reach these objectives, we must obtained global information on the hydrological states and properties of the land-surface. The microwave remote sensing instruments are an adequate way to provide soil moisture information at large scale. Microwave remote sensing data are linked to the soil moisture but also to the roughness, texture and the physicochemical properties of the soil. In that context, the objective of this study is to develop an integrated approach to estimate effective electromagnetic properties of soils layers using ground-penetrating radar (GPR), L-band radiometer, dielectric laboratory measurements, modelling approaches and in situ measurements of essential state variables.
We report a unique multiyear L-band microwave radiometry dataset collected at the Maqu site on th... more We report a unique multiyear L-band microwave radiometry dataset collected at the Maqu site on the eastern Tibetan Plateau and demonstrate its utilities in advancing our understandings of microwave observations of land surface processes. The presented dataset contains measurements of L-band brightness temperature by an ELBARA-III microwave radiometer in horizontal and vertical polarization, profile soil moisture and soil temperature, turbulent heat fluxes, and meteorological data from the beginning of 2016 till August 2019, while the experiment is still continuing. Auxiliary vegetation and soil texture information collected in dedicated campaigns are also reported. This dataset can be used to validate the Soil Moisture and Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) satellite based observations and retrievals, verify radiative transfer model assumptions and validate land surface model and reanalysis outputs, retrieve soil properties, as well as to quantify land-atm...
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
This study reports on four consecutive winter campaigns (2016-2020) at the "Davos-Laret Remote Se... more This study reports on four consecutive winter campaigns (2016-2020) at the "Davos-Laret Remote Sensing Field Laboratory" in the Swiss Alps to gain insight into the L-band microwave emission of ground covered with seasonal snow. Closerange L-band Brightness temperatures T p,φ B (θ) were measured over the site scanning different observation nadir angles θ and azimuth angles φ at horizontal and vertical polarization p = {H,V}. State parameters (SPs) of the snowpack (e.g., height, density, and snow water equivalent) and the subnivean soil (permittivity, temperature) were measured quasi-simultaneously using in-situ sensors and sampling, as well as meteorological data. In each campaign, T p,φ B (θ) were measured over a "natural area" and a "reflector area" with a metal mesh reflector laid on the ground before snow accumulation. The radiometer measurements over "reflector area" allowed to retrieve the time-series of Snow liquid Water-content W S and Snow liquid Water-Column W C S , which are employed as "derived measurements" to support interpretation of T p,φ B (θ) measured over "natural areas" during different winter phases. The detailed approach for the estimation of W S and W C S using L-band radiometer data is presented. The data and analyses in this article address the following major points: 1) determination of the characteristic features of measured T p,φ B (θ) during different periods in each of the four winter campaigns; 2) effects of dry and wet snow precipitation on L-band radiometer data compared to corresponding simulations; 3) effect of removal and compression of the snowpack on T p,φ B (θ); 4) effects of spatial heterogeneity on brightness temperatures. Finally, the study is concluded with recommendations relevant for future close-range remote sensing campaigns.
Soil moisture and soil freezing are important for diverse hydrological, biogeochemical, and clima... more Soil moisture and soil freezing are important for diverse hydrological, biogeochemical, and climatological applications. They affect surface energy balance, surface and subsurface water flow, and exchange rates of carbon with the atmosphere. Soil freezing controls important biogeochemical processes, like photosynthetic activity of plants and microbial activity within soils. Permafrost covers approximately 24% of the land surface in the Northern Hemisphere and seasonal freezing occurs on approximately 51% of the area.
IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium, 2019
We demonstrate an application of the L-band specific Microwave Emission Model of Layered Snowpack... more We demonstrate an application of the L-band specific Microwave Emission Model of Layered Snowpacks (LS-MEMLS) to snow over the Greenland Ice Sheet to retrieve density and snow wetness from SMOS satellite data. Retrievals of these parameters have previously been demonstrated using ground-based L-band radiometry over snow covered ground in alpine conditions. Existing passive microwave data products over ice sheets include empirical and threshold-based techniques but until recently have not used radiative-transfer physics-based modelling. We discuss the retrieval method based on inversion of LS-MEMLS and present a comparison between our retrievals and in-situ weather station air temperature data. We also mention ongoing work investigating the applicability of the novel retrieval method for mapping the ablation zone of the Greenland Ice Sheet.
Observation and Measurement of Ecohydrological Processes, 2019
Soil water content is a key variable for understanding and modeling ecohydrological processes. In... more Soil water content is a key variable for understanding and modeling ecohydrological processes. In this chapter, we review the state of the art of ground-based methods to characterize the spatiotemporal dynamic of soil water content, from point to field scale. First, point measurements methods are briefly discussed. Then, field-scale hydrogeophysical approaches such as ground-penetrating radar, ground-based L-band radiometry, electromagnetic induction, electrical resistivity tomography, cosmic-ray neutron probes, global navigation satellite system reflectometry, and nuclear magnetic resonance are described in more details. The basic principles of the different techniques, the spatial and temporal characteristics of their measurements, their advantages and limitations, as well as the recent developments in the data processing are presented
HAL (Le Centre pour la Communication Scientifique Directe), Jul 14, 2012
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
International audienceThe SMOS mission was launched in November 2009 and allows for measuring of ... more International audienceThe SMOS mission was launched in November 2009 and allows for measuring of the surface soil moisture and vegetation optical depth over continental land areas, covering the entire globe every 3 days. The ESA’s DPGS (European Space Agency’s Data Processing Ground Segment) has been delivering the so called Level 2 products, consisting in ½ orbits data. The CNES (Centre National d’Etudes Spatiales) has developed the CATDS (Centre Aval de Traitement des Données SMOS) ground segment that now provides spatial and temporal synthesis products (referred to as Level 3 products) of soil moisture, vegetation optical depth, ocean salinity and brightness temperature, which now cover the whole SMOS operation period, from January 2010 onwards. After developing the level 3 products over land and oceans, a wealth of new science applications started to appear and are being put into the level 4 scheme after validation. These products are currently in their validation stage, with so...
After the successful acquisition by a coarse L-band radiometer on board Skylab in the early seven... more After the successful acquisition by a coarse L-band radiometer on board Skylab in the early seventies, the potential of L-band radiometry was made clear in spite of a strict limitation linked to minimum antenna dimensions required for appropriate spatial resolution. More than 20 years later new antenna concepts emerged to mitigate this physical constraint. The first to emerge, in 1997, and to become a reality, was the Soil Moisture and Ocean Salinity (SMOS) mission (Kerr, 1997, Kerr, 1998). It is European Space Agency’s (ESA’s) second Earth Explorer Opportunity mission (Kerr et al., 2001), launched in November 2009. It is a joint program between ESA, CNES (Centre National d’Etudes Spatiales), and CDTI (Centro para el Desarrollo Tecnologico Industrial). SMOS carries a single payload, an L-band 2D interferometric radiometer in the 1400–1427 MHz protected band. This wavelength penetrates well through the atmosphere, and hence, the instrument probes the Earth surface emissivity from space. Surface emissivity can be related to the moisture content in the first few centimeters of soil, and after some surface roughness and temperature corrections, to the sea surface salinity over ocean.Soil moisture retrieval from SMOS observations with a required accuracy of 0.04 m3/m3 is challenging and involves many steps. The retrieval algorithms are developed and implemented in the ground segment, which processes level 1 and level 2 data. Level 1 consists mainly of directional brightness temperatures, while level 2 consists of geophysical products in swath mode, i.e., for successive imaging snapshots acquired by the sensor during a half orbit from pole to pole. Level 3 consists in composites of brightness temperatures, or geophysical products over time and space, i.e., global maps over given temporal periods from 1 day to 1 month. In this context, a group of institutes prepared the soil moisture and ocean salinity Algorithm Theoretical Basis Documents (ATBD), used to in operational soil moisture and sea salinity retrieval algorithms (Kerr et al., 2010a).The principle of the level 2 soil moisture retrieval algorithm is based on an iterative approach, which aims at minimizing a cost function. The main component of the cost function is given by the sum of the squared weighted differences between measured and modeled brightness temperature (TB) at horizontal and vertical polarizations, for a variety of incidence angles. The algorithm finds the best set of parameters, e.g., soil moisture (SM) and vegetation characteristics, which drive the TB model and minimizes the cost function. From this algorithm, a more sophisticated one was developed to take into account multiorbit retrievals (i.e., level 3). Subsequently, after several years of data acquisition and algorithm improvements, a neural network approach was developed so as to be able to infer soil moisture fields in near-real time. In parallel, several simplified algorithms were tested, the goal being to achieve a seamless transition with other sensors, along with other studies targeted on specific targets such as dense forests, organic rich soils, or frozen and snow-covered grounds. Finally, it may be noted that most of these approaches deliver not only the surface soil moisture but also other quantities of interest such as vegetation optical depth, surface roughness, and surface dielectric constant. The goal of this article is to give an overview of these different approaches and corresponding results and adequate references for those wishing to go further. Sea surface salinity is not covered in this article, while the focus is SMOS data.
Ring-capacitor sensors are used widely for real-time estimation of volumetric soil water content ... more Ring-capacitor sensors are used widely for real-time estimation of volumetric soil water content u from measured resonant frequency f r, which is directly affected by the bulk soil permittivity e. However,the relationship f r(e) requires improved quantification. We conducted laboratory experiments to characterize the response of the Sentek EnviroSMART sensor system for a full range of e values from air to water and a range of temperatures. Water–dioxane mixtures were placed into a solvent-resistant container equipped with custom tools for heating and mixing the fluid, removing air bubbles from sensitive surfaces, measuring permittivity in situ, and creating an axisymmetric metal disturbance to the electric field. Total capacitance C was measured using a vector network analyzer (VNA) connected to one sensor, while four other sensors provided replicated fr readings. The measured temperature response of free water permittivity was linear with a negative slope, which is
In this presentation, the SMOSHiLat project will be presented with special focus on the SML2PP st... more In this presentation, the SMOSHiLat project will be presented with special focus on the SML2PP studies
La misión de SMOS (Soil Moisture and Ocean Salinity) se lanzó el 2 de Noviembre de 2009 con el ob... more La misión de SMOS (Soil Moisture and Ocean Salinity) se lanzó el 2 de Noviembre de 2009 con el objetivo de proporcionar datos de humedad del suelo y salinidad del mar. La principal actividad de la conocida como Valencia Anchor Station (VAS) es asistir en la validación a largo plazo de productos de suelo de SMOS. El presente estudio se centra en una validación de datos de nivel 3 de SMOS en la VAS con medidas in situ tomadas en el periodo 2010-2012. El radiómetro Elbara-II está situado dentro de los confines de la VAS, observando un campo de viñedos que se considera representativo de una gran proporción de un área de 50×50 km, suficiente para cubrir un footprint de SMOS. Las temperaturas de brillo (TB) adquiridas por ELBARA-II se compararon con las observadas por SMOS en las mismas fechas y horas. También se utilizó la inversión del modelo L-MEB con el fin de obtener humedades de suelo (SM) que, posteriormente, se compararon con datos de nivel 3 de SMOS. Se ha encontrado una buena co...
International audienceThe Valencia Anchor Station (VAS) is a validation site of SMOS (Soil Moistu... more International audienceThe Valencia Anchor Station (VAS) is a validation site of SMOS (Soil Moisture and Ocean Salinity) since 2010. For this purpose, different in situ measurements are performed there. This paper will focus on the parameterization of roughness, a key topic for the SMOS and SMAP (Soil Moisture Active Passive) missions. The area covered by the VAS is quite homogeneous, a surface of 50 x 50 km2 mainly composed by vineyards (65%) and other Mediterranean vegetation (30%), which is very stable along the year. The vegetative period of the vineyards lasts approximately from April to October. MELBEX-III is a station inside the area of the VAS, where among other equipments (meteorological station, thermistors, etc.), there is an ELBARA-II Lband radiometer performing multi-angular measurements over a vineyard. There are also two Delta-T ML2x soil moisture probes, one measuring between two rows of vines and the other one next to a vine stump. In the year 2013, measurements of r...
Energy and matter fluxes between the atmosphere and the land surface are affected by hydrological... more Energy and matter fluxes between the atmosphere and the land surface are affected by hydrological states of the terrestrial land surface . We must increase our knowledge of these transfer processes to improve research on climate change. To reach these objectives, we must obtained global information on the hydrological states and properties of the land-surface. The microwave remote sensing instruments are an adequate way to provide soil moisture information at large scale. Microwave remote sensing data are linked to the soil moisture but also to the roughness, texture and the physicochemical properties of the soil. In that context, the objective of this study is to develop an integrated approach to estimate effective electromagnetic properties of soils layers using ground-penetrating radar (GPR), L-band radiometer, dielectric laboratory measurements, modelling approaches and in situ measurements of essential state variables.
We report a unique multiyear L-band microwave radiometry dataset collected at the Maqu site on th... more We report a unique multiyear L-band microwave radiometry dataset collected at the Maqu site on the eastern Tibetan Plateau and demonstrate its utilities in advancing our understandings of microwave observations of land surface processes. The presented dataset contains measurements of L-band brightness temperature by an ELBARA-III microwave radiometer in horizontal and vertical polarization, profile soil moisture and soil temperature, turbulent heat fluxes, and meteorological data from the beginning of 2016 till August 2019, while the experiment is still continuing. Auxiliary vegetation and soil texture information collected in dedicated campaigns are also reported. This dataset can be used to validate the Soil Moisture and Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) satellite based observations and retrievals, verify radiative transfer model assumptions and validate land surface model and reanalysis outputs, retrieve soil properties, as well as to quantify land-atm...
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
This study reports on four consecutive winter campaigns (2016-2020) at the "Davos-Laret Remote Se... more This study reports on four consecutive winter campaigns (2016-2020) at the "Davos-Laret Remote Sensing Field Laboratory" in the Swiss Alps to gain insight into the L-band microwave emission of ground covered with seasonal snow. Closerange L-band Brightness temperatures T p,φ B (θ) were measured over the site scanning different observation nadir angles θ and azimuth angles φ at horizontal and vertical polarization p = {H,V}. State parameters (SPs) of the snowpack (e.g., height, density, and snow water equivalent) and the subnivean soil (permittivity, temperature) were measured quasi-simultaneously using in-situ sensors and sampling, as well as meteorological data. In each campaign, T p,φ B (θ) were measured over a "natural area" and a "reflector area" with a metal mesh reflector laid on the ground before snow accumulation. The radiometer measurements over "reflector area" allowed to retrieve the time-series of Snow liquid Water-content W S and Snow liquid Water-Column W C S , which are employed as "derived measurements" to support interpretation of T p,φ B (θ) measured over "natural areas" during different winter phases. The detailed approach for the estimation of W S and W C S using L-band radiometer data is presented. The data and analyses in this article address the following major points: 1) determination of the characteristic features of measured T p,φ B (θ) during different periods in each of the four winter campaigns; 2) effects of dry and wet snow precipitation on L-band radiometer data compared to corresponding simulations; 3) effect of removal and compression of the snowpack on T p,φ B (θ); 4) effects of spatial heterogeneity on brightness temperatures. Finally, the study is concluded with recommendations relevant for future close-range remote sensing campaigns.
Soil moisture and soil freezing are important for diverse hydrological, biogeochemical, and clima... more Soil moisture and soil freezing are important for diverse hydrological, biogeochemical, and climatological applications. They affect surface energy balance, surface and subsurface water flow, and exchange rates of carbon with the atmosphere. Soil freezing controls important biogeochemical processes, like photosynthetic activity of plants and microbial activity within soils. Permafrost covers approximately 24% of the land surface in the Northern Hemisphere and seasonal freezing occurs on approximately 51% of the area.
IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium, 2019
We demonstrate an application of the L-band specific Microwave Emission Model of Layered Snowpack... more We demonstrate an application of the L-band specific Microwave Emission Model of Layered Snowpacks (LS-MEMLS) to snow over the Greenland Ice Sheet to retrieve density and snow wetness from SMOS satellite data. Retrievals of these parameters have previously been demonstrated using ground-based L-band radiometry over snow covered ground in alpine conditions. Existing passive microwave data products over ice sheets include empirical and threshold-based techniques but until recently have not used radiative-transfer physics-based modelling. We discuss the retrieval method based on inversion of LS-MEMLS and present a comparison between our retrievals and in-situ weather station air temperature data. We also mention ongoing work investigating the applicability of the novel retrieval method for mapping the ablation zone of the Greenland Ice Sheet.
Observation and Measurement of Ecohydrological Processes, 2019
Soil water content is a key variable for understanding and modeling ecohydrological processes. In... more Soil water content is a key variable for understanding and modeling ecohydrological processes. In this chapter, we review the state of the art of ground-based methods to characterize the spatiotemporal dynamic of soil water content, from point to field scale. First, point measurements methods are briefly discussed. Then, field-scale hydrogeophysical approaches such as ground-penetrating radar, ground-based L-band radiometry, electromagnetic induction, electrical resistivity tomography, cosmic-ray neutron probes, global navigation satellite system reflectometry, and nuclear magnetic resonance are described in more details. The basic principles of the different techniques, the spatial and temporal characteristics of their measurements, their advantages and limitations, as well as the recent developments in the data processing are presented
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