Issues

Estimation of Radiative Transfer Parameters from L-Band Passive Microwave Brightness Temperatures Using Advanced Data Assimilation
The temporal evolution of radiative transfer parameters vegetation opacity and soil surface roughness is estimated by assimilating L-band brightness temperatures. The L-MEB model is used within a particle filter in synthetic applications with increasing complexity. Finally, a real-world experiment is conducted with multiangular SMOS observations covering a SCAN site.
Field Level Soil Moisture Variability at 6- and 3-cm Sampling Depths: Implications for Microwave Sensor Validation
Field-level statistical moments of volumetric soil moisture were compared between the 6- and 3-cm measurement depths. Results are of interest for the ground calibration/validation of microwave remote sensing algorithms, which is commonly performed only at a fixed 6-cm measurement depth.
Joint Assimilation of Surface Temperature and L-Band Microwave Brightness Temperature in Land Data Assimilation
Brightness temperature and land surface temperature are two important remote sensing assimilation data sources. Several land data assimilation experiments were proposed to evaluate the impact of their joint assimilation on the soil moisture and soil temperature profiles, and characterization of surface fluxes
Management of Postharvest Deficit Irrigation of Peach Trees Using Infrared Canopy Temperature
Midday infrared canopy to air temperature difference was used to manage postharvest deficit irrigation of early season peach trees. The relationship between fruit mass and postharvest irrigation amount showed 50% water saving without impacting fruit size. The method can provide growers with a practical tool to save water without reduction in yield.
Estimating Effective Soil Hydraulic Properties Using Spatially Distributed Soil Moisture and Evapotranspiration
We developed an improved data assimilation scheme for estimating effective soil hydraulic parameters at the remote sensing footprint scale by linking remotely sensed soil moisture and evapotranspiration (ET) time series. Inclusion of ET (multiobjective) in the optimization algorithm reduced the uncertainty in the estimated soil hydraulic parameters in comparison to the objective based on soil moisture only.
Global Automated Quality Control of In Situ Soil Moisture Data from the International Soil Moisture Network
The International Soil Moisture Network contains more than 6100 in situ soil moisture data sets from all over the world to support the development of remote sensing products and land surface models, and to facilitate studying the behavior of our climate over space and time. We present a new, automated quality control system for these measurements.
Satellite-Based Radar Interferometry to Estimate Large-Scale Soil Water Depletion from Clay Shrinkage: Possibilities and Limitations
Satellite-based radar interferometry applications to vadose zone processes are reviewed. The potential is illustrated with cases of frost heave and clay soil shrinkage. Upcoming sensors and well-designed studies might enable large-scale soil water storage estimations in clay soils in the near future.
How Many Measurements of Soil Moisture within the Footprint of a Ground-Based Microwave Radiometer Are Required to Account for Meter-Scale Spatial Variability?
Validation of ground-based microwave remote sensing measurements with point measurements of soil moisture remains an important task. We investigated the spatial process of soil moisture and sampling strategies for estimating the mean soil moisture of an area on the order of tens of square meters, over various soil moisture conditions.
Soil Moisture Estimation in Alpine Catchments through Modeling and Satellite Observations
Knowledge of soil moisture is of upmost importance for many applications (e.g., flood and landslide prediction). In alpine areas, its estimation is difficult mainly due to complex topography and presence of snow. In this study, modeled and satellite data obtained by the Advanced SCATterometer have shown good agreement with in situ observations.
Deriving Hourly Evapotranspiration Rates with SEBS: A Lysimetric Evaluation
Surface Energy Balance System (SEBS) is one of the widely used surface EB methods for deriving ET rates from remote sensing data. It does not require subjective selection of hot and cold pixels for deriving ET. However, the SEBS has never been evaluated for its ability to estimate ET using lysimetric measurements. In this study, we evaluated the SEBS for estimating ET using Landsat 5 satellite data for summer crops in the Southern High Plains. Performance statistics indicated that SEBS performance was equally good in estimating hourly ET on both dryland and irrigated fields.
Multidecadal Trend of Basin-Scale Evapotranspiration Estimated Using AVHRR Data in the Krishna River Basin, India
The AVHRR data were used to estimate evapotranspiration in the Krishna River Basin, India, for the period 1983 to 2001. Results show that the basin-average evapotranspiration (ET) increased continuously at the mean rate of 4.97 mm yr−1 yr−1 during this period. The land-use information showed that the increased ET was mainly due to the development of irrigation in the basin.
Characterizing Heterogeneous Processes of Water Flow and Solute Transport in Soils Using Multiple Tracer Experiments
This study was performed to quantify heterogeneous soil water flow and solute transport processes by using multiple tracers and a random cascade model. The heterogeneous processes were attributable to macropore flow, change of flow paths, and unstable infiltration fronts. The solute transport process included more heterogeneous information than the water flow.
Multi-Stage Inversion Method to Retrieve Soil Moisture from Passive Microwave Measurements over the Mackenzie River Basin
This work proposes a satellite-based approach to retrieve soil moisture in the Mackenzie River Basin using dual polarization C-band AMSR-E data. Because of the scarcity of in situ observations, a two-stage method based on the sensitivity of the signal to soil and vegetation parameters was applied for the calibration of a simplified radiative transfer model.
Diffusivity and Sorptivity of Berea Sandstone Determined using Neutron Radiography
Neutron radiography was used to investigate capillary uptake of water in Berea sandstone, which is widely used as a standard porous medium in flow and transport studies. The sorptivity and unsaturated diffusivity function were estimated from analyses of the neutron radiographs. These parameters have not been previously reported for this material.
Nitrogen Fate and Transport in a Conventional Onsite Wastewater Treatment System Installed in a Clay Soil: Experimental Results
Relationships between N transport and hydraulic function of onsite wastewater treatment systems in clay-textured soils are largely unknown. An onsite wastewater treatment system was installed an a clay textured soil in the Piedmont region of Georgia. The drainfield was instrumented with sensors to measure soil water content and pressure. Suction lysimeters were installed under the drainfield and samples were collected for two years. Soil water was analyzed for nitrogen and chloride concentrations. The fate and transport of N was dynamic in this system due to variable moisture conditions near the trench-soil interface which may have intermittently stimulated denitrification.
Nitrogen Fate and Transport in a Conventional Onsite Wastewater Treatment System Installed in a Clay Soil: A Nitrogen Chain Model
Nitrogen cycling in clay-textured soils with onsite wastewater treatment systems is studied and modeled much less often than sand- and loam-textured soils because there is little data on onsite wastewater treatment system performance in these soils. An N chain model with water-content dependent first-order transformation rates for nitrification and denitrification was developed and calibrated using data from a conventional onsite wastewater treatment system installed in a clay-textured soil. The model predicted the N removal in the system. Estimates of N loss were specific to clay-textured soils and should be valuable to TMDL developers who need to predict load allocations for non-point sources in the Piedmont.
Anisotropic Scaling of Berea Sandstone Log Air Permeability Statistics
Minipermeameter Berea sandstone data and their increments are found to be consistent with sub-Gaussian random fields subordinated to truncated fractional Gaussian noise. Their statistics and scaling behavior are shown to depend on direction.
Estimation of Contaminant Subslab Concentration in Vapor Intrusion Including Lateral Source–Building Separation
Most vapor intrusion screening tools focus on the one-dimensional vertical transport of contaminant vapor by assuming the homogenous distribution of contaminant vapor source, an assumption that is unrealistic. In this study, a new semi-analytical method including lateral source-building separation, was introduced and compared with three-dimensional simulations.
Virtual Soils: Moisture Measurements and Their Interpretation by Inverse Modeling
Heterogeneity strongly affects water dynamics in soils and therefore local measurements of hydraulic state variables. Inverse modeling is used to investigate hydrological data obtained from local measurements in heterogeneous virtual soils. Variability, estimated hydraulic properties, and predicted water balances are interpreted in the light of the known truth.
New Local Thresholding Method for Soil Images by Minimizing Grayscale Intra-Class Variance
Advances in imaging offer the possibility of visualizing the three-dimensional structure of soils at very fine scales. As part of analysis, thresholding is used to separate the image into solid particles and pores. Existing methods cannot cope with the complexity of soil structure. We propose a new thresholding method to overcome the challenges imposed by soils.
Forward Prediction of Height-Averaged Capillary Pressure–Saturation Parameters Using the BC-vG Upscaler
The BC-vG Upscaler program predicts van Genuchten (vG) parameters as a function of column height. It converts point Brooks and Corey (BC) parameters into vG parameters for inclusion in numerical models used for large-scale simulations of variably saturated flow. It can also be used to develop new relationships between the BC and vG parameters.
Assessment of Solar Irradiation Models in A Coruña by Multifractal Analysis
Models for global, diffuse, and direct radiation referred to A Coruña (Northwest of Spain) have been developed making use of the autoregressive integrated moving average methodology. It was found that multifractal detrending fluctuation analysis can be used as a complement for model assessment, since it offers an analysis of model behavior to different timescales.
The Effects of Bulk Density and Water Potential on Multifractal Characteristics of Soil Penetration Resistance Microprofiles Measured on Disturbed Soil Samples
Penetration resistance microprofiles measured on disturbed soil samples exhibited a well-defined multifractal structure. Increasing bulk density gradually decreased its degree of multifractality. High water contents showed no significant effects on this property, but multifractality increased with increasing soil dryness near the wilting point.
Global Relationships of Pedodiversity and Biodiversity
Biodiversity and pedodiversity conform to the power law at planetary level. The two types of diversity are strongly correlated. When a country has high pedodiversity it has also high biodiversity. A novel “soil–regolith taxonomy” should improve the analysis of pedodiversity–biodiversity relations.
Multifractal Analysis of Soil Properties along Two Perpendicular Transects
Soil textural fractions, organic carbon content, pH, and attributes of the soil exchange complex were sampled parallel and perpendicular to land slope, along two transects. All data sets have been found to exhibit slight to strong multifractal behavior. Most variables showed different scaling properties between the two transects.
Specific Surface Area and Multifractal Parameters of Associated Nitrogen Adsorption and Desorption Isotherms in Soils from Santa Catarina, Brazil
Multifractal analysis was used to quantify the inner structure of both nitrogen adsorption (NAI) and desorption (NDI) isotherms. The former showed higher scaling heterogeneity and were less persistent than the later. Multifractal parameters gathered from NAIs and NDIs provided more information than specific surface area (SSA) estimates and best correlated with organic carbon and clay content and, respectively.
Characterizing Weathering of Granite Buildings by Multifractal Analysis of Mercury Intrusion Porosimetry
The assessment of weathering of stones requires the use of high resolution techniques. We explored the joint use of elemental chemical analysis, mercury intrusion porosimetry, and multifractal analysis of pore size distributions (PSDs). Our results show that multifractal analysis of PSDs may be an appropriate tool for assessing weathering.
Lithologic Control on the Scaling Properties of the First-Order Streams of Drainage Networks: A Monofractal Analysis
The movement of water through the landscape can be investigated at different scales. This study dealt with the interrelation between bedrock lithology and the geometry of the overlying drainage systems. Parameters of fractal analysis, such as fractal dimension and lacunarity, were used to measure and quantify this relationship.
Multifractal Analysis of Nitrogen Adsorption Isotherms Obtained from Organoclays Exposed to Different Temperatures
Multifractal analysis was applied to N2 adsorption isotherms of clays exchanged with various cations and after thermal treatments. Parameters from Rényi and singularity spectra varied with the type of cation. An interaction with temperature was observed. The parameters were correlated with organic C content, indicating a relation between thermal transformation of organic cations and sorption heterogeneity.
On the Generative Equations of Fractal Self-Similarity in Granular Media and the Related PSD Models
The physical appearance of granular media suggests the existence of geometrical scale invariance. The paper discuss how this physico-empirical property can be mathematically encoded leading to different generative models: a smooth one encoded by a differential equation and another encoded by an equation coming from a measure theoretical property.
Morphological Functions to Quantify Three-Dimensional Tomograms of Macropore Structure in a Vineyard Soil with Two Different Management Regimes
Soil tomography and morphological functions built over Minkowski functionals were used to describe the impact on pore structure of two soil management practices in a Mediterranean vineyard.
Lacunarity of the Spatial Distributions of Soil Types in Europe
Lacunarity as a means of quantifying textural properties of spatial distributions suggests a classification into three main classes of the most abundant soils that cover 92% of Europe. Soils with a well-defined self-similar structure of the linear class are related to widespread spatial patterns that are nondominant but ubiquitous at continental scale.
Structure-Dependent Water-Induced Linear Reduction Model for Predicting Gas Diffusivity and Tortuosity in Repacked and Intact Soil
The water-induced linear reduction (WLR) model for gas diffusivity in sieved, repacked soil is extended with a media complexity factor (Cm) representing local-scale soil heterogeneity. The new structure-dependent WLR (SWLR) model hereby allows for predicting gas diffusivity in both repacked soil (Cm = 1) and intact soil (Cm typically around 2).
Changes in Water Flow and Solute Transport Pathways During Long-Term Column Experiments
In a long-term column experiment non-uniform water flow and transport developed over time. This was confirmed by tracer experiments and mathematical modeling. Changes in flow paths were attributed to biomass accumulation and calcite precipitation near the inlet. Transport parameters need to be determined over the entire course of column experiments.
Measuring the Dynamic Soil Response During Repeated Wheeling Using Seismic Methods
A seismic method was used in situ to assess the dynamic soil response due to loading with an agricultural tire. P-wave velocity increased due to loading and decreased again after loading but was not recovered due to induced compaction. Relationships between P-wave velocity and soil bulk density and penetrometer resistance were established.
Estimation of Regional Groundwater Recharge Using Data from a Distributed Soil Moisture Network
Calibrating one-dimensional soil–vegetation–atmosphere models against soil moisture measurements from stations arranged in a network representing the spatial variation in land use, precipitation, and soil texture has proved capable of providing reliable estimates of continuous groundwater recharge and actual evapotranspiration at land use and catchment scales.
Modeling Water Potentials and Flows in the Soil–Plant System Comparing Hydraulic Resistances and Transpiration Reduction Functions
Crop transpiration depends on resistances in the soil–plant–atmosphere system. We present a new deterministic root water uptake model to estimate transpiration and compare it with two other models. We show the sensitivity of actual transpiration to parameters like soil and plant hydraulic properties and root length density distribution with depth.
Simulation of Fumigant Transport and Volatilization from Tarped Broadcast Applications
We evaluated the HYDRUS 2D/3D model for simulating chloropicrin and 1,3-dichloropropene fate and transport in broadcast applications. The calibrated model provided relatively accurate estimates of fumigant soil gas concentrations, and volatilization in two data sets using input data were measured, estimated, or obtained by independent calibration.
Gas Diffusivity-Based Design and Characterization of Greenhouse Growth Substrates
Five potential growth media and two mixtures thereof were characterized on the basis of soil gas diffusivity and critical window of diffusivity. A modeling approach to account for inactive pore space and gas percolation threshold both in inter aggregate and intra-aggregate regions was presented. A simple gas diffusivity mixing model was also discussed.
Passive Microwave Soil Moisture Downscaling Using Vegetation Index and Skin Surface Temperature
A soil moisture downscaling algorithm based on the thermal inertia relationship between daily temperature changes and daily average soil moisture is presented and the remote sensed products skin surface temperature and vegetation index are used. The downscaled soil moisture estimates are applied to the passive microwave radiometer AMSR-E soil moisture for enhancing its spatial resolution to 1 km.
Evaluating Bias-Corrected AMSR-E Soil Moisture using in situ Observations and Model Estimates
Satellite derived soil moisture products are sometimes biased and need to be corrected. We implemented a statistical method by matching the cumulative distribution method of the soil moisture derived using the satellite data with that of derived using in situ data. Using this method for the AMSR-E data over Nebraska and Idaho, we showed the methodology in which both in situ data from 37 automated weather data network and modeled data can be useful in improving the quality of the satellite product. The resulting soil moisture estimates showed a much better correlation with the in situ data.
Special Section: Scaling in Soil and Complex Porous Media
Scaling in Soil and Other Complex Porous Media
Scaling is becoming an increasingly important topic in the earth and environmental sciences as researchers attempt to understand complex natural systems through the lens of an ever-increasing set of methods and scales. The guest editors introduce the papers in this issue’s special section and present an overview of some of the work being done.
ANNOUNCEMENTS
Special Section: Remote Sensing for Vadose Zone Hydrology
Remote Sensing for Vadose Zone Hydrology—A Synthesis from the Vantage Point
The guest editors introduce the special section, highlighting the latest remote sensing techniques for characterizing the vadose zone.
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