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Christian Schmidt - One of the best experts on this subject based on the ideXlab platform.
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Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based Water Flux calculation
Hydrology and Earth System Sciences, 2011Co-Authors: Mathias Munz, Sascha E. Oswald, Christian SchmidtAbstract:Abstract. Quantification of subsurface Water Fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical Water Flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled Water Fluxes in the range of ±1.3 m d−1. Pass band filtering provided amplitude differences and phase shifts of the diurnal temperature signal varying with depth depending on Water Flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of Water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to temperature sensor spacing, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with Water Flux direction only. Temperature time lags of small sensor distances of all setups were found to be insensitive to vertical Water Flux.
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Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based Water Flux calculation
Hydrology and Earth System Sciences Discussions, 2011Co-Authors: Mathias Munz, Sascha E. Oswald, Christian SchmidtAbstract:Abstract. Quantification of subsurface Water Fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical Water Flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled Water Fluxes in the range of ±1.3 m d−1. Pass band filtered time series provided amplitude and phase of the diurnal temperature signal varying with depth depending on Water Flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of Water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to probe distance, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with Water Flux direction only. Temperature time lags of small probe distances of all setups were found to be insensitive to vertical Water Flux.
Mathias Munz - One of the best experts on this subject based on the ideXlab platform.
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Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based Water Flux calculation
Hydrology and Earth System Sciences, 2011Co-Authors: Mathias Munz, Sascha E. Oswald, Christian SchmidtAbstract:Abstract. Quantification of subsurface Water Fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical Water Flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled Water Fluxes in the range of ±1.3 m d−1. Pass band filtering provided amplitude differences and phase shifts of the diurnal temperature signal varying with depth depending on Water Flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of Water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to temperature sensor spacing, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with Water Flux direction only. Temperature time lags of small sensor distances of all setups were found to be insensitive to vertical Water Flux.
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Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based Water Flux calculation
Hydrology and Earth System Sciences Discussions, 2011Co-Authors: Mathias Munz, Sascha E. Oswald, Christian SchmidtAbstract:Abstract. Quantification of subsurface Water Fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical Water Flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled Water Fluxes in the range of ±1.3 m d−1. Pass band filtered time series provided amplitude and phase of the diurnal temperature signal varying with depth depending on Water Flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of Water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to probe distance, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with Water Flux direction only. Temperature time lags of small probe distances of all setups were found to be insensitive to vertical Water Flux.
Glendon W. Gee - One of the best experts on this subject based on the ideXlab platform.
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Letters to the Editor: Comments on "Improvements to Measuring Water Flux in the Vadose Zone".
Journal of Environmental Quality, 2005Co-Authors: Glendon W. GeeAbstract:This letter contains comments on the paper ''Improvements to Measuring Water Flux in the Vadose Zone'' (K.C. Masarik, J.M. Norman, K.R. Brye, and J.M Baker; J. Environ. Qual. 33:1152-1158).
Sascha E. Oswald - One of the best experts on this subject based on the ideXlab platform.
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Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based Water Flux calculation
Hydrology and Earth System Sciences, 2011Co-Authors: Mathias Munz, Sascha E. Oswald, Christian SchmidtAbstract:Abstract. Quantification of subsurface Water Fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical Water Flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled Water Fluxes in the range of ±1.3 m d−1. Pass band filtering provided amplitude differences and phase shifts of the diurnal temperature signal varying with depth depending on Water Flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of Water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to temperature sensor spacing, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with Water Flux direction only. Temperature time lags of small sensor distances of all setups were found to be insensitive to vertical Water Flux.
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Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based Water Flux calculation
Hydrology and Earth System Sciences Discussions, 2011Co-Authors: Mathias Munz, Sascha E. Oswald, Christian SchmidtAbstract:Abstract. Quantification of subsurface Water Fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical Water Flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled Water Fluxes in the range of ±1.3 m d−1. Pass band filtered time series provided amplitude and phase of the diurnal temperature signal varying with depth depending on Water Flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of Water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to probe distance, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with Water Flux direction only. Temperature time lags of small probe distances of all setups were found to be insensitive to vertical Water Flux.
Scott B. Jones - One of the best experts on this subject based on the ideXlab platform.
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An analytical model for estimation of land surface net Water Flux from near-surface soil moisture observations
Journal of Hydrology, 2019Co-Authors: Morteza Sadeghi, Markus Tuller, Arthur W. Warrick, Ebrahim Babaeian, Kshitij Parajuli, Mohammad R. Gohardoust, Scott B. JonesAbstract:Abstract The accurate determination of land surface Water Fluxes at various spatiotemporal scales remains a challenge in hydrological sciences. It is intuitive that land surface net Water Flux (i.e., infiltration minus evapotranspiration) directly affects near-surface soil moisture. However, there exists no hydrological model suitable to calculate net Water Flux based on measured near-surface soil moisture data. This is a consequence of the mathematical structure of existing models that use ‘boundary conditions’ to determine ‘internal conditions’, whereas what is needed is a model amenable to use near-surface soil moisture data (an internal condition) to determine the surface Water Flux (a boundary condition). To pursue the idea of utilizing remotely-sensed or in situ (i.e., sensor networks) near surface soil moisture data for estimation of net Water Flux, we derived an analytical model via inversion of Warrick’s 1975 analytical solution to the linearized Richards’ equation for arbitrary time-varying surface Flux boundary conditions. The applicability of the new analytical solution was evaluated based on actual Water Flux observations as well as HYDRUS-1D simulations for four vastly different sites in Arizona, California, Idaho, and Indiana. Our results demonstrate that the proposed model reasonably captures net Water Flux variations in natural settings, including layered and vegetated soils, especially at larger time scales (e.g., monthly). While the model works for a wide range of climatic conditions, the prediction accuracy is somewhat lower for extreme dry or wet conditions. A major advantage of the new model is that it does not require calibration, which provides an unprecedented opportunity for large scale estimation of land surface net Water Flux using remotely sensed near-surface soil moisture observations.
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Inverse method for simultaneous determination of soil Water Flux density and thermal properties with a penta‐needle heat pulse probe
Water Resources Research, 2013Co-Authors: Changbing Yang, Masaru Sakai, Scott B. JonesAbstract:[1] An accurate method for determination of in situ soil Water Flux density continues to be the most sought after and yet elusive hydrologic measurement. The penta-needle heat pulse probe (PHPP) employs a central heater needle surrounded by an orthogonal arrangement of four thermistor needles for two-component Water Flux density estimation. An analytical solution and inverse fitting method are presented for simultaneous estimation of thermal properties and soil Water Flux density using PHPP measurements. The approach yields estimates of both components of the Flux in a plane normal to the axis of the PHPP needles. The method was evaluated using data measured by PHPPs in a laboratory experiment using a wide range of saturated Water Fluxes ranging from 1.2 to 33,200 cm d−1. Improved Water Flux density determination was achieved from zero-Flux adjusted estimates of the apparent heater-thermistor radii, radj, which were used in the inverse analysis. Thermal diffusivity and conductivity were estimated with coefficients of variation less than 1.35%, indicating that the inverse problem is well posed and yields unique parameter estimates when Water Flux is less than 2000 cm d−1. Estimates of the x and y components of Water Flux density agreed well with measured Water Fluxes up to 7000 cm d−1 exhibiting R2 values greater than 0.976. Estimation of Water flow direction based on 2-D Water Flux density was in good agreement with installation angle for Water Fluxes ranging from 10 to 7000 cm d−1.
