1,721,044 research outputs found
SiSPAT-Isotope code for modelling stable water isotopologue transport within soils
No full textSiSPAT-Isotope source code to reproduce the results presented in J. Schneider, S. Kiemle, K. Heck, Y. Rothfuss, I. Braud, R. Helmig, J. Vanderborght (2024) Analysis of experimental and simulation data of evaporation-driven isotopic fractionation in unsaturated porous media. Vadose Zone Journal, e20363.
SiSPAT is a one-dimensional numerical model of water and energy fluxes in the soil-plant-atmosphere continuum. The extension SiSPAT-Isotope allows to sequentially solve the transport of stable water isotopologues and their fractionation behaviour in soils. The source code is stored in the files Sispat_isotope_it.f and Subrsispat_isotope_it.f.
With gfortran Sispat_isotope_it.f the program is executed. The file nomfich.dat contains all input and output files used in the simulation and is read into Sispat_isotope_it.f.</p
In-situ monitoring of soil water isotopic composition for partitioning of evapotranspiration during one growing season of sugar beet (Beta vulgaris)
No full textField-based quantitative observations of hydrological feedbacks of terrestrial vegetation to the atmosphere are crucial for improving land-surface model parametrizations. This is especially true in the specific context of partitioning of evapotranspiration (ET) into soil evaporation (E) and plant transpiration (T): land surface models are able to compute E and T separately while observed transpiration fractions (T/ET) are still sparse.In this study, we present the application of an on-line non-destructive method based on gas-permeable tubing for the in-situ collection of soil water vapor. This allowed for monitoring of the hydrogen and oxygen isotopic compositions (δ2H and δ18O) of soil water during a field campaign where ET of sugar beet (Beta vulgaris) was partitioned. T/ET estimates obtained with the non-destructive method were compared with the commonly used destructive sampling of soil and subsequent cryogenic extraction of soil water under vacuum. Finally, isotope-based T/ET estimates were compared to those obtained from a combination of micro-lysimeter and eddy covariance (EC) measurements. Significant discrepancies between the values of isotopic composition of evaporation derived destructively and non-destructively from those of soil water using a well-known transfer resistance model led in turn to significant differences in T/ET. This is in line with recent findings on the systematic offsets of soil water isotopic composition values in relation to the water sampling and extraction measurement techniques and calls for further investigation of these isotopic offsets for accurate separation of E from T in the field. These discrepancies were, however, smaller than those observed between δ2H- or δ18O-based T/ET estimates, and more than three times smaller than those between isotope-based and lysimeter-based estimates
Ecohydrological response of a grassland species to drought from an isotopic and hydraulic perspective
No full textMonitoring water stable isotope composition in soils using gas-permeable tubing and infrared laser absorption spectroscopy
No full textAbstract: The water stable isotopologues 1H2H16O and 1H218O are powerful tracers of processes occurring in nature. Their slightly different masses as compared to the most abundant water isotopologue (1H216O) affect their thermodynamic (e.g. during chemical equilibrium reactions or physical phase transitions with equilibration) and kinetic (liquid and vapor phases transport processes and chemical reactions without equilibration) properties. This results in measurable differences of the isotopic composition of water within or between the different terrestrial ecosystem compartments (i.e. sub-soil, soil, surface waters, plant, and atmosphere). These differences can help addressing a number of issues, among them water balance closure and flux partitioning from the soil-plant-atmosphere continuum at the field to regional scales. In soils particularly, the isotopic composition of water (δ2H and δ18O) provides qualitative information about whether water has only infiltrated or already been re-evaporated since the last rainfall event or about the location of the evaporation front. From water stable isotope composition profiles measured in soils, it is also possible, under certain hypotheses, to derive quantitative information such as soil evaporation flux and the identification of root water uptake depths. In addition, water stable isotopologues have been well implemented into physically based Soil–Vegetation–Atmosphere Transfer models (e.g. SiSPAT-Isotope; Soil–Litter iso; TOUGHREACT) and have demonstrated their potential. However, the main disadvantage of the use of stable isotopes in soil water studies is that, contrary to other state variables (e.g. water content and tension) that can be monitored over long periods (e.g. by time-domain reflectometry, capacitive sensing, tensiometry or micro-psychrometry), stable isotope compositions are analyzed following destructive sampling, and thus are available only at a given time. As a consequence, there are important time discrepancies between soil water and stable isotope information which greatly limit the insight potential of the latter. Recently, a novel technique based on direct infrared laser absorption spectroscopy was developed that allows simultaneous and direct measurements of 1H216O, 1H2H16O and 1H218O composition in water vapour, which constitutes a major breakthrough in stable isotope analysis. Many applications can be found in the literature for varying temporal and spatial scales. In this study, we present a simple methodology for monitoring soil liquid water stable isotope composition (δ2H, δ18O) in a non-destructive manner by sampling and measuring water vapour equilibrated with soil water, using gas-permeable polypropylene tubing and a cavity ring-down laser absorption spectrometer. We will first give a detailed presentation of our laboratory controlled experimental setup and water vapour sampling protocol. We will then show that, following a preliminary calibration in a saturated fine sand, it is possible to follow the changes of isotopic composition of soil water over a wide range of water availability conditions. Limits of this technique as well as advices to potential field users will be given
Partition de l'évapotranspiration réelle en évaporation du sol et transpiration des couverts végétaux à partir du traçage isotopique (18O) en milieu contrôlé : expérimentation et modélisation SiSPAT_Isotope
No full text[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAU [Encadrant_IRSTEA]Braud, I.Evapotranspiration (ET) is a major component of continental precipitation recycling. In order to improve our knowledge of the water cycle at different scales, it is therefore crucial to know the amount and origin of water lost to the atmosphere through ET (i.e. Soil Evaporation and/or Plant Transpiration). ET from a monolith of soil with a tall fescue cover (Festuca arundinacea L.) was measured in a series of controlled conditions (climat chamber) experiments over the course of the growing period. Heavy stable isotopes were used to partition ET into Soil Evaporation and Plant Transpiration components at different stages of growth from bare soil to full canopy. The contribution of Soil Evaporation to Evapotranspiration decreased during the experiment from 100% (bare soil) to 94% (at 16 days after seeding), 83% (at 28 days), 70% (at 36 days) and finally dropped down to 5% (at 43 days). Experiment under controlled conditions allowed each partition value to be associated with a detailed description of vegetation characteristics (Leaf Area Index, Root Distribution Densitiy) as well as soil and climat conditions. The nature and amount of data gathered here gave us the opportunity to evaluate the performance of a model of heat, water and isotopes transfer through the soil, vegetation and atmosphere, SiSPAT_Isotopes (Simple Soil Plant Atmosphere Transfer model, Braud et al., 1995; 2000; 2002). The model proved reliable under the monolith experimental conditions. Moreover, this study enabled the evaluation of the model's isotopes transfer module within the soil and the plant: isotopic profiles and fluxes within the soil as well as plant extraction depths could be modelled. It was possible to simulate continuously the experiment and analyse into more details the outputs of the model that cannot be normally measured.L'évapotranspiration est un terme majeur du recyclage des précipitations au niveau des surfaces continentales. En vue de compléter notre connaissance du cycle de l'eau à différentes échelles, il est donc essentiel de connaître à la fois les quantités d'eau libérées par évapotranspiration dans l'atmosphère ainsi que leurs origines possibles (évaporation du sol et/ou transpiration des couverts végétaux). L'utilisation des isotopes stables et lourds de l'eau lors d'une série d'études réalisées sur monolithes de sol en milieu contrôlé (réacteur biogéochimique) nous a permis de déterminer l'évolution de la partition de l'évapotranspiration en évaporation du sol et transpiration des plantes au cours du développement d'un couvert de fétuque élevée. Il a fallu pour cela maintenir le système sol-plante en régime hydrique permanent de manière à ce qu'il atteigne l'état isotopique stationnaire. La contribution de l'évaporation du sol à l'évapotranspiration réelle a diminué durant l'expérience de 100% (sol nu) à 94% (16 jours suivant le semis), 83% (28 jours), 70% (36 jours) pour finalement atteindre 5% (43 jours). Le recours au milieu contrôlé nous a permis d'atteindre l'état isotopique stationnaire recherché et associer à chaque valeur de partition une description détaillée du couvert végétal (indice foliaire, profil de densité racinaire) ainsi que des conditions climatiques dans l'atmosphère du réacteur et hydriques dans le sol. La nature et la quantité de données à disposition permettent l'évaluation du fonctionnement d'un modèle de flux de chaleur, d'eau et d'isotopes à travers le continuum sol-plante-atmosphère SiSPAT_Isotopes (Simple Soil Plant Atmosphere Transfer model, Braud et al., 1995 ; 2000 ; 2002). On a pu constater que la structure du modèle était suffisamment souple pour être adaptée aux conditions expérimentales. Ce travail a tout particulièrement permis l'évaluation du module de transport des isotopes dans le sol et la plante : on a pu modéliser les profils ainsi que les flux d'isotopes dans le sol et déterminer les profondeurs d'extraction racinaire. Il a été possible de simuler l'expérience en continu, y compris en régime transitoire et d'analyser plus en détail, en s'appuyant sur les sorties du modèle non accessibles à la mesure, les hypothèses faites lors de l'expérience, notamment l'atteinte de régime hydrique permanent et d'état isotopique stationnaire
Partition de l'évapotranspiration réelle en évaporation du sol et transpiration des couverts végétaux à partir du traçage isotopique (18O) en milieu contrôlé : expérimentation et modélisation SiSPAT_Isotope
No full text[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAU [Encadrant_IRSTEA]Braud, I.Evapotranspiration (ET) is a major component of continental precipitation recycling. In order to improve our knowledge of the water cycle at different scales, it is therefore crucial to know the amount and origin of water lost to the atmosphere through ET (i.e. Soil Evaporation and/or Plant Transpiration). ET from a monolith of soil with a tall fescue cover (Festuca arundinacea L.) was measured in a series of controlled conditions (climat chamber) experiments over the course of the growing period. Heavy stable isotopes were used to partition ET into Soil Evaporation and Plant Transpiration components at different stages of growth from bare soil to full canopy. The contribution of Soil Evaporation to Evapotranspiration decreased during the experiment from 100% (bare soil) to 94% (at 16 days after seeding), 83% (at 28 days), 70% (at 36 days) and finally dropped down to 5% (at 43 days). Experiment under controlled conditions allowed each partition value to be associated with a detailed description of vegetation characteristics (Leaf Area Index, Root Distribution Densitiy) as well as soil and climat conditions. The nature and amount of data gathered here gave us the opportunity to evaluate the performance of a model of heat, water and isotopes transfer through the soil, vegetation and atmosphere, SiSPAT_Isotopes (Simple Soil Plant Atmosphere Transfer model, Braud et al., 1995; 2000; 2002). The model proved reliable under the monolith experimental conditions. Moreover, this study enabled the evaluation of the model's isotopes transfer module within the soil and the plant: isotopic profiles and fluxes within the soil as well as plant extraction depths could be modelled. It was possible to simulate continuously the experiment and analyse into more details the outputs of the model that cannot be normally measured.L'évapotranspiration est un terme majeur du recyclage des précipitations au niveau des surfaces continentales. En vue de compléter notre connaissance du cycle de l'eau à différentes échelles, il est donc essentiel de connaître à la fois les quantités d'eau libérées par évapotranspiration dans l'atmosphère ainsi que leurs origines possibles (évaporation du sol et/ou transpiration des couverts végétaux). L'utilisation des isotopes stables et lourds de l'eau lors d'une série d'études réalisées sur monolithes de sol en milieu contrôlé (réacteur biogéochimique) nous a permis de déterminer l'évolution de la partition de l'évapotranspiration en évaporation du sol et transpiration des plantes au cours du développement d'un couvert de fétuque élevée. Il a fallu pour cela maintenir le système sol-plante en régime hydrique permanent de manière à ce qu'il atteigne l'état isotopique stationnaire. La contribution de l'évaporation du sol à l'évapotranspiration réelle a diminué durant l'expérience de 100% (sol nu) à 94% (16 jours suivant le semis), 83% (28 jours), 70% (36 jours) pour finalement atteindre 5% (43 jours). Le recours au milieu contrôlé nous a permis d'atteindre l'état isotopique stationnaire recherché et associer à chaque valeur de partition une description détaillée du couvert végétal (indice foliaire, profil de densité racinaire) ainsi que des conditions climatiques dans l'atmosphère du réacteur et hydriques dans le sol. La nature et la quantité de données à disposition permettent l'évaluation du fonctionnement d'un modèle de flux de chaleur, d'eau et d'isotopes à travers le continuum sol-plante-atmosphère SiSPAT_Isotopes (Simple Soil Plant Atmosphere Transfer model, Braud et al., 1995 ; 2000 ; 2002). On a pu constater que la structure du modèle était suffisamment souple pour être adaptée aux conditions expérimentales. Ce travail a tout particulièrement permis l'évaluation du module de transport des isotopes dans le sol et la plante : on a pu modéliser les profils ainsi que les flux d'isotopes dans le sol et déterminer les profondeurs d'extraction racinaire. Il a été possible de simuler l'expérience en continu, y compris en régime transitoire et d'analyser plus en détail, en s'appuyant sur les sorties du modèle non accessibles à la mesure, les hypothèses faites lors de l'expérience, notamment l'atteinte de régime hydrique permanent et d'état isotopique stationnaire
Replication data for analyzing stable water isotopologue transport within soils using fractionation parameterizations
No full textReplication data to reproduce the results presented in J. Schneider & S. Kiemle, K. Heck, Y. Rothfuss, I. Braud, R. Helmig, J. Vanderborght (2024) Analysis of Experimental and Simulation Data of Evaporation-Driven Isotopic Fractionation in Unsaturated Porous Media. (Under review) Vadose Zone. The replication data contains numerical data sets generated via the numerical simulator tools DuMuX and SiSPAT-isotope and experimental data published by Rothfuss (2015). Further, this data set provides python scripts and a MatLAB script to reproduce the displayed figures in the linked publication.
Structure of the dataset:
input_experimental_data.tar.gz: contains the modified experimental data from Rotfuss et al.(2015). The raw data have been structured and organized to ease the evaluation and the comparison with the numerical simulation.
input_sispat_data.tar.gz: contains the numerical results derived by SiSPAT-isotope. This dataset aims to replicate the experiments.
input_dumux_data.tar.gz: contains the numerical results derived by DuMuX. This dataset aims to replicate the experiments.
input_sispat_data_sensitivity.tar.gz: contains the numerical results derived by SiSPAT-isotope. This dataset contains the data to analyze the model toward its sensitivity to the residual water saturation.
input_dumux_data_sensitivity.tar.gz: contains the numerical results derived by DuMuX. This dataset contains the data to analyze the model toward its sensitivity to the residual water saturation.
evaluation_scripts_comparison.tar.gz: contains all evaluation scripts to reproduce the figures dealing with comparing DuMuX, SiSPAT-isotope, and the experiments.
evaluation_scripts_sensitivity.tar.gz: contains all evaluation scripts to reproduce the figures dealing with comparing DuMuX and SiSPAT-isotope in terms of analyzing their sensitivity towards the residual water saturation.
The main focus lies on the folder evaluation_scripts_comparison.tar.gz and evaluation_scripts_sensitivity.tar.gz which contains all python scripts which have been used to further post-process all data which are stored in the other folders.
evaluation_scripts_comparison.tar.gz:
plot_depthprofiles_H2O18_all.py : plots the H2O18 isotope concentration over time for various depths, and compares the results for Dumux, SiSPAT-isotope and the experiments.
plot_depthprofiles_HDO_all.py : plots the HDO isotope concentration over time for various depths and compares the results for Dumux, SiSPAT-isotope, and the experiments.
plot_depthprofiles_Sat_all.py : plots the Saturation over time for various depths and compares the results for Dumux, SiSPAT-isotope, and the experiments.
plot_evaporation.py : plots the evaporation rate and the cumulative evaporation rate over the regarded time for Dumux, SiSPAT-isotope, and the experiments.
plot_evaporation_front.py : plots the evaporation front for the numerical results derived by Dumux, and compares a fine resolved resolution with different approximation methods.
plot_isotopeprofile.py : plots the isotope profiles over depth at specific days. The script can compare the solutions between Dumux, SiSPAT-isotope, and the experiments.
plot_isotopeprofile_close.py : plots a close-up near the soil surface of the isotope profile. This helps to focus on the area of interest. Currently, this only plots the results for Dumux
code_fig_10_11.R : plots the derivation process of the aerodynamic resistance in SiSPAT-isotope and the isotope profiles for different boundary conditions using SiSPAT-isotope.
evaluation_scripts_sensitivity.tar.gz:
plot_depthprofiles_all.py : compares both numerical models towards their sensitivity to the residual water saturation.
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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