Direct measurement of evapotranspiration from a forest using a superconducting gravimeter

Camp, Michel Van; Viron, O. de; Pajot-Métivier, Gwendoline; Casenave, Fabien; Watlet, Arnaud; Dassargues, Alain; Vanclooster, Marnik

doi:10.1002/2016gl070534

Cited by 22 publications

(38 citation statements)

References 34 publications

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“…Following the Bouguer approximation, the corresponding BPE corresponds to

Δ g = 2 italicπρGh = 4.2 nm / s^{2}

with ρ the density of water, G the gravitational constant, and h the thickness of the slab. Considering that the precision of measurements performed using a superconducting gravimeter can reach a level of 0.1 nm/s 2 (Van Camp, de Viron, Pajot‐Métivier, et al, , p. 2016), the groundwater signal can be detected with a layer as thin as 0.02 mm. Additionally, one can demonstrate, as it is done in Deville (), that 90% of the BPE comes from a volume represented by a cone of which the base radius equals about 10 times its height.…”

Section: Monitoring Geophysical Phenomenamentioning

confidence: 99%

Section: Monitoring Geophysical Phenomenamentioning

confidence: 99%

“…Ground‐based gravimetry can determine the change of gravity related to Earth rotation fluctuations, to celestial body and Earth attractions, to the mass variations in the direct vicinity of the instruments, and also to distant sources, and to displacement of the instrument itself due to ground deformation. Gravity measurements contribute to risk assessment and mitigation, by improving our understanding of past and present ice mass changes (Kazama et al, ; Lambert et al, ; Larson & van Dam, ; Mazzotti et al, ; Mémin et al, ; Omang & Kierulf, ; Ophaug et al, ; van Dam et al, ), subsidence of low‐lying areas (Van Camp et al, ; Zerbini et al, ), ground water resources (Creutzfeldt et al, ; Fores et al, ; Hector et al, ; Imanishi et al, ; Jacob et al, ; Kennedy et al, ; Lampitelli & Francis, ; Van Camp, de Viron, Pajot‐Métivier, et al, ; Van Camp et al, ), and earthquakes (Imanishi, ; Montagner et al, ; Van Camp et al, ). Concurrently, terrestrial gravity measurements play a key role in the new definition of the kilogram (Stock, ), and our understanding of environmental effects affecting the gravity measurements will be useful to assess the Newtonian noise affecting gravitational wave detectors (Coughlin et al, ; Harms & Venkateswara, ).…”

Section: Introductionmentioning

confidence: 99%

“…The subsurface lateral flow was separated from the diurnal evapotranspiration signal by removing a linear trend fitted over the nighttime pattern. FromVan Camp, de Viron, Pajot-Métivier et al (2016).Reviews of Geophysics10.1002/2017RG000566 VAN CAMP ET AL. TIME-VARIABLE GRAVITY MEASUREMENTS…”

mentioning

confidence: 99%

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Geophysics From Terrestrial Time‐Variable Gravity Measurements

Camp

Viron

Watlet

et al. 2017

Reviews of Geophysics

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184

105

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In a context of global change and increasing anthropic pressure on the environment, monitoring the Earth system and its evolution has become one of the key missions of geosciences. Geodesy is the geoscience that measures the geometric shape of the Earth, its orientation in space, and gravity field. Time‐variable gravity, because of its high accuracy, can be used to build an enhanced picture and understanding of the changing Earth. Ground‐based gravimetry can determine the change in gravity related to the Earth rotation fluctuation, to celestial body and Earth attractions, to the mass in the direct vicinity of the instruments, and to vertical displacement of the instrument itself on the ground. In this paper, we review the geophysical questions that can be addressed by ground gravimeters used to monitor time‐variable gravity. This is done in relation to the instrumental characteristics, noise sources, and good practices. We also discuss the next challenges to be met by ground gravimetry, the place that terrestrial gravimetry should hold in the Earth observation system, and perspectives and recommendations about the future of ground gravity instrumentation.

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“…Following the Bouguer approximation, the corresponding BPE corresponds to

Δ g = 2 italicπρGh = 4.2 nm / s^{2}

Section: Monitoring Geophysical Phenomenamentioning

confidence: 99%

Section: Monitoring Geophysical Phenomenamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Geophysics From Terrestrial Time‐Variable Gravity Measurements

Camp

Viron

Watlet

et al. 2017

Reviews of Geophysics

Self Cite

184

105

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show abstract

“…Many geophysical data present strong periodic or quasi-periodic signals masking the observations of the phenomena of interest. For the case of precise surface gravimetry, phenomena of interest are polar ice cap variations and melting [1], hydrological effects including remote assessment of underground water reservoirs [2] forest evapotranspiration rates [3], co-seismic and post-seismic deformations [4,5], and proposals of gravity-field perturbations before arrival of compressional seismic waves [6]. However these effects, typically on the range of 0.1−100 nm s −2 , are hindered by gravity tides, with amplitudes of 2000 nm s −2 .…”

Section: Introductionmentioning

confidence: 99%

Methods for removal of unwanted signals from gravity time-series: Comparison using linear techniques complemented with analysis of system dynamics

Valencio

Grebogi

Baptista

2017

Chaos: An Interdisciplinary Journal of Nonlinear Science

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The presence of undesirable dominating signals in geophysical experimental data is a challenge in many subfields. One remarkable example is surface gravimetry, where frequencies from Earth tides correspond to time-series fluctuations up to a thousand times larger than the phenomena of major interest, such as hydrological gravity effects or co-seismic gravity changes. This work discusses general methods for removal of unwanted dominating signals by applying them to 8 long-period gravity time-series of the International Geodynamics and Earth Tides Service, equivalent to the acquisition from 8 instruments in 5 locations representative of the network. We compare three different conceptual approaches for tide removal: frequency filtering, physical modelling and data-based modelling. Each approach reveals a different limitation to be considered depending on the intended application. Vestiges of tides remain in the residues for the modelling procedures, whereas the signal was distorted in different ways by the filtering and data-based procedures. The linear techniques employed were power spectral density, spectrogram, cross-correlation and classical harmonics decomposition, while the system dynamics was analysed by state-space reconstruction and estimation of the largest Lyapunov exponent. Although the tides could not be completely eliminated, they were sufficiently reduced to allow observation of geophysical events of interest above the 10 nm s −2 level, exemplified by a hydrology-related event of 60 nm s −2 . The implementations adopted for each conceptual approach are general, so that their principles could be applied to other kinds of data affected by undesired signals composed mainly by periodic or quasi-periodic components.

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Vertical Gravimeter Array Observations and Their Performance in Groundwater‐Level Monitoring

Toshiyuki

Honda

2018

Earth and Space Science

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The gravitational effects of the atmosphere and subsurface water are significant obstacles to observing gravity variations on the sub‐μGal (1 μGal = 10 nm/s2) scale. The goal of this study is to detect changes in gravity that are caused by mass redistributions deep underground related to seismological phenomena by reducing environmental gravity effects using multiple gravimeters belowground and aboveground, which we term a “vertical gravimeter array.” Based on an evaluation of the responses to atmospheric effects and rainfall events identified in observations made with individual relative gravimeters, the vertical gravimeter array succeeds in stacking the target signals from deep underground and in reducing errors due to rainfall or free groundwater and atmospheric effects. To enable accurate interpretation, we introduce a physical approach that is based on attraction and loading deformation effects for atmospheric reduction using state‐of‐the‐art gridded weather data products. Changes in the water levels of confined groundwater can be regarded as a signal from deep underground, and a response coefficient of approximately −15 μGal/m was obtained. In addition, the response coefficient of the free groundwater level was determined to be approximately 5 μGal/m. Such array observations are expected to contribute to monitoring crustal activity and hydrological studies.

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Direct measurement of evapotranspiration from a forest using a superconducting gravimeter

Cited by 22 publications

References 34 publications

Geophysics From Terrestrial Time‐Variable Gravity Measurements

Geophysics From Terrestrial Time‐Variable Gravity Measurements

Methods for removal of unwanted signals from gravity time-series: Comparison using linear techniques complemented with analysis of system dynamics

Vertical Gravimeter Array Observations and Their Performance in Groundwater‐Level Monitoring

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