Resolving Geophysical Signals by Terrestrial Gravimetry: A Time Domain Assessment of the Correction‐Induced Uncertainty

Mikolaj, Michal; Reich, Marvin; Güntner, Andreas

doi:10.1029/2018jb016682

Cited by 16 publications

(13 citation statements)

References 60 publications

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“…Typically, the gravity residuals of SGs in Central Europe show seasonal variations of around 100 nm/s² range(Abe et al, 2012). However, it should also be noted that the gravity residuals also include uncertainties in the model-based signal separation, which are typically at the level of a few nm/s² root-mean-square error(Mikolaj et al, 2019). In addition, non-hydrological signals from alpine geological mass redistributions are also included in the gravity residuals.…”

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confidence: 99%

Introduction of a Superconducting Gravimeter as Novel Hydrological Sensor for the Alpine Research Catchment Zugspitze

Voigt

Schulz

Koch

et al. 2021

Preprint

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Abstract. The Zugspitze Geodynamic Observatory Germany has been set up with a worldwide unique installation of a superconducting gravimeter at the summit of Mount Zugspitze. With regard to hydrology, this karstic high-alpine site is largely dominated by high precipitation amounts and a long seasonal snow cover period with significant importance for water supply to its forelands, while it shows a high sensitivity to climate change. However, regarding the majority of alpine regions worldwide there is only weak knowledge on temporal water storage variations due to only sparsely distributed hydrological and meteorological point sensors and the large variability and complexity of alpine signals. This underlines the importance of well-equipped areas such as Mount Zugspitze serving as natural test laboratories for an improved monitoring, understanding and prediction of alpine hydrological processes. The observatory superconducting gravimeter OSG 052 supplements the existing sensor network as a novel hydrological sensor system for the direct observation of the integral gravity effect of total water storage variations in the alpine research catchment Zugspitze. Besides the experimental setup and the available datasets, the required gravimetric prerequisites are presented such as calibration, tidal analysis and signal separation of the superconducting gravimeter observations from the first 2 years. The snowpack is identified as primary contributor to seasonal water storage variations and thus to the gravity residuals with a signal range of up to 750 nm/s2 corresponding to 1957 mm snow water equivalent measured at a representative station at the end of May 2019. First hydro-gravimetric sensitivity analysis are based on simplified assumptions of the snowpack distribution within the area around Mount Zugspitze. These reveal a snow-gravimetric footprint of up to 4 km distance around the gravimeter with a dominant gravity contribution from the snowpack in the Partnach spring catchment. This study already shows that the hydro-gravimetric approach can deliver important and representative integral insights into this high-alpine site. This work is regarded as a concept study showing preliminary gravimetric results and sensitivity analysis for upcoming long-term hydro-gravimetric research projects.

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confidence: 99%

Introduction of a Superconducting Gravimeter as Novel Hydrological Sensor for the Alpine Research Catchment Zugspitze

Voigt

Schulz

Koch

et al. 2021

Preprint

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“…The median standard deviation of this series results in 2.1 and 1.6 nm.s −2 for the GG and SG, respectively. The 2σ threshold (4.2 and 3.2 nm.s −2 for the GG and SG, respectively) provides a reasonable empiric estimation based on observed noise for characterizing flash flood events at the RCL site, as investigated in Mikolaj et al (2019).…”

Section: Water Resources Researchmentioning

confidence: 82%

Gravity Monitoring of Underground Flash Flood Events to Study Their Impact on Groundwater Recharge and the Distribution of Karst Voids

Watlet

Camp

Francis

et al. 2020

Water Resources Research

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Flash flood events are expected to become increasingly common with the global increases in weather extremes. They are a significant natural hazard that affects karst landscapes, which host large resources of drinking water worldwide. The role played by underground flood events in the karst aquifer recharge is complex due to the heterogeneity of the basement which remains poorly understood. We present the analysis of 20 incave flash flood events affecting the Rochefort karst system (Belgium) using continuous gravity measurements at one single station and water level sensors installed in caves. Underground flood events typically produce a peak in the gravity signal, due to an increase in the associated mass change. After the flood, the gravity values drop but remain slightly increased compared to before the flood event. Via forward gravity modeling, we demonstrate that this remaining anomaly can be reasonably explained by the infiltration of local rainfall within the karst system rather than by allogenic recharge of the aquifer. Flash floods are mainly restricted to connected voids. This allows us to utilize them as proxies to investigate the distribution of cavities in the karst system. Forward modeling of the gravitational attraction induced by the mapped caves being flooded yields a gravity signal much smaller than the observed one. We conclude that at least 50% more cavities than those previously mapped are required to match the measured anomalies. This presents opportunities for implementing similar approaches in other diverse porous media, using gravity monitoring of hydrological processes (e.g., infiltration fronts, hydrothermalism, or tide effects in coastal aquifers) as proxies to characterize underground properties.

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“…The residuals reduced for the large-scale gravity effects using all other model combinations are shown in grey (105 combinations in total). The uncertainty of large-scale gravity corrections as modelled in this study is discussed in Mikolaj et al (2019).…”

Section: Large-scale Modelmentioning

confidence: 95%

Hydrometeorological and gravity signals at the Argentine-German Geodetic Observatory (AGGO) in La Plata

Mikolaj

Güntner

Brunini

et al. 2019

Earth Syst. Sci. Data

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The Argentine-German Geodetic Observatory (AGGO) is one of the very few sites in the Southern Hemisphere equipped with comprehensive cutting-edge geodetic instrumentation. The employed observation techniques are used for a wide range of geophysical applications. The data set provides gravity time series and selected gravity models together with the hydrometeorological monitoring data of the observatory. These parameters are of great interest to the scientific community, e.g. for achieving accurate realization of terrestrial and celestial reference frames. Moreover, the availability of the hydrometeorological products is beneficial to inhabitants of the region as they allow for monitoring of environmental changes and natural hazards including extreme events. The hydrological data set is composed of time series of groundwater level, modelled and observed soil moisture content, soil temperature, and physical soil properties and aquifer properties. The meteorological time series include air temperature, humidity, pressure, wind speed, solar radiation, precipitation, and derived reference evapotranspiration. These data products are extended by gravity models of hydrological, oceanic, La Plata estuary, and atmospheric effects. The quality of the provided meteorological time series is tested via comparison to the two closest WMO (World Meteorological Organization) sites where data are available only in an inferior temporal resolution. The hydrological series are validated by comparing the respective forward-modelled gravity effects to independent gravity observations reduced up to a signal corresponding to local water storage variation. Most of the time series cover the time span between April 2016 and November 2018 with either no or only few missing data points. The data set is available at https://doi.

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Resolving Geophysical Signals by Terrestrial Gravimetry: A Time Domain Assessment of the Correction‐Induced Uncertainty

Cited by 16 publications

References 60 publications

Introduction of a Superconducting Gravimeter as Novel Hydrological Sensor for the Alpine Research Catchment Zugspitze

Introduction of a Superconducting Gravimeter as Novel Hydrological Sensor for the Alpine Research Catchment Zugspitze

Gravity Monitoring of Underground Flash Flood Events to Study Their Impact on Groundwater Recharge and the Distribution of Karst Voids

Hydrometeorological and gravity signals at the Argentine-German Geodetic Observatory (AGGO) in La Plata

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