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Mark O. Cuthbert - One of the best experts on this subject based on the ideXlab platform.

  • Technical Note: Disentangling the groundwater response to Earthand Atmospheric Tides to improve subsurface characterisation
    2020
    Co-Authors: Gabriel C. Rau, R. Ian Acworth, Mark O. Cuthbert, Philipp Blum
    Abstract:

    Abstract. The groundwater response to Earth Tides and Atmospheric pressure changes can be used to understand subsurface processes and estimate hydraulic and hydro-mechanical properties. We develop a generalised frequency domain approach to disentangle the impacts of Earth and Atmospheric Tides on groundwater level responses. By considering the complex harmonic properties of the signal, we improve upon a previous method for estimating barometric efficiency (BE) estimation while simultaneously assessing system confinement and estimating hydraulic conductivity as well as specific storage. We demonstrate and validate the novel approach using an example barometric and groundwater pressure record with strong Earth tide influences. Our method enables improved and rapid assessment of subsurface processes and properties using standard pressure measurements.

  • quantifying compressible groundwater storage by combining cross hole seismic surveys and head response to Atmospheric Tides
    Journal of Geophysical Research, 2018
    Co-Authors: Ian R Acworth, Mark O. Cuthbert, Landon J S Halloran, Wendy Timms
    Abstract:

    Groundwater specific storage varies by orders of magnitude, is difficult to quantify, and prone to significant uncertainty. Estimating specific storage using aquifer testing is hampered by the nonuniqueness in the inversion of head data and the assumptions of the underlying conceptual model. We revisit confined poroelastic theory and reveal that the uniaxial specific storage can be calculated mainly from undrained poroelastic properties, namely, uniaxial bulk modulus, loading efficiency, and the Biot‐Willis coefficient. In addition, literature estimates of the solid grain compressibility enables quantification of subsurface poroelastic parameters using field techniques such as cross‐hole seismic surveys and loading efficiency from the groundwater responses to Atmospheric Tides. We quantify and compare specific storage depth profiles for two field sites, one with deep aeolian sands and another with smectitic clays. Our new results require bulk density and agree well when compared to previous approaches that rely on porosity estimates. While water in clays responds to stress, detailed sediment characterization from a core illustrates that the majority of water is adsorbed onto minerals leaving only a small fraction free to drain. This, in conjunction with a thorough analysis using our new method, demonstrates that specific storage has a physical upper limit of urn:x-wiley:jgrf:media:jgrf20879:jgrf20879-math-0001 m−1. Consequently, if larger values are derived using aquifer hydraulic testing, then the conceptual model that has been used needs reappraisal. Our method can be used to improve confined groundwater storage estimates and refine the conceptual models used to interpret hydraulic aquifer tests.

  • an objective frequency domain method for quantifying confined aquifer compressible storage using earth and Atmospheric Tides
    Geophysical Research Letters, 2016
    Co-Authors: Ian R Acworth, Gabriel C. Rau, Mark O. Cuthbert, Landon J S Halloran, Tony L Bernardi
    Abstract:

    The groundwater hydraulic head response to the worldwide and ubiquitous Atmospheric tide at 2 cycles per day (cpd) is a direct function of confined aquifer compressible storage. The ratio of the responses of hydraulic head to the Atmospheric pressure change is a measure of aquifer barometric efficiency, from which formation compressibility and aquifer specific storage can be determined in situ rather than resorting to laboratory or aquifer pumping tests. The Earth tide also impacts the hydraulic head response at the same frequency, and a method is developed here to quantify and remove this interference. As a result, the barometric efficiency can be routinely calculated from 6-hourly hydraulic head, Atmospheric pressure, and modeled Earth tide records where available for a minimum of 15 days duration. This new approach will be of critical importance in assessing worldwide problems of land subsidence or groundwater resource evaluation that both occur due to groundwater abstraction

Yun Gong - One of the best experts on this subject based on the ideXlab platform.

  • Atmospheric Tides in the low latitude e and f regions and their responses to a sudden stratospheric warming event in january 2010
    Journal of Geophysical Research, 2013
    Co-Authors: Yun Gong, Qihou Zhou, Shaodong Zhang
    Abstract:

    An extensive analysis of Atmospheric Tides in the low-latitude thermosphere and their responses to a major sudden stratospheric warming (SSW) event (18-23 January 2010) is presented. The analysis is based on observational data from the Arecibo dual-beam incoherent scatter radar. Important findings of the present study are as follows. (1) The diurnal tide with an evanescent phase structure dominates the F region meridional wind field. The diurnal tide has a peak amplitude of 45 m/s occurring at about 245 km, and it is very stable throughout the nine consecutive days' observation. Below 114 km, the vertical structures of the diurnal tide in the meridional and zonal components are consistent, which resemble the classical solar S-1,S- 1 tidal mode. (2) The F region semidiurnal tide is much weaker and has larger day-to-day variability than the diurnal tide. In the E region, the semidiurnal amplitudes in the meridional and zonal components grow continuously in the altitude ranges from 106 to 121 km and from 100 to 115 km, respectively. The vertical wavelength of the zonal component is estimated to be 45 km above 100 km, which is close to the solar S-2,S- 4 and S-2,S- 5 tidal modes. (3) The semidiurnal and terdiurnal Tides respond strongly to the SSW while the impact that the SSW has on the diurnal tide in the meridional wind is limited. During the SSW event, the amplitudes of the semidiurnal and terdiurnal Tides are enhanced in the F region but reduced in the upper E region.

Yinghwa Kuo - One of the best experts on this subject based on the ideXlab platform.

  • analysis of migrating diurnal Tides detected in formosat 3 cosmic temperature data
    Journal of Geophysical Research, 2010
    Co-Authors: B Pirscher, Ulrich Foelsche, M Borsche, G Kirchengast, Yinghwa Kuo
    Abstract:

    [1] The characteristics of Atmospheric Tides in the upper troposphere and lower stratosphere region are investigated using radio occultation (RO) measurements performed by the Formosa Satellite Mission-3/Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC) satellite constellation and compared to Tides observed in short-term forecast model fields of European Centre for Medium-Range Weather Forecasts (ECMWF) and National Centers for Environmental Prediction (NCEP). Spectral analysis of 2 years of monthly data (2007 to 2008) yields the migrating diurnal tide to be the largest spectral component. This diurnal tide shows similar temporal, latitudinal, and altitudinal characteristics in all data sets equatorward of 50°. Beyond 50°, COSMIC local time sampling is insufficient within 1 month, which prevents space-time spectral analysis from isolating Atmospheric waves. Diurnal Tides of temperature are characterized by largest amplitudes in the tropics (0.8 K to 1.0 K at an altitude of 30 km). Amplitudes of diurnal Tides analyzed in model data are more pronounced by ∼20%. An annual cycle of the amplitudes, characteristically linked to the movement of the intertropical convergence zone, is clearly revealed. Tropical diurnal phase features downward progression of waves fronts with a vertical wavelength of 20 km. Extratropical diurnal Tides are most pronounced in the model data sets with amplitudes of up to 0.5 K at 30 km. In this analysis we also see the influence of high-altitude initialization of RO data by background information in using data processed by two different centers (University Corporation for Atmospheric Research (UCAR) and Wegener Center (WEGC)). UCAR data, initialized by a climatology without tidal information, exhibit no appreciable extratropical diurnal Tides, while WEGC data, initialized by ECMWF forecasts, show more pronounced ones. Overall the results underpin the utility of the local-time resolving COSMIC RO constellation data for monitoring diurnal tide dynamics in the stratosphere. The agreement between observational and model data further confirms that the tidal dynamics is appropriately captured in the models, which is important for other (middle/upper) atmosphere models relying on ECMWF or NCEP dynamics.

Jeanpaul Boy - One of the best experts on this subject based on the ideXlab platform.

  • qualitative comparisons of global ocean tide models by analysis of intersatellite ranging data
    Journal of Geophysical Research, 2009
    Co-Authors: S B Luthcke, Jeanpaul Boy
    Abstract:

    [1] Four global ocean tide models are compared in terms of their contribution to Gravity Recovery and Climate Experiment (GRACE) satellite-to-satellite tracking residuals. The residuals are computed relative to a comprehensive model of Earth's time-varying gravity, including allowance for mass motions in the atmosphere, ocean, terrestrial hydrology, and mantle, in addition to Tides. For each analyzed tide model, 4 years of GRACE range rate data are processed. Range and range acceleration residuals are tidally analyzed by geographic location. All four global tide models are shown to be error prone in various ways, leaving tidally coherent residuals especially in polar regions but also in some lower-latitude regions. Considerable power in the solar semidiurnal S2 tide in low latitudes suggests errors in our adopted model of Atmospheric Tides, which is based on 3 hourly European Centre for Medium-Range Weather Forecasts operational analyses. Anomalies in the μ2 tidal constituent over some shallow seas suggest the presence of unmodeled nonlinear compound Tides, in this case 2MS2. Similarly, anomalies in the nonlinear M4 tide are seen if this constituent is omitted from the models. Errors in assumed seawater density may be contributing to some residuals.

  • study of the Atmospheric pressure loading signal in very long baseline interferometry observations
    Journal of Geophysical Research, 2004
    Co-Authors: Leonid Petrov, Jeanpaul Boy
    Abstract:

    [1] Redistribution of air masses due to Atmospheric circulation causes loading deformation of the Earth's crust, which can be as large as 20 mm for the vertical component and 3 mm for horizontal components. Rigorous computation of site displacements caused by pressure loading requires knowledge of the surface pressure field over the entire Earth surface. A procedure for computing three-dimensional displacements of geodetic sites of interest using a 6 hourly pressure field from the National Centers for Environmental Prediction numerical weather models and the Ponte and Ray [2002] model of Atmospheric Tides is presented. We investigated possible error sources and found that the errors of our pressure loading time series are below the 15% level. We validated our model by estimating the admittance factors of the pressure loading time series using a data set of 3.5 million very long baseline interferometry observations from 1980 to 2002. The admittance factors averaged over all sites are 0.95 ± 0.02 for the vertical displacement and 1.00 ± 0.07 for the horizontal displacements. For the first time, horizontal displacements caused by Atmospheric pressure loading have been detected. The closeness of these admittance factors to unity allows us to conclude that on average, our model quantitatively agrees with the observations within the error budget of the model. At the same time we found that the model is not accurate for several stations that are near a coast or in mountain regions. We conclude that our model is suitable for routine data reduction of space geodesy observations.

  • study of the Atmospheric pressure loading signal in vlbi observations
    arXiv: Geophysics, 2003
    Co-Authors: Leonid Petrov, Jeanpaul Boy
    Abstract:

    Redistribution of air masses due to Atmospheric circulation causes loading deformation of the Earth's crust which can be as large as 20 mm for the vertical component and 3 mm for horizontal components. Rigorous computation of site displacements caused by pressure loading requires knowledge of the surface pressure field over the entire Earth surface. A procedure for computing 3-D displacements of geodetic sites of interest using a 6-hourly pressure field from the NCEP numerical weather models and the Ponte and Ray [2002] model of Atmospheric Tides is presented. We investigated possible error sources and found that the errors of our pressure loading time series are below the 15% level. We validated our model by estimating the admittance factors of the pressure loading time series using a dataset of 3.5 million VLBI observations from 1980 to 2002. The admittance factors averaged over all sites are 0.95 -+ 0.02 for the vertical displacement and 1.00 -+ 0.07 for the horizontal displacements. For the first time horizontal displacements caused by Atmospheric pressure loading have been detected. The closeness of these admittance factors to unity allows us to conclude that on average our model quantitatively agrees with the observations within the error budget of the model. At the same time we found that the model is not accurate for several stations which are near a coast or in mountain regions. We conclude that our model is suitable for routine data reduction of space geodesy observations.

Tzuwei Fang - One of the best experts on this subject based on the ideXlab platform.

  • plausible effect of Atmospheric Tides on the equatorial ionosphere observed by the formosat 3 cosmic three dimensional electron density structures
    Geophysical Research Letters, 2007
    Co-Authors: C H Lin, L J Paxton, M E Hagan, T J Immel, Wenbin Wang, C C Hsiao, M L Hsu, Jannyenq Liu, Tzuwei Fang
    Abstract:

    [1] The plausible effect of Atmospheric Tides on the longitudinal structure of the equatorial ionosphere is observed by the FORMOSAT-3/COSMIC (F3/C) constellation during September Equinox, 2006, near solar minimum. The longitudinal structure was first reported in IMAGE satellite airglow observations at the far-ultraviolet (FUV) 135.6-nm wavelength during March Equinox, 2002, near solar maximum. The global three-dimensional ionospheric electron density observed by F3/C shows a prominent four-peaked wave-like longitudinal enhancement in the equatorial ionization anomaly (EIA). The vertical electron density structures observed by F3/C reveal that the feature exists mainly above 250 km altitude indicating that the feature is an F-region phenomenon. The four longitudinal F-region enhancements of the EIA peaks may result from a stronger equatorial plasma fountain at each longitude region produced by a stronger F-region eastward electric field transmitted along the magnetic field lines from E-region where longitudinal variations in Atmospheric Tides affect the ionospheric dynamo process.