Aquifer Parameters Estimation from Natural Groundwater Level Fluctuations at the Mexican Wine-Producing Region Guadalupe Valley, BC

Determining hydrogeological properties of the rock materials that constitute an aquifer through stress tests or laboratory tests presents inherent complications. An alternative tool that has significant advantages is the study of the groundwater-level response as a result of the pore-pressure variation caused by the internal structure deformation of the aquifer induced by barometric pressure and solid Earth tide. The purpose of this study was to estimate the values of the physical/hydraulic properties of the geological materials that constitute the Guadalupe Valley Aquifer based on the analysis of the groundwater-level response to barometric pressure and solid Earth tide. Representative values of specific storage (1.27 × 10−6 to 2.78 × 10−6 m−1), porosity (14–34%), storage coefficient (3.10 × 10−5 to 10.45 × 10−5), transmissivity (6.67 × 10−7 to 1.29 × 10−4 m2∙s−1), and hydraulic conductivity (2.30 × 10−3 to 2.97 × 10−1 m∙d−1) were estimated. The values obtained are consistent with the type of geological materials identified in the vicinity of the analyzed wells and values reported in previous studies. This analysis represents helpful information that can be considered a framework to design and assess management strategies for groundwater resources in the overexploited Guadalupe Valley Aquifer.

ABSOLUTE LOCALIZATION OF CORNER REFLECTORS WITH TERRASAR-X SPOTLIGHT IMAGES

Synthetic aperture radar, capable of imaging the Earth surface from space in nearly all-weather conditions and high spatial resolution, has shown its outstanding capability for a variety of ground mapping applications. With well-controlled orbits of the new generation SAR satellites, high accuracy absolute localization with multiple SAR images has been demonstrated and become one of the hot spots with increasing attention. In this paper, high-resolution Spotlight-mode TerraSAR-X images acquired from the single orbit track were applied to 3D absolute positioning of three triangular trihedral corner reflectors. In order to overcome the limitation imposed by the acquisitions with very short baselines, a height constraint was introduced and the sub-meter accuracy was derived after carefully compensating for the known error sources, such as atmospheric delays and solid earth tide shifts.

ANALYSIS OF OCEAN TIDE LOADING ESTIMATED FROM THE GPS COORDINATE TIME SERIES: A CASE STUDY FOR THE BELÉM, BRASÍLIA, EUSÉBIO, MANAUS AND SANTA MARIA STATIONS, BRAZIL

ABSTRACT. The Earth suffers deformations due to the gravitational attraction of the celestial bodies and the redistribution of water mass occurring by the action of the ocean tide. These effects are known as solid Earth tide and ocean tide loading, and can be estimated by observations of the amplitudes and phases of their tidal wave constituents. Considering that GNSS observations may be used to estimate these effects and that the solid Earth tide displacement is well resolved, this work estimated and analyzed the amplitudes and phases of the 11 principal constituents of ocean tide loading, using GPS observations. The methodology was applied to data collected from five stations in Brazil, and the amplitudes and phases of the tidal constituents were estimated and evaluated regarding their values and convergence times. The results showed that most of the estimated parameters converged during the analyzed period. In addition, after correcting the effects of ocean tide loading in each GPS solution, using the computed parameters and the existing models, the coordinates were compared and the results presented some local differences, allowing to recommend the use of GPS to estimate tidal constituents considering the local behavior of the point.Keywords: GPS, ocean tide loading, tidal constituents.RESUMO. A Terra sofre deformações devido à atração gravitacional de corpos celestes e também em função da redistribuição de massa d’água que ocorre por ação da maré oceânica. Estes fenômenos são denominados maré terrestre e carga oceânica, e podem ser estimados por meio das amplitudes e fases das componentes de onda de maré. Considerando que as observações GNSS podem ser usadas na estimativa destes efeitos e que os deslocamentos devido à maré terrestre são teoricamente bem resolvidos, este trabalho estimou e analisou as amplitudes e fases das 11 componentes principais de carga oceânica, utilizando observações GPS. A metodologia foi aplicada a dados coletados em cinco estações instaladas no Brasil, e as amplitudes e fases para as componentes de maré foram estimadas e avaliadas, considerando seus valores e tempo de convergência. Os resultados mostraram que a maioria dos parâmetros estimados convergiu durante o período analisado. Além disso, após corrigir os efeitos de carga oceânica em cada solução GPS, utilizando os parâmetros calculados e os modelos existentes, as coordenadas corrigidas foram comparadas e os resultados apresentaram diferenças locais, permitindo recomendar o uso do GPS na estimativa de componentes de maré considerando o comportamento local do ponto.Palavras-chave: GPS, carga oceânica, componentes de maré.

Frequency dependence of the polar motion resonance

SUMMARY The nutation of the Celestial Intermediate Pole can be considered as a retrograde diurnal polar motion. As the common polar motion, it presents a resonance, but with period TPM and quality factor QPM differing from the ones characterizing the Chandler wobble (TCW = 430.2−431.6 d, QCW in the interval (56 255) according to Nastula & Gross): according to the nutation analysis presented in a separate paper, this period is about TPM = 380 d and the quality factor becomes −10. In this study, we aim to revisit the geophysical interpretation of this result. Two complementary factors account for the observed values: the non-equilibrium response of the ocean to the pole tide potential in the diurnal band, and the resonance of the solid Earth tide at the free core nutation period. This leads to a resonance of TPM in the vicinity of the free core nutation period, confirmed by estimates derived from nutation analysis.

ANALYSIS OF THE PRINCIPAL CONSTITUENTS OF SOLID EARTH TIDES ESTIMATED WITH GRAVIMETRIC AND GNSS DATA IN MANAUS AND BRASÍLIA

ABSTRACT. Solid Earth tide is the periodic displacement due to the tidal force. This effect is present in all geodesic and geophysical observations and should be eliminated when high accuracy surveying is required. It is necessary to determine the amplitudes and phases of the harmonic constituents to estimate the terrestrial tide effect magnitude. This article presents a methodology for estimating and analyzing the amplitudes and phases of the solid Earth tide principal constituents from gravimetric/GNSS observations. The methodology was applied to data collected in the Manaus/AM and Brasília/DF stations, Brazil, to determine the amplitude and phase values for the long period, monthly, diurnal and semidiurnal constituents, besides determining the time required for the convergence of the estimated constituent values. The estimated amplitude and phase values, using gravimetric data, converged between the 2nd and 6th months of the time series. For the positioning observations, the constituents values converged between the 2nd and 17th month of the data series, except for the long period constituent, which requires a longer time series to obtain satisfactory values for both methods. The results show that the solid Earth tide constituents were better estimated by the gravimetric data compared to the positioning data considering the series analyzed.Keywords: gravimetry, GNSS, solid Earth tide, tidal constituents.RESUMO. Maré terrestre é o deslocamento periódico decorrente da força de maré. Este é um efeito que deve ser eliminado quando se deseja realizar levantamentos nos quais é necessária alta acurácia tanto em observações geodésicas quanto geofísicas. Para estimar o efeito de maré terrestre deve-se determinar as amplitudes e fases de suas componentes harmônicas. Este artigo apresenta uma metodologia para a estimativa das amplitudes e fases das principais componentes de maré terrestre, a partir de observações gravimétricas/GNSS. A metodologia foi aplicada a dados coletados em estações instaladas em Manaus/AM e Brasília/DF, Brasil, resultando na determinação dos valores de amplitude e fase para componentes de longo período, mensais, diurnas e semidiurnas, além da análise da convergência dos valores estimados para estas componentes. As amplitudes e fases calculadas, utilizando dados gravimétricos, convergiram entre o 2_ e o 6_ mês analisados, enquanto para os dados de posicionamento a convergência ocorreu entre o 2_ e o 17_ mês observado, com exceção da componente de longo período, que não pôde ser determinada em ambos os métodos. Para o período analisado, as componentes de maré terrestre foram melhor estimadas utilizando dados gravimétricos, se comparadas aos resultados obtidos com dados de posicionamento.Palavras-chave: gravimetria, GNSS, maré terrestre, componentes de maré.

INVESTIGATION OF THE SOLID EARTH TIDE BASED ON GPS OBSERVATION AND SUPERCONDUCTING GRAVIMETER DATA

<p class="Abstract"><em>According to Zheng (2006), vertical displacement caused by the solid earth tide often reaches in range 20 cm, and can exceed 30 cm in some stations. To measure solid earth tide we can use satellite system or sensitive gravimeters (Ito et al., 2009). This paper aims to investigate solid earth tide based on Global Positioning System (GPS) data compare with Superconducting Gravimeter (SG) data and solid earth tide global model. Processing GPS data using Kinematic Precise Point Positioning (KPPP) method within a year data from 1^st January – 31^st December 2011. We use BAKO GPS Permanent station data and Cibinong SG Station data. The location of BAKO station is close to Cibinong SG station, which is about 50 meters. </em><em>The result of this paper are solid earth tide which is derived from both devices have the same pattern, and it is dominated by semi-diurnal components. Applicability global models with SG observations has smaller residue with standard deviation is </em><em>0.0031</em><em> mgal, this result is equivalent with </em><em>0.0098</em><em> meter</em><em>. Comparison between the results of GPS observations to global models which have a standard deviation residue for vertical component is </em><em>0.0360 meters</em><em>.</em><em></em></p>