On fast multigrid iteration techniques for the solution of normal equations in satellite gravity recovery

2002 ◽  
Vol 33 (1-2) ◽  
pp. 173-186 ◽  
Author(s):  
Jürgen Kusche
Keyword(s):  
Satellite Gravity ◽  
Normal Equations ◽  
Gravity Recovery

scholarly journals Study of water storage variations at the Pantanal wetlands area from GRACE monthly mass grids

2019 ◽  
Vol 9 (1) ◽  
pp. 133-143
Author(s):  
Ayelen Pereira ◽  
Cecilia Cornero ◽  
Ana C. O. C. Matos ◽  
M. Cristina Pacino ◽  
Denizar Blitzkow
Keyword(s):  
Water Mass ◽  
Spatial Scales ◽  
Water Storage ◽  
Transport Processes ◽  
Satellite Gravity ◽  
The North ◽  
Paraguay River ◽  
Gravity Recovery ◽  
Grace Mission ◽  
Phase Differences

Abstract The continental water storage is significantly in-fluenced by wetlands, which are highly affected by climate change and anthropogenic influences. The Pantanal, located in the Paraguay river basin, is one of the world’s largest and most important wetlands because of the environmental biodiversity that represents. The satellite gravity mission GRACE (Gravity Recovery And Climate Experiment) provided until 2017 time-variable Earth’s gravity field models that reflected the variations due to mass transport processes-like continental water storage changes-which allowed to study environments such as wetlands, at large spatial scales. The water storage variations for the period 2002-2016, by using monthly land water mass grids of Total Water Storage (TWS) derived from GRACE solutions, were evaluated in the Pantanal area. The capability of the GRACE mission for monitoring this particular environment is analyzed, and the comparison of the water mass changes with rainfall and hydrometric heights data at different stations distributed over the Pantanal region was carried out. Additionally, the correlation between the TWS and river gauge measurements, and the phase differences for these variables, were also evaluated. Results show two distinct zones: high correlations and low phase shifts at the north, and smaller correlation values and consequently significant phase differences towards the south. This situation is mainly related to the hydrogeological domains of the area.

scholarly journals Accuracy Analysis of Gravity Field Changes from Grace RL06 and RL05 Data Compared to in Situ Gravimetric Measurements in the Context of Choosing Optimal Filtering Type

2020 ◽  
Vol 55 (3) ◽  
pp. 100-117
Author(s):  
Viktor Szabó ◽  
Dorota Marjańska
Keyword(s):  
Gravity Field ◽  
Ocean Circulation ◽  
Gravity Data ◽  
The Other ◽  
Subsurface Water ◽  
Satellite Gravity ◽  
Absolute Gravimetry ◽  
The Earth ◽  
Gravity Measurements ◽  
Gravity Recovery

AbstractGlobal satellite gravity measurements provide unique information regarding gravity field distribution and its variability on the Earth. The main cause of gravity changes is the mass transportation within the Earth, appearing as, e.g. dynamic fluctuations in hydrology, glaciology, oceanology, meteorology and the lithosphere. This phenomenon has become more comprehensible thanks to the dedicated gravimetric missions such as Gravity Recovery and Climate Experiment (GRACE), Challenging Minisatellite Payload (CHAMP) and Gravity Field and Steady-State Ocean Circulation Explorer (GOCE). From among these missions, GRACE seems to be the most dominating source of gravity data, sharing a unique set of observations from over 15 years. The results of this experiment are often of interest to geodesists and geophysicists due to its high compatibility with the other methods of gravity measurements, especially absolute gravimetry. Direct validation of gravity field solutions is crucial as it can provide conclusions concerning forecasts of subsurface water changes. The aim of this work is to present the issue of selection of filtration parameters for monthly gravity field solutions in RL06 and RL05 releases and then to compare them to a time series of absolute gravimetric data conducted in quasi-monthly measurements in Astro-Geodetic Observatory in Józefosław (Poland). The other purpose of this study is to estimate the accuracy of GRACE temporal solutions in comparison with absolute terrestrial gravimetry data and making an attempt to indicate the significance of differences between solutions using various types of filtration (DDK, Gaussian) from selected research centres.

scholarly journals A framework for deriving drought indicators from the Gravity Recovery and Climate Experiment (GRACE)

2020 ◽  
Vol 24 (1) ◽  
pp. 227-248 ◽  
Author(s):  
Helena Gerdener ◽  
Olga Engels ◽  
Jürgen Kusche
Keyword(s):  
Hydrological Cycle ◽  
Water Storage ◽  
Synthetic Data ◽  
Satellite Gravity ◽  
Spatially Correlated ◽  
Grace Data ◽  
Spatial Noise ◽  
Drought Indicators ◽  
Gravity Recovery ◽  
Linear Trends

Abstract. Identifying and quantifying drought in retrospective is a necessity for better understanding drought conditions and the propagation of drought through the hydrological cycle and eventually for developing forecast systems. Hydrological droughts refer to water deficits in surface and subsurface storage, and since these are difficult to monitor at larger scales, several studies have suggested exploiting total water storage data from the GRACE (Gravity Recovery and Climate Experiment) satellite gravity mission to analyze them. This has led to the development of GRACE-based drought indicators. However, it is unclear how the ubiquitous presence of climate-related or anthropogenic water storage trends found within GRACE analyses masks drought signals. Thus, this study aims to better understand how drought signals propagate through GRACE drought indicators in the presence of linear trends, constant accelerations, and GRACE-specific spatial noise. Synthetic data are constructed and existing indicators are modified to possibly improve drought detection. Our results indicate that while the choice of the indicator should be application-dependent, large differences in robustness can be observed. We found a modified, temporally accumulated version of the Zhao et al. (2017) indicator particularly robust under realistic simulations. We show that linear trends and constant accelerations seen in GRACE data tend to mask drought signals in indicators and that different spatial averaging methods required to suppress the spatially correlated GRACE noise affect the outcome. Finally, we identify and analyze two droughts in South Africa using real GRACE data and the modified indicators.

scholarly journals ANALYSIS OF WATER MASS VARIATION IN WETLANDS REGIONS USING DATA FROM GRACE SATELLITE MISSION: THE PANTANAL CASE

2016 ◽  
Vol 34 (4) ◽  
Author(s):  
Cecilia Cornero ◽  
Ayelen Pereira ◽  
Ana Cristina Oliveira Cancoro de Matos ◽  
María Cristina Pacino
Keyword(s):  
Spatial Scales ◽  
Transport Processes ◽  
Satellite Mission ◽  
Satellite Gravity ◽  
Earth’S Gravity Field ◽  
Paraguay River ◽  
Using Data ◽  
Gravity Recovery ◽  
Gravity Field Models ◽  
Gravity Mission

ABSTRACT. The natural heritage of biodiversity of the Paraguay river basin is subject to potential impacts due to climate change. To monitor these environments at large spatial scales, the satellite gravity mission GRACE (Gravity Recovery and Climate Experiment) provides time-variable Earth’s gravity field models that reflect the variations due to mass transport processes, like continental...Keywords: water storage, satellite gravity mission, river gauge, rainfall. RESUMO. O patrimônio natural de biodiversidade da bacia do rio Paraguai está sujeito a potenciais impactos das mudanças climáticas. Para monitorar esse ambiente em escala espacial, a missão satelital GRACE (Gravity Recovery and Climate Experiment) fornece modelos do campo de gravidade da Terra variáveis no tempo devido ao processo de transporte de massa, como as variações de armazenamento de água...Palavras-chave: armazenamento de água, missão satelital, cotas do nível d’água, precipitação.

scholarly journals Unification of European height system realizations

2012 ◽  
Vol 2 (4) ◽  
pp. 343-354 ◽  
Author(s):  
A. Rülke ◽  
G. Liebsch ◽  
M. Sacher ◽  
U. Schäfer ◽  
U. Schirmer ◽  
...  
Keyword(s):  
Gravity Field ◽  
Ocean Circulation ◽  
Reference Frames ◽  
Satellite Gravity ◽  
Global Gravity ◽  
Height System ◽  
Regional Gravity ◽  
Gravity Recovery ◽  
Satellite Gravity Missions

AbstractA suitable representation of the regional gravity field is used to estimate relative offsets between national height system realizations in Europe. The method used is based on a gravimetric approach and benefits from the significant improvements in the determination of the global gravity field by the recent satellite gravity missions the Gravity Recovery and Climate Experiment (GRACE) and the Gravity field and steady-state Ocean Circulation Explorerr (GOCE). The potential of these missions for the unification of height reference frames is analyzed in terms of accuracy and spatial resolution. The results of the gravimetric approach are compared to the independent results of the geodetic leveling approach. Advantages and drawbacks of both methods are discussed.

scholarly journals ANALYSIS OF WATER MASS VARIATIONS AT WETLANDS REGIONS FROM GRACE: THE PANTANAL CASE

2018 ◽  
Vol 35 (4) ◽  
pp. 307
Author(s):  
Cecilia Cornero ◽  
AYELEN PEREIRA ◽  
MARÍA CRISTINA PACINO
Keyword(s):  
Water Mass ◽  
Spatial Scales ◽  
Water Storage ◽  
Transport Processes ◽  
Satellite Gravity ◽  
The North ◽  
Paraguay River ◽  
Gravity Recovery ◽  
Gravity Mission

ABSTRACT. The natural heritage of biodiversity of the Paraguay river basin is subject to potential impacts due to climate change. To monitor these environments at large spatial scales, the satellite gravity mission GRACE (Gravity Recovery and Climate Experiment) provides time-variable Earth’s gravity field models that reflect the variations due to mass transport processes, like continental water storage changes. The purpose of this work is to analyze the spatial and temporal water storage changes for period 2003-2014 using the Equivalent Water Height (EWH) derived from the GRACE solutions in the Pantanal region, one of the most biologically rich environments of the planet. The comparison with EWH and river gauge data at different stations distributed over the Pantanal area was carried out. In order to validate the satellite results, the correlation analysis between the water mass changes and river gauge measurements was obtained, and also the phase differences were analyzed. High correlations were detected at the north, and lower ones towards the south of the Pantanal. The EWH were also contrasted with soil moisture and rainfall data models. The results showed a good agreement between the signals for the area under study.Keywords: water storage, satellite gravity mission, river gauge, rainfall. RESUMO. O patrimônio natural de biodiversidade da bacia do rio Paraguai está sujeito a potenciais impactos das mudanças climáticas. Para monitorar esse ambiente em escala espacial, a missão satelital GRACE (Gravity Recovery and Climate Experiment) fornece modelos do campo de gravidade da Terra variáveis no tempo devido ao processo de transporte de massa, como as variações de armazenamento de água continentais. O objetivo deste artigo é analisar a variabilidade espacial e temporal de armazenamento de água para o período 2003-2014 através da altura equivalente d’água (EWH) derivada das soluções deGRACE na região do Pantanal, um dos ambientes biologicamente mais ricos do planeta. Comparações dos dados de EWH e alturas d’água in-situ foram feitas para diferentes estações distribuídas na região do Pantanal. Com a finalidade de validar os resultados de satélite, foi feita a análise de correlação entre as mudanças de massa d’água e as medições das réguas linimétricas fixadas nas margens dos rios. As diferenças de fase também foram analisadas. Ao Norte do Pantanal foram detectadas altas correlações entre as duas alturas (EWH versus in-situ), e baixas em direção ao sul. O EWH também foi validado com modelos de umidade do solo e precipitação. Os resultados mostraram uma boa concordância entre os sinais para a área em estudo. Palavras-chave: armazenamento de água, missão satelital, cotas do nível d’água, precipitação.

scholarly journals Geophysical interpretation of GPS loading deformation over western Europe using GRACE measurements

2016 ◽  
Vol 59 (5) ◽  
Author(s):  
Songyun Wang ◽  
Jianli Chen ◽  
Jin Li ◽  
Xiaogong Hu ◽  
Shengnan Ni
Keyword(s):  
Western Europe ◽  
International Gnss Service ◽  
Satellite Gravity ◽  
Surface Mass ◽  
Grace Data ◽  
Surface Displacements ◽  
Residual Series ◽  
Vertical Displacements ◽  
Gravity Recovery ◽  
Improved Accuracy

<p>We analyze more than 10 years of Global Positioning System (GPS) height residuals and vertical displacements predicted from surface mass loading observed by the Gravity Recovery and Climate Experiment (GRACE) for 36 International GNSS Service (IGS) stations over Europe. Seasonal surface displacements, mostly due to atmospheric and hydrological loading, are significant in both GPS and GRACE measurements. With an extended time period, our new analysis based on release 05 GRACE data from Center for Space Research (CSR) shows considerably improved agreement between GPS and GRACE than that from previous studies, for not only annual but also interannual signals. The GPS height residual series at most stations exhibit reduced weighted root-mean-squares (WRMS) after removing GRACE-derived vertical displacements, which is attributed to improved accuracy of both GPS and GRACE data products. Furthermore, we demonstrate the necessity of reducing leakage bias in GRACE estimates for the study of surface loading deformation using GRACE satellite gravity observations.</p>

scholarly journals A framework for deriving drought indicators from GRACE

2019 ◽  
Author(s):  
Helena Gerdener ◽  
Olga Engels ◽  
Jürgen Kusche
Keyword(s):  
Hydrological Cycle ◽  
Water Storage ◽  
Synthetic Data ◽  
Satellite Gravity ◽  
Spatially Correlated ◽  
Grace Data ◽  
Spatial Noise ◽  
Drought Indicators ◽  
Gravity Recovery ◽  
Hydrological Droughts

Abstract. Identifying and quantifying drought in retrospective is a necessity for better understanding drought conditions and the propagation of drought through the hydrological cycle, and eventually for developing forecast systems. Hydrological droughts refer to water deficits in surface and subsurface storage, and since these are difficult to monitor at larger scales, several studies have suggested to exploit total water storage data from the GRACE (Gravity Recovery and Climate Experiment) satellite gravity mission to analyse them. This has led to the development of GRACE-based drought indicators. However, it is unclear how the ubiquitous presence of climate-related or anthropogenic water storage trends, which has been found from GRACE analyses, masks drought signals. Thus, this study aims at a better understanding of how drought signals, in the presence of trends and GRACE-specific spatial noise, propagate through GRACE drought indicators. Synthetic data are constructed and existing indicators are modified to possibly improve drought detection. Our results indicate that while the choice of the indicator should be application dependent, larger differences in robustness can be observed. We found a modified, temporally accumulated version of the Zhao et al. (2017) indicator in particular robust under realistic simulations. We show that trends and accelerations seen in GRACE data tend to mask drought signals in indicators, and that different spatial averaging methods required to suppress the spatially correlated GRACE noise affect the outcome. Finally, we identify and analyse two droughts in South Africa using real GRACE data and the modified indicators.

Structure of the system of normal equations in the construction and equalization of analytical phototriangulation by the ligament method using the coplanarity condition

2020 ◽  
Vol 64 (5) ◽  
pp. 507-514
Author(s):  
Bezmenov V.M. ◽  
Keyword(s):  
Normal Equations

Рассматривается построение и уравнивание аналитической пространственной фототриангуляции, ос- нованной на совместном использованием условия коллинеарности и условия компланарности векторов. Получена структура системы нормальных уравнений. Предлагаемое решение позволяет выполнять по- строение фототриангуляции с одновременным определением (уточнением) элементов внешнего ори- ентирования и внутреннего ориентирования съёмочной камеры. Для назначения начальных значений весов уравнений, составленных с использованием условия компланарности, для некоторой точки ис- следуемого объекта (местности) предлагается использовать ошибки определения пространственных координат точки, рассчитанные методом прямой фотограмметрической засечки для произвольного случая съёмки.

Sign in / Sign up

Export Citation Format

Share Document