Difference between pages "IC SG3" and "IC SG5"

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<big>'''JSG 0.12: Advanced computational methods for recovery of high-resolution gravity field models'''</big>
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<big>'''JSG 0.5: Multi-sensor combination for the separation of integral
 +
geodetic signals'''</big>
  
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Chairs: ''Robert Čunderlík (Slovakia)''<br>
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Chair: ''F. Seitz (Germany)''<br>
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Affiliation: ''Comm. 2 and GGOS''
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Affiliation: ''Comm. 2, 3 and GGOS''
  
 
__TOC__
 
__TOC__
 +
===Objectives===
 +
 +
A large part of the geodetic parameters derived from space geodetic observation techniques are integral quantities of the Earth system. Among the most prominent ones are parameters related to Earth rotation and the gravity field. Variations of those parameters reflect the superposed effect of a multitude of dynamical processes and interactions in various subsystems of the Earth. The integral geodetic quantities provide fundamental and unique information for different balances in the Earth system, in particular for the balances of mass and angular momentum that are directly related to (variations of) the gravity field and Earth rotation. In respective balance equations the geodetic parameters describe the integral effect of exchange processes of mass and angular momentum in the Earth system. In contrast to many other disciplines of geosciences, geodesy is characterized by a very long observation history. Partly, the previously mentioned parameters have been determined over many decades with continuously improved space observation techniques. Thus geodesy provides an excellent data base for the analysis of long term changes in the Earth system and contributes fundamentally to an improved understanding of large-scale processes.
 +
 +
However, in general the integral parameter time series cannot be separated into contributions of specific processes without further information. Their separation and therewith their geophysical interpretation requires complementary data from observation techniques that are unequally sensitive for individual effects and/or from numerical models. Activities of the study group are focussed on the development of strategies for the separation of the integral geodetic signals on the basis of modern space-based Earth observation systems. A multitude of simultaneously operating satellite systems with different objectives is available today. They offer a broad spectrum of information on global and regional-scale processes at different temporal resolutions. Within the study group it shall be investigated in which way the combination of heterogeneous data sets allows for the quantification of individual contributors to the balances of mass and angular momentum.
 +
 +
The research activities shall be coordinated between the participating scientists and shall be conducted in interdisciplinary collaboration. At all times the group is open for new contacts and members in order to embed the activities in a wide context. The study group is primarily affiliated with the IAG commissions 2 (Gravity field) and 3 (Earth rotation and geodynamics).
  
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===Introduction===
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===Objectives===
  
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Efficient numerical methods and HPC (high performance computing) facilities provide new opportunities in many applications in geodesy. The goal of the JSG is to apply numerical methods and/or HPC techniques mostly for gravity field modelling and nonlinear filtering of various geodetic data. The discretization numerical methods like the finite element method (FEM), finite volume method (FVM) and boundary element method (BEM) or the meshless methods like the method of fundamental solutions (MFS) or singular boundary method (SOR) can be efficiently used to solve the geodetic boundary value problems and nonlinear diffusion filtering, or to process e.g. the GOCE observations. Their parallel implementations and large-scale parallel computations on clusters with distributed memory using the MPI (Message Passing Interface) standards allows to solve such problems in spatial domains while obtaining high-resolution numerical solutions.  
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The primary objective of the study group is the development of strategies for multi-sensor combinations with the aim of separating time series of integral geodetic parameters related to Earth rotation and gravity field. The separation of the parameter time series into contributions of individual underlying effects fosters the understanding of dynamical processes and interactions in the Earth system. This is of particular interest in the view of global change.
  
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Our JSG is also open for researchers dealing with the classical approaches of gravity field modelling (e.g. the spherical or ellipsoidal harmonics) that are using high performance computing to speed up their processing of enormous amount of input data. This includes large-scale parallel computations on massively parallel architectures as well as heterogeneous parallel computations using graphics processing units (GPUs).
+
Individual contributions from various subsystems of the Earth shall be quantified and balanced. In particular our investigations focus on the separation of the Earth rotation parameters (polar motion and variations of length-of-day) into contributions of atmospheric and hydrospheric angular momentum variations, and on the separation of GRACE gravity field observations over continents into the contributions of individual hydrological storage compartments, such as groundwater, surface water, soil moisture and snow.
 +
Investigations in the frame of the study group will exploit the synergies of various observation systems (satellite altimetry, optical and radar remote sensing, SMOS, and others) for the separation of the signals and combine their output with numerical models. Among the most important steps are compilation and assessment of background information for individual observation systems and sensors (mode of operation, sensitivity, accuracy, deficiencies) as well as theoretical studies which (new) information on the Earth system can be gained from a combination of different observation methods.
  
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Applications of the aforementioned numerical methods for gravity field modelling involve a detailed discretization of the real Earth’s surface considering its topography. It naturally leads to the oblique derivative problem that needs to be treated. In case of FEM or FVM, unstructured meshes above the topography will be constructed. The meshless methods like MFS or SBM that are based on the point-masses modelling can be applied for processing the gravity gradients observed by the GOCE satellite mission. To reach precise and high-resolution solutions, an elimination of far zones’ contributions is practically inevitable. This can be performed using the fast multipole method or iterative procedures. In both cases such an elimination process improves conditioning of the system matrix and a numerical stability of the problem.  
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In particular the research comprises the following topics:
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The aim of the JSG is also to investigate and develop nonlinear filtering methods that allow adaptive smoothing, which effectively reduces the noise while preserves main structures in data. The proposed approach is based on a numerical solution of partial differential equations using a surface finite volume method. It leads to a semi-implicit numerical scheme of the nonlinear diffusion equation on a closed surface where the diffusivity coefficients depend on a combination of the edge detector and a mean curvature of the filtered function. This will avoid undesirable smoothing of local extremes.
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* potential und usability of contemporary spaceborne and terrestrial sensors for an improved understanding of processes within atmosphere and hydrosphere,
 +
* analysis of accuracy, temporal and spatial resolution and coverage of different data sets,
 +
* theoretical and numerical studies on the combination of heterogeneous observation types; this comprehends investigations on appropriate methods for parameter estimation including error propagation, the analysis of linear dependencies between parameters and the solution of rank deficiency problems,
 +
* mathematical methods for the enhancement of the information content (e.g., filters),
 +
* quantification of variations of mass and angular momentum in different subsystems from multi-sensor analysis,
 +
* analysis of the consistencies of balances between individual effects and integral geodetic parameters on different spatial scales,
 +
* formulation of recommendations for future research and (if possible) for future satellite missions on the basis of balance inconsistencies.
  
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===Objectives===
+
===Planned Activities===
  
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The main objectives of the study group are as follows:
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* Set-up of a JSG webpage for dissemination of information (activities and a bibliographic list of references) and for presentation and communication of research results.
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* to develop algorithms for detailed discretization of the real Earth’s surface including the possibility of adaptive refinement procedures,
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* Organization of conference sessions / workshops:
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* to create unstructured meshes above the topography for the FVM or FEM approach,
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** planned in 2013: Conference Session in the Hotine Marussi Symposium
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* to develop the FVM, BEM or FEM numerical models for solving the geodetic BVPs that will treat the oblique derivative problem,
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** planned in 2014: 2nd workshop on the Quality of Geodetic Observing and Monitoring Systems (QuGOMS’ 14)
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* to develop numerical models based on MFS or SBM for processing the GOCE observations,
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* Common publications of SG members
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* to develop parallel implementations of algorithms using the standard MPI procedures,
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* Common fund raising activities (e.g., for PhD. positions)
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* to perform large-scale parallel computations on clusters with distributed memory,
 
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* to investigate and develop methods for nonlinear diffusion filtering of data on the Earth’s surface where the diffusivity coefficients depend on a combination of the edge detector and a mean curvature of the filtered function,
 
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* to derive the semi-implicit numerical schemes for the nonlinear diffusion equation on closed surfaces using the surface FVM,
 
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* and to apply the developed nonlinear filtering methods to real geodetic data.
 
  
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===Program of Activities===
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===Principal Scientific Outcome/Results===
  
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* Active participation at major geodetic workshops and conferences.  
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By the end of the 4-year period 2011-2015 the following outcome shall be achieved:
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* Organization of group working meetings at main international symposia.
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Mature experience in geodetic multi-sensor data combina-tion including data availability, formats, combination strategies and accuracy aspects.
−
* Organization of conference sessions.
+
Numerical results for separated hydrological contributions to integral mass variations observed by GRACE for selected study areas.
 +
Numerical results for separated atmospheric/hydrospheric contributions Earth rotation parameters on seasonal to inter-annual time scales.
 +
Initiation of at least one common funded project with positions for PhD students working in the topical field of the study group.
  
 
===Members===
 
===Members===
  
−
'' '''Róbert Čunderlík (Slovakia), chair <br /> Karol Mikula (Slovakia), vice-chair''' <br /> Jan Martin Brockmann (Germany) <br /> Walyeldeen Godah (Poland) <br /> Petr Holota (Czech Republic) <br /> Michal Kollár (Slovakia) <br /> Marek Macák (Slovakia) <br />  
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'' '''Florian Seitz (Germany), chair''' <br /> Sarah Abelen (Germany) <br /> Rodrigo Abarca del Rio (Chile) <br /> Andreas Güntner (Germany) <br /> Karin Hedman (Germany) <br /> Franz Meyer (USA) <br /> Michael Schmidt (Germany) <br /> Manuela Seitz (Germany) <br /> Alka Singh (India) <br />''
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Zuzana Minarechová (Slovakia) <br /> Otakar Nesvadba (Czech Republic) <br /> Wolf-Dieter Schuh (Germany) <br />''
 

Revision as of 11:49, 2 July 2012

JSG 0.5: Multi-sensor combination for the separation of integral geodetic signals

Chair: F. Seitz (Germany)
Affiliation: Comm. 2, 3 and GGOS

Objectives

A large part of the geodetic parameters derived from space geodetic observation techniques are integral quantities of the Earth system. Among the most prominent ones are parameters related to Earth rotation and the gravity field. Variations of those parameters reflect the superposed effect of a multitude of dynamical processes and interactions in various subsystems of the Earth. The integral geodetic quantities provide fundamental and unique information for different balances in the Earth system, in particular for the balances of mass and angular momentum that are directly related to (variations of) the gravity field and Earth rotation. In respective balance equations the geodetic parameters describe the integral effect of exchange processes of mass and angular momentum in the Earth system. In contrast to many other disciplines of geosciences, geodesy is characterized by a very long observation history. Partly, the previously mentioned parameters have been determined over many decades with continuously improved space observation techniques. Thus geodesy provides an excellent data base for the analysis of long term changes in the Earth system and contributes fundamentally to an improved understanding of large-scale processes.

However, in general the integral parameter time series cannot be separated into contributions of specific processes without further information. Their separation and therewith their geophysical interpretation requires complementary data from observation techniques that are unequally sensitive for individual effects and/or from numerical models. Activities of the study group are focussed on the development of strategies for the separation of the integral geodetic signals on the basis of modern space-based Earth observation systems. A multitude of simultaneously operating satellite systems with different objectives is available today. They offer a broad spectrum of information on global and regional-scale processes at different temporal resolutions. Within the study group it shall be investigated in which way the combination of heterogeneous data sets allows for the quantification of individual contributors to the balances of mass and angular momentum.

The research activities shall be coordinated between the participating scientists and shall be conducted in interdisciplinary collaboration. At all times the group is open for new contacts and members in order to embed the activities in a wide context. The study group is primarily affiliated with the IAG commissions 2 (Gravity field) and 3 (Earth rotation and geodynamics).

Objectives

The primary objective of the study group is the development of strategies for multi-sensor combinations with the aim of separating time series of integral geodetic parameters related to Earth rotation and gravity field. The separation of the parameter time series into contributions of individual underlying effects fosters the understanding of dynamical processes and interactions in the Earth system. This is of particular interest in the view of global change.

Individual contributions from various subsystems of the Earth shall be quantified and balanced. In particular our investigations focus on the separation of the Earth rotation parameters (polar motion and variations of length-of-day) into contributions of atmospheric and hydrospheric angular momentum variations, and on the separation of GRACE gravity field observations over continents into the contributions of individual hydrological storage compartments, such as groundwater, surface water, soil moisture and snow. Investigations in the frame of the study group will exploit the synergies of various observation systems (satellite altimetry, optical and radar remote sensing, SMOS, and others) for the separation of the signals and combine their output with numerical models. Among the most important steps are compilation and assessment of background information for individual observation systems and sensors (mode of operation, sensitivity, accuracy, deficiencies) as well as theoretical studies which (new) information on the Earth system can be gained from a combination of different observation methods.

In particular the research comprises the following topics:

  • potential und usability of contemporary spaceborne and terrestrial sensors for an improved understanding of processes within atmosphere and hydrosphere,
  • analysis of accuracy, temporal and spatial resolution and coverage of different data sets,
  • theoretical and numerical studies on the combination of heterogeneous observation types; this comprehends investigations on appropriate methods for parameter estimation including error propagation, the analysis of linear dependencies between parameters and the solution of rank deficiency problems,
  • mathematical methods for the enhancement of the information content (e.g., filters),
  • quantification of variations of mass and angular momentum in different subsystems from multi-sensor analysis,
  • analysis of the consistencies of balances between individual effects and integral geodetic parameters on different spatial scales,
  • formulation of recommendations for future research and (if possible) for future satellite missions on the basis of balance inconsistencies.

Planned Activities

  • Set-up of a JSG webpage for dissemination of information (activities and a bibliographic list of references) and for presentation and communication of research results.
  • Organization of conference sessions / workshops:
    • planned in 2013: Conference Session in the Hotine Marussi Symposium
    • planned in 2014: 2nd workshop on the Quality of Geodetic Observing and Monitoring Systems (QuGOMS’ 14)
  • Common publications of SG members
  • Common fund raising activities (e.g., for PhD. positions)

Principal Scientific Outcome/Results

By the end of the 4-year period 2011-2015 the following outcome shall be achieved: Mature experience in geodetic multi-sensor data combina-tion including data availability, formats, combination strategies and accuracy aspects. Numerical results for separated hydrological contributions to integral mass variations observed by GRACE for selected study areas. Numerical results for separated atmospheric/hydrospheric contributions Earth rotation parameters on seasonal to inter-annual time scales. Initiation of at least one common funded project with positions for PhD students working in the topical field of the study group.

Members

Florian Seitz (Germany), chair
Sarah Abelen (Germany)
Rodrigo Abarca del Rio (Chile)
Andreas Güntner (Germany)
Karin Hedman (Germany)
Franz Meyer (USA)
Michael Schmidt (Germany)
Manuela Seitz (Germany)
Alka Singh (India)

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