Difference between pages "IC SG7" and "JSG T.33"

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<big>'''JSG 0.7: Computational methods for high-resolution gravity field modelling and nonlinear dif-fusion filtering'''</big>
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<big>'''JSG 0.20: Space weather and ionosphere'''</big>
  
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Chairs: ''R. Čunderlík (Slovakia), K. Mikula (Slovakia)''<br>
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Chair: '': Klaus Börger (Germany)''<br>
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Affiliation: ''Comm. 2, 3 and GGOS''
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Affiliation:''Commissions 1, 4 and GGOS''
  
 
__TOC__
 
__TOC__
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===Introduction===
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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 IC SG is to apply numerical methods like the finite element method (FEM), finite volume method (FVM), boundary element method (BEM) and others mostly for gravity field modelling and non-linear filtering of data on the Earth’s surface. An advantage is that such numerical methods use finite elements as basis functions with local supports. Therefore a refinement of the discretization is very straightforward allowing adaptive refinement procedures as well.
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===Terms of Reference===
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In case of gravity field modelling, a parallelization of algorithms using the standard MPI (Message Passing Interface) procedures and computations on clusters with distributed memory allows to achieve global or local gravity field models of very high-resolution, where a level of the discretization practically depends on capacity of available HPC facilities. The aforementioned numerical methods allow a detailed discretization of the real Earth’s surface considering its topography. To get precise numerical solution to the geodetic boundary-value problems (BVPs) on such complicated surface it is also necessary handle problems like the oblique derivative.
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Data filtering occurs in many applications of geosciences. A quality of filtering is essential for correct interpretations of obtained results. In geodesy we usually use methods based on the Gaussian filtering that corresponds to a linear diffusion. Such filtering has a uniform smoothing effect, which also blurs “edges” representing important structures in the filtered data. In contrary, a nonlinear diffusion allows adaptive smoothing that can preserve main structures in data, while a noise is effectively reduced. In image processing there are known at least two basic nonlinear diffusion models; (i) the regularized Perona-Malik model, where the diffusion coefficient depends on an edge detector, and (ii) the geodesic mean curvature flow model based on a geometrical diffusion of level-sets of the image intensity.
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It is well known that space geodetic methods are under influence of ionospheric refraction, and therefore from the very beginning of these techniques geodesy deals with the ionosphere. In this context sophisticated methods and models have been developed in order to determine, to represent and to predict the ionosphere. Apart from this the ionosphere fits into another issue called „space weather“, which describes the interactions between the constituents of space and earth. To be more precise space weather means the conditions in space with a significant impact on space-based and ground-based technology as well as on earth and its inhabitants. Solar radiation, that is electromagnetic emission as well as particle emission, is the main cause or “drive” of space weather.
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The aim of the SG is to investigate and develop nonlinear filtering methods that would be useful for a variety of geodetic data, e.g., from satellite missions, satellite altimetry and others. A choice of an appropriate numerical technique is open to members of the SG. An example of 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.
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Originally, geodesy, or to be more precise, space geodetic methods have considered the ionosphere as a disturbing factor that affects signal propagation and that has to be corrected. This (geodetic) perspective has been changed over time and the ionosphere has become a target value so that geodetic observations are used to determine the ionosphere. Different groups have developed models of high quality, e.g. 3D-models which describe the ionosphere as a function of longitude, latitude and time or even 4D-models accounting for the height as well. However, since the ionosphere is a manifestation of space weather, geodesy should contribute to space weather research, and in this respect completely new scientific questions arise, in particular with respect to the so called “geo-effect”, which is the impact of space weather in general.
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There are two principal goals of the proposed study group. First, to connect the “geodetic” ionosphere research with solar-terrestrial physics, in order to consider the complete cause-effect-chain. Second, the above mentioned “geo-effect” has to be investigated in detail, which is an important aspect, because modern society depends to a great extent on technology, i.e. technology that can be disturbed, that can be harmed or that even can be destroyed by extreme space weather events
  
 
===Objectives===
 
===Objectives===
  
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* to develop numerical models for solving the geodetic BVPs using numerical methods like FEM, FVM, BEM and others,
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* improvements and enlargements of ionosphere models (including scintillations)
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* to investigate the problem of oblique derivative,
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* geodetic contributions to investigate the impact of space weather/the ionosphere (extreme events) on satellite motion
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* to implement parallelization of numerical algorithms using the standard MPI procedures,
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* geodetic contributions to investigate the impact of space weather/the ionosphere (extreme events) on communication
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* to perform large-scale parallel computations on clusters with distributed memory,
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* investigations of the impact of space weather/the ionosphere (extreme events) on remote sensing products
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* to investigate methods for nonlinear filtering of data on closed surfaces using the regularized Perona-Malik model or mean curvature flow model,
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* investigations of the impact of space weather/the ionosphere (extreme events) on terrestrial technical infrastructure (metallic networks, power grids)
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* to derive fully-implicit and semi-implicit numerical schemes for the linear and nonlinear diffusion equation on closed surfaces using the surface FVM,
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* “geodetic observations” of currents (ring current, electrojets)
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* to develop algorithms for the nonlinear filtering of data on the Earth’s surface,
 
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* to summarize the developed methods and achieved numerical results in journal papers.
 
  
 
===Program of activities===
 
===Program of activities===
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active participation in major geodetic conferences,
 
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working meetings at international symposia,
 
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organization of a conference session.
 
  
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===Members===
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* the maintaining of a website for general information as well as for internal exchange of data sets and results
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* organization of a workshop w.r.t. space weather and geo-effects
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* publication of important findings
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===Membership===
  
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'' '''Róbert Čunderlík (Slovakia), chair<br />
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'' '''Klaus Börger (Germany), chair''' <br /> Mahmut Onur Karsioglu (Turkey), vice-chair <br /> Michael Schmidt (Germany) <br /> Jürgen Matzka (Germany) <br /> Barbara Görres (Germany) <br /> George Zhizhao Liu (Hong Kong, China) <br /> Ehsan Forootan (Germany) <br /> Johannes Hinrichs (Germany) <br />''
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Karol Mikula (Slovakia), chair'''<br />
 
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Ahmed Abdalla, New Zealand<br />
 
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Michal Beneš (Czech Republic)<br />
 
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Zuzana Fašková (Slovakia)<br />
 
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Marek Macák (Slovakia)<br />
 
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Otakar Nesvadba (Czech Republic)<br />
 
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Róbert Špir (Slovakia)<br />
 
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Róbert Tenzer (New Zealand)<br />''
 

Revision as of 10:15, 29 April 2016

JSG 0.20: Space weather and ionosphere

Chair: : Klaus Börger (Germany)
Affiliation:Commissions 1, 4 and GGOS

Terms of Reference

It is well known that space geodetic methods are under influence of ionospheric refraction, and therefore from the very beginning of these techniques geodesy deals with the ionosphere. In this context sophisticated methods and models have been developed in order to determine, to represent and to predict the ionosphere. Apart from this the ionosphere fits into another issue called „space weather“, which describes the interactions between the constituents of space and earth. To be more precise space weather means the conditions in space with a significant impact on space-based and ground-based technology as well as on earth and its inhabitants. Solar radiation, that is electromagnetic emission as well as particle emission, is the main cause or “drive” of space weather.

Originally, geodesy, or to be more precise, space geodetic methods have considered the ionosphere as a disturbing factor that affects signal propagation and that has to be corrected. This (geodetic) perspective has been changed over time and the ionosphere has become a target value so that geodetic observations are used to determine the ionosphere. Different groups have developed models of high quality, e.g. 3D-models which describe the ionosphere as a function of longitude, latitude and time or even 4D-models accounting for the height as well. However, since the ionosphere is a manifestation of space weather, geodesy should contribute to space weather research, and in this respect completely new scientific questions arise, in particular with respect to the so called “geo-effect”, which is the impact of space weather in general.

There are two principal goals of the proposed study group. First, to connect the “geodetic” ionosphere research with solar-terrestrial physics, in order to consider the complete cause-effect-chain. Second, the above mentioned “geo-effect” has to be investigated in detail, which is an important aspect, because modern society depends to a great extent on technology, i.e. technology that can be disturbed, that can be harmed or that even can be destroyed by extreme space weather events

Objectives

  • improvements and enlargements of ionosphere models (including scintillations)
  • geodetic contributions to investigate the impact of space weather/the ionosphere (extreme events) on satellite motion
  • geodetic contributions to investigate the impact of space weather/the ionosphere (extreme events) on communication
  • investigations of the impact of space weather/the ionosphere (extreme events) on remote sensing products
  • investigations of the impact of space weather/the ionosphere (extreme events) on terrestrial technical infrastructure (metallic networks, power grids)
  • “geodetic observations” of currents (ring current, electrojets)

Program of activities

  • the maintaining of a website for general information as well as for internal exchange of data sets and results
  • organization of a workshop w.r.t. space weather and geo-effects
  • publication of important findings

Membership

Klaus Börger (Germany), chair
Mahmut Onur Karsioglu (Turkey), vice-chair
Michael Schmidt (Germany)
Jürgen Matzka (Germany)
Barbara Görres (Germany)
George Zhizhao Liu (Hong Kong, China)
Ehsan Forootan (Germany)
Johannes Hinrichs (Germany)

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