Difference between pages "JSG T.26" and "JSG T.33"

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(Created page with "<big>'''JSG 0.13: Integral equations of potential theory for continuation and transformation of classical and new gravitational observables'''</big> Chair:''Michal Šprlák (...")
 
 
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<big>'''JSG 0.13: Integral equations of potential theory for continuation and transformation of classical and new gravitational observables'''</big>
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<big>'''JSG 0.20: Space weather and ionosphere'''</big>
  
Chair:''Michal Šprlák (Czech Republic)''<br>
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Chair: '': Klaus Börger (Germany)''<br>
Affiliation:''Commission 2 and GGOS''
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Affiliation:''Commissions 1, 4 and GGOS''
  
 
__TOC__
 
__TOC__
  
===Introduction===
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===Terms of Reference===
  
The description of the Earth's gravitational field and its temporal variations belongs to fundamental pillars of modern geodesy. The accurate knowledge of the global gravitational field is important in many applications including precise positioning, metrology, geophysics, geodynamics, oceanography, hydrology, cryospheric and other geosciences. Various observation techniques for collecting gravitational data have been invented based on terrestrial, marine, airborne and more recently, satellite sensors. On the other hand, different parametrization methods of the gravitational field were established in geodesy, however, with many unobservable parameters. For this reason, the geodetic science has traditionally been formulating various gravitational parameter transformations, including those based on solving boundary/initial value problems of potential theory, through Fredholm's integral equations.
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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.
  
Traditionally, Stokes’s, Vening-Meinesz’s and Hotine’s integrals have been of interest in geodesy as they accommodated geodetic applications. In recent history, new geodetic integral transformations were formulated. This effort was mainly initiated by new gravitational observables that became gradually available to geodesists with the advent of precise GNSS (Global Navigation Satellite Systems) positioning, satellite altimetry and aerial gravimetry/gradiometry. The family of integral transformations has enormously been extended with satellite-to-satellite tracking and satellite gradiometric data available from recent gravity-dedicated satellite missions.
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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.
  
Besides numerous efforts in developing integral equations to cover new observables in geodesy, many aspects of integral equations remain challenging. This study group aims for systematic treatment of integral transformation in geodesy, as many formulations have been performed by making use of various approaches. Many solutions are based on spherical approximation that cannot be justified for globally distributed satellite data and with respect to requirements of various data users requiring gravitational data to be distributed the reference ellipsoid or at constant geodetic altitude. On the other hand, the integral equations in spherical approximation possess symmetric properties that allow for studying their spatial and spectral properties; they also motivate for adopting a generalized notation. New numerically efficient, stable and accurate methods for upward/downward continuation, comparison, validation, transformation, combination and/or for interpretation of gravitational data are also of high interest with increasing availability of large amounts of new data.
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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===
  
* To consider different types of gravitational data, i.e., terrestrial, aerial and satellite, available today and to formulate their mathematical relation to the gravitational potential.
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* improvements and enlargements of ionosphere models (including scintillations)
* To study mathematical properties of differential operators in spherical and Jacobi ellipsoidal coordinates, which relate various functionals of the gravitational potential.
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* geodetic contributions to investigate the impact of space weather/the ionosphere (extreme events) on satellite motion
* To complete the family of integral equations relating various types of current and foreseen gravitational data and to derive corresponding spherical and ellipsoidal Green’s functions.
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* geodetic contributions to investigate the impact of space weather/the ionosphere (extreme events) on communication
* To study accurate and numerically stable methods for upward/downward continuation of gravitational field parameters.
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* investigations of the impact of space weather/the ionosphere (extreme events) on remote sensing products
* To investigate optimal combination techniques of heterogeneous gravitational field observables for gravitational field modelling at all scales.
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* investigations of the impact of space weather/the ionosphere (extreme events) on terrestrial technical infrastructure (metallic networks, power grids)
* To investigate conditionality as well as spatial and spectral properties of linear operators based on discretized integral equations.
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* “geodetic observations” of currents (ring current, electrojets)
* To classify integral transformations and to propose suitable generalized notation for a variety of classical and new integral equations in geodesy.
 
  
===Program of Activities===
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===Program of activities===
  
* Presenting research results at major international geodetic and geophysical conferences, meetings and workshops.
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* the maintaining of a website for general information as well as for internal exchange of data sets and results
* Organizing a session at the forthcoming Hotine-Marussi Symposium 2017.
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* organization of a workshop w.r.t. space weather and geo-effects
* Cooperating with related IAG Commissions and GGOS.
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* publication of important findings
* Monitoring activities of JGS members as well as other scientists related to the scope of JGS activities.
 
* Providing bibliographic list of relevant publications from different disciplines in the area of JSG interest.
 
  
===Members===
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===Membership===
  
'' '''Michal Šprlák (Czech Republic), chair''' <br /> Alireza Ardalan (Iran) <br /> Mehdi Eshagh (Sweden) <br /> Will Featherstone (Australia) <br /> Ismael Foroughi (Canada) <br /> Petr Holota (Czech Republic) <br /> Juraj Janák (Slovakia) <br /> Otakar Nesvadba (Czech Republic) <br /> Pavel Novák (Czech Republic) <br /> Martin Pitoňák (Czech Republic) <br /> Robert Tenzer (China) <br /> Guyla Tóth (Hungary) <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 />''

Revision as of 09:15, 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)