... Nils Reidar B. Olsen & Stefan Haun Department of Hydraulic and Environmental Engineer... more ... Nils Reidar B. Olsen & Stefan Haun Department of Hydraulic and Environmental Engineering, The Norwegian University of Science and Technology, Trondheim ... height of the centre of the bed cell was different from what Van Rijn subscribed, the Hunter-Rouse extrapola-tion ...
5 Commitment and Relationship Maintenance Mechanisms Caryl E. Rusbult Nils Olsen Jody L. Davis Pe... more 5 Commitment and Relationship Maintenance Mechanisms Caryl E. Rusbult Nils Olsen Jody L. Davis Peggy A. Hannon University of North ... display in the context of a specific interaction, interdependence di-lemmas can be construed as diagnostic situations (Holmes & Rempel ...
A proper description of magnetic field contributions from large-scale magnetospheric current syst... more A proper description of magnetic field contributions from large-scale magnetospheric current systems, like the ring-current, is indispensable for obtaining good models of the core and crustal fields. In order to take full advantage of the improved measure- ment accuracy of the new generation of magnetic satellites it is therefore necessary to elaborate on improved models of magnetospheric sources. We present a combined analysis of data from Ørsted, CHAMP and Ørsted-2/SAC-C that aims to describe the time-space structure of the magnetic signature of the ring-current and other magneto- spheric sources.
Satellite observations have always been crucial in determining and regularizing the IRI model by ... more Satellite observations have always been crucial in determining and regularizing the IRI model by providing global data bases for empirical models. Special attraction may have local time precessing, polar orbiting satellites which cover the Earth ionosphere from polar to equatorial regions at all local times and longitudes. Out of these, CHAMP is a successful example with a presently unique orbit altitude of 400 km, and a live time and continuous data base of 10 years at the time of COSPAR 2010. We want to present results of global climatologies on plasma parameters, such as electron density and temperature and emphasis their special characteristics. CHAMP magnetic field and electron density observations have also enabled the statistical global review of the occurrence rates of equatorial plasma irregularities. Even enhanced knowledge on the climatological distribution of these parameters is expected from multi-spacecraft satellite missions, such as is the upcoming ESA Swarm mission. It will provide a multitude of ionospheric and magnetospheric parameters, such as plasma densities and temperatures, the electric and the magnetic field, neutral density and wind, as well as GPS Total Electron Content at three satellites in two different altitudes. We will present products and scientific possibilities arising from the Swarm mission in view of enriching the development of empirical models.
An approach is presented to detect deep-seated regional conductivity anomalies by analysis of mag... more An approach is presented to detect deep-seated regional conductivity anomalies by analysis of magnetic observations taken by low-Earth-orbiting satellites. The approach deals with recovery of C-responses on a regular grid and starts with a determination of time series of external and internal coefficients of the magnetic potential. From the coefficients, time series of the magnetic vertical component and of the horizontal divergence of the horizontal components are synthesized on the grid and the C-responses are determined by means of signal processing of the corresponding time series. For validation of the approach, 3 years of realistic synthetic data at simulated orbits of the forthcoming Swarm constellation of 3 satellites have been used. To obtain the synthetic data for a given 3-D conductivity Earth's model a time-domain scheme has been applied which relies on a Fourier transformation of the inducing field, and on a frequency domain forward modelling. The conductivity model consists of a thin surface layer of realistic conductance and a 3-D mantle that incorporates a hypothetic deep regional anomaly beneath the Pacific Ocean plate. To establish the ability of the approach to capture the geometry of the mantle heterogeneities used in the forward approach, numerical experiments have been undertaken using various satellite combinations, sampling periods of the resulting time series, and numbers of internal coefficients. The possibility of the approach to map anomalies in the mantle using satellite data that contain contributions from the core and lithosphere, from the magnetosphere and ionosphere (and their Earth-induced counterparts), as well as payload noise has been investigated. The model studies have shown that C-responses obtained on a regular grid might be used to map regional deep-seated conductivity anomalies. Moreover, it has been demonstrated that these C-responses are successfully recovered from magnetic data collected by the proposed Swarm constellation of 3 satellites.
We reexamine the problem of inverting global transfer functions to constrain the internal structu... more We reexamine the problem of inverting global transfer functions to constrain the internal structure of the Earth. We go beyond the conventional approach of inverting electromagnetic induction data by inverting directly for chemical composition and thermal state, using the model system CaO-FeO-MgO-Al2O3-SiO2, rather than subsurface electrical conductivity structure, which is only an indirect means of estimating the former parameters. Using minimisation of Gibbs free energy, we calculate the stable mineral phases, their modes and densities. The mineral modes are combined with recent laboratory measurements to estimate the bulk lunar electrical conductivity structure from which transfer functions are calculated. To further constrain the radial density profile in the inversion we added constraints imposed by mass and moment of inertia. Our results indicate that electromagnetic sounding and experimental mineral electrical conductivity data are consistent with a silicate earth, with a composition close to the pyrolite model and additionally seem to require a low temperature mantle geotherm.
... Nils Reidar B. Olsen & Stefan Haun Department of Hydraulic and Environmental Engineer... more ... Nils Reidar B. Olsen & Stefan Haun Department of Hydraulic and Environmental Engineering, The Norwegian University of Science and Technology, Trondheim ... height of the centre of the bed cell was different from what Van Rijn subscribed, the Hunter-Rouse extrapola-tion ...
5 Commitment and Relationship Maintenance Mechanisms Caryl E. Rusbult Nils Olsen Jody L. Davis Pe... more 5 Commitment and Relationship Maintenance Mechanisms Caryl E. Rusbult Nils Olsen Jody L. Davis Peggy A. Hannon University of North ... display in the context of a specific interaction, interdependence di-lemmas can be construed as diagnostic situations (Holmes & Rempel ...
A proper description of magnetic field contributions from large-scale magnetospheric current syst... more A proper description of magnetic field contributions from large-scale magnetospheric current systems, like the ring-current, is indispensable for obtaining good models of the core and crustal fields. In order to take full advantage of the improved measure- ment accuracy of the new generation of magnetic satellites it is therefore necessary to elaborate on improved models of magnetospheric sources. We present a combined analysis of data from Ørsted, CHAMP and Ørsted-2/SAC-C that aims to describe the time-space structure of the magnetic signature of the ring-current and other magneto- spheric sources.
Satellite observations have always been crucial in determining and regularizing the IRI model by ... more Satellite observations have always been crucial in determining and regularizing the IRI model by providing global data bases for empirical models. Special attraction may have local time precessing, polar orbiting satellites which cover the Earth ionosphere from polar to equatorial regions at all local times and longitudes. Out of these, CHAMP is a successful example with a presently unique orbit altitude of 400 km, and a live time and continuous data base of 10 years at the time of COSPAR 2010. We want to present results of global climatologies on plasma parameters, such as electron density and temperature and emphasis their special characteristics. CHAMP magnetic field and electron density observations have also enabled the statistical global review of the occurrence rates of equatorial plasma irregularities. Even enhanced knowledge on the climatological distribution of these parameters is expected from multi-spacecraft satellite missions, such as is the upcoming ESA Swarm mission. It will provide a multitude of ionospheric and magnetospheric parameters, such as plasma densities and temperatures, the electric and the magnetic field, neutral density and wind, as well as GPS Total Electron Content at three satellites in two different altitudes. We will present products and scientific possibilities arising from the Swarm mission in view of enriching the development of empirical models.
An approach is presented to detect deep-seated regional conductivity anomalies by analysis of mag... more An approach is presented to detect deep-seated regional conductivity anomalies by analysis of magnetic observations taken by low-Earth-orbiting satellites. The approach deals with recovery of C-responses on a regular grid and starts with a determination of time series of external and internal coefficients of the magnetic potential. From the coefficients, time series of the magnetic vertical component and of the horizontal divergence of the horizontal components are synthesized on the grid and the C-responses are determined by means of signal processing of the corresponding time series. For validation of the approach, 3 years of realistic synthetic data at simulated orbits of the forthcoming Swarm constellation of 3 satellites have been used. To obtain the synthetic data for a given 3-D conductivity Earth's model a time-domain scheme has been applied which relies on a Fourier transformation of the inducing field, and on a frequency domain forward modelling. The conductivity model consists of a thin surface layer of realistic conductance and a 3-D mantle that incorporates a hypothetic deep regional anomaly beneath the Pacific Ocean plate. To establish the ability of the approach to capture the geometry of the mantle heterogeneities used in the forward approach, numerical experiments have been undertaken using various satellite combinations, sampling periods of the resulting time series, and numbers of internal coefficients. The possibility of the approach to map anomalies in the mantle using satellite data that contain contributions from the core and lithosphere, from the magnetosphere and ionosphere (and their Earth-induced counterparts), as well as payload noise has been investigated. The model studies have shown that C-responses obtained on a regular grid might be used to map regional deep-seated conductivity anomalies. Moreover, it has been demonstrated that these C-responses are successfully recovered from magnetic data collected by the proposed Swarm constellation of 3 satellites.
We reexamine the problem of inverting global transfer functions to constrain the internal structu... more We reexamine the problem of inverting global transfer functions to constrain the internal structure of the Earth. We go beyond the conventional approach of inverting electromagnetic induction data by inverting directly for chemical composition and thermal state, using the model system CaO-FeO-MgO-Al2O3-SiO2, rather than subsurface electrical conductivity structure, which is only an indirect means of estimating the former parameters. Using minimisation of Gibbs free energy, we calculate the stable mineral phases, their modes and densities. The mineral modes are combined with recent laboratory measurements to estimate the bulk lunar electrical conductivity structure from which transfer functions are calculated. To further constrain the radial density profile in the inversion we added constraints imposed by mass and moment of inertia. Our results indicate that electromagnetic sounding and experimental mineral electrical conductivity data are consistent with a silicate earth, with a composition close to the pyrolite model and additionally seem to require a low temperature mantle geotherm.
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