The Experts below are selected from a list of 36132 Experts worldwide ranked by ideXlab platform
Paola De Michelis - One of the best experts on this subject based on the ideXlab platform.
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scaling features of high latitude Geomagnetic Field fluctuations at swarm altitude impact of imf orientation
Journal of Geophysical Research, 2017Co-Authors: Paola De Michelis, G Consolini, Roberta Tozzi, M F MarcucciAbstract:This paper attempts to explore the statistical scaling features of high-latitude Geomagnetic Field fluctuations at Swarm altitude. Data for this study are low-resolution (1 Hz) magnetic data recorded by the vector Field magnetometer on board Swarm A satellite over 1 year (from 15 April 2014 to 15 April 2015). The first- and second-order structure function scaling exponents and the degree of intermittency of the fluctuations of the intensity of the horizontal component of the magnetic Field at high northern latitudes have been evaluated for different interplanetary magnetic Field orientations in the GSM Y-Z plane and seasons. In the case of the first-order structure function scaling exponent, a comparison between the average spatial distributions of the obtained values and the statistical convection patterns obtained using a Super Dual Auroral Radar Network dynamic model (CS10 model) has been also considered. The obtained results support the idea that the knowledge of the scaling features of the Geomagnetic Field fluctuations can help in the characterization of the different ionospheric turbulence regimes of the medium crossed by Swarm A satellite. This study shows that different turbulent regimes of the Geomagnetic Field fluctuations exist in the regions characterized by a double-cell convection pattern and in those regions near the border of the convective structures.
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observations of high latitude Geomagnetic Field fluctuations during st patrick s day storm swarm and superdarn measurements
Earth Planets and Space, 2016Co-Authors: Paola De Michelis, G Consolini, Roberta Tozzi, M F MarcucciAbstract:The aim of this work is to study the properties of the magnetic Field’s fluctuations produced by ionospheric and magnetospheric electric currents during the St. Patrick’s Day Geomagnetic storm (17 March 2015). We analyse the scaling features of the external contribution to the horizontal Geomagnetic Field recorded simultaneously by the three satellites of the Swarm constellation during a period of 13 days (13–25 March 2015). We examine the different latitudinal structure of the Geomagnetic Field fluctuations and analyse the dynamical changes in the magnetic Field scaling features during the development of the Geomagnetic storm. Analysis reveals consistent patterns in the scaling properties of magnetic fluctuations and striking changes between the situation before the storm, during the main phase and recovery phase. We discuss these dynamical changes in relation to those of the overall ionospheric polar convection and potential structures as reconstructed using SuperDARN data. Our findings suggest that distinct turbulent regimes characterised the mesoscale magnetic Field’s fluctuations and that some factors, which are known to influence large-scale fluctuations, have also an influence on mesoscale fluctuations. The obtained results are an example of the capability of Geomagnetic Field fluctuations data to provide new insights about ionospheric dynamics and ionosphere–magnetosphere coupling. At the same time, these results could open doors for development of new applications where the dynamical changes in the scaling features of the magnetic fluctuations are used as local indicators of magnetospheric conditions.
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on the local hurst exponent of Geomagnetic Field fluctuations spatial distribution for different Geomagnetic activity levels
Journal of Geophysical Research, 2015Co-Authors: Paola De Michelis, G ConsoliniAbstract:This study attempts to characterize the spatial distribution of the scaling features of the short time scale magnetic Field fluctuations obtained from 45 ground-based Geomagnetic observatories distributed in the Northern Hemisphere. We investigate the changes of the scaling properties of the Geomagnetic Field fluctuations by evaluating the local Hurst exponent and reconstruct maps of this index as a function of the Geomagnetic activity level. These maps permit us to localize the different latitudinal structures responsible for disturbances and related to the ionospheric current systems. We find that the Geomagnetic Field fluctuations associated with the different ionospheric current systems have different scaling features, which can be evidenced by the local Hurst exponent. We also find that in general, the local Hurst exponent for quiet magnetospheric periods is higher than that for more active periods suggesting that the dynamical processes that are activated during disturbed times are responsible for changes in the nature of the Geomagnetic Field fluctuations.
Martin Frank - One of the best experts on this subject based on the ideXlab platform.
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comparison of cosmogenic radionuclide production and Geomagnetic Field intensity over the last 200 000 years
Philosophical transactions - Royal Society. Mathematical physical and engineering sciences, 2000Co-Authors: Martin FrankAbstract:The production rate of cosmogenic radionuclides such as 10Be or 14C is known to vary as a function of the Geomagnetic Field intensity. It should, therefore, be possible to extract a record of palaeoField intensity from the deposition record of these radionuclides in marine or terrestrial sediments and ice cores. Field intensity variations, however, are not the only factor that has influenced the cosmogenic radionuclide records. In the case of 14C, variations of the global carbon cycle, caused by reorganization of the ocean circulation patterns from the last glacial to the present interglacial, are superimposed. 10Be is not affected by these variations because it is not part of the carbon cycle, but its deposition rates in marine sediments vary as a function of lateral sediment redistribution and boundary scavenging intensity. A global stacked record of 10Be deposition rates, corrected for sediment redistribution by normalizing to 230Thex, was shown to remove most of the disturbances, and provides a record of 10Be production rate variations over the last 200 000 years, which translates into Geomagnetic Field intensity variations. This dataset is compared with palaeoField intensities reconstructed from marine sediments by palaeomagnetic methods, from variations in atmospheric 14C/12C derived from independent calibrations of 14C ages, such as U/Th dating and tree ring chronology, and from 36Cl and 10Be fluxes in polar ice cores. Potential influences of the Earth’s orbital parameters and insufficient correction for orbitally triggered climate variations on the palaeointensity reconstructions are assessed. It is argued that the palaeointensity records derived from marine sediments are not significantly affected by these factors.
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a 200 kyr record of cosmogenic radionuclide production rate and Geomagnetic Field intensity from 10be in globally stacked deep sea sediments
Earth and Planetary Science Letters, 1997Co-Authors: Martin Frank, Peter W Kubik, Bernd Schwarz, Sabine Baumann, Martin Suter, Augusto ManginiAbstract:The reconstruction of Geomagnetic Field intensity variations during the last 200 kyr from paleomagnetic data is at present the subject of numerous studies and major debate. There is currently no generally accepted record. Here we present a global stacked record of (230Thex-normalized)10Be deposition in marine sediments representing relative variations in 10Be production rate which are translated into Field intensity variations. The record shows major periods during which the Field intensity was between 10% and 40% of the present day value; namely 30–42, 60–75, 85–110 and 180–192 kyr B.P. Our results are compared to independently derived paleomagnetic studies and Th/U calibrations of 14C dates on corals. During most of the observed period the Geomagnetic Field intensity was weaker than today, resulting in an overall 30% reduced value for the last 200 kyr.
G Consolini - One of the best experts on this subject based on the ideXlab platform.
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scaling features of high latitude Geomagnetic Field fluctuations at swarm altitude impact of imf orientation
Journal of Geophysical Research, 2017Co-Authors: Paola De Michelis, G Consolini, Roberta Tozzi, M F MarcucciAbstract:This paper attempts to explore the statistical scaling features of high-latitude Geomagnetic Field fluctuations at Swarm altitude. Data for this study are low-resolution (1 Hz) magnetic data recorded by the vector Field magnetometer on board Swarm A satellite over 1 year (from 15 April 2014 to 15 April 2015). The first- and second-order structure function scaling exponents and the degree of intermittency of the fluctuations of the intensity of the horizontal component of the magnetic Field at high northern latitudes have been evaluated for different interplanetary magnetic Field orientations in the GSM Y-Z plane and seasons. In the case of the first-order structure function scaling exponent, a comparison between the average spatial distributions of the obtained values and the statistical convection patterns obtained using a Super Dual Auroral Radar Network dynamic model (CS10 model) has been also considered. The obtained results support the idea that the knowledge of the scaling features of the Geomagnetic Field fluctuations can help in the characterization of the different ionospheric turbulence regimes of the medium crossed by Swarm A satellite. This study shows that different turbulent regimes of the Geomagnetic Field fluctuations exist in the regions characterized by a double-cell convection pattern and in those regions near the border of the convective structures.
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observations of high latitude Geomagnetic Field fluctuations during st patrick s day storm swarm and superdarn measurements
Earth Planets and Space, 2016Co-Authors: Paola De Michelis, G Consolini, Roberta Tozzi, M F MarcucciAbstract:The aim of this work is to study the properties of the magnetic Field’s fluctuations produced by ionospheric and magnetospheric electric currents during the St. Patrick’s Day Geomagnetic storm (17 March 2015). We analyse the scaling features of the external contribution to the horizontal Geomagnetic Field recorded simultaneously by the three satellites of the Swarm constellation during a period of 13 days (13–25 March 2015). We examine the different latitudinal structure of the Geomagnetic Field fluctuations and analyse the dynamical changes in the magnetic Field scaling features during the development of the Geomagnetic storm. Analysis reveals consistent patterns in the scaling properties of magnetic fluctuations and striking changes between the situation before the storm, during the main phase and recovery phase. We discuss these dynamical changes in relation to those of the overall ionospheric polar convection and potential structures as reconstructed using SuperDARN data. Our findings suggest that distinct turbulent regimes characterised the mesoscale magnetic Field’s fluctuations and that some factors, which are known to influence large-scale fluctuations, have also an influence on mesoscale fluctuations. The obtained results are an example of the capability of Geomagnetic Field fluctuations data to provide new insights about ionospheric dynamics and ionosphere–magnetosphere coupling. At the same time, these results could open doors for development of new applications where the dynamical changes in the scaling features of the magnetic fluctuations are used as local indicators of magnetospheric conditions.
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on the local hurst exponent of Geomagnetic Field fluctuations spatial distribution for different Geomagnetic activity levels
Journal of Geophysical Research, 2015Co-Authors: Paola De Michelis, G ConsoliniAbstract:This study attempts to characterize the spatial distribution of the scaling features of the short time scale magnetic Field fluctuations obtained from 45 ground-based Geomagnetic observatories distributed in the Northern Hemisphere. We investigate the changes of the scaling properties of the Geomagnetic Field fluctuations by evaluating the local Hurst exponent and reconstruct maps of this index as a function of the Geomagnetic activity level. These maps permit us to localize the different latitudinal structures responsible for disturbances and related to the ionospheric current systems. We find that the Geomagnetic Field fluctuations associated with the different ionospheric current systems have different scaling features, which can be evidenced by the local Hurst exponent. We also find that in general, the local Hurst exponent for quiet magnetospheric periods is higher than that for more active periods suggesting that the dynamical processes that are activated during disturbed times are responsible for changes in the nature of the Geomagnetic Field fluctuations.
M F Marcucci - One of the best experts on this subject based on the ideXlab platform.
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scaling features of high latitude Geomagnetic Field fluctuations at swarm altitude impact of imf orientation
Journal of Geophysical Research, 2017Co-Authors: Paola De Michelis, G Consolini, Roberta Tozzi, M F MarcucciAbstract:This paper attempts to explore the statistical scaling features of high-latitude Geomagnetic Field fluctuations at Swarm altitude. Data for this study are low-resolution (1 Hz) magnetic data recorded by the vector Field magnetometer on board Swarm A satellite over 1 year (from 15 April 2014 to 15 April 2015). The first- and second-order structure function scaling exponents and the degree of intermittency of the fluctuations of the intensity of the horizontal component of the magnetic Field at high northern latitudes have been evaluated for different interplanetary magnetic Field orientations in the GSM Y-Z plane and seasons. In the case of the first-order structure function scaling exponent, a comparison between the average spatial distributions of the obtained values and the statistical convection patterns obtained using a Super Dual Auroral Radar Network dynamic model (CS10 model) has been also considered. The obtained results support the idea that the knowledge of the scaling features of the Geomagnetic Field fluctuations can help in the characterization of the different ionospheric turbulence regimes of the medium crossed by Swarm A satellite. This study shows that different turbulent regimes of the Geomagnetic Field fluctuations exist in the regions characterized by a double-cell convection pattern and in those regions near the border of the convective structures.
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observations of high latitude Geomagnetic Field fluctuations during st patrick s day storm swarm and superdarn measurements
Earth Planets and Space, 2016Co-Authors: Paola De Michelis, G Consolini, Roberta Tozzi, M F MarcucciAbstract:The aim of this work is to study the properties of the magnetic Field’s fluctuations produced by ionospheric and magnetospheric electric currents during the St. Patrick’s Day Geomagnetic storm (17 March 2015). We analyse the scaling features of the external contribution to the horizontal Geomagnetic Field recorded simultaneously by the three satellites of the Swarm constellation during a period of 13 days (13–25 March 2015). We examine the different latitudinal structure of the Geomagnetic Field fluctuations and analyse the dynamical changes in the magnetic Field scaling features during the development of the Geomagnetic storm. Analysis reveals consistent patterns in the scaling properties of magnetic fluctuations and striking changes between the situation before the storm, during the main phase and recovery phase. We discuss these dynamical changes in relation to those of the overall ionospheric polar convection and potential structures as reconstructed using SuperDARN data. Our findings suggest that distinct turbulent regimes characterised the mesoscale magnetic Field’s fluctuations and that some factors, which are known to influence large-scale fluctuations, have also an influence on mesoscale fluctuations. The obtained results are an example of the capability of Geomagnetic Field fluctuations data to provide new insights about ionospheric dynamics and ionosphere–magnetosphere coupling. At the same time, these results could open doors for development of new applications where the dynamical changes in the scaling features of the magnetic fluctuations are used as local indicators of magnetospheric conditions.
Angelo De Santis - One of the best experts on this subject based on the ideXlab platform.
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a Geomagnetic Field model for the holocene based on archaeomagnetic and lava flow data
Earth and Planetary Science Letters, 2014Co-Authors: F J Pavoncarrasco, Maria Luisa Osete, J M Torta, Angelo De SantisAbstract:Abstract We propose a new Geomagnetic Field model for the Holocene period based on archaeomagnetic and lava flow data, avoiding the use of lake sediment data. The source of data comes from the GEOMAGIA50v2 database which has been updated with the new archaeomagnetic and volcanic studies published during the last 3 yr. The model, called SHA.DIF.14k, allows us to analyse the behaviour of the Geomagnetic Field for the last 14 000 yr: from 12 000 BC to 1900 AD. For the model construction we use the spherical harmonic analysis in space and the penalized cubic B-splines in time. Both spatial and temporal regularization norms are used to constrain the inversion problem and applied at the core–mantle boundary (CMB) to assure the convergence of the model. For the last 3 ka, the model predictions agree with those given by the global model ARCH3k.1 and the European model SCHA.DIF.3k. For older epochs, the new model presents a clear improvement in Field resolution with respect to other current models of the Geomagnetic Field for the Holocene. For the last 9 ka, the time evolution of the dipolar moment obtained from the dipole Field shows a clear minimum between 5500 BC and 3000 BC, and the well-known continuous decreasing trend of the Geomagnetic Field strength for the last millennium and a half. A general view of the time-average evolution of the Geomagnetic Field flux lobes at the CMB for the northern hemisphere suggests a marked lobe of positive magnetic flux when the dipole moment was maximum. This lobe vanishes when the dipolar Field is decreasing. The north polar wander paths of both north magnetic dip and Geomagnetic poles were obtained showing an average rate of motion of 5.1 km/yr and 3.7 km/yr respectively. The model shows that the Geomagnetic Field can be averaged as axial dipolar in ∼ 2000 yr within an error of 5°, the typical uncertainty of the palaeomagnetic studies. Finally, and following the recent definition of archaeomagnetic jerks, we found 8 critical events in the time evolution of the Geomagnetic Field for the last 8 ka characterized by a maximum in the hemispheric asymmetry of the proposed model. The model is available in the Earth Ref Digital Archive at http://earthref.org/ERDA/1897/ .
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a Geomagnetic Field model for the holocene based on archaeomagnetic and lava flow data
Earth and Planetary Science Letters, 2014Co-Authors: F J Pavoncarrasco, Maria Luisa Osete, J M Torta, Angelo De SantisAbstract:Abstract We propose a new Geomagnetic Field model for the Holocene period based on archaeomagnetic and lava flow data, avoiding the use of lake sediment data. The source of data comes from the GEOMAGIA50v2 database which has been updated with the new archaeomagnetic and volcanic studies published during the last 3 yr. The model, called SHA.DIF.14k, allows us to analyse the behaviour of the Geomagnetic Field for the last 14 000 yr: from 12 000 BC to 1900 AD. For the model construction we use the spherical harmonic analysis in space and the penalized cubic B-splines in time. Both spatial and temporal regularization norms are used to constrain the inversion problem and applied at the core–mantle boundary (CMB) to assure the convergence of the model. For the last 3 ka, the model predictions agree with those given by the global model ARCH3k.1 and the European model SCHA.DIF.3k. For older epochs, the new model presents a clear improvement in Field resolution with respect to other current models of the Geomagnetic Field for the Holocene. For the last 9 ka, the time evolution of the dipolar moment obtained from the dipole Field shows a clear minimum between 5500 BC and 3000 BC, and the well-known continuous decreasing trend of the Geomagnetic Field strength for the last millennium and a half. A general view of the time-average evolution of the Geomagnetic Field flux lobes at the CMB for the northern hemisphere suggests a marked lobe of positive magnetic flux when the dipole moment was maximum. This lobe vanishes when the dipolar Field is decreasing. The north polar wander paths of both north magnetic dip and Geomagnetic poles were obtained showing an average rate of motion of 5.1 km/yr and 3.7 km/yr respectively. The model shows that the Geomagnetic Field can be averaged as axial dipolar in ∼ 2000 yr within an error of 5°, the typical uncertainty of the palaeomagnetic studies. Finally, and following the recent definition of archaeomagnetic jerks, we found 8 critical events in the time evolution of the Geomagnetic Field for the last 8 ka characterized by a maximum in the hemispheric asymmetry of the proposed model. The model is available in the Earth Ref Digital Archive at http://earthref.org/ERDA/1897/ .
