scholarly journals Features of formation of small-scale wave disturbances during a sudden magnetospheric compression

2017 ◽  
Vol 3 (2) ◽  
pp. 34-42
Author(s):  
Алексей Моисеев ◽  
Aleksey Moiseev ◽  
Дмитрий Баишев ◽  
Dmitry Baishev ◽  
Владимир Мишин ◽  
...  
Keyword(s):  
Wave Front ◽  
Geomagnetic Field ◽  
Compression Wave ◽  
Interplanetary Medium ◽  
Interplanetary Shock ◽  
Satellite Observations ◽  
Small Scale ◽  
Plasma Parameters ◽  
Wave Disturbances ◽  
Periodic Changes

Quasi-periodic changes of the geomagnetic field and plasma parameters in the range of Pc 5 pulsations, which occurred immediately after the interaction of interplanetary shock (IPS) with Earth’s magnetosphere in the event of April 24, 2009 at 00:53 UT are examined using ground and satellite observations. The pulsations were localized at latitudes 66–74° in the noon (11 MLT) and evening (20 MLT) sectors. The analysis of hodographs of the geomagnetic field changes both from satellite and ground observations has shown the presence of vortical disturbances. In this event, both the IPS front in the interplanetary medium and the compression wave front in the magnetosphere had a slope in the ZGSM=0 plane; the inclination angle was 14° in the interplanetary medium and 34° in the magnetosphere.

scholarly journals Features of formation of small-scale wave disturbances during a sudden magnetospheric compression

2017 ◽  
Vol 3 (2) ◽  
pp. 36-44
Author(s):  
Алексей Моисеев ◽  
Aleksey Moiseev ◽  
Дмитрий Баишев ◽  
Dmitry Baishev ◽  
Владимир Мишин ◽  
...  
Keyword(s):  
Wave Front ◽  
Geomagnetic Field ◽  
Compression Wave ◽  
Interplanetary Medium ◽  
Front Propagation ◽  
Interplanetary Shock ◽  
Satellite Observations ◽  
Small Scale ◽  
Plasma Parameters ◽  
Wave Disturbances

Quasi-periodic changes of the geomagnetic field and plasma parameters in the range of Pc 5 pulsations, which occurred immediately after the interaction of interplanetary shock (IPS) with Earth’s magnetosphere in the event of April 24, 2009 at 00:53 UT are examined using ground and satellite observations. The pulsations were localized at latitudes 66–74° in the noon (11 MLT) and evening (20 MLT) sectors. The analysis of hodographs of the geomagnetic field changes both from satellite and ground observations has shown the presence of vortical disturbances. In this event, both the IPS front in the interplanetary medium and the compression wave front in the magnetosphere had a slope in the ZGSM=0 plane; the inclination angle was 14° in the interplanetary medium and 34° in the magnetosphere. The location of the vortical disturbances in the magnetosphere at different radial distances, i.e. X~5.5 Re in the noon sector and X ~–6.3 ÷–7.3 Re in the evening sector, is in agreement with the front inclination. As inferred from satellite observations, the maximum intensity of wave disturbances in both the sectors was registered in the toroidal component of the magnetic field. This suggests the resonant mechanism of excitation of these disturbances. The analysis of distribution of velocities of plasma flow and compression wave front propagation in the magnetosphere’s equatorial plane has revealed that the vortical disturbances occurred in regions where these velocities were noticeably different in magnitude.

scholarly journals Reconstruction of the Parker spiral with the Reverse In situ data and MHD APproach - RIMAP

2020 ◽  
Author(s):  
Ruggero Biondo ◽  
Alessandro Bemporad ◽  
Andrea Mignone ◽  
Fabio Reale
Keyword(s):  
Interplanetary Medium ◽  
Small Scale ◽  
Reconstruction Technique ◽  
The Sun ◽  
Plasma Parameters ◽  
In Situ Data ◽  
Mhd Simulations ◽  
Solar Eruptions ◽  
In Situ Observations

The reconstruction of plasma parameters in the interplanetary medium is very important to understand the interplanetary propagation of solar eruptions and for Space Weather application purposes. Because only a few spacecraft are measuring in situ these parameters, reconstructions are currently performed by running complex numerical Magneto-hydrodynamic (MHD) simulations starting from remote sensing observations of the Sun. Current models apply full 3D MHD simulations of the corona or extrapolations of photospheric magnetic fields combined with and semiempirical relationships to derive the plasma parameters on a sphere centered on the Sun (inner boundary). The plasma is then propagated in the interplanetary medium up to the Earth’s orbit and beyond. Nevertheless, this approach requires significant theoretical and computational efforts, and the results are only in partial agreement with the in situ observations. In this paper we describe a new approach to this problem called RIMAP - Reverse In situ data and MHD APproach. The plasma parameters in the inner boundary at 0.1 AU are derived directly from the in situ measurements acquired at 1 AU, by applying a back reconstruction technique to remap them into the inner heliosphere. This remapping is done by using the Weber and Davies solar wind theoretical model to reconstruct the wind flowlines. The plasma is then re-propagated outward from 0.1 AU by running a MHD numerical simulation based on the PLUTO code. The interplanetary spiral reconstructions obtained with RIMAP are not only in a much better agreement with the in situ observations, but are also including many more small-scale longitudinal features in the plasma parameters that are not reproduced with the approaches developed so far.

Beacon-satellite observations of wave disturbances in the plasma of near-earth space

2004 ◽  
Vol 10 (2-3) ◽  
pp. 16-21
Author(s):  
O.F. Tyrnov ◽  
◽  
Yu.P. Fedorenko ◽  
L.F. Chernogor ◽  
◽  
...  
Keyword(s):  
Satellite Observations ◽  
Earth Space ◽  
Near Earth Space ◽  
Wave Disturbances

scholarly journals CM6: a comprehensive geomagnetic field model derived from both CHAMP and Swarm satellite observations

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Terence J. Sabaka ◽  
Lars Tøffner-Clausen ◽  
Nils Olsen ◽  
Christopher C. Finlay
Keyword(s):  
Geomagnetic Field ◽  
Field Model ◽  
Satellite Observations ◽  
Geomagnetic Field Model ◽  
Swarm Satellite

scholarly journals A spherical cap model of the geomagnetic field over southeast Asia from CHAMP and Swarm satellite observations

2021 ◽  
Vol 130 (1) ◽  
Author(s):  
Le Truong Thanh ◽  
Le Huy Minh ◽  
Vafi Doumbia ◽  
Christine Amory-Mazaudier ◽  
Nguyen Thanh Dung ◽  
...  
Keyword(s):  
Southeast Asia ◽  
Geomagnetic Field ◽  
Satellite Observations ◽  
Spherical Cap ◽  
Cap Model ◽  
Swarm Satellite

Internal Wave Generation by a Combination of Tidal and Steady Currents

2021 ◽  
Author(s):  
Xiaolin Bai ◽  
Kevin Lamb ◽  
José da Silva
Keyword(s):  
Internal Wave ◽  
Wave Generation ◽  
Satellite Observations ◽  
Internal Tides ◽  
Small Scale ◽  
Western Boundary ◽  
Boundary Current ◽  
Reanalysis Dataset ◽  
Amazon Shelf ◽  
Internal Wave Generation

<p>In the presence of topography, two main contributors for internal wave energy are tide-topography interaction transferring energy from the barotropic tide to internal tides, and lee wave generation when geostrophic currents or eddying abyssal flows interact with topography. In the past few decades, many studies considered the respective contribution of the oscillating flows or steady background flows, but few investigations have considered both.  </p><p>In this talk, we consider the joint effects of tidal and steady currents to investigate internal wave generation and propagation on the Amazon shelf, a hotspot for internal solitary wave (ISW) generation. The Amazon Shelf is off the mouth of the Amazon River in the southwest tropical Atlantic Ocean, affected by strong tidal constituents over complex bottom bathymetry and a strong western boundary current, the North Brazilian Current (NBC). Both satellite observations and numerical modelling are used in this study. Satellite observations provide a clear visualization of the wave characteristics, such as temporal and spatial distributions, propagating direction and its relation to background currents. Based on parameters from satellite observations and reanalysis dataset, we set up a model to numerically investigate the dynamics of the ISW generation. We demonstrate that the small-scale topography contributes to a rich generation of along-shelf propagating ISW, which significantly contribute to the ocean mixing and potentially cause sediment resuspension. Moreover, the ISW-induced currents also contribute to the sea surface wave breaking as observed by satellite measurements. In addition, statistics based on a decade of satellite images and numerical investigations on seasonal variations of the ISWs and the NBC improve our understanding of the generation and evolution of these nonlinear internal waves in the presence of background currents.</p>

Kalmag: a high spatio temporal model of the Geomagnetic field

2021 ◽  
Author(s):  
Julien Baerenzung ◽  
Matthias Holschneider
Keyword(s):  
Geomagnetic Field ◽  
Learning Algorithm ◽  
Dynamical Evolution ◽  
Small Scale ◽  
Large Set ◽  
The Core ◽  
Resolution Model ◽  
Auto Regressive ◽  
Spatio Temporal ◽  
Marine Vessels

<p>We present a new high resolution model of the Geomagnetic field spanning the last 121 years. The model derives from a large set of data taken by low orbiting satellites, ground based observatories, marine vessels, airplane and during land surveys. It is obtained by combining a Kalman filter to a smoothing algorithm. Seven different magnetic sources are taken into account. Three of them are of internal origin. These are the core, the lithospheric  and the induced / residual ionospheric fields. The other four sources are of external origin. They are composed by a close, a remote and a fluctuating magnetospheric fields as well as a source associated with field aligned currents. The dynamical evolution of each source is prescribed by an auto regressive process of either first or second order, except for the lithospheric field which is assumed to be static. The parameters of the processes were estimated through a machine learning algorithm with a sample of data taken by the low orbiting satellites of the CHAMP and Swarm missions. In this presentation we will mostly focus on the rapid variations of the core field, and the small scale lithospheric field.  We will also discuss the nature of model uncertainties and the limitiations they imply.</p>

scholarly journals Development and application of problem-oriented digital twins for magnetic observatories and variation stations

2021 ◽  
pp. 60-71
Author(s):  
Andrei Vorobev ◽  
Vyacheslav Pilipenko ◽  
Gulnara Vorobeva ◽  
Olga Khristodulo
Keyword(s):  
Time Series ◽  
Geomagnetic Field ◽  
Missing Values ◽  
Information Environment ◽  
Small Scale ◽  
Geomagnetic Variation ◽  
Digital Twin ◽  
Digital Twins ◽  
Geomagnetic Data ◽  
Magnetic Station

Introduction: Magnetic stations are one of the main tools for observing the geomagnetic field. However, gaps and anomalies in time series of geomagnetic data, which often exceed 30% of the number of recorded values, negatively affect the effectiveness of the implemented approach and complicate the application of mathematical tools which require that the information signal is continuous. Besides, the missing values ​​add extra uncertainty in computer simulation of dynamic spatial distribution of geomagnetic variations and related parameters. Purpose: To develop a methodology for improving the efficiency of technical means for observing the geomagnetic field. Method: Creation of problem-oriented digital twins of magnetic stations, and their integration into the collection and preprocessing of geomagnetic data, in order to simulate the functioning of their physical prototypes with a certain accuracy. Results: Using Kilpisjärvi magnetic station (Finland) as an example, it is shown that the use of digital twins, whose information environment is made up of geomagnetic data from adjacent stations, can provide the opportunity for reconstruction (retrospective forecast) of geomagnetic variation parameters with a mean square error in the auroral zone of up to 11.5 nT. The integration of problem-oriented digital twins of magnetic stations into the processes of collecting and registering geomagnetic data can provide automatic identification and replacement of missing and abnormal values, increasing, due to the redundancy effect, the fault tolerance of the magnetic station as a data source object. For example, the digital twin of Kilpisjärvi station recovers 99.55% of annual information, and 86.73% of it has an error not exceeding 12 nT. Discussion: Due to the spatial anisotropy of geomagnetic field parameters, the error at the digital twin output will be different in each specific case, depending on the geographic location of the magnetic station, as well as on the number of the surrounding magnetic stations and the distance to them. However, this problem can be minimized by integrating geomagnetic data from satellites into the information environment of the digital twin. Practical relevance: The proposed methodology provides the opportunity for automated diagnostics of time series of geomagnetic data for outliers and anomalies, as well as restoration of missing values and identification of small-scale disturbances.

scholarly journals Electromagnetic pollution of near-Earth space by power line emission

2021 ◽  
Vol 7 (3) ◽  
pp. 105-113
Author(s):  
Vyacheslav Pilipenko ◽  
Eugeny Fedorov ◽  
Nikolay Mazur ◽  
Stanislav Klimov
Keyword(s):  
Transmission Line ◽  
Geomagnetic Field ◽  
Power Transmission ◽  
Line Emission ◽  
Power Line ◽  
Satellite Observations ◽  
Electromagnetic Response ◽  
Power Transmission Line ◽  
Earth Space ◽  
Near Earth Space

We present an overview, based on satellite observations at low Earth orbits, on electromagnetic radiation from ground power transmission lines at an industrial frequency 50–60 Hz. Particular attention has been given to Chibis-M and DEMETER satellite observations. The electric 40-cm antenna of the micro-satellite often recorded 50–60 Hz radiation (known as Power Line Emission (PLE)) when it flew over industrialized areas of the planet. The PLE spectral amplitude varied from 1.2 to 18 (μV/m)/Hz0.5, which corresponds to the electric field amplitude E~1 μV/m. We report results of numerical calculations of the electromagnetic response of the atmosphere and ionosphere to a large-scale surface emitter at a frequency of 50 Hz. According to simulation results, PLE with an intensity of ~1 μV/m observed on satellites in the nightside ionosphere at midlatitudes can be excited by an unbalanced current 8–10 A in a power transmission line above the earth's crust with conductivity of 10–3 S/m. At middle and low latitudes with an inclined geomagnetic field, the maximum response in the upper ionosphere to the transmission line radiation should be seen shifted equatorward, although this shift is less than that upon guidance by the geomagnetic field. The maximum amplitude of the electromagnetic response of the ionosphere to the power transmission line emission decreases for an inclined geomagnetic field, but insignificantly. To date, the PLE intensity in near-Earth space has turned out to be higher than the intensity of natural radiation in this range (Schumann resonances and ion whistlers), and continues to grow with the technological development of mankind.

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