scholarly journals Nightside ULF Waves Observed in the Topside Ionosphere by the DEMETER Satellite

2018 ◽  
Vol 123 (9) ◽  
pp. 7726-7739 ◽  
Author(s):  
X. Y. Ouyang ◽  
Q. G. Zong ◽  
J. Bortnik ◽  
Y. F. Wang ◽  
P. J. Chi ◽  
...  
Keyword(s):  
Topside Ionosphere ◽  
Ulf Waves ◽  
Demeter Satellite

A Deep Learning Technique for Automated Detection of ULF Waves in Swarm Time Series

2020 ◽  
Author(s):  
Alexandra Antonopoulou ◽  
Constantinos Papadimitriou ◽  
Georgios Balasis ◽  
Adamantia Zoe Boutsi ◽  
Konstantinos Koutroumbas ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Deep Learning ◽  
Building Blocks ◽  
Data Availability ◽  
Topside Ionosphere ◽  
Ulf Waves ◽  
Dense Layer ◽  
Ulf Wave ◽  
The Earth ◽  
Swarm Satellites

<p>Ultra-low frequency (ULF) magnetospheric plasma waves play a key role in the dynamics of the Earth’s magnetosphere and, therefore, their importance in Space Weather studies is indisputable. Magnetic field measurements from recent multi-satellite missions (e.g. Cluster, THEMIS, Van Allen Probes and Swarm) are currently advancing our knowledge on the physics of ULF waves. In particular, Swarm satellites, one of the most successful mission for the study of the near-Earth electromagnetic environment, have contributed to the expansion of data availability in the topside ionosphere, stimulating much recent progress in this area. Coupled with the new successful developments in artificial intelligence (AI), we are now able to use more robust approaches devoted to automated ULF wave event identification and classification. The goal of this effort is to use a deep learning method in order to classify ULF wave events using magnetic field data from Swarm. We construct a Convolutional Neural Network (CNN) that takes as input the wavelet spectra of the Earth’s magnetic field variations per track, as measured by each one of the three Swarm satellites, and whose building blocks consist of two convolution layers, two pooling layers and a fully connected (dense) layer, aiming to classify ULF wave events in four different categories: 1) Pc3 wave events (i.e., frequency range 20-100 MHz), 2) non-events, 3) false positives, and 4) plasma instabilities. Our primary experiments show promising results, yielding successful identification of more than 95% accuracy. We are currently working on producing larger training/test datasets, by analyzing Swarm data from the mid-2014 onwards, when the final constellation was formed, aiming to construct a dataset comprising of more than 50000 wavelet image inputs for our network.</p>

scholarly journals Concentration of ions in the topside ionosphere as measured onboard the DEMETER satellite: Morphology and dependence on solar and geomagnetic activity

2012 ◽  
Vol 50 (2) ◽  
pp. 103-115 ◽  
Author(s):  
V. A. Gladyshev ◽  
A. Yu. Shchekotov ◽  
N. V. Yagova ◽  
J. -J. Berthelier ◽  
M. Parrot ◽  
...  
Keyword(s):  
Geomagnetic Activity ◽  
Topside Ionosphere ◽  
Demeter Satellite ◽  
Concentration Of Ions

scholarly journals Multi-satellite study of the excitation of Pc3 and Pc4-5 ULF waves and their penetration across the plasmapause during the 2003 Halloween superstorm

2015 ◽  
Vol 33 (10) ◽  
pp. 1237-1252 ◽  
Author(s):  
G. Balasis ◽  
I. A. Daglis ◽  
I. R. Mann ◽  
C. Papadimitriou ◽  
E. Zesta ◽  
...  
Keyword(s):  
Solar Wind ◽  
Field Line ◽  
Magnetic Data ◽  
Topside Ionosphere ◽  
Ulf Waves ◽  
Inhomogeneous Field ◽  
Range Analysis ◽  
Field Line Resonance ◽  
Time Frequency ◽  
Line Resonance

Abstract. We use multi-satellite and ground-based magnetic data to investigate the concurrent characteristics of Pc3 (22–100 mHz) and Pc4-5 (1–22 mHz) ultra-low-frequency (ULF) waves on the 31 October 2003 during the Halloween magnetic superstorm. ULF waves are seen in the Earth's magnetosphere, topside ionosphere, and Earth's surface, enabling an examination of their propagation characteristics. We employ a time–frequency analysis technique and examine data from when the Cluster and CHAMP spacecraft were in good local time (LT) conjunction near the dayside noon–midnight meridian. We find clear evidence of the excitation of both Pc3 and Pc4-5 waves, but more significantly we find a clear separation in the L shell of occurrence of the Pc4-5 and Pc3 waves in the equatorial inner magnetosphere, separated by the density gradients at the plasmapause boundary layer. A key finding of the wavelet spectral analysis of data collected from the Geotail, Cluster, and CHAMP spacecraft and the CARISMA and GIMA magnetometer networks was a remarkably clear transition of the waves' frequency into dominance in a higher-frequency regime within the Pc3 range. Analysis of the local field line resonance frequency suggests that the separation of the Pc4-5 and Pc3 emissions across the plasmapause is consistent with the structure of the inhomogeneous field line resonance Alfvén continuum. The Pc4-5 waves are consistent with direct excitation by the solar wind in the plasma trough, as well as Pc3 wave absorption in the plasmasphere following excitation by upstream waves originating at the bow shock in the local noon sector. However, despite good solar wind coverage, our study was not able to unambiguously identify a clear explanation for the sharp universal time (UT) onset of the discrete frequency and large-amplitude Pc3 wave power.

scholarly journals ULF wave activity during the 2003 Halloween superstorm: multipoint observations from CHAMP, Cluster and Geotail missions

2012 ◽  
Vol 30 (12) ◽  
pp. 1751-1768 ◽  
Author(s):  
G. Balasis ◽  
I. A. Daglis ◽  
E. Zesta ◽  
C. Papadimitriou ◽  
M. Georgiou ◽  
...  
Keyword(s):  
Low Frequency ◽  
Wave Activity ◽  
Low Earth Orbit ◽  
Topside Ionosphere ◽  
Ulf Waves ◽  
Satellite Mission ◽  
Ulf Wave ◽  
Activity Frequency ◽  
Field Lines ◽  
First Time

Abstract. We examine data from a topside ionosphere and two magnetospheric missions (CHAMP, Cluster and Geotail) for signatures of ultra low frequency (ULF) waves during the exceptional 2003 Halloween geospace magnetic storm, when Dst reached ~−380 nT. We use a suite of wavelet-based algorithms, which are a subset of a tool that is being developed for the analysis of multi-instrument multi-satellite and ground-based observations to identify ULF waves and investigate their properties. Starting from the region of topside ionosphere, we first present three clear and strong signatures of Pc3 ULF wave activity (frequency 15–100 mHz) in CHAMP tracks. We then expand these three time intervals for purposes of comparison between CHAMP, Cluster and Geotail Pc3 observations but also to be able to search for Pc4–5 wave signatures (frequency 1–10 mHz) into Cluster and Geotail measurements in order to have a more complete picture of the ULF wave occurrence during the storm. Due to the fast motion through field lines in a low Earth orbit (LEO) we are able to reliably detect Pc3 (but not Pc4–5) waves from CHAMP. This is the first time, to our knowledge, that ULF wave observations from a topside ionosphere mission are compared to ULF wave observations from magnetospheric missions. Our study provides evidence for the occurrence of a number of prominent ULF wave events in the Pc3 and Pc4–5 bands during the storm and offers a platform to study the wave evolution from high altitudes to LEO. The ULF wave analysis methods presented here can be applied to observations from the upcoming Swarm multi-satellite mission of ESA, which is anticipated to enable joint studies with the Cluster mission.

A technique to investigate plasma mass density in the topside ionosphere using ULF waves

1999 ◽  
Vol 104 (A6) ◽  
pp. 12723-12732 ◽  
Author(s):  
I. A. Price ◽  
C. L. Waters ◽  
F. W. Menk ◽  
G. J. Bailey ◽  
B. J. Fraser
Keyword(s):  
Mass Density ◽  
Topside Ionosphere ◽  
Ulf Waves

ULF Waves in the Topside Ionosphere: Satellite Observations and Modeling

2011 ◽  
pp. 257-269 ◽  
Author(s):  
V. Pilipenko ◽  
E. Fedorov ◽  
B. Heilig ◽  
M.J. Engebretson ◽  
P. Sutcliffe ◽  
...  
Keyword(s):  
Satellite Observations ◽  
Topside Ionosphere ◽  
Ulf Waves

scholarly journals Looking for a proxy of the ionospheric turbulence with Swarm data

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paola De Michelis ◽  
Giuseppe Consolini ◽  
Alessio Pignalberi ◽  
Roberta Tozzi ◽  
Igino Coco ◽  
...  
Keyword(s):  
Electron Density ◽  
Geomagnetic Activity ◽  
Density Fluctuations ◽  
Rate Of Change ◽  
Topside Ionosphere ◽  
Joint Probability Distribution ◽  
Activity Levels ◽  
Scaling Exponents ◽  
Electron Density Fluctuations ◽  
Scaling Features

AbstractThe present work focuses on the analysis of the scaling features of electron density fluctuations in the mid- and high-latitude topside ionosphere under different conditions of geomagnetic activity. The aim is to understand whether it is possible to identify a proxy that may provide information on the properties of electron density fluctuations and on the possible physical mechanisms at their origin, as for instance, turbulence phenomena. So, we selected about 4 years (April 2014–February 2018) of 1 Hz electron density measurements recorded on-board ESA Swarm A satellite. Using the Auroral Electrojet (AE) index, we identified two different geomagnetic conditions: quiet (AE < 50 nT) and active (AE > 300 nT). For both datasets, we evaluated the first- and second-order scaling exponents and an intermittency coefficient associated with the electron density fluctuations. Then, the joint probability distribution between each of these quantities and the rate of change of electron density index was also evaluated. We identified two families of plasma density fluctuations characterized by different mean values of both the scaling exponents and the considered ionospheric index, suggesting that different mechanisms (instabilities/turbulent processes) can be responsible for the observed scaling features. Furthermore, a clear different localization of the two families in the magnetic latitude—magnetic local time plane is found and its dependence on geomagnetic activity levels is analyzed. These results may well have a bearing about the capability of recognizing the turbulent character of irregularities using a typical ionospheric plasma irregularity index as a proxy.

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