Automatic detection of magnetopause and bow shock crossing signatures in MESSENGER magnetometer data

2020 ◽  
Author(s):  
Alexander Lavrukhin ◽  
David Parunakian ◽  
Dmitry Nevskiy ◽  
Ute Amerstorfer ◽  
Andreas Windisch ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Bow Shock ◽  
Cycle Phase ◽  
Close Proximity ◽  
Magnetometer Data ◽  
Spacecraft Mission ◽  
Dimensional Shape

<p>The magnetosphere of Mercury is rather small and highly dynamic, due to its weak internal magnetic field and its close proximity to the Sun. The changing solar wind conditions principally determine the locations of both the Hermean bow shock and magnetopause. In 2011 – 2015 MESSENGER spacecraft completed more than 4000 orbits around Mercury, thus giving a data of more than 8000 crossings of bow shock and magnetopause of the planet. This makes it possible to study in detail the bow shock, the magnetopause and the magnetosheath structures.</p> <p>In this work, we determine crossings of the bow shock and the magnetopause of Mercury by applying machine learning methods to the MESSENGER magnetometer data. We try to identify the crossings for the complete orbital mission and model the average three-dimensional shape of these boundaries depending on the external interplanetary magnetic field (IMF). Further, we try to clarify the dependence of the two boundary locations on the heliocentric distance of Mercury and on the solar activity cycle phase. Also, we study the effect of the IMF partial penetration into the Hermean magnetosphere. The results are compared with the obtained previously in other works.</p> <p>This work may be of interest for future Mercury research related to the BepiColombo spacecraft mission, which will enter the orbit around the planet at December 2025.</p>

Automatic detection of magnetopause and bow shock crossing signatures in MESSENGER magnetometer data using Convolutional Neural Networks.

2021 ◽  
Author(s):  
Alexander Lavrukhin ◽  
David Parunakian ◽  
Dmitry Nevskiy ◽  
Sahib Julka ◽  
Michael Granitzer ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Bow Shock ◽  
Cycle Phase ◽  
Small Subset ◽  
Magnetometer Data ◽  
Spacecraft Mission ◽  
Planetary Magnetic Field

<p>During its 2011-2015 lifetime the MESSENGER spacecraft completed more than 4000 orbits around Mercury, producing vast amounts of information regarding the planetary magnetic field and magnetospheric processes. During each orbit the spacecraft left and re-entered the Hermean magnetosphere, giving us information about more than 8000 crossings of the bow shock and the magnetopause of Mercury's magnetosphere. The information obtained from the magnetometer data offers the possibility to study in depth the structures of the bow shock and magnetopause current sheets and their shapes. In this work, we take a step in this direction by automatically detecting the crossings of bow-shock and magnetopause. To this end, we propose a five-class problem and train a Convolutional Neural Network based classifier using the magnetometer data. Our key experimental results indicate that an average precision and recall of at least 87% and 96% can be achieved on the bow hock and magnetopause crossings by using only a small subset of the data. We also model the average three-dimensional shape of these boundaries depending on the external interplanetary magnetic field . Furthermore, we attempt to clarify the dependence of the two boundary locations on the heliocentric distance of Mercury and on the solar activity cycle phase. This work may be of particular interest for future Mercury research related to the BepiColombo spacecraft mission, which will enter Mercury’s orbit around December 2025.</p>

Determination of magnetopause and bow shock shape based on convolutional neural network modelling of MESSENGER data

2021 ◽  
Author(s):  
Alexander Lavrukhin ◽  
David Parunakian ◽  
Dmitry Nevsky ◽  
Sahib Julka ◽  
Michael Granitzer ◽  
...  
Keyword(s):  
Neural Network ◽  
Three Dimensional ◽  
Bow Shock ◽  
Network Modelling ◽  
Machine Learning Methods ◽  
Magnetometer Data ◽  
Spacecraft Mission ◽  
Planetary Magnetic Field ◽  
Orbital Mission

<p><span id="E87">The magnetosphere of Mercury is relatively small and highly dynamic, mostly due to the weak planetary magnetic field. Varying solar wind conditions principally determine the location of both the </span><span id="E89">Hermean</span><span id="E91"> bow shock and magnetopause. In 2011 – 2015 MESSENGER spacecraft completed over 4000 orbits around Mercury, thus giving a data of more than 8000 crossings of bow shock and magnetopause of the planet, this makes it possible to study in detail the bow shock, the magnetopause and the </span><span id="E93">magnetosheath</span><span id="E95"> structures.</span></p> <p>In this work we determine crossings of the bow shock and the magnetopause of Mercury by applying machine learning methods to the MESSENGER magnetometer data. We attempt to identify the crossings during the whole duration of the orbital mission and model the average three-dimensional shapes of these boundaries. The results are compared with those previously obtained in other works.</p> <p><span id="E101">This work may be of interest for future Mercury research related to the </span><span id="E103">BepiColombo</span><span id="E105"> spacecraft mission, which will enter the orbit around the planet in December 2025.</span></p>

Diagnostic Tools for Sunspots: the Molecules C2, Mg H and Ti O

1994 ◽  
Vol 154 ◽  
pp. 489-492
Author(s):  
K Sinha
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Diagnostic Tools ◽  
Present Communication ◽  
Quiet Sun ◽  
Molecular Lines ◽  
Field Strengths

The aim of the present communication is to draw attention to the value of simultaneous observations of sunspot umbrae and the quiet Sun in selected molecular lines. It is felt that such observations may lead to an array of sunspot models which account for sunspot sizes, magnetic field strengths, and the solar activity cycle.

scholarly journals Cluster observations of structures at quasi-parallel bow shocks

2004 ◽  
Vol 22 (7) ◽  
pp. 2309-2313 ◽  
Author(s):  
E. A. Lucek ◽  
T. S. Horbury ◽  
A. Balogh ◽  
I. Dandouras ◽  
H. Rème
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Field Enhancement ◽  
Statistical Characteristics ◽  
Magnetic Structures ◽  
Spatially Extended ◽  
Bow Shocks ◽  
Dimensional Shape ◽  
Shock Transition ◽  
Magnetic Field Enhancement

Abstract. Collisionless quasi-parallel shocks are thought to be composed of a patchwork of short, large-amplitude magnetic structures (SLAMS) which act to thermalise the plasma, giving rise to a spatially extended and time varying shock transition. With the launch of Cluster, new observations of the three-dimensional shape and size of shock structures are available. In this paper we present SLAMS observations made when the Cluster tetrahedron scale size was ~100km. The SLAMS magnetic field enhancement is typically well correlated between spacecraft on this scale, although small differences are observed. The statistical characteristics of these differences contain information on the typical gradients of magnetic field changes within the SLAM structure which, in the case studied here, occur on scales of 100-150km, comparable with the upstream ion inertial length.

scholarly journals Dipolar and Quadrupolar Magnetic Field Evolution over Solar Cycles 21, 22, and 23

2010 ◽  
Vol 6 (S271) ◽  
pp. 94-101 ◽  
Author(s):  
M. L. DeRosa ◽  
A. S. Brun ◽  
J. T. Hoeksema
Keyword(s):  
Magnetic Field ◽  
Spherical Harmonic ◽  
Transport Model ◽  
Activity Cycle ◽  
Surface Flux ◽  
Solar Activity Cycle ◽  
Solar Photosphere ◽  
Solar Cycles ◽  
Flux Transport ◽  
The Past

AbstractTime series of photospheric magnetic field maps from two observatories, along with data from an evolving surface-flux transport model, are decomposed into their constituent spherical harmonic modes. The evolution of these spherical harmonic spectra reflect the modulation of bipole emergence rates through the solar activity cycle, and the subsequent dispersal, shear, and advection of magnetic flux patterns across the solar photosphere. In this article, we discuss the evolution of the dipolar and quadrupolar modes throughout the past three solar cycles (Cycles 21–23), as well as their relation to the reversal of the polar dipole during each solar maximum, and by extension to aspects of the operation of the global solar dynamo.

scholarly journals Supplemental Material: Three-dimensional shape and structure of the Susitna basin, south-central Alaska, from geophysical data

2020 ◽  
Author(s):  
A.K. Shah ◽  
et al.
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Geophysical Data ◽  
Metavolcanic Rock ◽  
South Central ◽  
Total Gradient ◽  
Dimensional Shape ◽  
Surface Geology ◽  
Three Dimensional Shape

Figure S1 showing locations of magnetic high-low anomalies that exhibit total gradient highs, numbered 1–3 as described in the text with: (A) simplified surface geology (colors as in Fig. 2), arrow marks an area near metavolcanic rock described as Triassic to Pennsylvanian? by Wilson et al. (2015); (B) reduced-to-pole magnetic field; and (C) total gradient and thick black lines delineate faults interpreted in this study and by Haeussler and Saltus (2011).<br>

scholarly journals Cluster magnetic field observations at a quasi-parallel bow shock

2002 ◽  
Vol 20 (11) ◽  
pp. 1699-1710 ◽  
Author(s):  
E. A. Lucek ◽  
T. S. Horbury ◽  
M. W. Dunlop ◽  
P. J. Cargill ◽  
S. J. Schwartz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Field Enhancement ◽  
Solar Wind Plasma ◽  
Bow Shock ◽  
Dimensional Structure ◽  
Ulf Waves ◽  
Interplanetary Physics ◽  
Bow Shocks ◽  
Field Enhancements

Abstract. We present four-point Cluster magnetic field data from a quasi-parallel shock crossing which allows us to probe the three-dimensional structure of this type of shock for the first time. We find that steepened ULF waves typically have a scale larger than the spacecraft separation ( ~ 400–1000 km), while SLAMS-like magnetic field enhancements have different signatures in | B | at the four spacecraft, suggesting that they have a smaller scale size. In the latter case, however, the angular variations of B are similar, consistent with the space-craft making different trajectories through the same structure. The field enhancements have different orientations relative to a model bow shock normal, which might arise from different degrees of deceleration and deflection of the surrounding solar wind plasma. The observed rotation of the magnetic field rising from a direction approximately parallel to the model bow shock normal to a direction more perpendicular to the model normal across the field enhancement is consistent with previously published results. Successive magnetic field enhancements or ULF waves, and the leading and trailing edges of the same structure, are found to have different orientations.Key words. Interplanetary physics (planetary bow shocks)

PERIODICITY IN DAILY VARIATION OF COSMIC RAY INTENSITY AS AN EFFECT OF SOLAR POLOIDAL MAGNETIC FIELD ORIENTATION

2004 ◽  
Vol 13 (02) ◽  
pp. 253-262 ◽  
Author(s):  
REKHA AGARWAL MISHRA ◽  
RAJESH K. MISHRA
Keyword(s):  
Magnetic Field ◽  
Daily Variation ◽  
Cosmic Ray ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Significant Shift ◽  
Poloidal Magnetic Field ◽  
Field Orientation ◽  
Cosmic Ray Intensity ◽  
Diurnal Anisotropy

A detailed analysis of the Deep River neutron monitor (NM) data for four different phases of solar activity cycle and for four groups of days chosen according to their different geomagnetic conditions is being carried out. It is found that the 60 quiet day (QD) in a year serve a better purpose for investigating the short/long term variation in cosmic ray (CR) intensity. Furthermore, data has been harmonically analysed for the period 1964–95 to investigate the effect of solar poloidal magnetic field (SPMF) orientation in daily variation (diurnal/semi-diurnal) of CR on geomagnetically QD. The phase of the diurnal and semi-diurnal anisotropy vectors on QD has shown a significant shift to early hours when the SPMF in the northern hemisphere (NH) is positive during the periods 1971–79 and 1992–95 as compared to that during the periods 1964–70 and 1981–90 when the SPMF in NH is negative, showing a periodic nature of daily variation in CR intensity with SPMF.

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