scholarly journals Northern preference for terrestrial electromagnetic energy input from space weather

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
I. P. Pakhotin ◽  
I. R. Mann ◽  
K. Xie ◽  
J. K. Burchill ◽  
D. J. Knudsen
Keyword(s):  
Space Weather ◽  
Energy Input ◽  
Rotation Axis ◽  
Electromagnetic Energy ◽  
Magnetic Pole ◽  
Poynting Flux ◽  
Auroral Emissions ◽  
Energy And Momentum ◽  
Swarm Satellite ◽  
Northern And Southern Hemispheres

AbstractTerrestrial space weather involves the transfer of energy and momentum from the solar wind into geospace. Despite recently discovered seasonal asymmetries between auroral forms and the intensity of emissions between northern and southern hemispheres, seasonally averaged energy input into the ionosphere is still generally considered to be symmetric. Here we show, using Swarm satellite data, a preference for electromagnetic energy input at 450 km altitude into the northern hemisphere, on both the dayside and the nightside, when averaged over season. We propose that this is explained by the offset of the magnetic dipole away from Earth’s center. This introduces a larger separation between the magnetic pole and rotation axis in the south, creating different relative solar illumination of northern and southern auroral zones, resulting in changes to the strength of reflection of incident Alfvén waves from the ionosphere. Our study reveals an important asymmetry in seasonally averaged electromagnetic energy input to the atmosphere. Based on observed lower Poynting flux on the nightside this asymmetry may also exist for auroral emissions. Similar offsets may drive asymmetric energy input, and potentially aurora, on other planets.

scholarly journals Northern Preference for Terrestrial Electromagnetic Energy Input from Space Weather

2020 ◽  
Author(s):  
Ivan Pakhotin ◽  
I R Mann ◽  
K Xie ◽  
J Burchill ◽  
D Knudsen
Keyword(s):  
Space Weather ◽  
Energy Input ◽  
Electromagnetic Energy

Multi-scale Analysis of Electromagnetic Energy Input using Swarm: Quantifying Key Scales in Magnetosphere-Ionosphere Coupling

2020 ◽  
Author(s):  
Ivan Pakhotin ◽  
Ian Mann ◽  
Kai Xie ◽  
David Knudsen ◽  
Johnathan Burchill
Keyword(s):  
Energy Input ◽  
Energy Content ◽  
Field Measurements ◽  
Electromagnetic Energy ◽  
Small Scale ◽  
Poynting Flux ◽  
Modelling Studies ◽  
New Instrumentation ◽  
Auroral Phenomena ◽  
Electromagnetic Disturbances

<p>Electromagnetic energy transfer in magnetosphere-ionosphere coupling (MIC) is an inherently multiscale process, where the relative contributions of various scale sizes, linked to various auroral phenomena, are largely unknown. While work in previous decades has largely focused on large scales, in recent years with the development of new instrumentation smaller scale electromagnetic disturbances have once again come into focus. Recent work by the authors has demonstrated evidence that small-scale processes appear to be so important as to potentially account for a global interhemispheric asymmetry in ionospheric energy input. This study attempts to statistically quantify the contribution of energy at the small and mesoscales using Poynting flux, calculated using the unprecedented ESA Swarm mission dataset of simultaneous electric and magnetic field measurements at 16 Hz, with statistics now spanning several years. We find important contributions at small scales to the total energy budget, while at the same time noting that there appears to be a limit above which energy content tends to drop off. In the context of previous observations from other spacecraft this may shed light on key small-scale processes happening in and around the auroral acceleration region, in particular discrete arcs and Alfvén wave reflection from the ionosphere, which are important in forming inputs to coupled magnetosphere-ionosphere-thermosphere modelling studies.</p>

scholarly journals Circumstellar environment of 55 Cancri

2020 ◽  
Vol 633 ◽  
pp. A48 ◽  
Author(s):  
C. P. Folsom ◽  
D. Ó Fionnagáin ◽  
L. Fossati ◽  
A. A. Vidotto ◽  
C. Moutou ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Stellar Wind ◽  
Large Scale ◽  
Rotation Axis ◽  
Doppler Imaging ◽  
Magnetic Pole ◽  
Average Strength ◽  
Detailed Understanding ◽  
The Magnetic Field ◽  
Circumstellar Environment

Context. 55 Cancri hosts five known exoplanets, most notably the hot super-Earth 55 Cnc e, which is one of the hottest known transiting super-Earths. Aims. Because of the short orbital separation and host star brightness, 55 Cnc e provides one of the best opportunities for studying star-planet interactions (SPIs). We aim to understand possible SPIs in this system, which requires a detailed understanding of the stellar magnetic field and wind impinging on the planet. Methods. Using spectropolarimetric observations and Zeeman Doppler Imaging, we derived a map of the large-scale stellar magnetic field. We then simulated the stellar wind starting from the magnetic field map, using a 3D magneto-hydrodynamic model. Results. The map of the large-scale stellar magnetic field we derive has an average strength of 3.4 G. The field has a mostly dipolar geometry; the dipole is tilted by 90° with respect to the rotation axis and the dipolar strength is 5.8 G at the magnetic pole. The wind simulations based on this magnetic geometry lead us to conclude that 55 Cnc e orbits inside the Alfvén surface of the stellar wind, implying that effects from the planet on the wind can propagate back to the stellar surface and result in SPI.

scholarly journals High-latitude poynting flux from combined Iridium and SuperDARN data

2004 ◽  
Vol 22 (8) ◽  
pp. 2861-2875 ◽  
Author(s):  
C. L. Waters ◽  
B. J. Anderson ◽  
R. A. Greenwald ◽  
R. J. Barnes ◽  
J. M. Ruohoniemi
Keyword(s):  
Electric Fields ◽  
Energy Flux ◽  
High Latitude ◽  
Electromagnetic Energy ◽  
Total Power ◽  
Data Sets ◽  
Poynting Flux ◽  
Magnetic Perturbations ◽  
Magnetometer Data ◽  
A New Technique

Abstract. Field-aligned currents convey stress between the magnetosphere and ionosphere, and the associated low altitude magnetic and electric fields reflect the flow of electromagnetic energy to the polar ionosphere. We introduce a new technique to measure the global distribution of high latitude Poynting flux, S||, by combining electric field estimates from the Super Dual Auroral Radar Network (SuperDARN) with magnetic perturbations derived using magnetometer data from the Iridium satellite constellation. Spherical harmonic methods are used to merge the data sets and calculate S|| for any magnetic local time (MLT) from the pole to 60° magnetic latitude (MLAT). The effective spatial resolutions are 2° MLAT, 2h MLT, and the time resolution is about one hour due to the telemetry rate of the Iridium magnetometer data. The technique allows for the assessment of high-latitude net S|| and its spatial distribution on one hour time scales with two key advantages: (1) it yields the net S|| including the contribution of neutral winds; and (2) the results are obtained without recourse to estimates of ionosphere conductivity. We present two examples, 23 November 1999, 14:00-15:00 UT, and 11 March 2000, 16:00-17:00 UT, to test the accuracy of the technique and to illustrate the distributions of S|| that it gives. Comparisons with in-situ S|| estimates from DMSP satellites show agreement to a few mW/m2 and in the locations of S|| enhancements to within the technique's resolution. The total electromagnetic energy flux was 50GW for these events. At auroral latitudes, S|| tends to maximize in the morning and afternoon in regions less than 5° in MLAT by two hours in MLT having S||=10 to 20mW/m2 and total power up to 10GW. The power poleward of the Region 1 currents is about one-third of the total power, indicating significant energy flux over the polar cap.

Propagation of electromagnetic energy and momentum through an absorbing dielectric

1997 ◽  
Vol 55 (1) ◽  
pp. 1071-1085 ◽  
Author(s):  
R. Loudon ◽  
L. Allen ◽  
D. F. Nelson
Keyword(s):  
Electromagnetic Energy ◽  
Energy And Momentum

Investigating magnetopause dynamics using global magnetosphere simulation 

2021 ◽  
Author(s):  
Austin Brenner ◽  
Tuija Pulkkinen
Keyword(s):  
Energy Transfer ◽  
Space Weather ◽  
Flow Line ◽  
Storm Event ◽  
Closed Volume ◽  
Modeling Framework ◽  
Area Element ◽  
Poynting Flux ◽  
Total Energy Flux ◽  
Tracing Techniques

<p>Detailed 3D magnetopause surface is identified using field line and flow line tracing techniques on Space Weather Modeling Framework (SWMF) global magnetosphere simulation results. A total energy flux vector dominated by poynting flux is dotted with area element surface normals and integrated to determine energy transfer into the closed volume. Magnetopause characteristics, power and energy terms are compared with space weather indices such as Disturbance Storm-Time (Dst), Auroral Electrojet (AE), Cross Polar Cap Potential (CPCP) and emperical models such as Shue et al (1997) and Shue et al (1998) to investigate magnetopause dynamics. The storm event of Feb 18, 2014  is simulated with SWMF and analyzed. This event starts in the middle of a multi-CME impact, during a delay between the first and second CME's. While some preconditioning may have occured, it provides an excellent case for observing magnetopause variations. Results show close agreement with empirical models of integrated energy transfer through magnetopause surface. Energy accumulation inside magnetopause volume cuttoff at x=-20Re shows similar behavior to Dst.</p>

Solar cycle variation of simple and complex active regions

2020 ◽  
Author(s):  
Shabnam Nikbakhsh ◽  
Eija Tanskanen ◽  
Maarit Käpylä ◽  
Thomas Hackman
Keyword(s):  
Solar Cycle ◽  
Space Weather ◽  
Active Regions ◽  
Weather Forecast ◽  
Solar Cycle Variation ◽  
Magnetic Structures ◽  
Latitudinal Band ◽  
Second Peak ◽  
Northern And Southern Hemispheres

<p>Solar active regions (ARs) emerge on the Sun’s photosphere and they frequently produce flares and coronal mass ejections which are among major space weather drivers. Therefore, studying ARs can improve space weather forecast.</p><p>The Mount Wilson Classification has been used since 1919 in order to group groups ARs according to their magnetic structures. In this study, we investigated the magnetic classification of 4797 ARs and their cyclic variation, using our daily approach for the period of January 1996 to December 2018.</p><p>We show that the monthly number of the simple ARs (SARs) attained their maximum during first peak of the solar cycle, whereas more complex ARs (CARs) reached their maximum roughly two years later, during the second peak of the cycle. We also demonstrate that the total abundance of CARs is very similar during a period of four years around their maximum number. We also studied the latitudinal distributions of SARs and CAR in northern and southern solar hemispheres and show that the independent of the complexity type, the distributions are the same in both hemispheres.</p><p>Furthermore, we investigated the earlier claim of increase in number of CARs due to the decrease in ARs latitudinal band. Here we show that, contrary to this claim, CARs attained their maximum number before the latitudinal band started to decrease in both northern and southern hemispheres.</p>

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