Auroral ionospheric plasma flow extraction using subsonic retarding potential analyzers

2020 ◽  
Vol 91 (9) ◽  
pp. 094503
Author(s):  
Michael Fraunberger ◽  
K. A. Lynch ◽  
Robert Clayton ◽  
Thomas Max Roberts ◽  
David Hysell ◽  
...  
Keyword(s):  
Plasma Flow ◽  
Ionospheric Plasma

Two‐Dimensional Maps of In Situ Ionospheric Plasma Flow Data Near Auroral Arcs Using Auroral Imagery

2019 ◽  
Author(s):  
Robert Clayton ◽  
Kristina Lynch ◽  
Matt Zettergren ◽  
Meghan Burleigh ◽  
Mark Conde ◽  
...  
Keyword(s):  
Plasma Flow ◽  
Ionospheric Plasma ◽  
Two Dimensional ◽  
Flow Data ◽  
Auroral Arcs

Crustal magnetic field advection on Mars from MAVEN observations

2020 ◽  
Author(s):  
Isabela de Oliveira ◽  
Markus Fränz ◽  
Adriane Franco ◽  
Ezequiel Echer
Keyword(s):  
Magnetic Field ◽  
Plasma Flow ◽  
Ionospheric Plasma ◽  
Global Analysis ◽  
Dynamic Pressure ◽  
General Idea ◽  
Mars Atmosphere ◽  
Low Intensity ◽  
Single Orbit ◽  
Field Lines

<p>The plasma environment of Mars is highly influenced by regions of remnant magnetism in the planetary crust, above which mini-magnetospheres are created. In this work, we study whether the ionospheric plasma flow can move crustal magnetic field lines, by the process of advection. According to this hypothesis, the magnetic field lines are dragged away in anti-solar direction, westward at dawn and eastward at dusk-side, due to the day-to-night flow of the ionospheric plasma. The altitude of interest is between 200 km and 1000 km, because the plasma flow velocity is significant in this region.</p><p>MAVEN (Mars Atmosphere and Volatile EvolutioN) data is used for a direct comparison between magnetic field data and a crustal magnetic field model. The difference between the observed and the model field at each point of the grid is a measure of the sum of the induced day magnetic field and the possible displacement of the crustal field lines by advection. The results of the analysis show that, except for the lowest altitude range, minimum value of this difference is always observed for westward shift at dawn-side and eastward shift at dusk-side, in agreement with the expected motion of the crustal magnetic field lines.</p><p>For a general idea of the relative forces between the moving plasma and the crustal fields, we use MAVEN data to analyze the pressures involved in the advection process. These are the dynamic pressure of the ionospheric plasma flow, the magnetic pressure of the field lines and the thermal pressure of the plasma related to the mini-magnetospheres. The balance between these quantities should dictate the occurrence of advection. This analysis suggests that advection could take place at low altitude (up to ~450 km) dawn-side regions above low intensity magnetic fields.</p><p>Although the global analysis results showed agreement with our hypothesis, we could not observe evidence of advection from the local observations in order to unambiguously prove the occurrence of this process. Future works include the investigation of single orbit data in regions of low intensity magnetic field, especially at dawn-side, and also magnetohydrodynamic modeling of the process using the plasma conditions prevalent in the Martian ionosphere.</p>

scholarly journals A multi-instrument approach to mapping the global dayside merging rate

2002 ◽  
Vol 20 (12) ◽  
pp. 1905-1920
Author(s):  
G. Provan ◽  
T. K. Yeoman ◽  
M. Lester ◽  
S. E. Milan
Keyword(s):  
Electric Fields ◽  
Plasma Flow ◽  
Ionospheric Plasma ◽  
Line Length ◽  
Convection Pattern ◽  
Polar Cap ◽  
Plasma Drift ◽  
Methods Of Calculation ◽  
Wind Measurements ◽  
First Time

Abstract. For the first time three different methods have been used to calculate the global merging rate during the same substorm growth phase. The ionospheric plasma drift was monitored by six of the Northern Hemisphere SuperDARN radars, allowing the convection pattern to be studied over 12 h of magnetic local time. The radars observed reconnection signatures on the dayside simultaneously with substorm signatures on the nightside. The three methods to calculate the global merging rate are: (i) the equatorward expansion of radar backscatter on the nightside, which provides an estimate of the rate of polar cap expansion, while upstream WIND measurements gave an estimate of the reconnection electric fields; (ii) the derivation of the dayside boundary normal plasma flow velocity and an estimate of the extent of the ionospheric merging gap, from radar observation of dayside reconnection; (iii) utilizing the map-potential technique to map the high-latitude plasma flow and cross polar cap potential (Ruohoniemi and Baker, 1998), allowing the global dayside merging rate to be calculated. The three methods support an extensive magnetopause X-line length of between 30 ± 12RE and 35 ± 15 RE (assuming a single X-line and constant merging rate). Such close agreement between the different methods of calculation are unexpected, especially as the length of the magnetopause X-line is not well known.Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; magnetosphere – ionosphere interactions; solar-wind magnetosphere interactions)

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