Temporal Evolution of Substorm‐Driven Global Alfvén Wave Power Above the Auroral Acceleration Region

2020 ◽  
Vol 125 (4) ◽  
Author(s):  
Andreas Keiling ◽  
Scott Thaller ◽  
John Dombeck ◽  
John Wygant
Keyword(s):  
Temporal Evolution ◽  
Alfven Wave ◽  
Wave Power ◽  
Acceleration Region ◽  
Auroral Acceleration Region

scholarly journals Temporal evolution and electric potential structure of the auroral acceleration region from multispacecraft measurements

2012 ◽  
Vol 117 (A12) ◽  
pp. n/a-n/a ◽  
Author(s):  
C. Forsyth ◽  
A. N. Fazakerley ◽  
A. P. Walsh ◽  
C. E. J. Watt ◽  
K. J. Garza ◽  
...  
Keyword(s):  
Electric Potential ◽  
Temporal Evolution ◽  
Acceleration Region ◽  
Auroral Acceleration Region ◽  
Potential Structure

scholarly journals Assessing the global Alfvén wave power flow into and out of the auroral acceleration region during geomagnetic storms

2019 ◽  
Vol 5 (6) ◽  
pp. eaav8411 ◽  
Author(s):  
Andreas Keiling ◽  
Scott Thaller ◽  
John Wygant ◽  
John Dombeck
Keyword(s):  
Energy Flow ◽  
Geomagnetic Storms ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Societal Implications ◽  
Alfvén Waves ◽  
Acceleration Region ◽  
Large Space ◽  
Fourfold Increase ◽  
Auroral Acceleration Region

Geomagnetic storms are large space weather events with potentially tremendous societal implications. During these storms, the transfer of energy from the solar wind into geospace is largely increased, leading to enhanced energy flow and deposition within the magnetosphere and ionosphere. While various energy forms participate, the rate of total Alfvén wave energy flowing into the auroral acceleration region—where the magnetosphere and ionosphere couple—has not been quantified. Here, we report a fourfold increase in hemispherical Alfvénic power (from 2.59 to 10.05 GW) over a largely expanded oval band covering all longitudes and latitudes between 50° and 85° during the main storm phase compared with nonstorm periods. The Poynting flux associated with individual Alfvén waves reached values of up to about 0.5 W/m2 (mapped to ionospheric altitude). These results demonstrate that Alfvén waves are an important component of geomagnetic storms and associated energy flow into the auroral acceleration region.

scholarly journals Sheared flows and small-scale Alfvén wave generation in the auroral acceleration region

2009 ◽  
Vol 36 (5) ◽  
Author(s):  
K. Asamura ◽  
C. C. Chaston ◽  
Y. Itoh ◽  
M. Fujimoto ◽  
T. Sakanoi ◽  
...  
Keyword(s):  
Wave Generation ◽  
Alfven Wave ◽  
Small Scale ◽  
Acceleration Region ◽  
Auroral Acceleration Region ◽  
Sheared Flows ◽  
Alfvén Wave Generation

scholarly journals Alfven wave modulation of the auroral acceleration region

2004 ◽  
Vol 56 (7) ◽  
pp. 649-661 ◽  
Author(s):  
E. N. Fedorov ◽  
V. A. Pilipenko ◽  
M. J. Engebretson ◽  
T. J. Rosenberg
Keyword(s):  
Alfven Wave ◽  
Acceleration Region ◽  
Wave Modulation ◽  
Auroral Acceleration Region

scholarly journals An Auroral Alfvén Wave Cascade

2021 ◽  
Vol 8 ◽  
Author(s):  
C. C. Chaston
Keyword(s):  
Space Plasma ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Acceleration Region ◽  
Electrical Currents ◽  
Auroral Acceleration Region ◽  
Field Lines ◽  
Auroral Arcs

Folding, kinking, curling and vortical optical forms are distinctive features of most bright auroral displays. These forms are symptomatic of non-linear forcing of the plasma above auroral arcs resulting from the intensification of electrical currents and Alfvén waves along high-latitude geomagnetic field-lines during periods of disturbed space weather. Electrons accelerated to energies sufficient to carry these currents impact the atmosphere and drive visible emission with spatial structure and dynamics that replicate the morphology and time evolution of the plasma region where the acceleration occurs. Movies of active auroral displays, particularly when combined with conjugate in-situ fields and plasma measurements, therefore capture the physics of a driven, non-linearly evolving space plasma system. Here a perspective emphasizing the utility of combining in-situ measurements through the auroral acceleration region with high time and spatial resolution auroral imaging for the study of space plasma turbulence is presented. It is demonstrated how this special capacity reveals the operation of a cascade of vortical flows and currents through the auroral acceleration region regulated by the physics of Alfvén waves similar to that thought to operate in the Solar wind.

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