Resolving Spatio-Temporal Ambiguity in Field-Aligned Current Dynamics Using Swarm Multi-Spacecraft Observations

Pakhotin, Ivan

Resolving Spatio-Temporal Ambiguity in Field-Aligned Current Dynamics Using Swarm Multi-Spacecraft Observations

Monday, 23 May 2016

Ivan Pakhotin¹, Ian Robert Mann², Johnathan K Burchill³, Colin Forsyth⁴, Jonathan Rae⁴, David J Knudsen³, Kyle R Murphy⁵, Jesper W Gjerloev⁶, Louis Ozeke², Georgios Balasis⁷ and Ioannis A. Daglis⁸, (1)University of Alberta, Department of Physics, Edmonton, AB, Canada, (2)University of Alberta, Edmonton, AB, Canada, (3)University of Calgary, Calgary, AB, Canada, (4)University College London, London, United Kingdom, (5)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (6)Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, (7)National Observatory of Athens, Athens, Greece, (8)National and Kapodistrian University of Athens, Athens, Greece

Abstract:

Intermediate-scale field-aligned current (FAC) systems ranging from 10 to 100 km are relatively under-investigated compared to the structure of global-scale Region 1 and 2 current systems. A common point of contention is whether the disturbances are static or Alfvenic in nature. Although some attempts were made to disentangle the spatial and temporal effects in statistical studies, most of these studies have used single spacecraft, which make such analysis difficult. Past multi-satellite observations that have been able to make the distinction have largely focused on opportunistic conjunctions.

The study conducts systematic time-domain statistical work on intermediate-scale currents using Swarm multi-spacecraft observations, separating static and dynamic effects and ultimately aiming to determine the nature of Alfven wave coupling between the magnetosphere and ionosphere and its role in overall FAC dynamics. Using the high resolution data available from the Swarm mission, we analyse both the magnetic and electric field and related Poynting vector.

It was found that even with a 10-second orbital lag time the magnetic configuration of FAC regions changes significantly, strongly suggesting not only the importance of Alfvenic effects, but also that fundamentally field-aligned currents in geospace may be much more dynamic than currently thought.