Articles | Volume 34, issue 9
Regular paper
13 Sep 2016
Regular paper |  | 13 Sep 2016

Current sheet flapping in the near-Earth magnetotail: peculiarities of propagation and parallel currents

Egor V. Yushkov, Anton V. Artemyev, Anatoly A. Petrukovich, and Rumi Nakamura

Abstract. We consider series of tilted current sheet crossings, corresponding to flapping waves in the near-Earth magnetotail. We analyse Cluster observations from 2005 to 2009, when spacecraft visited the magnetotail neutral plane near X ∈ [ − 17,  − 8], Y ∈ [ − 16,  − 2] RE (in the GSM system). Large separation of spacecraft allows us to estimate both local and global properties of flapping current sheets. We find significant variation in flapping wave direction of propagation between the middle tail and flanks. Th series of tilted current sheets represent the system of periodic, almost parallel currents with typical thickness of current filaments about L = 0.4 RE. The earthward gradients of Bz magnetic field are reduced within this current system in comparison with the gradients in the quiet near-Earth magnetotail. The wavelength (i.e. a distance between two crossings of current sheets with the same orientations) of the flapping waves is larger than 2πL for most of observations. The velocity of flapping wave propagation is about ion bulk velocity and is significantly lower than the velocity of ion drift relative to electrons. We discuss possible drivers of flapping and estimate the amplitude of the total parallel current generated by flapping waves.

Short summary
In the paper we study flapping wave structures, generated in the neutral plane of the Earth magnetotail. Investigated flapping is an important process of magnetosphere dynamics, connected with magnetic energy transformation and magnetic storm formation. Large separation of Cluster spacecraft allows us to estimate both local and global properties of flapping current sheets, the typical flapping times and propagation directions.