Statistical analysis of magnetotail fast flows and related magnetic disturbances
Other literature type
English
OPEN
Frühauff, Dennis
;
Glassmeier, Karl-Heinz
(2016)
This study presents an investigation on the occurrence of fast flows in the
magnetotail using the complete available data set of the THEMIS spacecraft
for the years 2007 to 2015. The fast flow events (times of enhanced ion
velocity) are detected through the use of a velocity criterion, therefore
making the resulting database as large as almost 16 000 events. First, basic
statistical findings concerning velocity distributions, occurrence rates,
group structures are presented. Second, Superposed Epoch Analysis is utilized
to account for average profiles of selected plasma quantities. The data
reveal representative time series in near and far tail of the Earth with
typical timescales of the order of 1–2 min, corresponding to scale
sizes of 3 <i>R</i><sub>E</sub>. Last, related magnetic field disturbances are
analyzed. It is found that the minimum variance direction is essentially
confined to a plane almost perpendicular to the main flow direction while, at
the same time, the maximum variance direction is aligned with flow and
background field directions. The presentation of the database and first
statistical findings will prove useful both as input for
magneto-hydrodynamical simulations and theoretical considerations of fast
flows.