[FPSPACE] Cluster observations of the mid-altitude cusp under strong northward Interplanet

[LARRY KLAES]

Cluster observations of the mid-altitude cusp under strong northward 
Interplanetary Magnetic Field

Authors: Renyu Hu, Yulia V. Bogdanova, Christopher J. Owen, Claire Foullon, 
Andrew N. Fazakerley, Henri Reme

(Submitted on 8 Mar 2008)

Abstract: We report on a Cluster multi-spacecraft cusp observation lasting 
more than 100 minutes. We determine the cusp boundary motion and reveal the 
effect on the cusp size of the interplanetary magnetic field (IMF) changing 
from southward to northward. The cusp shrinks at the beginning of the IMF 
rotation and it re-expands at the rate of 0.50$^{o}$ ILAT per hour under 
stable northward IMF.

Based on plasma signatures inside the cusp, such as counter-streaming 
electrons with balanced fluxes and quasi-periodic enhancement of ion fluxes 
with energy E$>$5keV, we propose that pulsed dual lobe reconnection operates 
during the time of interest. SC1 and SC4 observations suggest a long-term 
regular periodicity of the pulsed dual reconnection, which we estimate to be 
$\sim$ 1-5 minutes. Further, the distances from the spacecraft to the 
reconnection site are estimated based on observations from three satellites. 
The distance determined using SC1 and SC4 observations is $\sim$ 15 RE, and 
that determined from SC3 data is $\sim$ 8 RE. The large-scale speed of the 
reconnection site sunward motion is $\sim$ 16 km s$^{-1}$. We observe also a 
fast motion of the reconnection site by SC1, which provides new information 
about the transitional phase after the IMF rotation.

Finally, a statistical study of the dependency of plasma convection inside 
the cusp on the IMF clock angle is performed. The relationship between the 
cusp stagnation, the dual lobe reconnection process and the IMF clock angle 
is discussed.

Comments: JGR Space Physics, in press

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0803.1206v1 [astro-ph]

Submission history

From: Renyu Hu [view email]

[v1] Sat, 8 Mar 2008 02:41:43 GMT (2285kb)

http://arxiv.org/abs/0803.1206