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- Title
Hot Plasma in the Magnetotail Lobes Shows Characteristics Consistent With Closed Field Lines Trapped in the Lobes.
- Authors
Coxon, John C.; Fear, Robert C.; Reidy, Jade A.; Fryer, Laura J.; Plank, James
- Abstract
We examine the magnetotail using data from the Hot Ion Analyzer on Cluster 1 during 2001–2009. We develop and utilize an algorithm in order to identify times during which Cluster 1 is in the magnetotail lobe but observes plasma, which is hotter than our expectations of the lobe. We analyze the prevailing Interplanetary Magnetic Field (IMF) BZ conditions for our algorithm and a reference algorithm (with no particle energy criteria) and find that the periods we select are, on average, ∼2 nT more toward northward IMF. Examining the temperature in the magnetotail for our periods shows that the morphology of the average temperature is consistent with the Milan et al. (2005, https://doi.org/10.1029/2004JA010835) model of a magnetotail structure during northward IMF, in which closed field lines are prevented from convecting to the dayside, causing them and the plasma trapped on them to protrude into the magnetotail lobes. We also find evidence that ∼0.5% of our identified periods may be driven by direct entry into the magnetosphere from the solar wind. Plain Language Summary: We use data from a four‐spacecraft mission called Cluster to measure charged particles in Earth's magnetic field, on the night side of the Earth. We look for regions in which there would usually not be many charged particles, or these particles would not be very hot, and then look for times when the particles are hotter than we expect. We analyze these periods by looking at how different variables are distributed during these periods, and we use this to differentiate between two ideas which have been proposed to explain this sort of particle signature. Key Points: We identify field lines that are open according to the T96 model, but which have anomalously hot plasmaThe temperature of the plasma increases toward the center of the magnetosphere and away from EarthWe interpret this as evidence for closed field lines trapped in the lobe during mainly northward Interplanetary Magnetic Field
- Subjects
MAGNETOTAILS; MAGNETOSPHERE; INTERPLANETARY magnetic fields; MAGNETIC field effects; MAGNETIC fields
- Publication
Journal of Geophysical Research. Space Physics, 2021, Vol 126, Issue 9, p1
- ISSN
2169-9380
- Publication type
Article
- DOI
10.1029/2021JA029516