The Northward IMF Magnetosphere

Fear, R. C.

doi:10.1002/9781119815624.ch19

Cited by 11 publications

(15 citation statements)

References 157 publications

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“…We interpret this as evidence that C1 does not enter the magnetosheath and is still sampling the high‐latitude lobe. Therefore, we conclude that these events are likely to be indicative of direct entry by the solar wind, potentially due to Kelvin‐Helmholtz interactions (Ling et al., 2018; Nakamura, Eriksson, et al., 2017; Nakamura, Hasegawa, et al., 2017; Sorathia et al., 2019) or lobe reconnection (Cowley, 1981; Dungey, 1961; Fear, 2021 and references therein).…”

Section: Discussionmentioning

confidence: 85%

“…Fear et al (2014) concluded that the hot plasma was a signature of a closed field line trapped in the lobe (Milan et al, 2005), rather than direct entry due to high-latitude reconnection (Shi et al, 2013). Fear andMilan (2012a, 2012b) showed that the statistics of transpolar arcs are consistent with the Milan et al (2005) mechanism. In the Milan et al (2005) mechanism there will be conjugate auroral signatures, and interhemispheric observations and surveys of transpolar arcs have observed these (Carter et al, 2017;Reidy et al, 2018;Xing et al, 2018).…”

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confidence: 99%

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Hot Plasma in the Magnetotail Lobes Shows Characteristics Consistent With Closed Field Lines Trapped in the Lobes

et al. 2021

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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, 00∼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 00∼0.5% of our identified periods may be driven by direct entry into the magnetosphere from the solar wind.

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Section: Discussionmentioning

confidence: 85%

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confidence: 99%

Hot Plasma in the Magnetotail Lobes Shows Characteristics Consistent With Closed Field Lines Trapped in the Lobes

et al. 2021

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“…Auroral dynamics help to shine light on the complicated processes that occur under NBZ conditions (Fear, 2021; Hosokawa et al., 2020; Kullen, 2012; Zhu et al., 1997). NBZ auroral features can include a cusp spot (Carter et al., 2020; Frey et al., 2002; Milan et al., 2000b), high latitude dayside auroras or HiLDAs (Cai et al., 2021; Carter et al., 2018; Frey, 2007; Han et al., 2020; Zhang et al., 2021), and transpolar arcs (e.g., Carter et al., 2017; Cumnock & Blomberg, 2004; Cumnock et al., 2002; Fear et al., 2014; Frank et al., 1982; Kullen et al., 2002; Milan et al., 2005).…”

Section: Introductionmentioning

confidence: 99%

Lobe Reconnection and Cusp‐Aligned Auroral Arcs

et al. 2022

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Following the St. Patrick's Day (17 March) geomagnetic storm of 2013, the interplanetary magnetic field had near‐zero clock angle for almost two days. Throughout this period multiple cusp‐aligned auroral arcs formed in the polar regions; we present observations of, and provide a new explanation for, this poorly understood phenomenon. The arcs were observed by auroral imagers onboard satellites of the Defense Meteorological Satellite Program. Ionospheric flow measurements and observations of energetic particles from the same satellites show that the arcs were produced by inverted‐V precipitation associated with upward field‐aligned currents (FACs) at shears in the convection pattern. The large‐scale convection pattern revealed by the Super Dual Auroral Radar Network and the corresponding FAC pattern observed by the Active Magnetosphere and Planetary Electrodynamics Response Experiment suggest that dual‐lobe reconnection was ongoing to produce significant closure of the magnetosphere. However, we propose that once the magnetosphere became nearly closed complicated lobe reconnection geometries arose that produced interleaving of regions of open and closed magnetic flux and spatial and temporal structure in the convection pattern that evolved on timescales shorter than the orbital period of the DMSP spacecraft. This new model naturally explains many features of cusp‐aligned arcs, including why they focus in from the nightside toward the cusp region.

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“…Under southward IMF, reconnection occurs on the dayside and the cyclic process proposed by Dungey (1961) is widely accepted. However, under northward IMF, reconnection occurs at higher latitudes and the “traditional” convection process changes (Cowley, 1981; Crooker, 1992; Cumnock et al., 1995; Dungey, 1963; Fear, 2021; Russell, 1972). In particular, the configuration and composition of the magnetospheric lobes under northward IMF are not well understood and have yet to be extensively studied.…”

Section: Introductionmentioning

confidence: 99%

Observations of Closed Magnetic Flux Embedded in the Lobes During Periods of Northward IMF

et al. 2021

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The coupling between the Interplanetary Magnetic Field (IMF) and the magnetosphere has been extensively studied over the last few decades, but there are still many unanswered questions with regard to how the magnetosphere responds to different IMF conditions, particularly when the IMF is northward. Under southward IMF, reconnection occurs on the dayside and the cyclic process proposed by Dungey (1961) is widely accepted. However, under northward IMF, reconnection occurs at higher latitudes and the "traditional" convection process changes (

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The Northward IMF Magnetosphere

Cited by 11 publications

References 157 publications

Hot Plasma in the Magnetotail Lobes Shows Characteristics Consistent With Closed Field Lines Trapped in the Lobes

Hot Plasma in the Magnetotail Lobes Shows Characteristics Consistent With Closed Field Lines Trapped in the Lobes

Lobe Reconnection and Cusp‐Aligned Auroral Arcs

Observations of Closed Magnetic Flux Embedded in the Lobes During Periods of Northward IMF

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