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Spatial asymmetry and periodic time variations of X-ray microbursts in the auroral zone. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jz070i019p04976] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Relation of 5- to 40-Second-period geomagnetic micropulsations and electron precipitation to the auroral substorm. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jz071i023p05743] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Observations of ionospheric electron beams in the plasma sheet. PHYSICAL REVIEW LETTERS 2012; 109:205001. [PMID: 23215495 DOI: 10.1103/physrevlett.109.205001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Indexed: 06/01/2023]
Abstract
Electrons streaming along the magnetic field direction are frequently observed in the plasma sheet of Earth's geomagnetic tail. The impact of these field-aligned electrons on the dynamics of the geomagnetic tail is however not well understood. Here we report the first detection of field-aligned electrons with fluxes increasing at ~1 keV forming a "cool" beam just prior to the dissipation of energy in the current sheet. These field-aligned beams at ~15 R(E) in the plasma sheet are nearly identical to those commonly observed at auroral altitudes, suggesting the beams are auroral electrons accelerated upward by electric fields parallel (E([parallel])) to the geomagnetic field. The density of the beams relative to the ambient electron density is δn(b)/n(e)~5-13% and the current carried by the beams is ~10(-8)-10(-7) A m(-2). These beams in high β plasmas with large density and temperature gradients appear to satisfy the Bohm criteria to initiate current driven instabilities.
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Simultaneous observations of 5- to 15-second period modulated energetic electron fluxes at the synchronous altitude and the auroral zone. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja074i016p04003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Studies of the magnetospheric substorm: 3. Concept of the magnetospheric substorm and its relation to electron precipitation and micropulsations. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja073i005p01715] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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11
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Acceleration of energetic electrons observed at the synchronous altitude during magnetospheric substorms. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja073i017p05786] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Studies of the magnetospheric substorm: 1. Characteristics of modulated energetic electron precipitation occurring during auroral substorms. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja073i005p01685] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Plasma waves associated with energetic particles streaming into the solar wind from the Earth's bow shock. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja086ia06p04493] [Citation(s) in RCA: 179] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Studies of the magnetospheric substorm: 2. Correlated magnetic micropulsations and electron precipitation occurring during auroral substorms. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja073i005p01697] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Characteristics of magnetospheric particle injection deduced from events observed on August 18, 1974. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/ja082i032p05208] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Entropy generation across Earth's collisionless bow shock. PHYSICAL REVIEW LETTERS 2012; 108:061102. [PMID: 22401049 DOI: 10.1103/physrevlett.108.061102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Indexed: 05/31/2023]
Abstract
Earth's bow shock is a collisionless shock wave but entropy has never been directly measured across it. The plasma experiments on Cluster and Double Star measure 3D plasma distributions upstream and downstream of the bow shock allowing calculation of Boltzmann's entropy function H and his famous H theorem, dH/dt≤0. The collisionless Boltzmann (Vlasov) equation predicts that the total entropy does not change if the distribution function across the shock becomes nonthermal, but it allows changes in the entropy density. Here, we present the first direct measurements of entropy density changes across Earth's bow shock and show that the results generally support the model of the Vlasov analysis. These observations are a starting point for a more sophisticated analysis that includes 3D computer modeling of collisionless shocks with input from observed particles, waves, and turbulences.
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Abstract
Segregation ratios of offspring from disease-free sugar pines suggest that resistance to the white pine blister rust fungus is under major gene control and simply inherited.
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Nonlinear development of shocklike structure in the solar wind. PHYSICAL REVIEW LETTERS 2009; 103:031101. [PMID: 19659262 DOI: 10.1103/physrevlett.103.031101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Indexed: 05/28/2023]
Abstract
We report first in situ multispacecraft observations of nonlinear steepening of compressional pulses in the solar wind upstream of Earth's bow shock. The magnetic field of a compressional pulse formed at the upstream edge of density holes is shown to suddenly break and steepen into a shocklike structure. During the early phase of development thermalization of ions is insignificant. Substantial thermalization of ions occurs as gyrating ions are observed at the steepened edge. These observations indicate that the mechanisms causing the dissipation of magnetic fields (currents) and ions are different in the early phase of shock development.
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Longitudinal association between magnetotail reconnection and auroral breakup based on Geotail and Polar observations. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2008ja013127] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Satellite studies of magnetospheric substorms on August 15, 1968: 2. Solar wind and outer magnetosphere. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/ja078i016p03054] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Solitary electromagnetic pulses detected with super-Alfvénic flows in Earth's geomagnetic tail. PHYSICAL REVIEW LETTERS 2007; 98:265001. [PMID: 17678094 DOI: 10.1103/physrevlett.98.265001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Indexed: 05/16/2023]
Abstract
Solitary nonlinear (deltaB/B>>1) electromagnetic pulses have been detected in Earth's geomagnetic tail accompanying plasmas flowing at super-Alfvénic speeds. The pulses in the current sheet had durations of approximately 5 s, were left-hand circularly polarized, and had phase speeds of approximately the Alfvén speed in the plasma frame. These pulses were associated with a field-aligned current J(parallel) and observed in low density (approximately 0.3 cm(-3)), high temperature (T(e) approximately T(i) approximately 3x10(7) K), and beta approximately 10 plasma that included electron and ion beams streaming along B. The wave activity was enhanced from below the ion cyclotron frequency to electron cyclotron and upper hybrid frequencies. The detailed properties suggest the pulses are nonlinearly steepened ion cyclotron or Alfvén waves.
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Three-dimensional observations of gyrating ion distributions far upstream from the Earth's bow shock and their association with low-frequency waves. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000ja900079] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Precipitation of relativistic electrons by interaction with electromagnetic ion cyclotron waves. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999ja000283] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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33
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Sporadic plasma sheet ion injections into the high-altitude auroral bulge: Satellite observations. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999ja900293] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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34
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Magnetospheric and ionospheric response to a substorm: Geotail HEP-LD and Polar PIXIE observations. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999ja900216] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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35
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Earthward flow bursts in the inner magnetotail and their relation to auroral brightenings, AKR intensifications, geosynchronous particle injections and magnetic activity. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/98ja02661] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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36
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Structure and properties of the subsolar magnetopause for northward interplanetary magnetic field: Multiple-instrument particle observations. ACTA ACUST UNITED AC 1993. [DOI: 10.1029/93ja00606] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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37
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Large scale response of the magnetosphere to a southward turning of the interplanetary magnetic field. ACTA ACUST UNITED AC 1987. [DOI: 10.1029/ja092ia03p02365] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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A statistical study of plasma sheet dynamics using Isee 1 and 2 energetic particle flux data. ACTA ACUST UNITED AC 1986. [DOI: 10.1029/ja091ia06p06861] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Particle and field characteristics of the high-latitude plasma sheet boundary layer. ACTA ACUST UNITED AC 1984. [DOI: 10.1029/ja089ia10p08885] [Citation(s) in RCA: 135] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Plasma and energetic particle structure upstream of a quasi-parallel interplanetary shock. ACTA ACUST UNITED AC 1984. [DOI: 10.1029/ja089ia07p05419] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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