Tracing solar wind plasma entry into the magnetosphere using ion‐to‐electron temperature ratio

Abstract

When the solar wind Mach number is low, typically such as in magnetic clouds, the physics of the bow shock leads to a downstream ion‐to‐electron temperature ratio that can be notably lower than usual. We utilize this property to trace solar wind plasma entry into the magnetosphere by use of Cluster measurements in the vicinity of the dusk magnetopause during the passage of a magnetic cloud at Earth on November 25, 2001. The ion‐to‐electron temperature ratio was indeed low in the magnetosheath (Ti/Te ∼ 3). In total, three magnetopause boundary layer intervals are encountered on that day. They all show that the low ion‐to‐electron temperature ratio can be preserved as the plasma enters the magnetosphere, and both with and without the observation of Kelvin‐Helmholtz activity. This suggests that the ion‐to‐electron temperature ratio in the magnetopause boundary layer, which is usually high, is not prescribed by the heating characteristics of the plasma entry mechanism that formed these boundary layers. In the future, this property may be used to (1) further trace plasma entry into inner regions and (2) determine the preferred entry mechanisms if other theoretical, observational and simulation works can give indications on which mechanisms may alter this ratio.

Asymmetry of magnetosheath flows and magnetopause shape during low Alfvén Mach number solar wind

“…next paragraph), and their intermittent observation may be due to small-scale changes in the distance from the magnetopause to the spacecraft not accounted for in the MHD simulation. The reader is referred to Lavraud and Borovsky [2008] for aspects related to enhanced flows and associated magnetopause wave activity during low M A (see also Chen et al [1993], Lavraud et al [2009] and Taylor et al [2012]). However, this topic is beyond the focus of the present study.…”

Lower-hybrid (LH) oscillitons evolved from ion-acoustic (IA)/ion-cyclotron (IC) solitary waves: effect of electron inertia

“…Table 1 lists some plasma parameters in auroral regions where T e0 > T i0 , calculated from measurements by the GEODESIC rocket (Burchill et al, 2004), the Freja satellite , and the FAST satellite (Ergun, 1999), respectively. By contrast, in most magnetosphic plasmas (especially encountering some extreme situations like, e.g., substorms), ξ T lies between 1/12 and 1/3, as reported by, e.g., AMPTE/IRM and Cluster observations in the Earth's central plasma sheet, the sheet boundary layers, and magnetosheath (Baumjohann, 1993;Phan et al, 1994;Lavraud, 2009). It is another interesting topic on the excitation of oscillitons under the condition of ξ T < 1, besides the case introduced in this paper with ξ T > 1.…”

Exploring the High-altitude Nuclear Detonation and Magnetic Storms

“…Since the concept of solar atmosphere extension and expansion into interplanetary space [18] endorsed by Pioneer V [19], showed to contain loopholes [20], and Magnetosphere breached continually by solar wind in several places [21], it is suggested that, both the flow of energetic protons [22], and energetic electrons >200 keV [23], in Magnetosheath, and the concentration of high density solar wind positive ion ranging between 35 to 127 cm -3 at Magnetosheath [22], contrary to background proton's density of 5-10 cm -3 [24], and Magnetosheath plasma interaction with magnetosphere at magnetopause, which results in fluctuations and strong magnetic fields, leading to an intense geomagnetic storm Dst<200 n Tesla [25], a situation which is similar to the ionospheric elongated diamagnetic cavity created after High-altitude Nuclear Detonation (HND) [1], therefore it is suggested that, both MS and HND are similar in nature, and resulted from charged particles interaction with geomagnetic field.…”

“…The frequency of the produced EMP is given by 1 EMP f Hz t = (15) External Magnetic Field-Moment Ions (ExMF MI ) production HND earlier geomagnetic disturbances thought to have one initial phase [10], but as shown in Figure 1, Starfish Prim, Checkmate and Kingfish resulted magnetic field at Johnston Island, showed two initial phases, followed by a slow decrease and subsequent lengthy recovery to ambient conditions [28], the fields shown in Figure 1, are similar in shape to the Dst with one Sudden Storm Commencement (SSC) [16], the first initial phase of Starfish Prim shown in Figure 1, measured 150 γ at H+3.6 seconds, followed by 290 γ at H+25 [28]; comparing this mechanism, with energetic electrons >200 keV at Magnetosheath which related to the magnetopause electron layer [23], or Magnetosheath plasma, that interacts with the magnetosphere at the magnetopause, and fluctuates with strong magnetic field, leading to an intense geomagnetic storm with Dst <200 n Tesla [25], which is similar to the energetic Magnetosheath protons [22], or the energetic protons first detected by Pioneer V, and later caused geomagnetic disturbance measured at Honolulu and shown in Figure 2A [17], all of which suggesting the production of an Interplanetary External Magnetic Field (I-ExMF) [12].…”

“…It produced complex phenomena such as magnetic disturbances, aurora and electromagnetic pulse (EMP) [2]. Before it was banned in 1962, the USA carried 13 tests [3], and 7 by USSR [4], the Starfish Prime experiment detonated at an altitude of 400 km South-South-West (SSW) of Johnston Island (JI) at 23:00 hours, Honolulu time on July 8, 1962; intended among others to disrupt an enemy of the anti-missile radars [2], with a total of thirteen experiments carried by USA at altitudes ranged from 11 to 540 kilometers [3], the nuclear detonation created a great amount of beta particles, debris and gamma rays which ionized more electrons [2], the Starfish Prime total Injected electrons were 1.3x10 25 electrons [4], yield 1.4 megatons (mt) it caused minor damages of 300 street lights at Hawaii 1,445 km away, a probable failure of a microwave repeating station on Kauai, failure of the input stages of ionospheric sounders and damages to rectifiers in communication receivers [3], while the USSR Test 184, Operation K-3, on 22 October 1962, yield 300 kiloton (kt) burst at 290 km altitude near Dzhezkazgan, induced a current of 2,500 amps, this started a fire that burned down the Karaganda power plant, and shut down 1,000 km of shallow-buried power cables between Aqmola and Almaty [5], it injected 3.6x10 25 electrons [4], producing intense electromagnetic pulse (EMP) and magnetic disturbances recorded in magnetic observatories worldwide [6], the K-3 damage was due to higher altitude and greater geomagnetic field [7], while Starfish Prim injected 7.5×10 25 electrons, 10% initially trapped in the radiation belts, while the rest were captured by the atmosphere [1], the Starfish Prim produced an unusual events in the great variety and extent of the phenomena [8], it produced maximum magnetic field of 700 gamma intensity after 70 seconds, although the physical processes caused the disturbances was ambiguously interpreted, but it was thought due to ionospheric currents attributed to the Magneto-hydrodynamic (MHD) [9], the magnetic disturbances was interpreted by others as resulted from an enhanced dynamoaction in the ionosphere, or a hydromagnetic waves resulted from geomagnetic field distortion [10], while some associated perturbations onset with MHD arrival caused by detonation debris containment the geomagnetic field, others interpreted geomagnetic field fluctuations and variations in E-layer ionization density as evidence that the perturbations were caused by nuclear radiations interactions with the magnetic field and ionosphere [3], records and analysis at a coll...…”