Comparative analysis of Venus and Mars magnetotails
A. FedorovC. FerrierJ. A. SauvaudS. BarabashTielong ZhangC. MazelleR. LundinH. GunellH. AnderssonK. BrinkfeldtYoshifumi FutaanaA. GrigorievMats HolmströmM. YamauchiKazushi AsamuraW. BaumjohannH. LämmerA. J. CoatesD. O. KatariaD. R. LinderC. C. CurtisK. C. HsiehB.R. SandelJ.-J. ThocavenM. GrandéH. KoskinenE. KallioT. SälesW. SchmidtP. RiiheläJ. U. KozyraN. KruppJ. WochJ. G. LuhmannS. McKenna‐LawlorS. OrsiniR. Cerulli‐IrelliA. MuraA. MililloM. MaggiE. C. RoelofP. C. BrandtC. T. RussellK. SzegőJ. WinninghamR.A. FrahmJ. ScherrerJ. R. SharberP. WurzP. Bochsler
56
Citation
16
Reference
10
Related Paper
Citation Trend
Keywords:
Magnetosheath
Current sheet
Plasma sheet
Jupiter (rocket family)
Recent studies indicated that the magnetopause indentation plays an important role in magnetosphere-ionosphere coupling. Confirmation of magnetopause indentation requires joint observations with multiple satellites. So far, there have been few magnetopause indentation events reported. In this paper, a case of magnetopause indentation induced by fast magnetosheath flow is reported with multiple spacecraft analysis based on the observations of five THEMIS probes. During the interval from 10:00 UT to 10:45 UT on 21 July 2007, when the five THEMIS probes are located near the subsolar magnetopause, a fast anti-sunward flow (with a velocity of 400 km·s-1) was observed in the magnetosheath just before THEMIS crossed the magnetopause to the magnetosphere. A magnetopause local indentation event was identified by comparing the nominal magnetopause and the tangential magnetopause plane calculated using the MVA method. In order to explore the origin of this magnetosheath fast flow, solar wind data observed by WIND satellite at L1 point were analyzed. It is found that the solar wind is very stable during this period. The Interplanetary Magnetic Field (IMF) is mainly radial and the component of the north-south direction is very small. It is speculated that the generation of this magnetosheath fast anti-sunward flow may be related to the radial IMF.
Magnetosheath
Cite
Citations (0)
[1] We report in-situ measurements by three THEMIS spacecraft showing the evolution of reconnection in a solar wind current sheet as the current sheet transited from the solar wind across the bow shock and close to the magnetopause on July 11, 2008. The observations suggest that the solar wind reconnection exhaust within the current sheet was disrupted by its interaction with the bow shock, while the subsequent compression of the current sheet against the magnetopause significantly reduced both the current sheet thickness and the plasma β and initiated reconnection at a new X-line located within the magnetosheath. Furthermore, electrons were heated at the center of the magnetosheath exhaust, in contrast to the previously reported absence of electron heating in solar wind exhausts, but consistent with electron heating occasionally observed in association with magnetopause reconnection. This suggests that the level of electron heating in reconnection exhausts depends strongly on the boundary conditions.
Magnetosheath
Current sheet
Cite
Citations (72)
The shape and the structure of the magnetopause are examined during several passages of the magnetopause past ATS 5 and Explorer 45 on August 4, 1972. Determination of boundary normals and comparison of observations at the two satellites indicate that the magnetopause shape in the afternoon sector was close to the shape indicated by theory. Magnetopause normals for a series of closely spaced inward/outward magnetopause passages indicate that these passages were not caused by surface waves moving along the magnetopause. Hodograms of the magnetic field observed during the first two magnetopause passages indicate that the magnetopause was a tangential discontinuity. The magnetic field changes during these passages were used to derive the magnitude and the direction of electrical currents, principally eastward, flowing in the magnetopause. The third passage was very rapid, so a detailed evaluation of the structure was not possible, but it also indicated a tangential discontinuity. A rotational discontinuity was observed in the magnetosheath followed by several magnetopause crossings where the field changed from northeastward in the magnetosheath to northward in the magnetosphere. The magnetopause currents associated with these passages flow northeastward, parallel to the magnetic field. These last observations agree with either open or closed magnetosphere models.
Magnetosheath
Discontinuity (linguistics)
Cite
Citations (9)
Magnetosheath
Magnetosphere of Saturn
Magnetosphere of Jupiter
Cite
Citations (3)
Magnetic pressure inside the magnetopause is usually balanced with a sum of thermal plasma and magnetic pressures on the magnetosheath side. However, observations reveal that the magnetosheath magnetic field can be frequently larger than that in the magnetosphere (inverse magnetic field gradient across the magnetopause), and thus, the enhanced pressure from the magnetosheath side seems to be uncompensated. Such events are rare in the subsolar region, but their occurrence rate increases toward flanks. The analysis, based on statistical processing of about 35,000 THEMIS magnetopause crossings collected in the course of the years 2007–2017, shows that these events are more frequently observed under enhanced geomagnetic activity that is connected with a strong southward IMF. Case studies reveal that such a state of the magnetopause boundary layers can persist for several hours. This study discusses conditions and mechanisms keeping the pressure balance across the magnetopause under these conditions.
Magnetosheath
Pressure gradient
Cite
Citations (2)
Discontinuities in the solar wind, bow shock ripples or ionized dust clouds carried by the solar wind, high speed jets (HSJs) are observed in the magnetosheath. These HSJs have typically a Vx component larger than 200 km s-1 and their dynamic pressure can be a few times the solar wind dynamic pressure. We use a conjunction of Cluster and MMS, crossing simultaneously the magnetopause, to study the characteristics of these HSJs and their impact on the magnetopause. Over one hour-fifteen minutes interval in the magnetosheath, Cluster observed 21 HSJs. During the same period, MMS observed 12 HSJs and entered the magnetosphere several times. A jet was observed simultaneously by both MMS and Cluster and it is very likely that they were two distinct HSJs. TDuring this period, two and six magnetopause crossings were observed respectively on Cluster and MMS with a significant angle between the observation and the expected normal deduced from models. The angles observed range between from 11° up to 114°. One inbound magnetopause crossing observed by Cluster (magnetopause moving out at 142 km s-1) was observed simultaneous to an outbound magnetopause crossing observed by MMS (magnetopause moving in at -83 km s-1), showing that the magnetopause can have multiple local indentation places, most likely independent from each other. Under the continuous impacts of HSJs, the magnetopause is deformed significantly and can even move in opposite directions at different places. It can therefore not be considered as a smooth surface anymore but more as surface full of local indents. Four dust impacts were observed on MMS, although not at the time when HSJs are observed, showing that dust clouds would have been present during the observations. No dust cloud in the form of Interplanetary Field Enhancements was however observed in the solar wind which may exclude large clouds of dust as a cause of HSJs. Radial IMF and Alfven Mach number above 10 would fulfil the criteria for the creation of bow shock ripples and the subsequent crossing of HSJs in the magnetosheath.
Magnetosheath
Cite
Citations (37)
A model of the magnetosheath structure proposed in a recent paper from the authors is extended to estimate the magnetopause stand-off distance from solar wind data. For this purpose, the relationship of the magnetopause location to the magnetosheath and solar wind parameters is studied. It is shown that magnetopause erosion may be explained in terms of the magnetosheath magnetic field penetration into the magnetosphere. The coefficient of penetration (the ratio of the magnetospheric magnetic field depression to the intensity of the magnetosheath magnetic field Bmâ¥z=âBmsin2Θ/2, is estimated and found approximately to equal 1. It is shown that having combined a magnetosheath model presented in an earlier paper and the magnetosheath field penetration model presented in this paper, it is possible to predict the magnetopause stand-off distance from solar wind parameters.Key words. Magnetospheric physics · Magnetopause · Cusp and boundary layers-Magnetosheath
Magnetosheath
Cite
Citations (0)
Abstract. The paper analyses one long-term pass (26 August 2007) of the THEMIS spacecraft across the dayside low-latitude magnetopause. THEMIS B, serving partly as a magnetosheath monitor, observed several changes of the magnetic field that were accompanied by dynamic changes of the magnetopause location and/or the structure of magnetopause layers observed by THEMIS C, D, and E, whereas THEMIS A scanned the inner magnetosphere. We discuss the plasma and the magnetic field data with motivation to identify sources of observed quasiperiodic plasma transients. Such events at the magnetopause are usually attributed to pressure pulses coming from the solar wind, foreshock fluctuations, flux transfer events or surface waves. The presented transient events differ in nature (the magnetopause surface deformation, the low-latitude boundary layer thickening, the crossing of the reconnection site), but we found that all of them are associated with changes of the magnetosheath magnetic field orientation and with enhancements or depressions of the plasma density. Since these features are not observed in the data of upstream monitors, the study emphasizes the role of magnetosheath fluctuations in the solar wind-magnetosphere coupling.
Magnetosheath
Cite
Citations (14)
Abstract. A model of the magnetosheath structure proposed in a recent paper from the authors is extended to estimate the magnetopause stand-off distance from solar wind data. For this purpose, the relationship of the magnetopause location to the magnetosheath and solar wind parameters is studied. It is shown that magnetopause erosion may be explained in terms of the magnetosheath magnetic field penetration into the magnetosphere. The coefficient of penetration (the ratio of the magnetospheric magnetic field depression to the intensity of the magnetosheath magnetic field Bm⊥z=–Bmsin2Θ/2, is estimated and found approximately to equal 1. It is shown that having combined a magnetosheath model presented in an earlier paper and the magnetosheath field penetration model presented in this paper, it is possible to predict the magnetopause stand-off distance from solar wind parameters.Key words. Magnetospheric physics · Magnetopause · Cusp and boundary layers-Magnetosheath
Magnetosheath
Cite
Citations (24)
A theoretical model is presented for the plasma in the Jovian magnetosphere whose pressure is comparable to the corotational energy density. The model predicts a thin current sheet of 1 Jupiter radius to 2 Jupiter radii half-thickness. The current sheet lies almost precisely in the magnetic equatorial plane and is not appreciably warped as suggested previously.
Plasma sheet
Jupiter (rocket family)
Current sheet
Atmosphere of Jupiter
Magnetosphere of Jupiter
Cite
Citations (0)