The dipole tilt angle dependence of the bow shock for southward IMF: MHD results

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In this study we use the bow shock crossings contained in the Space Physics Data Facility database, collected by four spacecraft (IMP 8, Geotail, Magion‐4, and Cluster1) to analyze the effect of the interplanetary magnetic field (IMF) By component on the bow shock position and shape. Although the IMF Bz component is usually considered much more geoeffective than By, we find that the dayside bow shock is more responsive to the eastward component of the IMF than the north‐south one. We believe that the explanation lies in the changes that the Bz component induces on the magnetopause location and shape, which largely compensate the corresponding changes in the dayside bow shock location. In the tail, we find that the bow shock cross section is elongated roughly in the direction perpendicular to the IMF direction, which agrees with earlier modeling studies.

Section: Resultsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

The Influence of IMF B_y on the Bow Shock: Observation Result

Wang

Кабин

et al. 2018

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“…Recently, we have used the SWMF to study the global magnetopause shape and its dependence on the solar wind conditions [ Lu et al , , , ; Liu et al , , ], as well as the energy transfer across the magnetopause [ Lu et al , ; Jing et al , ]. This model was also used by Wang et al [] to analyze the influence of the dipole tilt angle on the shape and size of the bow shock. Our current study extends that of Wang et al [] by focusing on the effects of the IMF clock angle on the cross section of the tail bow shock.…”

Section: Methodsmentioning

confidence: 99%

“…We have previously developed an automatic identification technique to locate the bow shock surface [ Wang et al , ]. Figure shows two examples of the cross sections of the bow shock at X =− 20 R E , Figures a and b correspond to IMF clock angle φ = 0° and 45°, respectively.…”

Section: Methodsmentioning

confidence: 99%

The influence of IMF clock angle on the cross section of the tail bow shock

Wang

Кабин

et al. 2016

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We study effects of the interplanetary magnetic field (IMF) orientation on the terrestrial tail bow shock location and shape by using global MHD magnetosphere model and empirical bow shock models. It is shown that the tail bow shock cross section is well approximated by an ellipse with the direction of the major axis roughly perpendicular to the IMF clock angle direction. With the increasing IMF clock angle, the eccentricity of the bow shock cross section increases for northward IMF but decreases for southward IMF.

“…The new model is also compared with the previous findings of Jelínek et al () and Wang et al (). Our model shows that the nightside flaring angle increases with increasing dipole tilt angle, which is consistent with Jelínek et al ().…”

Section: Modeling the Bow Shock Shapementioning

confidence: 87%

Earth's Bow Shock: A New Three‐Dimensional Asymmetric Model With Dipole Tilt Effects

Zhou

et al. 2019

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Using the bow shock crossing events from four spacecraft: IMP 8, Geotail, Magion‐4, and Cluster 1, a new three‐dimensional asymmetric bow shock model is constructed. The model is parameterized by the solar wind dynamic pressure, the interplanetary magnetic field, magnetosonic Mach number, solar wind β, and the Earth's dipole tilt angle. It is shown that the shape and size of bow shock are both affected by the dipole tilt angle. The dipole tilt angle causes asymmetries in the meridional plane: (1) the bow shock subsolar standoff distance and the north‐south asymmetry increase with the dipole tilt angle; (2) as the dipole tilt angle increases, the shock flaring angle in the equatorial plane is slightly reduced, while in the meridional plane the flaring angle obviously decreases in Southern Hemisphere and keeps almost unchanged in the Northern Hemisphere. The flaring angle in the Northern Hemisphere is larger than in the Southern Hemisphere; (3) the effects of negative dipole tilt angle on shock flaring are just the opposite of those for positive tilt, and the effects of dipole tilt angle on the shape of the bow shock are north‐south symmetric. The model results are also validated by comparing with one previous empirical model and with observational crossings, and it is demonstrated that the new model is able to predict the observed crossings more accurately and can better describe the rotational asymmetry and north‐south asymmetry of the Earth's bow shock.