A Gauge Condition for Studying the Origin of Intrinsic Magnetospheres

Cassini observations of Saturn's southern polar cusp

The magnetospheric cusps are important sites of the coupling of a magnetosphere with the solar wind. The combination of both ground- and space-based observations at Earth have enabled considerable progress to be made in understanding the terrestrial cusp and its role in the coupling of the magnetosphere to the solar wind via the polar magnetosphere. Voyager 2 fully explored Neptune's cusp in 1989 but highly inclined orbits of the Cassini spacecraft at Saturn present the most recent opportunity to repeatedly studying the polar magnetosphere of a rapidly rotating planet. In this paper we discuss…

Beyond the mini-solar maximum of solar cycle 24: Declining solar magnetic fields and the response of the terrestrial magnetosphere

The present study examines the response of the terrestrial magnetosphere to the long-term steady declining trends observed in solar magnetic fields and solar wind micro-turbulence levels since mid-1990's that has been continuing beyond the mini-solar maximum of cycle 24. A detailed analysis of the response of the terrestrial magnetosphere has been carried out by studying the extent and shape of the Earth's magnetopause and bow shock over the past four solar cycles. We estimate sub-solar stand-off distance of the magnetopause and bow shock, and the shape of the magnetopause using numerical as w…

Magnetic Flux Transport Identification of Active Reconnection: MMS Observations in Earth's Magnetosphere

Magnetic reconnection plays an important role in converting energy while modifying field topology. This process takes place in varied plasma environments in which the transport of magnetic flux is intrinsic. Identifying active magnetic reconnection sites in in-situ observations is challenging. A new technique, Magnetic Flux Transport (MFT) analysis, has been developed recently and proven in numerical simulation for identifying active reconnection efficiently and accurately. In this study, we examine the MFT process in 37 previously reported electron diffusion region (EDR)/reconnection-line cro…

具有类地磁层的系外行星在极端空间天气条件下的MHD研究：关于宜居性条件与射电辐射

MHD study of extreme space weather conditions for exoplanets with Earth-like magnetospheres: On habitability conditions and radio-emission

本文通过PLUTO代码的MHD模拟，研究类地磁层系外行星在M型和F型恒星宜居带内受恒星风和CME影响下的宜居性条件及射电辐射特征，并指出低射电辐射信号可能指示有利的宜居性。

Semi-annual, annual and Universal Time variations in the magnetosphere and in geomagnetic activity: 4. Polar Cap motions and origins of the Universal Time effect

We use the am, an, as and the a-sigma geomagnetic indices to the explore a previously overlooked factor in magnetospheric electrodynamics, namely the inductive effect of diurnal motions of the Earth's magnetic poles toward and away from the Sun caused by Earth's rotation. Because the offset of the (eccentric dipole) geomagnetic pole from the rotational axis is roughly twice as large in the southern hemisphere compared to the northern, the effects there are predicted to be roughly twice the amplitude. Hemispheric differences have previously been discussed in terms of polar ionospheric conductiv…

The initial temporal evolution of a feedback dynamo for Mercury

Various possibilities are currently under discussion to explain the observed weakness of the intrinsic magnetic field of planet Mercury. One of the possible dynamo scenarios is a dynamo with feedback from the magnetosphere. Due to its weak magnetic field Mercury exhibits a small magnetosphere whose subsolar magnetopause distance is only about 1.7 Hermean radii. We consider the magnetic field due to magnetopause currents in the dynamo region. Since the external field of magnetospheric origin is antiparallel to the dipole component of the dynamo field, a negative feedback results. For an alpha-o…

重新审视火星诱导磁场和钟角偏离在实时上游日冕层条件下的情况

Revisiting Mars' Induced Magnetic Field and Clock Angle Departures under Real-Time Upstream Solar Wind Conditions

本研究通过整合实时上游日冕层条件，重新审视火星诱导磁场特性，发现日冕层动态压力和IMF强度增强磁场，但对压缩比作用相反，且钟角偏离在磁鞘内较小，向诱导磁层内逐渐增大。

Scaling and a Fokker-Planck model for fluctuations in geomagnetic indices and comparison with solar wind epsilon as seen by WIND and ACE

The evolution of magnetospheric indices on temporal scales shorter than that of substorms is characterized by bursty, intermittent events that may arise from turbulence intrinsic to the magnetosphere or may reflect solar wind-magnetosphere coupling. This leads to a generic problem of distinguishing between the features of the system and those of the driver. We quantify scaling properties of short term (up to few hours) fluctuations in the geomagnetic indices AL and AU during solar minimum and maximum along with the parameter epsilon that is a measure of the solar wind driver. We find that self…

Effects of equatorial chorus wave normal azimuthal distribution on wave propagation

The non-ducted propagation characteristics of the VLF waves in the inner magnetosphere were studied with respect to their frequency, source localization, and initial wave normal angle, between the wave-normal and the background magnetic field. The ray tracing software based on multi-components cold plasma approach was developed by use of the IGRF magnetic field model and the GCPM model of plasma density. We described dynamics of the wave-normals direction during its propagation and magnetospheric reflection. We showed that whistler waves can be reflected when lower hybrid resonance frequency b…

太阳风湍流对行星弓激波的影响

Impact of solar wind turbulence on a planetary bow shock

本文利用混合 PIC 代码 Menura 开展全球三维模拟，首次揭示湍流太阳风如何改变类地行星弓激波、磁鞘和离子前激波的结构与动力学。