Numerical research on the interaction between coronal mass ejection and streamer

By proposing a two-dimensional triggering model with concentrically circular closed magnetic field line structure, numerical research is made on the asymmetric propagation feature of coronal mass ejection (CME) in two cases emerging at the solar northern latitudes 10° and 45° respectively. The numerical results can qualitatively explain some features of CME event observed by the spacecraft SOHO and show that: (i) In these two cases, the triggering model can initiate CME with an asymmetric closed magnetic field structure, (ii) Closed magnetic structure of CME event will keep deflecting to the current sheet when it propagates away from the sun and this deflecting effect mostly happens within tens of solar radii before CME travels finally along the current sheet, (iii) The triggering model emerging at different locations can introduce CME events with different magnetic shapes. This shape happens to be circular and crescent when the triggering model emerges at the northern latitudes 10° and 45°, respecti     

Prediction tests by using ISF method for the geomagnetic disturbances

A so-called ISF method for predicting geomagnetic disturbances caused by solar wind storm blowing to the earth is suggested. The method is based on a combined approach to solar activity, interplanetary scintillation (IPS) and geomagnetic disturbance observations in 1966-1982, dynamics of disturbance propagation and fuzzy mathematics. Prediction test has been made for 24 large geomagnetic disturbance events that produced space disasters during the period of 1980 -1998, with the three-dimensional propagation characteristics, the best close degree of each radio source and the influence of the south-north components of interplanetary magnetic fields considered. The main results are (i) for onset time of the geomagnetic disturbance, events with relative error △Tpred/Tobs≤10% between the observation Tobs and the prediction Tpred, account for 45.8% of all events, ≤30% for 78.3% and >30% for only 21.7%; (ii) as for the magnetic disturbance magnitude, events with relative error ΔΣKp,pred/ΣKp,obs≤10% betwee     

Modeling Density and Anisotropy of Energetic Electrons Along Magnetic Field Lines

The electromagnetic wave growth or damping depends basically on the number density and anisotropy of energetic particles as the resonant interaction takes place between the particles and waves in the magnetosphere. The variance of both the number density and anisotropy along the magnetic field line is evaluated systematically by modeling four typically prescribed distribution functions. It is shown that in the case of ＂the positive anisotropy＂ （namely, the perpendicular temperature T⊥ exceeds the parallel temperature T｜｜）, the number density of energetic electrons always decreases with the magnetic latitude for a regular increasing magnetic field and the maximum wave growth is therefore generally confined to the equator where the resonant energy is minimum, and the number density is the largest. However, the ＂loss-cone＂ anisotropy of the electrons with a ＂pancake＂ distribution or kappa distribution keeps invariant or nearly invariant, whereas the ＂temperature＂ anisotropy with a pure bi-Maxwellian distribution or Ashour-Abdalla and Kennel＇s distributions decreases with the magnetic latitude. The results may provide a useful approach to evaluating the number density and anisotropy of the energetic electrons at latitudes where the observation information is not available.     

Characteristics of the boundary layer of magnetic clouds and a new definition of the cloud boundary

The concept of magnetic clouds is the combination of the frozen-in magnetic field and of the plasma clouds proposed in the 1950s or earlier[1—5]. The necessary conditions to identify a mag-netic cloud are[6]: (ⅰ) enhanced magnetic field strength, (ⅱ) a smooth rotation of the magnetic field direction through a large angle at the interval of an order of one day, and (ⅲ) low proton temperature and low plasma b. As an important and distinct subset of interplanetary large-scale transient struct…