The ionosphere in ̄uences magnetohydrodynamic waves in the magnetosphere by damping because of Joule heating and by varying the wave structure itself. There are di€erent eigenvalues and eigensolutions of the three dimensional toroidal wave equation if the height integrated Pedersen conductivity exceeds a critical value, namely the wave conductance of the magnetosphere. As a result a jump in freq...

My thesis deals with a fundamental question of high energy gamma-ray astronomy. Namely, I studied the cut-off shape of the Crab pulsar spectrum to distinguish between the leading scenarios for the pulsar models. Pulsars are celestial objects, which emit periodic pulsed electromagnetic radiation (pulsation) from radio to high energy gamma-rays. Two major scenarios evolved in past 40 years to exp...

Monitoring electromagnetic waves in the Ultra Low Frequency (ULF) range between 1 mHz and 1 Hz is essential for an understanding of the processes in the earths magnetosphere. Also earthquake prone areas are under suspect to emit precursor ULF signals. We discuss a receiving system using a solenoid sensor and Negative Impedance Converter (NIC) as front end. The NIC effectively extends the freque...

We show that the Doppler shift on whistler mode signals from VLF transmitters may be used to infer the magnetic field of an hydromagnetic wave above the ionosphere in the magnetosphere. This inferred field can then be compared with that measured on the ground. We examine one event in detail and show the data imply that a it/2 rotation of the orientation of the wave ellipse has occurred between ...

[1] A constant dawn-dusk By component is set as an interplanetary magnetic field (IMF) condition in our global MHD simulations to investigate the effects of IMF By on the closure of the field-aligned current (FAC) in the magnetosphere. On the basis of the steady state magnetosphere results, we trace streamlines of FAC from the ionosphere to draw the global geometry of current streamlines in the...

Magnetospheric and plasma science studies at Saturn offer a unique opportunity to explore in-depth two types of magnetospheres. These are an ‘induced’ magnetosphere generated by the interaction of Titan with the surrounding plasma flow and Saturn’s ‘intrinsic’ magnetosphere, the magnetic cavity Saturn’s planetary magnetic field creates inside the solar wind flow. These two objects will be explo...

This tutorial review examines the role of O in the dynamics of magnetosphere–ionosphere coupling. The life cycle of an O plasma element is considered as it circulates from the midto high-latitude ionosphere. Energization and diversion of the convecting plasma element into outflows involves Alfvénic turbulence at the low-altitude base of the cusp and plasmasheet boundary layer and in downward-cu...

A one dimensional, computational model for the propagation of ultra low frequency (ULF; 1–100 mHz) wave fields from the Earth’s magnetosphere through the ionosphere, atmosphere and into the ground is presented. The model is formulated to include solutions for high latitudes where the Earth’s magnetic field, (B0), is near vertical and for oblique magnetic fields applicable at lower latitudes. Th...

Emissions from Titan’s dayside atmosphere at ultraviolet wavelengths were observed by Voyager. The major source was shown to be photoelectron interactions with the neutral N2 present in the atmosphere whether or not Titan was inside or outside Saturn’s magnetosphere. Since discrepancies exist between observations and models, and photoelectrons do not contribute significantly to emissions from t...

[1] Comparative studies of 3D multi-fluid simulations with Galileo magnetometer data are used to develop a quantitative model of the currents and fields within Ganymede’s magnetosphere as well as its bulk plasma environment. The model includes contributions from Jupiter’s magnetosphere and the flux of different ion species originating from Ganymede’s ionosphere. Comparisons between the magnetom...