Dependence of the Parameters of VLF Chorus Emissions in the Earth’s Magnetosphere on Quasi-Static Variations of the Magnetic Field

We present the results of numerical simulations of VLF chorus emissions in the magnetospheric cyclotron maser within the framework of the backward wave oscillator (BWO) regime model. Specific features of the dynamic wave spectrum at various points inside the generation region in the presence of quasi-static variations of the geomagnetic field are considered. We show that discrete elements with both increasing and decreasing frequency can be generated, and the dynamic spectrum shape can change qualitatively upon the shift of the observation point inside the generation region. We discuss this dependence of the dynamic spectrum of the generated waves on the position of the observer in the generation region for various parameters of the geomagnetic field distortion. We show that the formation of elements with an increasing (decreasing) frequency is determined by the presence of the regions with local minima (maxima) of the external magnetic field.