GLOBAL EXCITATION OF WAVE PHENOMENA IN A DISSIPATIVE MULTICONSTITUENT MEDIUM .2. IMPULSIVE PERTURBATIONS IN THE EARTHS THERMOSPHERE

The transfer function approach in terms of vector spherical harmonics is used to describe the thermospheric response to time-dependent sources on the globe. This function is extended to cover frequencies from omega equals 0 to 140 cycles per day (c/d), the latter corresponding to periods of 10 min. This makes it possible to describe a wide spectrum of phenomena ranging from long term variations to low-frequency acoustic waves. Using the Fourier integral representation, this transfer function is then used as a basis for describing impulsive perturbations such as those associated with geomagnetic substorms.