Observation of discrete VLF emissions at Indian low-latitude ground station Srinagar (L = 1.28)

摘要

During the routine analysis of recorded very low-frequency data during the period November, 2012 to February, 2013, at an Indian low-latitude ground station Srinagar (geomag. lat., 24°10′N; L = 1.28), we observed some interesting discrete emissions during quiet period on February 5, 2013, which has been presented in the present study. The spectral analysis of the observed discrete very low-frequency emissions consisting of risers, fallers, hooks and oscillating tones has been presented. To explain the observed dynamic spectra of the discrete chorus emissions, a possible generation mechanism has been presented based on the recent nonlinear theory. On the basis of this theory, frequency sweep rate of discrete chorus emissions has been computed and compared with those of our experimentally observed values.