Some Results Concerning the Regular Variation of VLF Atmospherics

Abstract

Regular behaviour of the integrated field intensity of atmospherics over Kalyani at 10, 21 and 27 kHz have been extensively analyzed for a period of 3-years. The characteristic variations of the noise level have been examined considering diurnal and seasonal variations as well as the activity of the sources and the wave propagation involved. The results exhibit a definite seasonal variation, having higher values during the monsoon months. Also the monthly mean ratios of afternoon maximum (or late afternoon minimum) to morning minimum of the noise level are found to decrease with increasing frequency.

Indexing terms:

• Atmospherics
• Lightning
• Electromagnetic radiation