Whistlers at Low Latitudes

Abstract

The contributions made by Indian workers towards a better appreciation of the low latitude ground observations of whistlers are reviewed. Though some routine results are included, the main emphasis is on those results which, the authors believe, elucidate some physical processes occurring in the magnetosphere. An example of such results is the experimental evidence for the duct formation and decay during geomagnetic disturbances. We also attempt to explain the riser, low dispersion and twin whistlers observed for the first time at ground stations, with the help of ray tracing in model magnetospheres, Elementary theoretical considerations are included only to make the presentation complete. Electron density estimates obtained from the whistler data are given to show the consistency of the observations. More accurate estimates require nose frequency data which, unfortunately, are not easily obtained at low latitudes. Directions for further researches in the field are indicated.