Whistlers recorded at Varanasi

Abstract

THE study of low-latitude whistlers dates back to the pioneering work of Japanese scientists. The whistlers were first recorded at Toyokawa (geomag. lat., 24.5°N)¹, and later efforts were made to record them at lower latitudes. The first successful records of whistlers in India were obtained at Gulmarg (geomag. lat., 24°10′N) by Somayajulu et al.². Recording was later carried out at Nainital (geomag. lat., 19°1′N) and whistlers with comparatively lower dispersion and reduced rate of occurrence were reported^3–5. Unsuccessful efforts were also made to record whistlers at Varanasi (geomag. lat., 15°6′N). Analysis of the low latitude whistler records by Rao et al.⁶ showed that the low-latitude whistler cut-off lies around 15° latitude, and apparently provided the reason for the non-recording of whistlers at Varanasi. Using an improved system, we have succeeded in recording whistler activity at Varanasi, and we describe here the categories of sonograms recorded in April, 1976.