Whistler and VLF Research at our Ground Station Jammu (L=1.17) India

This paper presents interesting observations based on the long term data of whistlers and VLF hiss emission at a low latitude ground station Jammu(geomagn. lat. 22?16? N, L = 1.17) showing that they are not limited to mid and high latitudes. These are observed during strong magnetic storm periods in post midnight sector. The simultaneous observations presented in this paper are unique and is reported for the ?rst time during geomagnetic storm period from low latitudes. The present observation of VLF emissions and whistlers along with ESD whistlers at Jammu clearly suggest that these VLF emissions are generated in the magnetosphere due to whistler mode wave-interaction with particles. Much detailed experimental and modeling study remains to be done in this area, but our results naturally account for the essential features of whistler and VLF hiss emission simultaneously observed during storm periods. This experimental study is unlikely to be the ?nal word on the origin of these events and further experimental con?rmation will, of course, be required at low latitudes. Nonetheless, the observation has the potential to be a ?circuit breaker? in our understanding of the generation mechanism of these events observed at low latitudes. However, further detailed mechanism (or process) of the data presented here is a challenging problem and this task will be left for further investigations. From the dispersion analysis of the day time whistlers recorded at Jammu, it is found that all the Whistlers have extremely small dispersion (ESD) in the range of 5-10 s1/2, which clearly supports non-ducted propagation of day-time whistlers at low latitudes, completely in contrast with the earlier findings of ducted propagation of day-time whistlers in the presence of equatorial anomaly.