Source Region Identification for Low Latitude Whistlers (L=1.08)

Wednesday, 17 December 2014
Sneha A Gokani1, Rajesh Singh1, Ajeet Kumar Maurya1, Veenadhari Bhaskara2, Morris Cohen3, Sushil Kumar4 and Janos Lichtenberger5, (1)Indian Inst of Geomagnetism, Allahabad, India, (2)Organization Not Listed, Washington, DC, United States, (3)Georgia Institute of Technology Main Campus, Atlanta, GA, United States, (4)University of the South Pacific Laucala, Suva, Fiji, (5)Eotvos University, Budapest, Hungary
Though whistlers are known and studied from past one century, the scientific community still strives to understand the generation and propagation mechanism of whistlers in very low latitude region. One of the solutions comes from locating the causative lightning discharges and source region of low latitude whistlers. In the present study, ~ 2000 whistlers recorded during period of one year (Dec, 2010 to Jan, 2011) at Allahabad (Geomag. lat. 16.79o N; L=1.08), India are correlated with lightning activity detected by World Wide Lightning Location Network (WWLLN) at and around conjugate region. About 63% of whistlers are correlated with the lightning strikes around conjugate region. Further to confirm this correlation, arrival azimuths of causative sferics are determined and the obtained azimuths points towards conjugate region of Allahabad. The characteristics of thunder cloud generating these whistlers are examined and found that the clouds with South-East alignment are more prone to trigger whistler waves. The seasonal and diurnal variation of whistler parameters such as occurrence rate, power spectral density and dispersion are also studied and explained on the basis of ionospheric conditions in low latitudes. The results obtained open a new window to look for the propagation mechanism of low latitude whistlers.