A statistical study of daytime pulsing hiss emission at low latitudes

A statistical study of pulsing hiss emissions observed during daytime at low latitude Indian ground stations Jammu (geomag. lat., 22°26′N; L = 1.17) and Srinagar (geomag. lat., 24°10′N; L = 1.28) is presented. From the detailed statistical analysis of the observed data it is found that the reported day time pulsing hiss emissions is a rare phenomena at low latitudes. The spectrograms of pulsing hiss emissions observed during daytime clearly show band limited spectrums regularly pulsing with almost equal period of the order of few seconds in the frequency range of 300 Hz–8 kHz. The intensity and bandwidth of daytime pulsing hiss remain almost constant in the frequency range of 300 Hz–8 kHz in clear contrast to the pulsing hiss emission observed during nighttime at low latitudes. The daytime pulsing hiss time period is about 0.5 s which is small in comparison to time period (~1.43 s) of the low latitude pulsing hiss observed during nighttime. The generation and propagation mechanisms of pulsing hiss emissions are discussed. The micropulsations propagating along the geomagnetic field lines modulate the growth rate of the wave resulting in hiss intensity.