Forward Acceleration of Ionospheric Electrons by NAU 40.75-kHz Whistler Waves Over Arecibo

We discuss a new mechanism to explain the forward acceleration of ionospheric electrons by whistler waves. We suggest this mechanism to be the key process responsible for our reported enhanced plasma lines detected by the Arecibo 430 MHz radar. These plasma lines are characterized by the frequency-downshifted spectra with a bandwidth of ~ 12 kHz. The backscatter radar operation indicates that electrons were accelerated upward along the Earth's magnetic field by the up-going 40.75 kHz whistler waves, which were launched from the NAU transmitter. They covered a broad range of altitudes ( ~ 300 km) and lasted for a period of a few minutes. This mechanism leads to the energization of electrons of ~ 13 eV inferred from Arecibo experiments.