What is Auroral Propagation of VHF in Amateur Radio?

What is Auroral Propagation of VHF in Amateur Radio?

Usually Aurora would mean a radio black out on HF due to ionospheric activity. But Aurora can be used to our advantage for propagation on VHF, and rarely on UHF. Good directional antennas are required for auroral propagation. Beams are directed towards the auroral zone and not in the direction of the station being contacted. Distortion is quite likely in voice signals and CW communication may fare better.

Contacts with stations up to 1800 Km away may be possible with auroral propagation on VHF. Suffix A like 5,7A is given for auroral signal reports, though the readability may not be truly 5! Digital communications do not fare well on auroral propagation. Though being a natural phenomenon it can occur at any time, aurora is more likely in February, April, July and October. Of course, being in tropics, auroral propagation is out of question for me as aurora is a polar event!