A Report of C-class Solar Flare Affecting NVIS Link at 5 MHz Band
Titon Dutono, Zulmi Zakariyah, Tri Budi Santoso · 2019
Throughout 2019 it is predicted as the minimum solar cycle period. It will make conditions less favorable for HF propagation. For this reason, we carried out day by day observations throughout 2019 to examine the existence of HF NVIS channel by WSPR method between Surabaya and Jombang which is separated by approximately 70 Km away. Ionospheric Wave Radio Frequency fading or even the radio-blackout in the band of HF could be caused by an increasing the solar activity, especially C-class level or higher Solar Flare. This occurrence only affects the sunlit region, and it could finish for within several hours. From 1st January 2019 until this report is written, the significant Solar Flare only reach C-class. During ongoing one year sounding activity, we found a measurement result nearly similar with the pattern of impacted ionosphere condition based on occurring solar flare, even though the Solar Flare still in C-class level. In order to verify the Solar-flare impact to the ionosphere, we use a simple qualitative model to verify the results of SNR measurements results to a suspected 3-consecutive-days, based on the nature of Solar-flare impact phenomena. The results show a case of C-class level could impact the ionospheric condition even though another case show that C-class level Solar flare do not affect the ionospheric condition.