Our life giving star, the Sun, has unleashed two massive solar flares, the second of which is the strongest flare in over a decade. The burst of radiation was so intense, it caused high frequency (HF) radio blackouts across the daytime side of Earth affecting HF communication over Africa, Europe and the Atlantic Ocean. The first flare erupted on 6 Sep 2017 from active region 2673 and measured in at X 2.2. Hot on its heels, another flare blasted off the Sun three hours later, measuring in at a whopping X 9.3 - the most powerful flare since 2005.
Solar flares are giant explosions on the surface of the Sun that occur when twisted magnetic field lines suddenly snap and release massive amounts of electromagnetic energy. Five categories — A, B, C, M and X — are used to rank solar flares based on their intensity. A-Class flares are the weakest, while X-Class are the most energetic.
The solar flares were accompanied by a coronal mass ejection (CME) which travelled towards Earth at speeds over 1200 km per second and impacted the Earth’s magnetic field early morning on 8 Sep 2017. The impact of the CME has sparked a strong (G3) geomagnetic storm on Earth which can have effects on HF communication, power grids, navigation systems such as GPS, and communication systems such as DStv, mobile phones and internet connectivity. Moderate disturbances are expected at this stage. The storm will gradually subside over the next 24 hours.
A CME is a large cloud of high energy particles ejected from the surface of the Sun when stored energy is suddenly released. When the magnetic field of a CME interacts with the Earth’s magnetic field it causes a temporary disturbance know as a geomagnetic storm.
The impact of the space weather storm will not harm humans and other life forms on Earth as we are protected by the Earth's magnetic field. The South African National Space Agency (SANSA) is monitoring the space weather storm closely and will continue to issue warnings and alerts as the storm develops.
Active region 2673 on the Sun erupted with the largest solar flare in over a decade. The flare measured in at a whopping X 9.3 causing high frequency (HF) radio blackouts across the daytime side of Earth.
LASCO image from SOHO satellite showing the CME which accompanied the solar flare on 6 Sep 2017. The CME is travelling towards Earth at speeds of over 1200 km per second and is expected to impact the Earth’s magnetic field on 8 Sep.
This image shows the high frequency black out map from the solar flare of 6 Sep 2017. Africa was greatly impacted by the black out.
NOAA geomagnetic storm scale
SANSA is host to the only Space Weather Regional Warning Centre for Africa which operates as part of the International Space Environment Service. Utilising data from NASA and ESA space weather satellites and SANSA’s ground based instruments located across Southern Africa, the Space Weather Centre conducts real-time monitoring and forecasting of space weather and provides a range of services to national power facilities, the Defence Force and other clients. These services include:
- T-Index predictions: the ionospheric index that indicates the highest frequencies that will be reflected, a critical input for HF propagation software and communications planning.
- Solar activity and geomagnetic activity indices for frequency prediction
- Daily and weekly HF prediction graphs for different signal paths, special frequency prediction and plots of signal-to-noise ratios, take-off angles and maximum useable frequencies versus time.
- Daily space weather bulletins.
- Space weather warnings and alerts.
The Space Weather Centre also presents training courses addressing the impact of space weather on HF communications and trains users on how to generate frequency predictions themselves.
For more space weather information see https://spaceweather.sansa.org.za/
Active region 2673