Wednesday, September 12, 2018

Moderately Strong Geomagnetic Storm Hits Earth


A G2-class (moderately strong) geomagnetic storm struck the Earth on Monday, September 10, when a solar wind stream hit our planet’s magnetic field. The storming continued throughout Tuesday, September 11.

The recent storm is due to the arrival of a positive polarity coronal hole high speed streams (CH HSSs). Fast CH HSSs can impact Earth’s magnetosphere enough to cause periods of geomagnetic storming to the G1 (minor)-G2 levels; although rarer cases of stronger storming may also occur. The larger and more expansive coronal holes can often be a source for high solar wind speeds that buffet Earth for many days.

Geomagnetic storms can increase the density and distribution of density in the upper atmosphere, causing extra drag on satellites in low-earth orbit. The local heating also creates strong horizontal variations in the in the ionospheric density that can modify the path of radio signals and create errors in the positioning information provided by GPS. While the storms create beautiful aurora, they also can disrupt navigation systems such as the Global Navigation Satellite System (GNSS) and create harmful geomagnetic induced currents (GICs) in the power grid and pipelines.

G2-class storm can cause voltage alarms and transformer damage in high-latitude power systems. When it comes to possible impact on spacecraft operations, in result of such storm, corrective actions to orientation may be required by ground control. Moderately strong geomagnetic storm can also spark auroras and cause fading of HF radio propagation at higher latitudes.

National Oceanic and Atmospheric Administration (NOAA) informs that solar activity is expected to be at low levels for the next three weeks, with a slight chance for C-class flare activity. Active levels of Earth’s geomagnetic fields are expected on September 13, 14 and 22 from the influence of recurrent CH HSSs.

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