Sunday, December 17, 2017

Minor Geomagnetic Storm Hits Earth

Credit: NOAA

A G1-class (minor) geomagnetic storm hit the Earth today (December 17) due to the arrival of an isolated, positive polarity coronal hole high-speed stream (CH HSS) and potential glancing blow effects from a coronal mass ejection (CME) that erupted on the Sun on Friday (December 15).

National Oceanic and Atmospheric Administration (NOAA) informs that the minor storm is expected to last until Tuesday, December 19. In result of the ongoing storming, visible auroras are concentrated around Earth's poles and weak power grid fluctuations could occur. The current storm could also have minor impact on satellite operations.

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 in the power grid and pipelines.

Fast CH HSSs can impact Earth’s magnetosphere enough to cause periods of geomagnetic storming to the G1-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.

NOAA reveals that solar activity is expected to be generally at very low levels until January 6, 2018. However, another G1-class geomagnetic storm is likely to occur on January 1, due to effects from a recurrent positive polarity CH HSS.

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