Monday, September 25, 2017

Minor Geomagnetic Storm May Hit Earth on Wednesday

Credit: NOAA

According to the National Oceanic and Atmospheric Administration (NOAA), a recurrent, positive polarity coronal hole high speed stream is expected to move into a geoeffective position on Wednesday, September 27, causing active to G1 (minor) geomagnetic storm conditions. The agency has issued a warning and is monitoring the situation.

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.

NOAA revealed that the geomagnetic field is expected to be at quiet to active levels on September 25 and quiet to unsettled levels on September 26 due to negative polarity coronal hole high speed stream effects. By Wednesday, a positive polarity coronal hole high speed stream is expected to become geoeffective causing active to G1 (minor) geomagnetic storm conditions.

Generally, coronal holes located at or near the solar equator are most likely to result in any co-rotating interaction region (CIR) passage and/or higher solar wind speeds at Earth. Strong CIRs and the faster coronal hole high speed stream can impact Earth’s magnetosphere enough to cause periods of geomagnetic storming to the G1-G2 (minor to moderate) levels; although rarer cases of stronger storming may also occur.

According to NOAA, solar activity is expected to be at very low levels with chance for C-class flare activity from September 25 to 27.

The agency also noted that solar wind parameters are expected to remain slightly enhanced for the remainder of September 25 and into September 26 under weak influence of a coronal hole high speed stream. By September 27, solar wind parameters are expected to become further enhanced as a stronger, positive polarity, polar connected, coronal hole high speed stream becomes geoeffective.

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