Sunday, July 16, 2017

Geomagnetic Storms Underway After Coronal Mass Ejection from the Sun

Credit: NOAA

Geomagnetic storms are underway today following a coronal mass ejection (CME) strike from the sun at 5:45 UTC. Auroras have been sighted in New Zealand as well as U.S. states such as Washington and Wyoming. The storms are intensifying as Earth moves into the CME's magnetized wake.

CMEs are huge explosions of magnetic field and plasma from the sun's corona. When CMEs impact the Earth’s magnetosphere, they are responsible for geomagnetic storms and enhanced aurora. The fastest CMEs erupt from large sunspot active regions, powered by the strongest magnetic field concentrations on the sun. These fast CMEs can reach Earth in as little as 14 to 17 hours.

The sunspot responsible for today’s CME, designated AR2665, is rotating toward the sun's western limb, turning away from Earth. It still poses a threat for solar flares and CMEs, but future eruptions won't likely be Earth directed. Nevertheless, this sunspot will still affect our planet in the days ahead.

National Oceanic and Atmospheric Administration (NOAA) reveals that G1-G2 (minor-moderate) geomagnetic storms are expected on July 16-17 due to CME effects. There is also a chance for S1 (minor) solar radiation storms on July 16-18 due to the flare potential of AR2665. When it comes to radio blackout forecast, NOAA informs that there is a chance for R1-R2 (minor-moderate) radio blackouts in the coming 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.

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