Sunday, November 26, 2017

Minor Geomagnetic Storm May Hit Earth on Wednesday

Credit: NASA

A G1-class (minor) geomagnetic storm may hit our planet on Wednesday, November 29, according to National Oceanic and Atmospheric Administration (NOAA). This is due to a coronal mass ejection (CME) that occurred on the sun on Saturday, November 25.

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.

NOAA noted that the latest CME could cause a minor geomagnetic storm. In result of the storm visible auroras could be visible around Earth's poles and weak power grid fluctuations could occur. Such G1-class storm could also have minor impact on satellite operations.

In general, 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.

NOAA added that generally solar activity is expected to be at very low levels until December 16. However, another G1-class or G2-class (moderate) geomagnetic storm may occur on December 4-7, due to recurrent 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-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.