From astrobites: “Cloudy with a chance of coronal mass ejections”

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astrobites

Nov 9, 2017
Kerrin Hensley

Title: Using the Coronal Evolution to Successfully Forward Model CMEs’ In Situ Magnetic Profiles
Authors: Christina Kay and Nat Gopalswamy
First Author’s Institution: NASA Goddard Space Flight Center

Status: Accepted to the Journal of Geophysical Research – Space Physics, open access

Coronal Mass Ejections and You

1
An eruption on April 16, 2012 was captured here by NASA’s Solar Dynamics Observatory in the 304 Angstrom wavelength, which is typically colored in red. Credit: NASA/SDO/AIA

NASA/SDO

Coronal mass ejections (CMEs) are immense eruptions of solar plasma and magnetic fields. When a CME strikes a planet, it can have huge effects; over billions of years, CMEs can strip away a planet’s atmosphere. In the short term, CMEs wreak havoc at Earth by causing dangerous and costly geomagnetic storms.

In 1859, a CME impacted the Earth and caused the most intense geomagnetic storm ever recorded, resulting in stunning auroral displays over much of the northern hemisphere (Figure 1) and widespread failure of telegraph systems. An event of this magnitude today would cause huge damage to power grids, satellites, and oil pipelines—resulting in a trillion dollars of damage in the United States alone. So, how can we prevent this from occurring?

Enter the growing field of space weather forecasting. Although we can’t stop the Sun from ejecting CMEs, we can try to figure out if a given CME will hit the Earth, and how severe the resulting geomagnetic storm will be if it does. The severity of a geomagnetic storm is linked to the CME’s magnetic field conditions, especially the magnitude of the southward-pointing magnetic field (i.e. the component of the magnetic field that opposes the Earth’s magnetic field at the equator). If the CME’s properties can be accurately estimated, the severity of the resulting geomagnetic storm can be estimated too, allowing for power grids and satellites to be put into safe mode if necessary.

See the full article here .

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