A Severe-Extreme (G4-G5) geomagnetic storm rocked the Earth’s atmosphere over the last 48 hours, creating a violent situation high above the surface which in turn created incredible aurora or Northern Lights in places that normally don’t see them around the hemisphere. However, according to the experts at NOAA’s Space Weather Prediction Center (SWPC), things are getting back to normal.

According to the SWPC, solar wind parameters began today strongly enhanced from the arrival of the November 9-10 coronal mass ejection (CME.)  “Solar wind speeds were initially around 730 km/s before the instrument began to show signs of contamination and became unreliable until 12/1000 UTC. Total field reached a high of 63 nT at 12/0035 UTC with the Bz component reaching a maximum southward  deflection of -52 nT. Total field continued around 18-43 nT thereafter with periods of southward Bz near -28 nT. Total field began to decrease after 12/1115 UTC until the arrival of the 11 Nov CME at 12/1853 UTC,” writes the SWPC in a very technical forecast discussion.

Solar wind parameters are expected to continue to be enhanced today as CME activity persists. Activity is expected to gradually subside tonight into tomorrow, with a return to  near nominal levels expected by November 15.

The atmosphere became excited this week from geomagnetic response  related to a series of coronal mass ejections (CME) that  erupted from the Sun towards the Earth  days ago. The result was a severe-extreme geomagnetic storm that drove the aurora through south Florida, the Texas Gulf coast, and even into central Mexico and Hawaii. A similar response was had in the southern hemisphere, where the phenomena there is known as “Aurora Australis” or “southern lights.”  Aurora lit up the night skies around the southern half of Australia and much of New Zealand.  In addition to lighting the night sky with aurora, these events can also damage or destroy electrical systems, including power plants, and other communications and navigations systems based on Earth and just above it in orbit.  Geomagnetic storms are rated on a 1-5 scale by the SWPC, with 1 considered minor and 5 considered extreme.

Coronal mass ejections (CMEs) are eruptions of solar material and strong magnetic fields. When they arrive at Earth, a geomagnetic storm can result. Fast wind streams from features called Coronal Holes can also drive geomagnetic storms.

The probability and location of aurora displays is based on the Kp index of the storm. The K-index, and by extension the Planetary K-index, are used to characterize the magnitude of geomagnetic storms. The SWPC says that Kp is an excellent indicator of disturbances in the Earth’s magnetic field and is used by SWPC to decide whether geomagnetic alerts and warnings need to be issued for users who are affected by these disturbances. Beyond signifying how bad a geomagnetic storm’s impact can be felt, the Kp index can also help indicate how low, latitude-wise the aurora will be. During this multi-day event, the Kp index went as high as 9.

 

Coronal Mass Ejections (CMEs) are large expulsions of plasma and magnetic field from the Sun’s corona. They can eject billions of tons of coronal material and carry an embedded magnetic field, frozen in flux, that is stronger than the background solar wind interplanetary magnetic field (IMF) strength. CMEs travel outward from the Sun at various speeds, with some reaching the Earth as quickly as 15-18 hours and others requiring days to arrive. According to the SWPC, CMEs expand in size as they propagate away from the Sun and larger ones can reach a size comprising nearly a quarter of the space between Earth and the Sun by the time it reaches our planet.

As the CME interacts with Earth and its magnetosphere, a variety of things could unfold based on the amount of energy hitting and the angle it impacts the Earth. Power system voltage irregularities are possible and false alarms may be triggered on some protection devices.  Minor impacts on satellite operations could also be possible, with intermittent satellite navigation (GPS) problems likely.  Should the geomagnetic storm become stronger, aurora could be brighter and could appear even more south while impacts to electrical systems could be more severe.

NOAA forecasters analyze a variety of solar data from spacecraft to determine what impacts a geomagnetic storm could produce.   Analyzing data from the DSCOVER and ACE satellite is one way forecasters can tell when the enhanced solar wind from a coronal hole is about to arrive at Earth. A few things they look for in the data to determine when the enhanced solar wind is arriving at Earth:

• Solar wind speed increases
• Temperature increases
• Particle density decreases
• Interplanetary magnetic field (IMF) strength increases

While these solar events can help illuminate the sky with stunning aurora, they can also do considerable harm to electronics, electrical grids, and satellite and radio communications.

The 1859 incident, which occurred on September 1-2 in 1859, is also known as the “Carrington Event.” This event unfolded as  powerful geomagnetic storm struck Earth during Solar Cycle 10. A CME hit the Earth and induced the largest geomagnetic storm on record.  The storm was so intense it created extremely bright, vivid aurora throughout the planet: people in California thought the sun rose early, people in the northeastern U.S. could read a newspaper at night from the aurora’s bright light, and people as far south as Hawaii and south-central Mexico could see the aurora in the sky.

 

The event severely damaged the limited electrical and communication lines that existed at that time; telegraph systems around the world failed, with some telegraph operators reporting they received electric shocks.

A June 2013 study by Lloyd’s of London and Atmospheric and Environmental Research (AER) in the U.S. showed that if the Carrington event happened in modern times, damages in the U.S. could exceed $2.6 trillion, roughly 15% of the nation’s annual GDP.

While typically known for their weather forecasts, the National Oceanic and Atmospheric Administration (NOAA) and its National Weather Service (NWS) is also responsible for “space weather.” While there are private companies and other agencies that monitor and forecast space weather, the official source for  alerts and warnings of the space environment is the Space Weather Prediction Center (SWPC). The SWPC is located in Boulder, Colorado and is a service center of the NWS, which is part of NOAA. The Space Weather Prediction Center is also one of nine National Centers for Environmental Prediction (NCEP) as they monitor current space weather activity 24/7, 365 days a year.