The Space Weather Prediction Center (SWPC) , a unit of the U.S. Department of Commerce under NOAA,which sits alongside its terrestrial National Weather Service, has upgraded their previously issued Geomagnetic Storm Watch for all of Earth. In addition to expecting G1 storm conditions on Sunday, G2 storm conditions are now expected on Monday. Also, the Planetary K-index which is an indicator of disturbances in the Earth’s magnetic field, is now forecast to spike to a KP level of 6. If this were to materialize, the aurora, also known as Northern Lights, would appear much more south than they usually are.
On Thursday, a sunspot, known as AR2871, experienced two explosive eruptions, each producing a significant M-class solar flare. Solar flares are classified according to their strength, on a B-C-M-X scale. B flares are the smallest while X are the largest. Similar to the Richter scale used to help quantify earthquakes, each letter represents a ten-fold increase in energy output. Within each letter class, there is also a finer scale that usually extends from 1-9. Within the powerful X class of flares, the number could exceed 9 to reflect a massive flare event.
While there are fears that a future blast from the sun will disrupt electricity, communication, and internet lines for weeks, this event does not seem to have that type of potential with it. However, some impacts, including an electrified display of the Northern Lights at northern latitudes, are expected.
AR2871 initially produced a M1.8 flare and a subsequent coronal mass ejection (CME). According to the SWPC, initial analysis and model run indicate an overtaking of the slightly slower CME that was also produced by region 2871 earlier on the 23rd with an arrival anticipated for the first half of September 27.
A coronal hole high speed stream, known as CH HSS for short, is due to hit the Earth by midday on the 26th. The National Weather Service’s Space Weather Prediction Center (SWPC) says, “The geomagnetic field is expected to be quiet to unsettled (today) under continued, but weakening, negative polarity CH HSS influence. The anticipated influence of a positive polarity, polar-connected, CH HSS is expected to cause periods of active and G1 (Minor) geomagnetic storm levels on (September 26) G1-G2 (Minor-Moderate) geomagnetic storm conditions are likely on (September 27) due to continued positive polarity CH HSS influence coupled with the possibility of a glancing blow from the (September 23) CMEs.”
Right now, the SWPC says there is a 15% chance of only active geomagnetic activity on the 26th, a 45% chance of a “minor storm”, a 25% chance of a “moderate storm”, and a 5% chance of a “strong-extreme storm.” Those odds increase on the 27th: 15% chance of only active geomagnetic activity, 25% of a “minor storm”, 45% chance of a “moderate storm”, and a 10% chance of a “strong or extreme storm.”
With a KP level of 6 in the forecast, the aurora could be visible in places that usually don’t see it across New England, the Great Lakes Region, and the Northern Plains. Should the KP levels increase even more, aurora could be visible in heavily populated areas of the Mid Atlantic, the Ohio Valley, and Northern Rockies.
The Sun is the primary cause of space weather. At times, the Sun can be thought of as going through a “stormy” period where its surface is more active than normal. When this happens, the Sun can send streams of energized particles out in all directions. When these energized particles interact with the outer reaches of our atmosphere, the aurora borealis (the Northern Lights) and the aurora australis (the Southern Lights) can result.
Dark regions on the Sun known as coronal holes are one of the main drivers of space weather now. According to the Space Weather Prediction Center, coronal holes appear as dark regions on the Sun because they are cooler than the surrounding plasma and are open magnetic field lines. The Sun’s outermost part of its atmosphere, which is known as the corona, is where these dark regions appear. The solar corona was also one of the main features of the Sun scientists were most excited to study during the past solar eclipse. You are able to notice these features in extreme ultraviolet (EUV) and soft x-ray solar images.
Solar wind is always flowing from the Sun and towards Earth but coronal holes are known for releasing enhanced solar wind. Coronal holes can develop anywhere on the sun and are more common during solar minimum. One solar rotation of the Sun occurs every 27 days and coronal holes are sometimes able to last several of these. It is common to see persistent coronal holes at the north and south pole of the Sun but sometimes they can expand towards the equator of the Sun resulting in a larger region. Normally, coronal holes located near the Sun’s equator, result in faster solar wind arriving at Earth. It is common to see coronal holes produce G1-G2 geomagnetic storming levels and sometimes on rare occasions, upwards to G3 levels have been met.
Geomagnetic storms are rated on a 1-5 scale, with 1 being the weakest and 5 having the most potential for damage. Even a G1 geomagnetic storm could create issues: there could be weak power grid fluctuations and minor impacts on satellite operations. Aurora, also known as the “Northern Lights”, could be visible at high latitudes from northern Michigan and Maine to points north. Impacts and aurora change as the geomagnetic storm scale increase.
NOAA forecasters analyze these features and have to take them into account during each forecast. If Earth is experiencing the effects of a coronal hole and a coronal mass ejection is forecasted to impact Earth, the combined effects could result in a more significant impact and more intense geomagnetic storming. 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. That isn’t expected this week, but such an event could happen in the future.
On September 1-2 in 1859, a 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.