Tag Archives: G1

Coronal Hole Prompts 48-Hour G1 Aurora Storm Watch December 6 2015

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UPDATE December 5, 2015: The G1 watch has been extended to 72 hours. This long duration event could produce aurora at almost any time over the next three days. Keep an eye on the KP to know when it may be possible to see northern lights in your area.

Original Post:
The expected high speed solar wind stream from a large Earth-directed coronal hole has prompted SWPC to issue a G1 geomagnetic storm watch for Sunday and Monday December 6 and 7. The coronal hole responsible for the watch, CH34, is one of three currently active coronal holes on the visible Solar disk at the moment. Coronal hole 34 is the nearly circular transequitorial dark area annotated with an orange outline on this AIA 211 image taken yesterday by SDO:

Coronal hole responsible for December 6 and 7 G1 geomagnetic storm watch
Coronal hole responsible for December 6 and 7 G1 geomagnetic storm watch

The other two coronal holes are visible in the same image. CH33 is the larger northern hemisphere dark area that has already moved past the Earth strike zone. CH35 is the long coronal hole to the South and East (to the right) of CH34. Coronal holes 34 and 35 almost appear to be merging into a single large big-dipper shaped coronal hole. You can see the demarcation clearly on the NOAA Solar Synoptic Map – coronal holes are outlined with a solid line with a hash to the inside of the coronal hole:

Synoptic Map shows Coronal Holes and active Regions
Synoptic Map shows Coronal Holes and active Regions

CH35’s extension to the north and west is responsible for second day of the extended watch. As both holes grow, there is a larger area of coronal hole pointed towards Earth for a longer time. The current 3-day forecast is calling for two 3-hour periods of KP=5 (G1 storming), with a long period of potential for G4 storming in the other times. If the Bz sets up correctly, this could turn into a long duration G1 or possibly G2 event, so stay tuned and keep an eye on the KP. Here’s the current 3-day Auroracast:

AuroraCast shows Das 2 and thee each with a period of expected KP=5
AuroraCast shows Das 2 and thee each with a period of expected KP=5

Happy Hunting!

Return of Long Lived Coronal Hole – November 28

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The transequatorial coronal hole that has been visible on the Sun since April is pointed towards Earth again today. On Each of it’s previous 4 rotations (August 12, September 8, October 4 and November 1), this coronal hole has produced solar wind in excess of 600 km/s about 3-4 days later and it has been responsible for several nice aurora displays. Here’s an image of the coronal hole during the previous four rotations and today

Long Lived Coronal Hole over 5 rotations
Long Lived Coronal Hole over 5 rotations

SWPC is anticipating the high speed stream from the CH to start arriving at Late on November 30th. Solar wind speeds will likely increase to at least 600km/s. It is likely a G1 watch will be posted for Dec 1.

Happy Hunting!

M-Class Flare Promts G1 Aurora Storm Watch For November 11, 2015

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An coronal mass ejection (CME) that resulted from a surprise M3.95 solar flare launched a from the Sun on Monday has prompted the NOAA Space Weather Prediction Center (SWPC) to issue a G1 geomagnetic storm watch for Veterans day and November 12th. As the CME arrives at Earth, aurora hunters may be treated to a display of northern lights further south than normal.

NLN Aurora cast clock from SWPC 3-day forecast shows 15 hours of G1 storming forecast.
NLN AuroraCast clock from SWPC 3-day forecast shows 15 hours of G1 storming forecast.

A G1 storm watch means that the KP, a global scale of geomagnetic and aurora activity, may reach five out on it’s 0-9 range. As the KP rises higher, aurora borealis can be seen at lower latitudes. KP=5 indicates that the lights can be seen throughout Canada, along the northern boarder of the Continental United States, Northern Europe, and southern New Zealand.

KP is notoriously hard to predict, about 50% of the time a G1 watch is in effect, the KP does not actually rise to that level, but a G1 watch also means that the KP could easily rise higher than five. If you want to know the current KP readings, your best option is to monitor live KP trackers, such as Northern Lights Now’s current live KP chart, which give an accurate KP forecast 35-70 minutes in advance.

The flare that launched the CME was a surprise. It launched from active region 2449, which had a Beta magnetic structure. Typically, active regions need to have a “delta” sunspot in their group and be classified Beta-Delta or Beta-Delta-Gamma. Nonetheless, the solar flare that launched was spectactular. Here is an animated gif of the solar region while the flare was happening. Note that this is a zoomed in image, but that the several Earths could fit in the flare area.

The M3.95 flare from November 9 from SDO imagery
The M3.95 flare from November 9 from SDO imagery over a 12 hour period

When flares eruptions are long duration, like this one was, they can generate CMEs. A coronal mass ejection is a cloud of solar plasma that shoots from the Sun. When a CME is moving towards Earth, it typically arrives between 2 and 4 days later. As the plasma cloud passes earth, it disrupts the magenetosphere and sends charged particles into our upper atmosphere. It is the interaction of those particles with the gases in out atmosphere that cause the dancing northern lights. Don’t worry though! This storm won’t be strong enough to have any impact at Earth’s surface – just enjoy the show!

Happy Hunting