Category Archives: Solar Storm Recap

“Stealth CME” Brings G3 Storm, Research Opportunity, 1/7/2015

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Aurora hunters, solar weather watchers, and satellite operators experienced a surprise geomagnetic storm that registered KP=7.67 (G3 on the NOAA geomagnetic storm scale) Thursday. The storm arrived just after sunrise on January 7th for the US East coast, but allowed people in mid and western North America to see northern lights just before sunrise. Some lucky people in New Zealand saw faint aurora as dusk was setting in.

This was the strongest geomagnetic disturbance since the arrival of a CME associated with a filament eruption October 1, 2013. In total, there was a period of about 75 minutes where the KP value was above 7. At it’s peak, the ovation model was showing a wide swath of activity above most of Central and Western Canada. (click to see image larger)

G3 Geomagnetic Storming on January 7, 2015
G3 Geomagnetic Storming on January 7, 2015

The storm was nearly a complete surprise. No watches were posted in advance, and it wasn’t until nearly a day after the CME’s arrival that plausible theories were suggested as a source of the storm. It now seems likely that this “Stealth CME” was launched from an area near a large southern hemisphere coronal hole. We’ve seen CME activity correlated with coronal holes in the past. A discussion on Twitter between Dr. Tamitha Skov (@TamithaSkov) and @haloCME was the first place NLN saw this suggestion:

As the hole expanded, it may have released a CME. NLN edited a larger before/after version of the AIA 211 you can click on to see the coronal hole expansion in detail. Here, we circled the arcade hanging over the upper right portion of the coronal hole in the before image. In the after image from about 12 hours later, the hole is clearly larger, and the arcade is gone:

Before and After Coronal hole expansion
Before and After Coronal hole expansion

There are several plausible theories about why the disappearance of the arcade may have caused a CME:

  • Did the arcade lift off the sun and become the materiral of the CME as it was propelled into space?
  • Did the arcade collapse and launch a CME?
  • Was the arcade dissipation correlated but unrelated to a CME that happened as a result of the expanding coronal hole?

Events like this leave more questions than answers and are part of what make understanding space weather exciting. Studying this CME event and others like it will make for excellent doctoral theses and post-doc research projects. These research projects will expand the space weather community’s understanding of our Sun. Maybe next time we’ll predict the arrival of the next “stealth-CME” and the onset of the geomagnetic storm. Are you still looking for a PhD thesis? This might be a good place to start!

Happy Hunting!

Coronal Hole High Speed Stream Means Possible Aurora Dec 6 2014

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KP value readings have been between 4 and 5.33 this evening. This means possible aurora in northern Europe, Iceland, Greenland, Canada and the northern United States.

Tonight’s active space weather is primarily the result of a large coronal hole in the southern hemisphere of the Sun. It was pointed towards Earth about 3 days ago. Coronal holes elevate the solar wind speed, and higher wind speeds make geomagnetic storming more likely. Here’s an image of the coronal hole in SDO AIA 211 wavelength from December 4, 2014 – two days ago. You can see the dark area in the southern hemisphere very clearly.

Coronal Hole
Clear Southern hemisphere Coronal Hole in AIA 211 from 12/4/2014

Tonight that wind is arriving at Earth. We’re seeing Wind Speeds recorded at the ACE satellite of over 750 km/sec. This chart of the last two hours of solar wind speed is from SpaceWeatherLive.com as measured by the ACE Satellite.

Solar Wind Speed is elevated from CH HSS arrival
Solar Wind Speed is elevated from CH HSS arrival

We’ve been watching the KP flirt with storm level all evening on our Real-time live KP charts. The higher the KP goes, the more likely places further south are to see the Northern Lights.

As exciting as it is that there may be aurora tonight, there is one major factor making it hard to see the show. It is a full moon – the Cold Moon. The moon will be high and bright. Any additional light in the skies makes it harder to see the faint glow of Aurora.

Happy hunting!

Busy Day For Aurora Activity and Space Weather 10/14/2014

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After about 10 days of very quite solar weather news, today we’ve seen several events. It is likely this is the start of the next uptick in solar activity.

First – Aurora are being reported in Northern Europe and Iceland already this evening. Do you have a picture you would like to share? We’re seeing elevated KP. So far the KP has been as high as 5.67. This is resulting from the arrival of higher solar wind speed which was perfectly timed and coincided with a shift to negative Bz. Here is the Bz Chart from spaceweatherlive.com

The Bz is south at the same time as solar wind speed increases
The Bz is south at the same time as solar wind speed increases

Second – There is a large filament rotating into view on the solar disk. This should be pointed towards earth in about 7 days. If it erupts while facing Earth, we could see a CME arrival at Earth.

Third – Two M-class flares were launched today from an Active Region that is rotating onto the disk. The first was an impulsive M1.1 flare. The second is a very long duration M2.28 flare. These won’t produce Earth-directed CMEs, but as they rotate, it is likely they will continue to produce flares.

Enjoy the show tonight, and keep tuned as next week may be very active.

Happy Hunting!