Tag Archives: coronal hole

Early March G2 Aurora Strom Puts on a Global Show

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Northern Lights Now – An extended period of high solar winds, the result of a large Earth-directed coronal hole, put on a three day long show for aurora hunters in high latitudes in early March. Photographers captured aurora glows, pillars, picket fences, dancing displays and illuminated night landscapes from around the world between mid March 1 through early March 4. Here’s a spectacular time lapse video from Adam Hill showing a wave of northern lights racing westward through the sky.

This extended storm was measured by the Space Weather Prediction Center (SWPC) as 9 periods of G1 storming and one period of G2 storming over 66 hours. G1 storming means the KP reached 4.67 and aurora can be visible as far south as Toronto, the upper midwest in the United States, Seattle and Scotland and can be seen as far north as Invercargill and Tasmania in the Southern Hemisphere. G2 storming means aurora can be seen at even lower latitudes near cities such as Portland, Boise, Dublin, Hamburg, Moscow and Christchurch. This chart show the first 5 days of March with the G1 and G2 3-hour periods showing in Red.

5 days of geomagnetic activity as measured by NOAA and SWPC
5 days of geomagnetic activity as measured by NOAA and SWPC

This early march storm is the result of a coronal hole that was pointed towards earth at the end of February. The hole is shown as a dark area on AIA 193 in the image below. It exposes the high speed solar wind emanating from the solar surface. Here’s an image of the coronal hole from the Solar Dynamics Observatory:

Coronal hole in AIA 193 shown as a dark finger reaching up toward center disk from the pole
Coronal hole in AIA 193 shown as a dark finger reaching up toward center disk from the pole

Those high speed solar winds take 2-5 days to arrive at Earth, and when they do they push on the magnetosphere and can cause aurora. This means that when there is a coronal hole pointed towards Earth solar scientists can predict that there is a good chance for activity 1-3 days in advance. Watch for those predictions on the NLN 3-day aurora cast – potential G1 storming shows as orange on those charts.

Let’s enjoy the view! Here are a few of our favorite tweets from this storm:

Watch the cloud clear and the lights come out to play in this time lapse

Stan’s take shows the aurora in black and white – this really brings out the texture and shapes

This panorama is worth clicking on and viewing full screen!

Finally, one of our favorite types of aurora – the “Picket Fence”

If you would like to have a chance to see the northern lights in person, consider following the NLN twitter feed (@northlightalert) to learn more about why aurora happen and when they may be visible.

G1 Aurora Storm Watch Posted for Feb 23, 2017

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Update – The storm watch has been continued to a second day. Solar wind speeds arrived later than predicted. Aurora will continue to be possible over the next 24 hours:

SWPC extends the G1 storm watch into the 24th (green) the yellow indicate ongoing KP=4 storming
SWPC extends the G1 storm watch into the 24th (green) the yellow indicate ongoing KP=4 storming

Northern Lights Now – SWPC has issued a geomagnetic storm watch for Thursday, February 23. This means KP values could exceed 5 with aurora visible in higher latitudes. Viewing conditions will be favorable with an almost new waning crescent Moon. The confidence on this storm is a little lower than other recent storms, but is high enough to merit a watch.

The potential aurora is due to the combination of a coronal hole that was pointed towards the Earth on February 20, and a filament eruption that produces a CME from just North of the coronal hole.

The coronal hole, pictured below, is likely to produce solar wind speeds at Earth in the 500-550 km/s range. The winds could pick up anytime between 20:00 GMT on the 22nd and 8:00am GMT on the 23rd. Once wind speeds increase, if the Bz shifts southward (negative), it will indicate northern lights activity is about to increase. Monitor solar wind speed and current Bz on NLN’s DSCOVR Solar Wind Data Page to know when aurora activity is about to increase.

Coronal hole, the dark area, shown in AIA 211 image from SDO
Coronal hole, the dark area, shown in AIA 211 image from SDO

The eruption was from a filament just to the north of center disk and February 19th. Watch the eruption in the animatedGIF below. The plasma cloud is visible shooting out, mostly northward, from the location of the filament. If the material from that cloud is pulled into the solar wind, it will be accelerated and pushed toward Earth. If that happened (forecasters can’t know for sure until the solar wind arrives) it could enhance the aurora activity by increasing the plasma density and accentuating the shifts in the Bz.

AnimatedGIF showing north-center disk filament eruption on Feb 19, 2017
AnimatedGIF showing north-center disk filament eruption on Feb 19, 2017

This is a slightly lower confidence prediction because the predicted solar wind speed is moderate, and there is a good chance that none of the plasma directed was toward Earth. The plasma may move off into space well above Earth’s North Pole. The image above showing the eruption does appear to show most of the material ejected moving to the north.

Happy Hunting

Coronal Hole Prompts Long Duration Aurora Watch Dec 7th, 8th & 9th

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Northern Lights Now – A large coronal hole that crosses the Solar equator will produce conditions conducive to aurora Thursday through Saturday this week. The expected enhanced solar winds could reach 700km/s and as a result SWPC has issued a three day G1 geomagnetic storm watch. This means KP values are likely to be enhanced and there is a good chance they will exceed KP=4.67.

G1 storm watch from SWPC has been extended to three days Dec 7 though Dec 9
G1 storm watch from SWPC has been extended to three days Dec 7 though Dec 9

This coronal hole is the return of a system that produced G1 storming on previous rotations in early October and November. Looking at the form and location of the coronal hole over the last four rotations, it is clear that it is a little farther north and bigger for this rotation. Each rotation takes about 27 days. Past experience has shown that the more of the coronal hole that passes through the center of the earth strike zone, the portion of the Solar disk pointed towards Earth, the longer the period of enhanced solar winds.

Mid September View of this month's Coronal Hole
Mid September View of this month’s Coronal Hole
Mid October View of this month's Coronal Hole
Mid October View of this month’s Coronal Hole
Early November view of this month's Coronal Hole
Early November view of this month’s Coronal Hole
Current view of this month's Coronal Hole
Current view of this month’s Coronal Hole

Close NLN readers and aurora hunters will recognize that this is a different coronal hole than the large system that has been producing storming in the second half of the month September, October and November. That system appeared to have been falling losing definition in the previous rotation, so when it rotates into view over the next couple weeks, watch it to see if it has regained organization or has continued to dissapate.

For this storm, the current expect timing of G1 storming conditions is just at the beginning of each UTC day during the watch period. The timing on these specific forecasts is difficult to predict but is often a good indicator of when it is worth keeping an eye on DSCOVR Solar wind data and the current KP.

NLN AuroraCast graphic shows the G1 periods should be at the start of each UTC day during the watch
NLN AuroraCast graphic shows the G1 periods should be at the start of each UTC day during the watch

Happy Hunting!