Tag Archives: coronal hole

CIR and Coronal Hole Bring Quick Burst of Aurora to Northern Europe Sept 14, 2017

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Northern Lights Now – The expected G1/G2 storming from the coronal hole pointed towards Earth on Sept 11 arrived late on Sept 13. It induced a period of fast solar wind, strong Bt and G2 storming. The timing was good for our aurora hunting followers in Northern Europe who had clear skies.

Boulder Recorded Planetary K shows two periods of G2 storming in last 15 hours.
Boulder Recorded Planetary K shows two periods of G2 storming in last 15 hours.

At the onset of the storm, Bz was strongly (-15 to -18 nT) south for over half an hour at the beginning of the storm, which set up Earth’s magnetosphere to be highly activated. This means that any additional strong wind, high density, or prolonged negative Bz can quickly jump the KP back into G1/G2 range.

Bz and Bt are strong and favorable at the onset of the storm.
Bz and Bt are strong and favorable at the onset of the storm.

Here are a couple Tweets share with NLN from tonight’s storming

From the Nidderdale in northern Yorks by @HudsonWeather

From Christopher Suarez in Iceland

It is still possible that there could be additional storming. Keep your eyes on the Solar Wind Data. If there is a prolonged people (more than 45 mins or so) of negative Bz, there could be another round of storming.

Note: The current storm is likely the last for a while. There are now active regions that pose M or X class flare threats on the Sun and the next Coronal hole isn’t expected to reach Earth until late September. Make hay while the Sun shines!

Happy Hunting

2017-18 Aurora season starts with a G1 storm watch for Aug 31 and Sept 1st

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Northern Lights Now – The fall aurora season kicks off around the end of August when the nights in the Nordic countries (Sweden, Finland, Norway, Iceland and Denmark) start to get long enough and dark enough to see the northern lights. This year, the season should start off with a bang as a G1 storm is predicted that should bring a nice show.

Northern Lights Now Twitter follower Mia Stålnacke captured these pictures in Sweden earlier this week as aurora season gets under way.

Earth will come under the influence of a coronal hole, a corotating interaction region (CIR) and a solar storm over the next several days. There is a chance conditions may reach G2 on September 1st as the edge of a solar storm delivers a glancing blow.

On August 31st the high speed winds generated by the coronal hole shown below will start to push on Earth’s magnetosphere. The CH, which is the dark area on the image below, covers much of the northern hemisphere and crosses into the southern hemisphere. That means it is highly likely the winds will pick up at Earth about 3 days after the region was pointed towards Earth on the center of the disk. At about the same time, the CIR will also arrive. Current models indicate the solar wind speeds could reach between 550 and 600 km/s.

Coronal Hole Pointed Towards Earth on August 29
Coronal Hole Pointed Towards Earth on August 29

Later, on Sept 1 a small solar storm that was released during an eruption near active region 2672. Watch that eruption in this video. The eruption happened on the very western edge of the Earth stike zone and is not large. Most of the plasma emitted will miss earth to the west, but in the WSA-Enlil model below, see that the flank of the cloud may brush by Earth. Earth’s magnetosphere is likely to be activated as a result of 36 hours of high speed wind. That activation should accentuate any impact from the solar storm.

WSA Enlil model shows the solar storm and the coronal hole high speed stream (CH HSS)
WSA Enlil model shows the solar storm and the coronal hole high speed stream (CH HSS)

With this space weather setup, there is a good chance that at least one of the features will produce G1 storming (KP=5 or higher) in the next three days. If the solar storm is oriented just right, and is moving slightly faster than modeled and arrives in closer proximity to the high speed solar wind, KP values may reach G2 storm levels. Below is the official forecast from SWPC as displayed by the NLN auroraCast clock. Orange shows periods when G1 storming is expected:

SWPC is predicting days two and three with KP=4 possible in every three hour period
SWPC is predicting days two and three with KP=4 possible in every three hour period

Aurora hunters should be watching the data over the next three days and have their cameras ready.

Happy Hunting

Mid August G1 Aurora as Prelude to 2017 Eclipse

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Northern Lights Now – Just a couple days before the 2017 total eclipse in the United States, there will be another exciting astonomical event. There is a chance for Aurora on August 17 and 18. The Space Weather Prediction Center (SWPC) has issued a G1 geomagnetic storm watch for Wednesday and Thursday. Global aurora activity levels could reach KP=5 on the 0-9 scale.

The expected activity is the result of a activity from a solar sector boundary crossing during high speed solar wind stream arriving from a coronal hole. The northern hemisphere coronal hole (below) pointed towards Earth on August 15th is releasing solar winds in excess of 650 km/s. The winds, and the plasma and solar particles carried on them will start to arrive early on 8/17

Northern Hemisphere Coronal Hole shown in AIA 193
Northern Hemisphere Coronal Hole shown in AIA 193

Embedded in the solar wind there will be disturbance along the solar sector boundary. This is basically a line on the in space between a positively charged region and a negatively charged region. As the boundary passes Earth, there will be enhanced geomagnetic activity leading to Northern Lights.

Happy Hunting!