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Coronal Hole High Speed Stream Now Impacting Earth – Live Updates

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Northern Lights Now – The Coronal Hole High Speed Wind Stream (CH HSS) that prompted the Jan 6, 2016 G1 #aurora watch started arriving at Earth just past Midnight GMT On Jan 6. Rather than updating the original article, NLN will be posting updates to this blog post instead, please come back soon for more updates!

13:44 UTC January 7, 2015 (08:45AM EST)

Solar winds are now gradually subsiding. This period shows too much variability in the Bz to produce wide-spread aurora.

23:45 UTC January 6, 2015 (18:15PM EST)

Around 21:45 UTC the Bz shifted softly to the south with measurements in the -2 to -4nT range at the ACE satellite. This is very mildly south, but it lasted for about 75 minutes. It was enough to start an aurora show in Finland. Here’s a skycam framegrab taken from the Sodankylä Geophysical Observatory from about an hour after the negative Bz was measured at Earth:

Aurora skycam from Sodankylä Geophysical Observatory in Finland
Aurora skycam from Sodankylä Geophysical Observatory in Finland

17:15 UTC January 6, 2015 (12:15PM EST)

Solar wind speeds have decreased slightly over the last 12 hours to around 525-550 km/s. In the last 2 hours readings have become more volatile. The Bz has stayed consistently north. As such, there have not been any signs of aurora. It is still possible that any transients or small CMEs traveling along the wind stream could push the Bz one way or the other. If that happens, there will be about 45 minutes of lead time.

04:15 UTC January 6, 2015 (11:15PM EST)

Just after midnight UTC solar wind speed started increasing. Reading moved up from 450km/s to 625km/s at the same time there was a 90 minute period of south point Bz. Together, these events pushed ground based KP monitors to register a KP of 4.67 (G1) for the 00:00 – 03:00 period. Wing KP responded by over-estimating the predicted 60 minute KP with a reading of 5.67 even though the Bz subsequently shifted to the north. The is expected to be a long duration high solar wind speed event, so there are ample opportunities for more aurora over the next 24-36 hours. Here’s the ACE data from SWPC with the increase in wind speed annotated:

Annotated ACE satellite date show increase in solar wind speed around midnight UTC
Annotated ACE satellite date show increase in solar wind speed around midnight UTC
WingKP registered a short term forecast of KP=5.67 around 03:45 UTC which was likely an over-estimate of actual conditions
WingKP registered a short term forecast of KP=5.67 around 03:45 UTC which was likely an over-estimate of actual conditions

Through this, there was a brief period where we’d have expected to see Aurora at lower latitudes. During that window this tweet came in from Scotland marking the first photographed aurora from this storm:

Winter Solstice 2015 Solar Storm Recap

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Northern Lights Now – On December 20th and 21st of 2015 the third largest geomagnetic storm of solar cycle 24 treated aurora hunters to 30 hours of dancing lights. The long duration of the storm gave nighttime photographers in North America two opportunities to see the northern lights through gaps in the clouds. Aurora reports on Twitter filled the NLN feed with images first from Wisconsin, then Alberta, Alaska, New Zealand, Northern Europe, Austria, Germany, England, Ireland, Iceland and then the North America again. Here is a chart of the official NOAA/SWPC recorded KP values from Boulder during the storm:

Boulder recorded 30 hours of G1-G2 storming during the winter solstice storm. of 2015
Boulder recorded 30 hours of G1-G2 storming during the winter solstice storm. of 2015

This solar storm started from two events on the Sun’s surface. The first was a long duration C6.69 flare at nearly dead center in the Earth strike zone. The second was a filament eruption to the south and east of the first eruption. Both events produced CMEs. Read more about the pair of eruptions NLN’s initial blog post on this storm.

Giants Causeway in Northern Ireland by Roy Smith Photo:

The CMEs from these two storms arrived later than initially predicted. Initial predictions were that the leading edge of the CME would reach Earth early in the day on December 19. The CME’s initial interplanetary shock was detected in ACE satellite data around 1520 GMT. Those 15 hours were time that many nighttime photographers wished they were sleeping instead!

Once they arrived, the two storms hit in sequence, not quite merging. As the storms played out, both had strongly negative Bz. Negative Bz is an aurora hunter’s dream. Once the field shifts south, a good show is sure to come – but we never know Bz until Earth is in the CME cloud. Space Weather scientists are still anticipate a long time before Bz can be accurately predicted in advance of a CME arrival. For now, forecasters assume arriving CMEs plasma clouds have a roughly 50/50 chance of being oriented with a Bz south.

In the Winter Solstice Storm of 2015, once the Bz shifted south, it stayed strongly south for 32 hours from 02:30GUTC on the 20th through 1030UTC on the 21st. During that time, the Bz deflection remained around -16 to -18 nT. Interestingly, after the initial shock, solar wind speeds stayed relatively low at below 450km/s for the duration of the storm. Had solar wind speeds been stronger, it’s possible that G3 level storming might have occurred. The slow wind speeds probably increased the duration of the storm (if the CME was moving faster, it would have completed it’s pass by Earth more quickly).

With a special shoutout to @VirtualAstro who helped surface some of these, here are some of our favorite images from this worldwide display of northern lights:

Swirls of green glow behind snow covered pine trees in Alaska by David W. Shaw

Green and yellow arches in the sky behind a church in Alberta by Célestine Aerden:

A string of pearls in the sky, technically called Auroral Beads, @Inukphysiker called this “lightsabors in the sky”

Another star wars reference came from Notanee Bourassa with this light-sabor aurora selfie

Team Tanner in Alberta often captures wonderful northern lights images, this anelic set was from Theresa (Tree) Tanner:

Finally, a stunning backdrop of purples and greens behind a solitary KW photography in Upstate New York:

Happy Hunting!