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COMMENTARY: Mixed Reports About Source of Earth-Directed CME Trigger Wave of Geomagnetic Confusion

SOURCE OF CONFUSION. Sunspot 1402 erupted on Thursday, January 19, 2012, however some websites reported this M-Class Flare originated from Sunspot 1401, causing confusion about when the Coronal Mass Ejection would be arriving at Earth. (YouTube Video: Special Thanks to Solarham.com / Solar Dynamics Observatory / EUV Variability Experiment / Solar-Terrestrial Relations Observatory)


By James Pugsley
Astronomy North

(YELLOWKNIFE, NORTHWEST TERRITORIES) When the eruption of an M3.2-Class solar flare occurred on January 19, launching a Coronal Mass Ejection (CME) in Earth’s general direction, geomagnetic forecasters quickly began predicting the trajectory, intensity and size of the expanding cloud of plasma. It didn’t take long for analysts at spaceweather.com and the Goddard Space Weather Lab to declare that Earth was in the direct path of the CME, and that a significant geomagnetic storm would be imminent on Saturday, January 21…likely around 22:30 UT (midday in Canada), give or take a few hours. In the same article it was identified that the CME originated from sunspot 1401.

Much like the solar flare itself, this story erupted. Mainstream and social media came alive with warnings and alerts, and why shouldn’t they…we don’t get Earth-directed events every day. True, this flare was not nearly as impressive as an X-Class event, but any kind of direct impact is media friendly. With so much chatter and Saturday’s “Extreme” geomagnetic forecast on the University of Alaska Fairbanks website it was no wonder the public was now bracing for auroras above Canada and the U.S. on Saturday.

Sunspots 1401 and 1402

What the media missed, however, is that there were multiple other space weather websites reporting that the flare did not originate from Sunspot 1401, rather it was the nearby Active Region 1402 that launched the CME, featuring a sunspot of gigantic proportions that is a small (but relatively significant) distance “North” of Sunspot 1401. The case for 1402 was reinforced on Friday when the National Oceanic and Atmospheric Administration announced a less optimistic geomagnetic forecast for the weekend, declaring that the incoming CME that originated from 1402 on Thursday would not result in a direct impact, but rather it would deliver a glancing blow, likely to trigger a minor geomagnetic storm beginning on January 22.

It seems the next 24 hours will have a direct impact on the credibility of space weather experts. Data collected close to Earth will tell the story about which sunspot was responsible for the CME. If impact is weak and does not arrive on January 21, the source of the event was most likely 1402, and a tip of the cap goes to NOAA forecasters.

So what created this wave of confusion? A lack of consensus on the source of the CME. If experts agreed that the event did indeed originate from 1401, there would be little disagreement about this weekend’s geomagnetic forecast. But if the source was 1402, the trajectory data is very different, and so is the arrival time, intensity and event duration.

This likely occurred because Sunspot 1401 and 1402 are somewhat close to each other, though a contributing factor may be that some analysts are making predictions using instruments (ie STEREO) that are designed to observe expanding clouds of plasma, not the source of the CME. In this case, the absence of consensus prior to calculating the CME arrival time resulted in a minor media frenzy that delivered mixed information in the public.

From an aurora forecaster’s point of view, it’s already hard enough to predict when a geomagnetic event is going to occur, but it’s even harder when there is a difference of opinion about the source of the CME.

Ultimately it appears the folks at Spaceweather.com and Goddard will have to answer to their critics if their January 21 predictions do not come true. Of course, if they do come true, they reap the rewards…but should do so with a side order of humble pie. Predictions about major solar storms should be handled with care, and in some circumstances (like this one) sites like Spaceweather.com should consider more than one scenario…in this case, they chose not to let the public know about 1402 and/or other possible outcomes this weekend.

Either way, skywatchers in the North (including northern BC, AB, SK, MB, ON, QC and NL) should be on alert for spectacular displays of auroras over the next few nights. Further south, skywatchers across Canada and the northern United States should be on alert for auroras, but should also be prepared for heightened levels of frustration if events don’t turn out as some analysts originally predicted.

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