[Dave Hancox]

Dave Hancox, on 26 February 2012 - 15:15, said:

Thanks for the heads up Glyn worth mentioning, shame though. It has been A very quiet event as it turns out.

That being said and having a look at the latest model forecast for later tonight for impact can only monitor it and see what develops.

http://www.swpc.noaa...nlil/cme-based/

[Bazmundo]

Something's bumped ACE at 21z onwards, initially northward oriented but with a little dip. The enormous increase in density (third graph, logarithmic) in the matter cloud has the ACE plots auto-adjusting. All eyes on the aurora plots even though as yet Kiruna hasn't wobbled too much - could this be too swift and not magnetically biased enough? It should have impacted the ionosphere by now, as ACE only has a lead time of 1 - 1.5hrs.

Ovation Prime isn't online for some reason.

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[Bazmundo]

So far only the initial impact trace signature from most magnetograms although Kiruna is registering more now, as are the GOES satellites. The fluctuations seem enough to stir the aurora plots a little. Density of the passing solar wind is still on the increase, hence so is the dynamic pressure on the magnetosphere as simulated. Attached are two high intensity simulated bowshocks, an hour ago and just now. Might be worth those in the north keeping an eye to the sky while the cloud is still clear and we rotate into midnight, though so far this has been a weaker response than I thought....

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[Bazmundo]

Looks like we've had a disappointing result from this CME as the magnetosphere took the initial force of the dense matter cloud but didn't reverberate nor soak up enough charge to generate aurora as we rotated through the fuller side of the oval. Aurora were observed in Scandinavia, though no surprise there really. In contrast, the middle portion of the CME did have southward magnetic orientations and danced aurora across NWrn N America (as observed by US and Canadian magnetometers between 11-21z), and also across Russia for the aft portion (POES stat oval attached) with a K-5 finale. Likely some of this was down to reverberations in the magnetosphere after the initial compression (attached magnetopause standoff distance, in R_E - Earth radii) and possibly magnetotail reflux as that also responded to an usually pressurised shock, but also noteworthy that the solar wind environment was mainly southward oriented prior so the 'finale' could have been that re-stabilising behind (less likely, as conditions have abruptly returned to 'average' since then).

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[Dave Hancox]

Not what we hoped for but some in Ne Scotland managed to capture it last night. Here's to some stronger displays. http://www.flickr.co...in/photostream/

[Bazmundo]

Dave Hancox, on 28 February 2012 - 08:46, said:

Not what we hoped for but some in Ne Scotland managed to capture it last night. Here's to some stronger displays. http://www.flickr.co...in/photostream/

Looks as though the longevity in this case was possibly down to the magnetosphere wobbling back into equilibrium with additional influx of charge from the returning IMF, and further evidence is mounting for magnetotail reflux being the cause of many post-shock aurora (not specific to this impact, but new research): http://www.scienceda...20228152214.htm

Quote

Egedal had initially proposed a theory to explain this large-scale acceleration of electrons in Earth's magnetotail -- a vast and intense magnetic field swept outward from Earth by the solar wind -- but until the new data was obtained from the computer simulation, "it used to be people said this was a crazy idea," Egedal says. Thanks to the new data, "I don't get that anymore," he says.

Solving the problem required a staggering amount of computer power from one of the world's most advanced supercomputers, at the National Institute for Computational Science at Oak Ridge National Laboratory in Tennessee. The computer, called Kraken, has 112,000 processors working in parallel and consumes as much electricity as a small town. The study used 25,000 of these processors for 11 days to follow the motions of 180 billion simulated particles in space over the course of a magnetic reconnection event, Egedal says. The processing time accumulated gradually, squeezed in during idle time between other tasks. The simulation was performed using a plasma-physics code developed at LANL that rigorously analyzes the evolution of magnetic reconnection.

Egedal explains that as the solar wind stretches Earth's magnetic-field lines, the field stores energy like a rubber band being stretched. When the parallel field lines suddenly reconnect, they release that energy all at once -- like releasing the rubber band. That release of energy is what propels electrons with great energy (tens of thousands of volts) back toward Earth, where they impact the upper atmosphere. This impact is thought, directly or indirectly, to generate the glowing upper-atmosphere plasma called the aurora, producing spectacular displays in the night sky.

[Bazmundo]

Possible glancing blow expected from a CME associated with an M-class flare in the NE quarter of the solar disc yesterday (4th, ~1050z). Plane of sky speed appears to be quite fast and impact is around tomorrow morning (6th). Analysis via imagery is ongoing. The radio burst from the M2 flare disrupted some instruments, so the earliest SOHO C3 image is 1518z (attached), but a quick look at a 'difference' comparison of that and a 1018z image shows the fresh matter outburst (also attached, greyscale) and also that some of it is directed our way. Also attached is a 1225z image from STEREO-Behind showing the outburst of matter to the upper right.

CME event alert and SWPC geomagnetic activity probabilities:

Quote

Event Issue Date: 2012-03-04 15:06:24.0 GMT
CME Arrival Time: 2012-03-06 04:29:07.0 GMT
Arival Time Confidence Level: ± 6 hours
Disturbance Duration: 13 hours
Disturbance Duration Confidence Level: ± 8 hours
Magnetopause Standoff Distance: 5.6 R_e
Tue, 06 Mar 2012 04:29:07 GMT
Tue, 06 Mar 2012 17:29:07 GMT

Geomagnetic Activity Probabilities 05 Mar-07 Mar
A. Middle Latitudes
Active 05/30/15
Minor storm 01/15/05
Major-severe storm 01/01/01
B. High Latitudes
Active 15/35/20
Minor storm 10/25/15
Major-severe storm 01/15/10

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[Bazmundo]

Most recent relevant ENLIL model run for CME detailed in previous post, apologies for quality but the GIFs weigh in a little above 2Mb and need compressing...

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[Bazmundo]

As Dave has noted in the Spaceweather Effects thread, the same active region has unleashed an X-class flare between 04z and 05z this morning, and an ENLIL run at 08z has been posted up: http://www.swpc.noaa...nlil/cme-based/ which tracks a new associated CME along the same path as the previous one (glancing blow).

SOHO wasn't knocked out this time, and saw the matter burst associated with the flare, as did Stereo-B (both attached). Also attached is an SDO AIA composite image of the full disc, with a close-up showing a beautiful eruption from the sunspot AR1429 (prob ten times the size of Earth at least).

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[Bazmundo]

More info from today's CME from Belgium SIDC:

Quote

:Issued: 2012 Mar 05 1326 UTC
:Product: documentation at http://www.sidc.be/products/presto
#--------------------------------------------------------------------#
# FAST WARNING 'PRESTO' MESSAGE from the SIDC (RWC-Belgium)
#--------------------------------------------------------------------#
The X1.1 flare from this morning was accompanied by a full halo CME
that first appeared in the SOHO/LASCO C2 field of view at 04:00 UT and
propagated at a projected plane of the sky speed of around 1300 km/s. We
expect the CME-associated interplanetary disturbance (most probably only
a CME-driven shock due to the source region position close to the limb)
to arrive at the Earth on March 7-8, possibly triggering a minor to
moderate geomagnetic storm. The eruption was associated with a strong
radio flux in the metric range.

To clarify, we're now expecting two CME's in the coming days; the first in the early hours of tomorrow (6th) and another fast shock between Wed and Thu (7-8th).

[Sam Jowett]

AR1429 seems to be sparking away nicely.... there has been a double spiking M1 flare this evening to follow the X1 and M class in the last 36 hours, along with several other high C class flares. The EMF is tilting S a bit already with strong aurora in northern latitudes: http://www.aurorasky.../live-camera/9/ - it seems likely to only get busier in the coming days...

[Bazmundo]

Certainly looks like a plump oval at the moment. The POES site is offline for upgrades, but it would appear the OVATION has a new home and a page dedicated to Europe:

http://helios.swpc.n...ion/Europe.html

[Andrew W]

Is this anything to do with the strange sounds being reported around the world in the sky?

[Dave Hancox]

Bazmundo, on 05 March 2012 - 22:53, said:

Certainly looks like a plump oval at the moment. The POES site is offline for upgrades, but it would appear the OVATION has a new home and a page dedicated to Europe:

http://helios.swpc.n...ion/Europe.html

That is a cracking format.

[Bazmundo]

Andrew W, on 05 March 2012 - 23:05, said:

Is this anything to do with the strange sounds being reported around the world in the sky?

No

[Bazmundo]

The first, and weakest, of the expected CME's has clipped us today. I've attached a combined image of ACE and Kiruna plots for comparison; remember Kiruna is only a spot location on the globe and rotates in and out of favourable aurora position, whereas ACE is some 1.5 million km away from us towards the Sun and near-stationary. The graphs have been aligned to almost match timeframe, and events are annotated A, B & C to demonstrate the lead time of detection at ACE.

A: A magnetically southward/negative (top graph) oriented solar wind, fluctuating in speed but even density. Result at Kiruna was detection of magnetic disturbance and probable aurora (in a favourable position near midnight).
B: Magnetic orientation suddenly flipped northward/positive, speed levelled off but density dropped sharply before rising gently. Result an hour later was a slight disturbance in the field (not favourably positioned). This was likely the impact of the CME shockwave. Brief aurora possible but not on our side.
C: Magnetic orientation has returned to previous level, as has density. Sudden flip again, drop in density and speed fluctuates. Kiruna responds with a building disturbance which suddenly drops away.

At 1530z ACE has returned to previous levels. Net result, probably a glancing blow from one CME resulting in a little curl at the edge/rear of the shockwave, so looks like two impacts on the magnetosphere but B-C was the passage of the matter cloud itself. If the IMF returns southward as before there could aurora tonight with additional resultant wobbles as the magnetosphere recovers from this little flick - however it's unlikely as we're also moving out of the wind stream that is magnetically southward oriented.

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[Bazmundo]

Looks like we had a big punch from the 5th Mar X1 flare-associated CME, currently Kp=6 and Alaska's getting a good light show!


Space Weather Message Code: ALTK06
Serial Number: 275
Issue Time: 2012 Mar 07 0852 UTC

ALERT: Geomagnetic K-index of 6
Threshold Reached: 2012 Mar 07 0848 UTC
Synoptic Period: 0600-0900 UTC
Active Warning: Yes
NOAA Scale: G2 - Moderate
Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washinton state.


Edit - added magnetopause standoff distance graph for this impact, it nearly reached the orbit of geosynchronous satellites - and this was a glancing blow from an associated X1 flare.

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[Bazmundo]

A run of the ENLIL model at 06z this morning confirms a large geoeffective CME due during tomorrow (8th) from the double X flare event. It doesn't slow down much, setting off at 1300km/s and arriving still tanking along at 900km/s so should give the magnetosphere quite a wobble.

Down to Kp=5 now.

[Bazmundo]

The situation tomorrow, as per an ENLIL run at 0144z today (available on the iSWA). The 06z run showed a later arrival time, but the statements so far appear to follow this earlier run.

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[Bazmundo]

From available data, it would appear that the X5.4-related Coronal Mass Ejection impacted the magnetosphere around 11z, with a very dense initial shock (SOHO) followed by a mostly northward oriented magnetic component (ACE). However, this has dipped slightly southward for periods of ten to twenty minutes which, considering that SOHO is registering a 700km/s mean velocity, could still deliver a fair amount of charge into the upper atmosphere. The IMF angle (phi) has also been wavering constantly, indicating a highly disturbed solar wind behind the shock.

GOES satellites hinted at compression of the magnetopause at around 12z, but not as severe as yesterday's compression, though a continuous estimate of Kp=5 is given. Given recent activity and the initial density, there could be a possibility of auroral generation due to lasting effects on the magnetosphere and magnetotail.

Best period will be around midnight for mid latitudes, chances becoming better from now onwards. Crooktree magnetometer has been active since the initial shock, but not to noteworthy levels, though this may change as we rotate into a favourable position. This Ovation product is the best plot to use, but check update times as per satellite passes.