[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.

Attached thumbnail(s)

• 

[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.

Attached thumbnail(s)

• 
• 
• 

[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.

Attached thumbnail(s)

• 

[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.

[Dave Hancox]

We also have this alert but no sign on the model http://www.swpc.noaa...nlil/cme-based/ Not sure (I see now its an earlier alert for the same event and was updated to 0625 this morning)

Event Issue Date: 2012-03-06 14:18:39.0 GMT
CME Arrival Time: 2012-03-08 23:59:04.0 GMT
Arival Time Confidence Level: ± 6 hours
Disturbance Duration: 11 hours
Disturbance Duration Confidence Level: ± 8 hours
Magnetopause Standoff Distance: 6.3 R_e
Thu, 08 Mar 2012 23:59:04 GMT
Fri, 09 Mar 2012 10:59:04 GMT

[Stuart Robinson]

I tend to use this product - the red view line is acually quite accurate.

http://helios.swpc.n...tion_Europe.png

[ChaserUK]

what are these strange sound reports? Sorry a bit off topic perhaps?

[Tony Sales]

clear spells over Northumberland, hope they persist past Midnight

[00ctober]

Surprisingly clear here currently, in fact it's clear right across the West. No sign of anything here yet though even with some good clear spells to the North and the moon covered by the cloudier skies to my East.

[Bazmundo]

Stuart Robinson, on 08 March 2012 - 19:53, said:

I tend to use this product - the red view line is acually quite accurate.

Sorry Stu, was out earlier, this is a good model but it's underestimating due to a reduced feed of data from ACE at the moment. The density, speed and temp readings are being corrupted by the associated Solar Energetic Particle event.

The old Ovation is reading off passes of DMSP satellites through the ionosphere and is noticeably stronger:

Attached thumbnail(s)

• 

[Bazmundo]

AR1429 again, this time an M6.3 flare and associated CME at 04z first detected by SOHO C2 and unsurprisingly earth-bound given that the sunspot group is nearly face-on. Expected on Sunday 11th. I've highlighted the crucial points, but it's good to see that RWC Belgium are on the ball wrt to false shock signatures in SOHO wind data and (unrelated) a corrected CACTUS alert concerning a proton surge in SOHO imagery mimicking a halo CME late last night.

Quote

PRESTO FROM SIDC - RWC BELGIUM Fri Mar 9 2012, 1323 UT

Catania sunspot group 65 (NOAA AR 1429) started to decay, although it still maintains the beta-gamma-delta configuration of its photospheric magnetic field. We expect M-class flares from this active region, although an X-class flare is still not excluded. An unnumbered sunspot group appeared from behind the north-east limb and produced a CME (not a halo) this morning. C- and even M-class flares are possible in this active region.
SOHO/LASCO detected a full halo CME in association with the M6.3 flare in Catania sunspot group 65 (NOAA AR 1429) this morning. The CME first appeared in the LASCO C2 field of view at 04:14 UT and had a speed around 750 km/s. We expect the CME arrival at the Earth late on March 11 - early on March 12. An evaluation of the possible erupting flux rope orientation on the basis of HMI photospheric magnetograms and AIA images of the post-eruption arcade gives the south-east-north (SEN, left-handed) configuration. Due to the position of the CME source region close to the solar central meridian, we expect a nearly central encounter of the resulting ICME, which will probably be a magnetic cloud with leading southward field. A strong geomagnetic storm (K = 7 or higher) is probable.
The Earth is now inside the post-shock solar wind flow generated by the ICME corresponding to the halo CME erupted on March 7. The interplanetary magnetic field (IMF) is currently southward, resulting in a severe magnetic storm (K = 7 reported by NOAA). Although the IMF magnitude is not very high (around 10 nT), it was strongly fluctuating in the past 24 hours, so a further development of the storm is not excluded. The solar wind speed measured by SOHO/CELIAS is currently high (around 900 km/s) and CELIAS data exhibit two important discontinuities in the solar wind speed today (at 03:44 UT and 08:18 UT). Neither of these discontinuities seems to correspond to a sudden increase of the IMF magnitude measured by ACE, so they do not appear to be shock waves.

This morning's SWPC ENLIL run makes for an earlier impact time, so we'll have to wait and see what the SWPC say at 22z. NASA Goddard's ENLIL run (available on the iSWA) is even earlier, and they've released this prediction:

Quote

Event Issue Date: 2012-03-09 06:26:04.0 GMT
CME Arrival Time: 2012-03-11 08:20:05.0 GMT
Arival Time Confidence Level: ± 6 hours
Disturbance Duration: 11 hours
Disturbance Duration Confidence Level: ± 8 hours
Magnetopause Standoff Distance: 5.4 R_e

That other active region coming over the NE limb will need watching, it had a huge arc visible over the horizon (limb) yesterday evening.

[Bazmundo]

A comparison of ACE and SOHO solar wind data indicates the CME impacted at 1300z, with an increase to high density particle flux and a change to the phi angle. The magnetic orientation is turning southward in the last half hour, so could begin to charge up some aurora for tonight.

Yesterday's M8 flare and prior C8 flare both had CMEs, the M8's is expected to be geoeffective and fast-moving and should actually arrive this evening, whereupon we'll be in the right position for the initial magnetoshock wobble which is needed for pushing aurora further south. The best heads-up for this will be ACE/SOHO solar wind speed data, with just under an hour lead time given how fast the CME will be.


The nearby magnetometers are already twitching to indicate the wobbles in the overall field from the 13-14z impact, but we won't see any substorm disturbance until we rotate into a favourable position into the dark side for which Kiruna and the other Scandi magnetometers should give a heads-up.

[Sam Jowett]

Aren't the C8 and M8 due tomorrow evening around 6pm Glyn?... that's what I'd read elsewhere...

[Bazmundo]

Sam Jowett, on 11 March 2012 - 17:41, said:

Aren't the C8 and M8 due tomorrow evening around 6pm Glyn?... that's what I'd read elsewhere...

According to the 22z SWPC update on the 10th (yesterday), the 9th March CME is due today (arrived already) and the second CME (from the M8 flare) is also due late on day 1 (11th March):

Quote

Geophysical Activity Forecast: The geomagnetic field is expected to be quiet to unsettled early on day 1 (11 March) until the arrival of the 09 March CME followed by today's CME associated with the M8 flare. Models show an arrival of the first CME early to midday on 11 March which is expected to cause minor to major storm conditions with isolated severe storm periods likely. Initial estimates on the second CME indicate an arrival late on day 1. Activity is expected to continue into day 2 (12 March) with minor to major storm conditions with isolated severe storm periods possible. Conditions are expected to decrease to unsettled to active levels by day 3 (13 March). The greater than 10 MeV proton event is still on-going and will likely be further enhanced by the M8 flare that occurred today as well as further enhancements from shock arrivals on 11 March.

The latest available ENLIL from the SWPC shows it as on the 13th, and the latest Goddard ENLIL run shows it as the 12th (6pm, as you've seen stated elsewhere) but they haven't published a predicted ETA on the iSWA cygnet yet. SIDC RWS Belgium expect it "early on the 13th". I've given up trusting the ENLIL runs explicitly, they are experimental after all, so only take available info from those sources as and when they update.

Given the source of the CME is face-on, if there's a chance of an impact as early as tonight I thought I'd give a head-ups here. Also, the eruption time was near 18z so an impact tonight at midnight would still be a travel time of 30hrs at just under 1400km/s, which is believable for a matter cloud emanating with such a punch behind it. Filament eruptions tend to produce slower CMEs.

Keep an eye on the SWPC link for the update at 22z. Maybe I'm just hopecasting...

[Sam Jowett]

Quite a variety of forecast arrival times then... good to see the weather forecast is clear for many!

[Flatlander]

Bright green aurora visible, with active streamers. Best I've ever seen.

Tim, gallivanting in Blair Atholl, N Scotland

PS Shame that I HAVE NO TRIPOD. AAAAGH.

[John Mason]

Here, the cloud is back! We have 8/8 again. Enjoy, Tim!!

Cheers - John

[Tony Sales]

Tim Prosser, on 11 March 2012 - 20:21, said:

Bright green aurora visible, with active streamers. Best I've ever seen.

Tim, gallivanting in Blair Atholl, N Scotland

PS Shame that I HAVE NO TRIPOD. AAAAGH.

Is this a recent report!?

[John Mason]

I reckon so Tony, looking at the oval. Anyone north of the Midland Valley should see this..... it'd be good to be up there with them.

Cheers - John