Recurrent coronal hole, possible kp5+?

[Kp6]

I know there's quite a few members on here take an interest in observing and imaging the aurora and I would like to share a few thoughts and gauge opinion.

Last month on the 6th of January the effects from a large trans-equitorial coronal hole hit earth sparking a geomagnetic storm measuring kp5. I was fortunate to see this display as it was just after midnight when it struck and was minutes from going to bed for the night.

It wasn't blazing streaks of light overhead but a definite glow of green arcing about 15 degrees above the northern horizon with a very faint pinkish/red above that to around 20 degrees. It was the first display I had seen since May 2010.

Now (nearly) 27 days later, this coronal hole has completed its rotation around the sun and is now earth directed once again, It looks larger than it did last month. Spaceweather.com referred to it initially as 'doughnut' shaped, later revising to a 'croissant' shape. I've been eagerly anticipating the arrival of this 'ch' because of it's impressive effect on our geomagnetic field last month.

My calculations determine that the effects from this coronal hole (ch435) will meet earth's magnetosphere on the 3rd of February but earlier today we had a magnetic disturbance sufficent enough to bump the kp to 4. Here's what tonights NOAA space weather report says.

Geophysical Activity Summary 31/2100Z to 01/2100Z:

The geomagnetic field was mostly quiet to unsettled until a period of

active conditions occurred at mid latitudes at 01/18Z associated

with the onset of recurrent coronal hole effects.

I'm now a little bit confused, are they wrong? I feel as if they might be and that this disturbance could possibly be related to the 27th Jan CME eruption on the sun's western limb.

However on the 28th Jan spaceweather.com writes (with regard to this CME)

Earth is not in the line of fire. No planet is. The plasma clouds ejected by these blasts will billow approximately midway between Mercury and Venus tomorrow without disturbing either world. After that, the clouds should dissipate harmlessly in the outer solar system.

Normally when I'm expecting geomagnetic disturbances I will leave the magnetometer running on the laptop which is a slight inconvenience but important none the less if I'm to catch the onset of a solar storm.

At this point I would normally say 'show's over, the coronal hole has shown it's hand' but on this occasion I think NOAA has possibly got it wrong and I will continue keeping an eye out for developments over the next 24-36 hours.

Also worth mentioning is this.

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 030 Issued at 2200Z on 30 Jan 2011

IA. Analysis of Solar Active Regions and Activity from 29/2100Z

to 30/2100Z: ................. A faint partial-halo CME,

visible in STEREO behind C2 imagery at 30/0310Z and LASCO C3 imagery

at 30/1954Z, indicate the CME is earthward directed. SDO/AIA 193

imagery associates this event with the 26 degree filament liftoff

observed yesterday at 29/1219Z.

I doubt this had anything to do with today's magnetic disturbance either. I think this will accompany the coronal hole wind stream enhancing it further. If my memory serves me right this CME measured B8 on the x-ray flux.

With all that said I would be interested in any other opinions out there not only on today's disturbance but also on this recurrent coronal hole, the 'partial halo cme' and their potential effects.

Thanks

[msinclairinork]

My opinion is....you should work at NOAA!! damn your good at this stuff!

I lost you on the second parograph but boy you did convince me all the same!

I belive you George!

Michael

[ako]

can i ask what magnetometer your using???

many thanks

matt

[Kp6]

Hi, This appeared on spaceweather.com sometime in the last few hours.

GEOMAGNETIC STORM WATCH: NOAA forecasters estimate a 60% chance of polar geomagnetic storms on Feb. 3rd. They say a high-speed solar wind stream and a CME could hit Earth's magnetic field on Wednesday--a double whammy almost certain to spark some degree of geomagnetic activity. High-latitude sky watchers should be alert for auroras.

It seems I was right.

can i ask what magnetometer your using???

many thanks

matt

Hi Matt, my preference is the magnetometer in Crooktree, Aberdeenshire due to it's locality. AuroraWatch Real-time Activity (Crooktree)

My opinion is....you should work at NOAA!! damn your good at this stuff!

I lost you on the second parograph but boy you did convince me all the same!

I belive you George!

Michael

I'm sorry Michael, I'm not the best with words I'm afraid. You should hear me trying to tell jokes, always back to front and timing the golden punchline poorly!

Basically noaa said a solar wind stream from a large coronal hole hit us yesterday but I didn't agree with that, I felt it was too early. I've never doubted or questioned their opinion or forecasts before and that was one of the reasons I made this post. The other reason is that I anticipate a 'reasonably' strong geomagnetic storm, One that should be powerful enough to see the northern lights from anywhere north of 54N.

Means very little though if the skies don't clear up.

[george7378]

I think it will be clear in the early hours of the morning for me - is it worth getting up to have a look? I want more than anything else to get a glimpse of aurora, but I will probably be asleep for the rest of the day if I get up too early!

[Kp6]

I think it will be clear in the early hours of the morning for me - is it worth getting up to have a look? I want more than anything else to get a glimpse of aurora, but I will probably be asleep for the rest of the day if I get up too early!

Hi George, the best time to view the aurora is between 10pm and 2am local time. Viewing before/after these times is still possible if there's a strong enough burst of geomagnetic activity. The effects of the aurora are most prevalent directly opposite the noon meridian, so midnight is the best time at any given location.

If you are lucky enough to have clear skies my suggestion would be to keep an eye on the magnetometer at the above link up until 1 or 2am, If the black line deviates from the blue line by more than 50 H(nt) then that's 'almost' definitely good for aurora viewing anywhere north of 54N.

Here's an example of what you are looking for, see between 1800ut and 2200ut on this graph taken from 11th October last year.

And below is a link to an image that was captured during the storm from an aurora photographer located near Stranraer. This pic was taken around 2130ut

http://www.spaceweather.com/aurora/images2010/11oct10b/Graeme-Whipps1.jpg

[george7378]

Thanks for the great links - I will keep an eye on that. Spaceweather says that the main event will probably be a the weekend - I can stay up to see it too.

[Kp6]

Sure enough we had a reasonably strong aurora last night and into the wee hours with a planetery kp of 6 peaking around midnight. It should have been visible at least as far south as Yorkshire and the lakes.

I was stuck under thick cloud here and with no prospect of finding clear skies anywhere nearby I had to accept defeat.

'''sigh'''

Did anyone have better luck than me?

[Trull]

I think I got a little lucky last night from 10pm til midnight we had some breaks in the total cloud cover

[Kp6]

A little reminder that the large recurrent coronal hole has completed another rotation and is facing earth today. It still looks big enough to cause some minor storming on the 3rd-4th of March when it's wind stream arrives. There's no reason why it's earth effects wont be as powerful as they have been on it's last 2 rotations, so with that in mind there's potential for aurora viewing north of 54N.

Just to the east of the hole there is a very active region of sunspots. If there is any cme activity from this area in the next 24 hours then the odds of a severe geomagnetic storm resulting shorten somewhat due to a 'double whammy' cme/ch effect. We shall see what comes!

Also today we have seen quite an unexpected geomagnetic disturbance, the current planetery kp is at 5. If this level of activity continues into this evening an opportunity may arise for some aurora viewing north of 54N. The cause of this disturbance is likely to be the wind stream from a very small coronal hole that was earth facing on 26/2.

(pic below shows the coronal hole dead centre with the active region to its left)