2024/02/10 M9.04 CME

[Jesterface23]

We've got a CME. We've got a Earth-directed CME with a halo.

Now we need a bit more data to see when it is coming.

[MinYoongi]

4 minutes ago, Jesterface23 said:

We've got a CME. We've got a Earth-directed CME with a halo.

Now we need a bit more data to see when it is coming.

so its not northward?

 

[Sam Warfel]

Bulk northward, faint asymmetrical halo?

[Jesterface23]

1 minute ago, MinYoongi said:

so its not northward?

The ejecta did go in a northwest direction, but it is possibly some of it is still coming at us. We just need more imagery to come in to see

[Parabolic]

Thank you, now following this topic as well.

[Philalethes]

I'll have my own go at estimating arrival on this one based on some extremely rough calculations: 54-66 hours since launch at 02-11T23Z, so arrival between 02-14T05Z and 02-14T17Z.

[MinYoongi]

38 minutes ago, Philalethes said:

I'll have my own go at estimating arrival on this one based on some extremely rough calculations: 54-66 hours since launch at 02-11T23Z, so arrival between 02-14T05Z and 02-14T17Z.

Nasa seems to go with impact late 13th  and Kp up to 6 or something.

40 minutes ago, Philalethes said:

I'll have my own go at estimating arrival on this one based on some extremely rough calculations: 54-66 hours since launch at 02-11T23Z, so arrival between 02-14T05Z and 02-14T17Z.

youre pretty damn close to their prediction so im stoked to see how it plays out!

[Jesterface23]

My early calculations come to an arrival in the early morning of the 13th so far. Hopefully SOHO isn't done for the night. I need about 4 or 5 more hours of imagery heh

[chronical]

27 minutes ago, Jesterface23 said:

My early calculations come to an arrival in the early morning of the 13th so far. Hopefully SOHO isn't done for the night. I need about 4 or 5 more hours of imagery heh

That would be approximately at the same time as the filament arrival, according to NASA’s prediction. Cannibal CME possible?

[Jesterface23]

17 minutes ago, chronical said:

That would be approximately at the same time as the filament arrival, according to NASA’s prediction. Cannibal CME possible?

It would be to be determined. Personally I'm expecting them to have their own separate arrivals unless this CME is faster than expected.

[Jesterface23]

Okay, I've got the imagery. The CME is fairly slow. My calculation have an arrival on the 13th at some time between noon and midnight UTC. G1 should be possible.

[Philalethes]

11 hours ago, MinYoongi said:

Nasa seems to go with impact late 13th  and Kp up to 6 or something.

youre pretty damn close to their prediction so im stoked to see how it plays out!

Yeah, I see they are modeling an even smaller angle than what I assumed from the dimming; using that angle of ~22.5° (rough estimate from looking at the model) combined with the latest imagery I'd say arrival would be as little as ~44 hours after launch, which would correspond to 02-13T19Z, but of course with uncertainty. Seems to correspond with their time, but from experience that's not exactly that reliable.

Edit:

Actually, scratch that; I realize now the launch was actually on the 10th, so clearly I'm greatly overestimating the speed, as I'd get almost a full day earlier than the above model.

I just tried again, this time to apply the speed I measured from LASCO to the bulk as seen in the imagery above, at around an angle of 30° instead, and now I'm getting values much more in agreement with what I see in the forecasts, with a speed of ~900 km/s and a transit time of ~54 hours. That's actually the same as the estimate I made in the previous post, heh; also seems to be in good agreement with the others (arrival between 02-13T05Z and 02-13T17Z instead, to account for me getting the day wrong).

Edited February 11 by Philalethes

[tniickck]

i'd go with G1 and G2 possible if early arrival 

[chronical]

23 hours ago, Philalethes said:

I see in the forecasts, with a speed of ~900 km/s and a transit time of ~54 hours. That's actually the same as the estimate I made in the previous post, heh; also seems to be in good agreement with the others (arrival between 02-13T05Z and 02-13T17Z instead, to account for me getting the day wrong).

 

On 2/11/2024 at 3:06 AM, Jesterface23 said:

Okay, I've got the imagery. The CME is fairly slow. My calculation have an arrival on the 13th at some time between noon and midnight UTC. G1 should be possible.

SWPC did their prediction and believes it’ll arrive slightly earlier than your predictions.

 

https://www.swpc.noaa.gov/products/wsa-enlil-solar-wind-prediction

Edited February 12 by chronical
Remove of the term « Cannibal CME »

[Parabolic]

24 minutes ago, chronical said:

 

SWPC did their prediction and believes it’ll arrive slightly earlier than your predictions, with a possible effect of cannibalism, certainly not guaranteed.

 

https://www.swpc.noaa.gov/products/wsa-enlil-solar-wind-prediction

I wish we would resist using the term "cannibal CME". Their magnetic configurations don't allow them to merge or pass through each other.

[chronical]

7 hours ago, Parabolic said:

I wish we would resist using the term "cannibal CME". Their magnetic configurations don't allow them to merge or pass through each other.

Oh okay, I didn’t know that. I thought CMEs could merge if one was faster than a slower ones ejected before. Would you mind explaining the situation a bit so I can know when the use of the term « cannibal CME »?

[Parabolic]

25 minutes ago, chronical said:

Oh okay, I didn’t know that. I thought CMEs could merge if one was faster than a slower ones ejected before. Would you mind explaining the situation a bit so I can know when the use of the term « cannibal CME »?

I can explain it in better detail you in a few hours if that's fine (it's 4am here haha). Also, I apologize if I came off rude as it wasn't my intention.

[chronical]

9 minutes ago, Parabolic said:

I can explain it in better detail you in a few hours if that's fine (it's 4am here haha). Also, I apologize if I came off rude as it wasn't my intention.

Oh no you’re just fine, I know it wasn’t your intention ;). I don’t mind waiting for a few hours for an explanation either.

[NEAurora]

In efforts to “read the tea leaves” during that “fog of war” time between the initial LASCO detection and L1 arrival, I’ve come to the following question:

the ENLIL model seems to predict an arrival around 03-04 UTC on the 13th, however ENLIL is also showing an ambient solar wind speed of about 300-400km/s prior to the event, which is maybe 100/200km/s slower than what’s being recorded by ACE.  Given that CMEs will accelerate (or decelerate) towards the ambient wind speed, does this suggest an earlier arrival than suggested by ENLIL?  
 

while this question is specific to this CME, I guess it’s also a more generalized question that could be applied to other situations.

With respect to this CME, I’m not entirely confident it won’t just skip over us entirely 😔, but I suppose we’ll see some enough.

Edited February 12 by NEAurora

[Philalethes]

48 minutes ago, NEAurora said:

In efforts to “read the tea leaves” during that “fog of war” time between the initial LASCO detection and L1 arrival, I’ve come to the following question:

the ENLIL model seems to predict an arrival around 03-04 UTC on the 13th, however ENLIL is also showing an ambient solar wind speed of about 300-400km/s prior to the event, which is maybe 100/200km/s slower than what’s being recorded by ACE.  Given that CMEs will accelerate (or decelerate) towards the ambient wind speed, does this suggest an earlier arrival than suggested by ENLIL?  
 

while this question is specific to this CME, I guess it’s also a more generalized question that could be applied to other situations.

With respect to this CME, I’m not entirely confident it won’t just skip over us entirely 😔, but I suppose we’ll see some enough.

I'm not sure I understood the question exactly, but I think the current slight increase in speed is due to impact from something, not sure if it's one one or more of the CMEs lately or a HSS or both. This will leave a slight "void" behind in its wake, but in this case it doesn't seem to be significant enough to have much of an effect on the larger one that is the topic of this thread; but maybe it could change the timing a bit as it gets closer.

If you look at the wake of the large one you can see the bigger "void" left behind, whose size will be a function of how fast the large one clears the path ahead of it. I think when talking about some of the historically famous events that were launched in succession it's due to having a clear path from relatively large earlier ejections that cleared the way, since smaller ones don't do the job quite as well.

Maybe you were asking about something else though, I guess you can clarify what you meant further. As for this CME I feel fairly sure we're going to take a hit, although it might not be for that long. Since it seems to be colliding with some previous CMEs it could also mean the magnetic field direction will fluctuate more, but if we get a little period of negative Bz in the densest part we could get some decent bursts of geomagnetic activity. I guess for all of you out there who are into photography it's a bit more "risky" to get your equipment ready and wander out into the night to wait just for the possibility though, heh.

[NEAurora]

30 minutes ago, Philalethes said:

I'm not sure I understood the question exactly, but I think the current slight increase in speed is due to impact from something, not sure if it's one one or more of the CMEs lately or a HSS or both. This will leave a slight "void" behind in its wake, but in this case it doesn't seem to be significant enough to have much of an effect on the larger one that is the topic of this thread; but maybe it could change the timing a bit as it gets closer.

If you look at the wake of the large one you can see the bigger "void" left behind, whose size will be a function of how fast the large one clears the path ahead of it. I think when talking about some of the historically famous events that were launched in succession it's due to having a clear path from relatively large earlier ejections that cleared the way, since smaller ones don't do the job quite as well.

Maybe you were asking about something else though, I guess you can clarify what you meant further. 

Thanks for the response, I think your answer largely gets to my question but guess if I wanted to sum up my question more clearly it would be this:

if ENLIL is underestimating the ambient solar wind speed for whatever reason (HSS, unaccounted for CME wake, etc), is this an indicator that a CME would arrive earlier than expected from ENLIL?

Of course there are dozens of other uncertainties involved with modeling the timing/magnitude of an impact, but just considering the above for this question.

 

[Philalethes]

4 minutes ago, NEAurora said:

if ENLIL is underestimating the ambient solar wind speed for whatever reason (HSS, unaccounted for CME wake, etc), is this an indicator that a CME would arrive earlier than expected from ENLIL?

All else held equal I would think so, since it would imply less pressure ahead, meaning less deceleration of the CME, even if it would be rather marginal for smaller ones.

This would also be true for the more constant HSSs (heh, nice plural), because as mentioned in some other posts you may or may not have read a HSS will pretty much have an inversely proportional relationship between density and speed due to the stream comprising roughly the same amount of particles that are simply faster, while the dynamic pressure will increase with the square of the speed and only linearly with density, simultaneously reducing the static pressure. To look at it analogously to regular fluid dynamics, you can see it illustrated as such:

In other words a CME would probably generally tend to follow the path of an HSS (again, all else held equal); I'm sure there might be some complicating factors, but when simplifying I think a basic analogy like this should work fairly well. It would be more or less like ending up in a rip current, which are notoriously dangerous due to being hard to get out from.

I should mention that in this case it does look like the current impacts have been modeled though, as you can see the increase in speed currently and also a small blue wake behind them right before the CME overtakes them, but it's definitely a good question whose answer is not so clear.

[Parabolic]

5 hours ago, chronical said:

Oh no you’re just fine, I know it wasn’t your intention ;). I don’t mind waiting for a few hours for an explanation either.

Thank you for you patience and understanding!

Each CME has their own magnetic field orientation. I believe the flux inside the magnetic field lines is similar to how a toroid is structured but with closed magnetic field lines (Imagine a magnetized slinky of sorts). When two CME's get too close, they will always behave like two magnets being pushed together and creating pole repulsion. This happens all the way down to atomic particles. Since they can't merge or pass thru each other they instead end up compressing. This allows for a greater propagation of dynamic pressure and shock inside the magnetic ejecta. This sort of CME interaction is one of the cause of the magnetosphere being pushed out of the magnetopause.

My best analogy I can think of is like this; multiple CME's behave similarly to traffic jams when stuck behind a snowplow. The snowplow creates a path of least resistance but nothing can pass the snowplow and all the cars get crammed together.

[HalfFeralHuman]

[edit: This is @Philalethes's last post, hadn't worked out forum's quoting system]

This is a really interesting way of looking at things. I'm wondering how on earth one could factor in the electromagnetic interplay resulting from rip current type effects. It sounds like chaos.

Edited February 12 by HalfFeralHuman
Clarifying what this was replying to

[Philalethes]

16 minutes ago, HalfFeralHuman said:

[edit: This is @Philalethes's last post, hadn't worked out forum's quoting system]

This is a really interesting way of looking at things. I'm wondering how on earth one could factor in the electromagnetic interplay resulting from rip current type effects. It sounds like chaos.

Yeah, the electromagnetic element complicates it and of course marks the difference between the already complex fluid dynamics and the even more complex magnetohydrodynamics, but at least in many cases for the Solar wind you can neglect those effects due the magnetic field being more or less the same in nearby areas (for e.g. two CMEs with very different field structures crashing into each other, like Parabolic talks about about above) it could lead to very different outcomes). And Solar wind is of course more compressible, with the density being able to change significantly, which makes it unlike e.g. water which is virtually incompressible, and that also makes the analogy more complicated.

2 hours ago, Parabolic said:

My best analogy I can think of is like this; multiple CME's behave similarly to traffic jams when stuck behind a snowplow. The snowplow creates a path of least resistance but nothing can pass the snowplow and all the cars get crammed together.

There's certainly truth to this, but I guess the most interesting situations that are usually referred to is when an even bigger snowplow comes up behind at double the mass and speed, and is then followed by a huge bulldozer with a turbomotor, at which point you get some rather interesting results (and usually some of the most complex magnetic field structures when they do end up passing us).