28-29 Jul S2 radiation storm

[tniickck]

dont you guys think this storm was caused by both M4.1 flare from 3376 and filament launched at Earth about 11-12 PM UTC 28 Jul? because as I can see the Proton flux went much higher after the filament launched from the Sun. I am just curious, wanna see your opinions

[Marcel de Bont]

My gut feeling says its all from the M4. The filament eruption wasn't in a great position for a proton event (due to the parker spiral) and filament eruptions are generally not eruptive enough to cause an increase in protons. If the filament eruption contributed to the increase to S2 (which I do not think it did) it is minimal.

[Philalethes]

5 hours ago, Marcel de Bont said:

My gut feeling says its all from the M4. The filament eruption wasn't in a great position for a proton event (due to the parker spiral) and filament eruptions are generally not eruptive enough to cause an increase in protons. If the filament eruption contributed to the increase to S2 (which I do not think it did) it is minimal.

Interesting. It seemed like to me too that the EPAM and the GOES proton flux (at least >10 MeV protons, not so much the higher-energy ones) both started to rise a bit more abruptly after the filament eruption, though that could just be coincidence of course. You're certainly right that the position was off and that filament eruptions wouldn't typically do that, and this eruption in particular didn't seem too energetic either.

I also saw someone talk about a secondary eruption associated with the M4 flare, maybe it was in a direction that was conducive to the second rise we saw later, or maybe that's just grasping at straws.

Edited July 29, 2023 by Philalethes
typo

[Sam Warfel]

9 hours ago, Philalethes said:

Interesting. It seemed like to me too that the EPAM and the GOES proton flux (at least >10 MeV protons, not so much the higher-energy ones) both started to rise a bit more abruptly after the filament eruption, though that could just be coincidence of course. You're certainly right that the position was off and that filament eruptions wouldn't typically do that, and this eruption in particular didn't seem too energetic either.

I also saw someone talk about a secondary eruption associated with the M4 flare, maybe it was in a direction that was conducive to the second rise we saw later, or maybe that's just grasping at straws.

Filament eruptions are less/not likely to cause a SEP event, compared to energetic flares?
Not too surprised given their less explosive nature, but didn't know that, thanks

[Philalethes]

21 hours ago, Sam Warfel said:

Filament eruptions are less/not likely to cause a SEP event, compared to energetic flares?
Not too surprised given their less explosive nature, but didn't know that, thanks

Apparently that is indeed the case. I didn't look too much into it, but it does make sense to me too for the same reason.

That being said, I did find an article that references a different article about a filament eruption that took place on August 31, 2012, which was seemingly even more off-center towards Solar east, but which ended up producing a glancing blow. This eruption apparently managed to increase the proton flux to 59 according to the article, although in the archive here on SWL it's listed as topping out at 44; I don't really know how strong that filament eruption was in comparison though, but at least it means that filament eruptions can in some cases in fact contribute meaningfully to the proton flux, at least if assuming the rise in that case was indeed due to the filament eruption (didn't seem to be any notable flares around the same time that would've caused it in that case, only the prolonged C8-flare that was associated with the filament eruption itself).

But generally speaking I still believe filament eruptions will indeed tend to, as you put it, be less explosive, and thus not contribute as much to SPEs, just as Marcel says. In this case it could definitely be that the continued rise was all from the flare on the limb. The EPAM with its less energetic protons probably had more of a contribution from the filament eruption, but as you know those don't count towards the GOES proton flux used to measure SPEs.

Addendum:

It just now occurred to me to check the day after the one I linked to above from the archive too, and apparently that's when the proton flux topped out at 59, and there weren't any notable flares that day after, so presumably, and according to the article, that filament eruption was indeed responsible for bringing the proton flux over halfway to S2 by itself.

Edited July 30, 2023 by Philalethes
addendum

[Newbie]

On 7/30/2023 at 7:14 PM, Philalethes said:

Apparently that is indeed the case. I didn't look too much into it, but it does make sense to me too for the same reason.

That being said, I did find an article that references a different article about a filament eruption that took place on August 31, 2012, which was seemingly even more off-center towards Solar east, but which ended up producing a glancing blow. This eruption apparently managed to increase the proton flux to 59 according to the article, although in the archive here on SWL it's listed as topping out at 44; I don't really know how strong that filament eruption was in comparison though, but at least it means that filament eruptions can in some cases in fact contribute meaningfully to the proton flux, at least if assuming the rise in that case was indeed due to the filament eruption (didn't seem to be any notable flares around the same time that would've caused it in that case, only the prolonged C8-flare that was associated with the filament eruption itself).

But generally speaking I still believe filament eruptions will indeed tend to, as you put it, be less explosive, and thus not contribute as much to SPEs, just as Marcel says. In this case it could definitely be that the continued rise was all from the flare on the limb. The EPAM with its less energetic protons probably had more of a contribution from the filament eruption, but as you know those don't count towards the GOES proton flux used to measure SPEs.

Addendum:

It just now occurred to me to check the day after the one I linked to above from the archive too, and apparently that's when the proton flux topped out at 59, and there weren't any notable flares that day after, so presumably, and according to the article, that filament eruption was indeed responsible for bringing the proton flux over halfway to S2 by itself.

PB I wrote this the other day wasn’t going to post it but noticed you updated your post!

I found a research paper that affirms that filament eruption can actually trigger strong proton events:

“An unusual filament eruption occurred on the north-west solar limb on August 14, 2010. It was one of the first strong eruptions of solar cycle 24, which had just started to rise in activity at the time. Therefore, space weather forecasters carefully tracked and analyzed the event. Although this eruption was associated with a fast coronal mass ejection (CME), the flare that accompanied it was atypically weak. However, the eruption was also the source of the first proton event recorded in nearly four years. Interestingly, the erupting filament exhibited a notable unwinding motion as it was accelerated away from the Sun. It is this twist in the unraveling filament that first attracts attention when studying the extreme ultraviolet (EUV) observations of the eruption. Despite the weakness of the associated C4.4 flare, it became immediately clear from the coronagraph data that this event would be significant for space weather: a wide CME was launched into interplanetary space with a very high velocity (over 900 km s⁻¹, see Sect. 3).”

My initial feeling was that this current proton event was enhanced by the filament eruption that occurred close by but I haven’t found any evidence to support this, information is scarce unfortunately. However proton levels rose for no other reason than the filament eruption.

By way of interest SolarSoft attributed this flare to 3372 but have since amended their website and attributed it to 3376. The difficulty is there was only 5 degrees of separation vertically between the two AR’s.

N.

 

 

 

[Philalethes]

3 hours ago, Newbie said:

PB I wrote this the other day wasn’t going to post it but noticed you updated your post!

 

I found a research paper that affirms that filament eruption can actually trigger strong proton events:

“An unusual filament eruption occurred on the north-west solar limb on August 14, 2010. It was one of the first strong eruptions of solar cycle 24, which had just started to rise in activity at the time. Therefore, space weather forecasters carefully tracked and analyzed the event. Although this eruption was associated with a fast coronal mass ejection (CME), the flare that accompanied it was atypically weak. However, the eruption was also the source of the first proton event recorded in nearly four years. Interestingly, the erupting filament exhibited a notable unwinding motion as it was accelerated away from the Sun. It is this twist in the unraveling filament that first attracts attention when studying the extreme ultraviolet (EUV) observations of the eruption. Despite the weakness of the associated C4.4 flare, it became immediately clear from the coronagraph data that this event would be significant for space weather: a wide CME was launched into interplanetary space with a very high velocity (over 900 km s⁻¹, see Sect. 3).”

My initial feeling was that this current proton event was enhanced by the filament eruption that occurred close by but I haven’t found any evidence to support this, information is scarce unfortunately. However proton levels rose for no other reason than the filament eruption.

By way of interest SolarSoft attributed this flare to 3372 but have since amended their website and attributed it to 3376. The difficulty is there was only 5 degrees of separation vertically between the two AR’s.

N.

Definitely evidence that filament eruptions can contribute to the proton flux, but it's indeed still difficult to determine to what extent it was the case here. From looking at the event in the SWL archive it seems like it only barely caused the proton flux to rise above S1-levels, topping out at 14. It was also seemingly stronger than this one, although I didn't check where on the disc that one took place. The one I referenced above which reached 59 was probably quite extreme in that regard.

It does seem reasonable that it could have had some contribution, but I would guess in this case that it's more so to lower-energy protons as measured by the EPAM, and probably not as much to the proton flux, although it will probably remain impossible to know for sure. I don't think you can reasonably say that proton levels rose for no other reason than the filament eruption though, because there was clearly still a lot of influence from the flare from the limb at that point.

So who knows how much it added to the proton flux at the most; my guess would be somewhere around 2-10, but certainly not ruling out the possibility of more (or less, for that matter) either.

[Newbie]

2 hours ago, Philalethes said:

I don't think you can reasonably say that proton levels rose for no other reason than the filament eruption though, because there was clearly still a lot of influence from the flare from the limb at that point.

PB: I meant proton levels increased from the already ongoing influence of the flare. 
Apologies for not making myself clear on this point. 😊

N.

[hamateur 1953]

Glad that got cleared up.   

[Philalethes]

2 hours ago, Newbie said:

PB: I meant proton levels increased from the already ongoing influence of the flare. 
Apologies for not making myself clear on this point. 😊

N.

Oh, I actually did understand that this is what you meant; this was in fact what I was initially saying in the other thread too, and earlier here as well, e.g. when I wrote:

Quote

It seemed like to me too that the EPAM and the GOES proton flux (at least >10 MeV protons, not so much the higher-energy ones) both started to rise a bit more abruptly after the filament eruption, though that could just be coincidence of course.

What I meant was rather, as I concluded with there, that it could simply have been coincidence that there seemed to have been a bit of a flattening out first, and that all of the ensuing increase was actually still from the large flare. I also briefly mentioned a possible secondary eruption from the region that was flaring as a possibility, but that's just speculation, more to say that I really don't know.

Hopefully that's clearer on my part as well, and my apologies as well for any confusion.

Edited August 1, 2023 by Philalethes
clarity

[Newbie]

15 hours ago, Philalethes said:

Oh, I actually did understand that this is what you meant; this was in fact what I was initially saying in the other thread too, and earlier here as well, e.g. when I wrote:

What I meant was rather, as I concluded with there, that it could simply have been coincidence that there seemed to have been a bit of a flattening out first, and that all of the ensuing increase was actually still from the large flare. I also briefly mentioned a possible secondary eruption from the region that was flaring as a possibility, but that's just speculation, more to say that I really don't know.

Hopefully that's clearer on my part as well, and my apologies as well for any confusion.

All good. PB.

I actually wrote my post before you posted yours but wasn’t going to post it on the forum.

Interesting that SolarSoft attributed the flare firstly to 3372 and later amended this to 3376. It’s not the first time SolarSoft has done this. Same thing happened yesterday with the M3.6 flare. 
Whenever there is an increase after flattening out of the curve it means another flare. I saw this yesterday concerning the M2 flare which followed the M3.6. 
The flare wasn’t reported initially but I see this morning where it was reported. 
Perhaps three events contributed to the S2 storm after all.

N.

 

[Philalethes]

6 hours ago, Newbie said:

All good. PB.

I actually wrote my post before you posted yours but wasn’t going to post it on the forum.

Interesting that SolarSoft attributed the flare firstly to 3372 and later amended this to 3376. It’s not the first time SolarSoft has done this. Same thing happened yesterday with the M3.6 flare. 
Whenever there is an increase after flattening out of the curve it means another flare. I saw this yesterday concerning the M2 flare which followed the M3.6. 
The flare wasn’t reported initially but I see this morning where it was reported. 
Perhaps three events contributed to the S2 storm after all.

N.

Yes, that's quite interesting; maybe that's the secondary eruption that I saw people talking about? Given their close spatial and temporal proximity I would guess they would have been strongly sympathetic eruptions in any case. That could explain the proton flux better, given how this filament eruption didn't seem that special and probably wouldn't have raised it much (as I mentioned I would guess it could have contributed something like 2-10 pfu, but that's a speculative guess on my part).

And yes, with regards to flaring an increase after flattening out does of course mean another flare, given the smoother nature of the X-ray flux; hopefully it was clear that I was talking about the proton flux above, which inherently isn't nearly as smooth given the more stochastic nature of the proton bombardment (e.g. even a single eruption could fling protons in certain directions more than others, leading to an increase in the rate of growth of the proton flux being measured at the arrival time corresponding to the speed along the field line for that specific direction).

Edited August 2, 2023 by Philalethes
clarification

[Newbie]

6 hours ago, Philalethes said:

Hopefully it was clear that I was talking about the proton flux above, which inherently isn't nearly as smooth given the more stochastic nature of the proton bombardment (e.g. even a single eruption could fling protons in certain directions more than others, leading to an increase in the rate of growth of the proton flux being measured at the arrival time corresponding to the speed along the field line for that specific direction).

Yes it was clear that you were talking about proton flux PB.
Proton bombardment is interesting in Itself.

During a solar filament eruption or a CME, electric and magnetic fields interact together. Electric fields are generated when charged particles move within the ejected plasma. Protons being charged particles will move according to the direction and strength of the electric field.

When protons move through the magnetic fields (created by the movement of electric currents within the plasma) they experience a force known as the Lorentz force. It acts perpendicular to both the direction of the proton's velocity and the magnetic field lines. The protons move in a curved path, following the shape of the magnetic field lines. 

The Lorentz force combines the effects of both the electric and magnetic forces on the proton's motion. Therefore the protons will experience both acceleration due to the electric field and circular motion due to the magnetic field simultaneously.
The actual path the protons take will depend on the relative strengths and orientations of the electric and magnetic fields. It is therefore difficult to predict how the protons will move during an eruption.

N.

[Philalethes]

12 minutes ago, Newbie said:

Yes it was clear that you were talking about proton flux PB.
Proton bombardment is interesting in Itself.

During a solar filament eruption or a CME, electric and magnetic fields interact together. Electric fields are generated when charged particles move within the ejected plasma. Protons being charged particles will move according to the direction and strength of the electric field.

When protons move through the magnetic fields (created by the movement of electric currents within the plasma) they experience a force known as the Lorentz force. It acts perpendicular to both the direction of the proton's velocity and the magnetic field lines. The protons move in a curved path, following the shape of the magnetic field lines. 

The Lorentz force combines the effects of both the electric and magnetic forces on the proton's motion. Therefore the protons will experience both acceleration due to the electric field and circular motion due to the magnetic field simultaneously.
The actual path the protons take will depend on the relative strengths and orientations of the electric and magnetic fields. It is therefore difficult to predict how the protons will move during an eruption.

N.

Yep, exactly! That's what I tried to outline in this post from a couple of weeks ago with regards to how the proton flux can remain elevated for so long after a big eruption. For anyone else that might be interested I would also add to that that the initial trajectory of each proton matters in this regard, not just in terms of travel time due to varying velocity components parallel to the field lines, but also because the interplanetary magnetic field isn't exactly a nice and uniform one that one would set up in a lab, but can be quite messy.

As you sum up nicely, this all makes it very difficult to predict the minutiae of when and where protons from an eruption will arrive indeed!

[Newbie]

3 hours ago, Philalethes said:

…but also because the interplanetary magnetic field isn't exactly a nice and uniform one that one would set up in a lab, but can be quite messy.

Hehe I believe the scientific word is lumpiness 🤣

N.