Unspecified geomagnetic activity

[Isatsuki San]

For now the conditions are 404 km/second in the solar wind and 14.38 bt and the bz 4.99 south, with kp4 conditions for now, it could be a Sir, but the curious thing is that the epam did not detect any arrival of cme, so it could be a cme that hit us indirectly or one weak enough not to be detected by the epam

[Landon Moeller]

8 minutes ago, Isatsuki San said:

For now the conditions are 404 km/second in the solar wind and 14.38 bt and the bz 4.99 south, with kp4 conditions for now, it could be a Sir, but the curious thing is that the epam did not detect any arrival of cme, so it could be a cme that hit us indirectly or one weak enough not to be detected by the epam

It actually was detected by EPAM! Protons do not always need to be rising before a CME impact, especially in the case where they have already been so elevated. The signature is that they started dropping off rapidly, going closer to their nominal levels. This is the indication that a shock front passed. I’m sure if we had data at the time, we would have seen a very small spike in EPAM before the falloff. Alas, ACE is struggling lately 😅
 

EPAM plot (24 Hours):
https://ibb.co/pzhQwt0

[Isatsuki San]

Hace 14 minutos, Landon Moeller dijo:

¡En realidad fue detectado por EPAM ! No siempre es necesario que los protones estén aumentando antes de un impacto de CME , especialmente en el caso en que ya han estado tan elevados. La señal es que comenzó a caer rápidamente, acercándose a sus niveles nominales. Esta es la indicación de que pasó un frente de choque. Estoy seguro de que si tuviéramos datos en ese momento, habríamos visto un aumento muy pequeño en EPAM antes de la caída. Por desgracia, ACE está teniendo problemas últimamente😅
 

Parcela EPAM (24 Horas):
https://ibb.co/pzhQwt0

Oh wow, I didn't notice it, I always look at the epam to see if a cme is coming, but did epam fall? I didn't know that epam would fall

Edited April 19 by Isatsuki San

[Philalethes]

Got ourselves a G1 out of this as well, the Bz has been very cooperative again, like the last one.

[AndrewB]

Quite a nice impact. I won't be surprised if we reach the G2 threshold. The speed is now around 480 km/s which is about 160 km/s higher than before impact and Bz still nice cooperating.

Edited April 19 by AndrewB

[Parabolic]

Would the steady rise in speed and temperature indicate that we've entered the negative polarity CH HSS a little earlier than anticipated? 

[SamDieGurke]

1 hour ago, AndrewB said:

Quite a nice impact. I won't be surprised if we reach the G2 threshold. The speed is now around 480 km/s which is about 160 km/s higher than before impact and Bz still nice cooperating.

Would be nice if this would continue for at least 2 more hours, then I could maybe see something... But will probably jump north just when it gets dark 

[Jesterface23]

It is hard to tell if we are in a weak HSS or the stronger small CH that started to pass center-disk late on the 16th, but we are certainly in a CH HSS (mixed with a CME+CIR).

[mozy]

bz will magically turn north now that clouds have cleared & it's finally getting dark here 😎

[owenb0576]

You think the storm will last through the night?

[SamDieGurke]

I shouldn’t have said that, Bz trolling now 😕 speed also decreased a bit, hope it‘ll increase again although I think thats unlikely

[Landon Moeller]

Really hoping we can get a core to rebound things.

[Jesterface23]

Welp, G3

[SamDieGurke]

hilarious, G3 and nothing to be seen at the horizon

[MinYoongi]

46 minutes ago, mozy said:

bz will magically turn north now that clouds have cleared & it's finally getting dark here 😎

Are you clear?  

12 minutes ago, Landon Moeller said:

Really hoping we can get a core to rebound things.

 

4 minutes ago, Jesterface23 said:

Welp, G3

How did we reach G3 from this ?

It’s pretty northward I think, how can it reach g3?

[Landon Moeller]

1 minute ago, MinYoongi said:

Are you clear?  

 

How did we reach G3 from this ?

Sustained -Bz. Even though data isn’t great anymore, KP is a slow process.

[MinYoongi]

4 minutes ago, Landon Moeller said:

Sustained -Bz. Even though data isn’t great anymore, KP is a slow process.

Oh. So it reacts with a delay ? Thank you  

[Jesterface23]

It's being in the position of the CME+CIR to CH HSS transition. High velocities, density is still elevated, and that negative Bz as well

[MinYoongi]

4 minutes ago, Jesterface23 said:

It's being in the position of the CME+CIR to CH HSS transition. High velocities, density is still elevated, and that negative Bz as well

So that all is causing the G3 conditions rather than just the neg. Bz? I’m a bit rusty   has been a while..

 

[Jesterface23]

5 minutes ago, MinYoongi said:

So that all is causing the G3 conditions rather than just the neg. Bz? I’m a bit rusty   has been a while..

Pretty much think of this transition period as the sheath of a CME in a way. Elevated velocities and density. Then hope the Bz does what it needs to

[MinYoongi]

6 minutes ago, Jesterface23 said:

Pretty much think of this transition period as the sheath of a CME in a way. Elevated velocities and density. Then hope the Bz does what it needs to

But im confused why after 12h it goes to G3. Have you seen the tweet i attached? Is that a possibility?

[Jesterface23]

1 minute ago, MinYoongi said:

But im confused why after 12h it goes to G3. Have you seen the tweet i attached? Is that a possibility?

It might be the velocities as it was the one parameter that is increasing.

[Isatsuki San]

7 minutes ago, Jesterface23 said:

Podrían ser las velocidades, ya que era el único parámetro que está aumentando.

ok the first thing I will say is that I am surprised, a cme that you have not seen or that arrived late is producing a geogmanetic storm g3
And the second thing, do you think it will rise more than the g3 or will it just stay there or will it go down?

[Jesterface23]

1 minute ago, Isatsuki San said:

ok the first thing I will say is that I am surprised, a cme that you have not seen or that arrived late is producing a geogmanetic storm g3
And the second thing, do you think it will rise more than the g3 or will it just stay there or will it go down?

You wouldn't expect a CME that takes 4 days to arrive to get a good geomagnetic storm out of it. It is pretty much by chance that it interacted with a CH and negative Bz for this to happen.

To compare, SA's IMF shock was ~7.5nT. 5 hours later the CHs interactions helped reach an IMF strength of almost 20nT.

And if there is a flux rope, there is a chance activity could continue. Or when the HSS fully kicks in the activity could come to a quick stop. Not really sure.

[Philalethes]

8 minutes ago, Isatsuki San said:

ok the first thing I will say is that I am surprised, a cme that you have not seen or that arrived late is producing a geogmanetic storm g3

Reminds me a bit of the surprise G4 we got under similar circumstances, also around April, which if I remember correctly was also a combination of a SIR and a CME that wasn't very noteworthy (maybe someone recalls the exact circumstances better). Probably also of help that we're still relatively close to the equinox (including the R-M effect, which for the March equinox is expected to occur for IMF toward Sol, exactly what you get from negative CHs).