How to interpret the strength of solar storm impacting on Earth?

[oemSpace]

Referring to following link, on 17 Apr, Plasma Density reach maximum level, but radial velocity is increasing.

I would like to know on how to interpret the strength of solar storm impacting on Earth.

Does anyone have any suggestions?
Thanks in advance

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

[Vancanneyt Sander]

You can’t interpret the strength of a storm based on the Enlil model. The only thing the Enlil model provides is a rough estimation of the arrival time of a CME or coronal hole wind stream. 

to know the strength of the storm, you would have to know the strength of the IMF and the dominant direction. Both factors are almost impossible to predict and thus you can’t accurately predict the true strength of a storm.

The only thing that’s possible with all models is that it’s a prediction of what MIGHT be possible. For example you can have an M8 flare with a full halo CME with a travel time of 2 days (based on one or multiple enlil runs or based on image processing of LASCO). The swpc would then likely give out a G2 watch, that means that there might be a possibility for G2 storming. But with each storm you can only know the real odds when it arrives because only then you’ll know what the actual arrival time is and how the IMF responds to it. 

[oemSpace]

If Plasma Density and radial velocity are increasing, that is easy to interpret increasing strength for estimation.

but when Plasma Density starts decreasing, and radial velocity is increasing.

I would like to know on how to interpret this relationship on developing solar storm.

Do you have any suggestions?
Thank you very much for any suggestions (^v^)

 

[Vancanneyt Sander]

Again, even if velocity and density get higher it doesn’t say much about the true strength of a geomagnetic storm. It only tells you what the expected velocity and density might be. When it’s above 700Km/sec. You could say that’s a moderately strong solar wind but if the IMF turns northward you can’t say it’s a strong storm because with the IMF being north it prevents the generation of a geomagnetic storm. 

[oemSpace]

When radial velocity is less than 700Km/sec, would you not consider geomagnetic storm to be strong at all? no matter if IMF turns northward or southward, correct?

Do you have any suggestions?
Thank you very much for any suggestions (^v^)

 

Edited April 16, 2021 by oemSpace

[Vancanneyt Sander]

I consider a geomagnetic storm 'strong' if the IMF has a prolonged period of southward directed field with a strength of at least 15nT. 

[oemSpace]

35 minutes ago, Vancanneyt Sander said:

I consider a geomagnetic storm 'strong' if the IMF has a prolonged period of southward directed field with a strength of at least 15nT. 

Referring to following link, it only provides Plasma Density and radial velocity, I would like to know on where to get information for strength in term of nT. Does strengh refer to Bt or Bz or other?

Do you have any suggestions?
Thank you very much for any suggestions (^v^)

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

Edited April 16, 2021 by oemSpace

[Vancanneyt Sander]

Again, the enlil model does not include the prediction for the strength (Bt) and direction (Bz) of the IMF (B).

There is no way of predicting the IMF upfront. 

[oemSpace]

if the IMF has a prolonged period of southward directed field with a strength of at least 15nT, could you please describe more about how to define prolonged period?

Furthermore, expecting K5 on 17 Apr, strength of Bt is never over 15nT within last 3 days (14 - 16 Apr), would it be possible for Bt suddenly jump up over 15nT for triggering "Strong" signals?

Do you have any suggestions?
Thank you very much for any suggestions (^v^)

 

Edited April 16, 2021 by oemSpace

[Vancanneyt Sander]

There is no definition of a prolonged period, a geomagnetic storm can only initiate if the direction of the IMF stays southward for a longer period of time (an hour or more). 

For example this strong G3 storm in 2012:

Kp5 is possible but that's still a minor geomagnetic storm and not a strong geomagnetic storm so the Bt and Bz won't be 15nT.

[oemSpace]

Thank you very much for suggestions (^v^)

[oemSpace]

On 4/16/2021 at 10:58 PM, Vancanneyt Sander said:

I consider a geomagnetic storm 'strong' if the IMF has a prolonged period of southward directed field with a strength of at least 15nT. 

I would like to know on where to find the historical data for strength.

Do you have any suggestions?
Thank you very much for any suggestions (^v^)

 

[Vancanneyt Sander]

Look at our huge archive full of space weather data since 1996. Check out our top 50 geomagnetic storm page with quick links to the archive where you can see the solar wind strength, density, IMF strength and direction

[oemSpace]

Could you please provide the link for archive?

Furthermore, K5 is expected on 16 May, but the current strength is below 15 nT,

1) could we validate the K5 based on current strength? which is below 15 nT (less chance for K5)

2) we should keep monitoring strength as time goes near 16 May (possible for K5)

Do you have any suggestions?
Thank you very much for any suggestions (^v^)

 

Edited May 13, 2021 by oemSpace

[Jesterface23]

The archive can be found here,
https://www.spaceweatherlive.com/en/auroral-activity/top-50-geomagnetic-storms.html

I don't see where the K5 is from, but take it the forecast as a preliminary forecast. Once the solar activity reaches the observation satellites at L1 the true forecast can be estimated.

[oemSpace]

I would like to confirm on whether those archive data are actual fact or forecast.

Do you have any suggestions?
Thanks, to everyone very much for any suggestions (^v^)

 

 

[Drax Spacex]

From a web browser desktop view of www.spaceweatherlive.com, click "Archive", then click "The aurora and solar activity archive".   Select desired Month then Year then click the magnifying glass.  Summary data for that month in that year will be shown.  Data shown are actual values, not predicted.  For detailed data on a specific day, click the day in that calendar month.  Then you have access to both predicted Kp in "Geophysical report" and actual Kp in "Kp values", and various other data for that day.  The data archive is very well-managed.

[oemSpace]

The data archive looks great, but that is script based, is there another source in text format?

Do you have any suggestions?
Thanks, to everyone very much for any suggestions (^v^)

 

[Jesterface23]

Just about all the text data you may ever want can be accessed here,

https://spdf.gsfc.nasa.gov/data_orbits.html

There are multiple export options.

Edited May 14, 2021 by Jesterface23

[oemSpace]

For historical Kp index, do you have any suggestions on which SPACECRAFT should be located?

Do you have any suggestions?
Thanks, to everyone very much for any suggestions (^v^)

 

[Vancanneyt Sander]

Kp index is measured on Earth from several magnetometer stations. No spacecraft involved.

[oemSpace]

so is there any place to find historical data for kp index in text format?

Do you have any suggestions?
Thanks, to everyone very much for any suggestions (^v^)

[Jesterface23]

Well, you can tell it was the end of the day for me with the wrong data heh. Ignore the previous link and satellites.

Past Kp index values can be found in a FTP archive below,
ftp.swpc.noaa.gov/pub/warehouse
Specifically for the images, /pub/warehouse/[YEAR]/[YEAR]_plots/kp/
I'm not sure if a text version is available somewhere in the archive.

It can be accessed using a client like Filezilla. A browser may or may not work.

 

Edit:
The text format of past Kp values can be found here,
ftp://ftp.swpc.noaa.gov/pub/indices/old_indices/

Edited May 14, 2021 by Jesterface23

[Vancanneyt Sander]

Official finalized Kp index is available at Potsdam https://www.gfz-potsdam.de/en/kp-index/

[MytiMouse]

This was a very interesting thread,  I am just starting out with all of this.  I just want to commend all of the responders,  you were very patient and polite while getting slammed with all these questions.