Understanding the Mass of Solar Wind and its Impact on Earth's Surface

[jovanovic_oliver]

TL;DR Summary

Can you help me find some references on mass of particles that falls to Earth after Coronal mass ejection (during one year).

Thank you

According to wiki sources "The average mass ejected is 1.6×1012 kg"

I would like to know, what part of that falls to surface of the Earth?

 

[anuttarasammyak]

How about multiplying solid angle of the Earth from the sun / 4$\pi$ , i.e.
$$2\pi r^2 / 4\pi R^2$$
where r is radius of the Earth and R is distance between the sun and the Earth.

 

[Ibix]

How about multiplying solid angle of the Earth from the sun / 4$\pi$ , i.e.
$$2\pi r^2 / 4\pi R^2$$
where r is radius of the Earth and R is distance between the sun and the Earth.

Do we know if coronal mass ejections are uniformly distributed across all angles, or preferentially in the Sun's equatorial plane, or other? @davenn?

 

[Vanadium 50]

Well, if we're going to do the "PF Quibble", I'd quibble with "surface of the earth". Probably relatively little reaches the surface.

 

[Ibix]

Oh, I agree @anuttarasammyak's approach is sensible. I can just see a few sources of potential systematic error and I don't know how big they are.

 

[jovanovic_oliver]

How about multiplying solid angle of the Earth from the sun / 4$\pi$ , i.e.
$$2\pi r^2 / 4\pi R^2$$
where r is radius of the Earth and R is distance between the sun and the Earth.

If nothing else, I will use 10 % of this calculation (for rough assessment), but it would be much better if there are some measurements conducted by anyone.

 

[anorlunda]

if there are some measurements conducted by anyone

Wow, that would be challenging.

Measure the daily net change in mass of Earth and its atmosphere. Even then, you couldn't be sure about the mass leaving and mass entering, you would know only the net difference.

 

[davenn]

If nothing else, I will use 10 % of this calculation (for rough assessment),

I doubt that there is anything more than 1 % that make it to the Earth's surface.
Pretty much all of it would be stopped by the Earth's magnetic field or upper atmosphere.
Any particles that makes it to the surface would come down at the polar regions rather than lower latitudes
I would have to do some deep research to clarify the numbers ( if they are even available)

Do we know if coronal mass ejections are uniformly distributed across all angles, or preferentially in the Sun's equatorial plane, or other? @davenn?

No, CME's are not uniformly radiated out. The CME can be blasted out at any angle between ~ -70 deg's to ~ +70 deg's ( Solar latitude).
CME's do not originate, or at least I have never seen, in 40+ years of study, them from the polar regions.

Their size can vary from small ones that don't even hit Earth if they are pointed away from us...

to full on monsters that can hit us with some material, even if the main plasma cloud is aimed in a slightly different direction from Earth

The large ones similar to that last one can become full halo events with a lot of material going out in almost every direction...
You can see an expanding ring of material 360 deg around the sun

Dave

 

[kimbyd]

If nothing else, I will use 10 % of this calculation (for rough assessment), but it would be much better if there are some measurements conducted by anyone.

Pretty sure the number that strike the Earth's atmosphere is actually larger by a good amount, because of the Earth's magnetic field.

The Earth's magnetic field captures many particles from the solar wind and redirects them towards the poles. The effect of the magnetic field is likely to greatly decrease the flux of solar wind particles across most of the Earth's surface, but increase it dramatically at the poles such that the total is larger than the simple area calculation would suggest. Edit: Nope, I'm wrong. Most of it isn't fully captured by the magnetic field. Some is redirected towards the poles, but most just misses.

The number that reaches the surface is probably vanishingly small.

 

[davenn]

Most of it isn't fully captured by the magnetic field. Some is redirected towards the poles, but most just misses.

exactly, the magnetic field as like a huge shield deflecting much of the solar wind/CME's

 

[kimbyd]

exactly, the magnetic field as like a huge shield deflecting much of the solar wind/CME's

I know it's described this way a lot, but it just seems like a weird description to me.

The magnetic field bends the trajectories of the particles perpendicular to the field lines. I.e., if the charged particle is moving towards a magnetic field that is oriented up/down, then it gets deflected to either the left or right depending upon the charge and direction of the magnetic field. If the particles are moving slowly enough, this results in them looping around the magnetic field lines, which ultimately causes them to impact the poles (this is the process I was thinking about).

Now, if the magnetic field were uniform, and the charged particles weren't captured by it, then this deflection would have no impact on the flux of charged particles. It would just change the direction they come from.

So I think it's more like the Earth's magnetic field acts like a lens. In one way of thinking about it, this "lens" makes the Earth look smaller to the charged particles, in that fewer trajectories impact the Earth.

I wasn't able to find a source describing the Earth's magnetic field as a lens, but did find this article regarding the solar system's magnetic field as it pertains to high-energy cosmic rays coming from outside the solar system:
https://arxiv.org/pdf/1005.4668.pdf

An interesting feature there is that the magnetic field for the solar system apparently disperses cosmic rays of one charge, while focusing cosmic rays of the opposite charge. If this effect is the same for the Earth's magnetic field, then I'm pretty sure what happens is that protons from the solar wind are dispersed, while electrons are focused. But electrons, having vastly smaller masses, may be captured much more efficiently than the protons. Their effects would be smaller too, however, so that they probably would get redirected to the poles. If this is correct, this would give the Earth a slight negative electric charge (it can't build up too much because a negative electric charge will push away electrons). I recall from astrophysics classes way back when that the stellar winds cause stars to be slightly charged through a similar process (protons and electrons are emitted with different efficiencies by the wind).

 

[hutchphd]

Can't you abstract this number from the pressure on a solar sail ?

Solar wind, the flux of charged particles blown out from the Sun, exerts a nominal dynamic pressure of about 3 to 4 nPa, three orders of magnitude less than solar radiation pressure on a reflective sail.[19]

 

[berkeman]

A very inappropriate post by the OP has been deleted, and he is now on a 10-day vacation from PF. Thank you all for your helpful contributions to this thread. Thread is now closed.