Northern Lights: Three Factors

At the request of the Trv-Feature, the chief researcher at IKI RAS (Institute of Space Research of the Russian Academy of Sciences), Sergey Pulinets talked with the head of the space weather forecasts of the Izmi RAS Sergey Gaidashom and the head. The analytical department of the Institute of Applied Geophysics of Roshydromet Vyacheslav Burov about the polar radiance observed in the Middle Strip Russia on March 17, 2015 (see alsoan article by B. Stern in this issue of the newspaper).

- What happens in the sun and with "cosmic weather" in recent months?

Sergey Gaidash : We are now at the beginning of the decline in the last solar cycle. By modern numbering, this is the 24th eleven-year cycle since regular observations are being carried out (since 1755). This cycle is characterized by the fact that in terms of amplitude it is almost half as much as all the previous ones. All manifestations of the activity of the Sun during it are also much weaker. And this is good, because the likelihood of catastrophic consequences that high solar activity can lead to.

Over the past two years, these manifestations have been laid in the range “Small Magnetic Storms - Moderate Magnetic Storms”. And more intense events, such as a large magnetic storm, a very large magnetic storm, an extremely large magnetic storm (in accordance with the international classification), are simply absent.

All forecast methods we use are very effective. We record solar outbreaks and other manifestations of solar activity and already in two or three days we make a forecast, which is expected, for example, a small magnetic storm. It was about the same on March 14, when a very small outbreak was registered in the sun, but after it there was an emission of mass in the form of a coronal fiber, and the next on the approach, March 15, was a coronal hole .

- For readers of the newspaper, I will explain that by the coronal hole this refers to a bunch of open power lines of the magnetic field of the Sun, according to which there is usually an intensive ejection of the plasma.

- Yes. As we know, coronal holes give magnetic disturbances that can lead to magnetic storms, and the level of magnetic indignation can reach 6 (it means a planetary index of geomagnetic activity KP ).

- Let's clarify. So, we had a sequentially solar flash ...

“But it was a very weak flash, she could not even pull on a small magnetic storm.”

- Then there was a mass release in the form of a fiber ...

- Yes, but this could be given in extreme cases the average magnetic storm. Well, then there was a coronal hole. Each of these events could have arisen, and on earth they would not have felt any consequences. But the fact is that they appeared almost simultaneously, and this whole cocktail worked. At first there was a very strong magnetic storm, the next day another, and then the storm is weaker, that is, in a row on March 17, 18 and 19. Then everything was calm. And our forecast for the coming week is as follows: earthlings are no more unusual, everything will be calm.

-Still, there were already a lot of strong magnetic storms, but the polar radiance before Moscow reached only in 2003 and 2004 ...

- It is known that the stronger the geomagnetic activity, the farther the Auroral oval goes to the south. Eight ( kp = 8) just corresponds to the radiance on the latitude of Moscow, and with 9, all central Europe is covered, including Italy or even Greece. The storm was this class in October 2004, and the largest storm in October 2003. But in 2004 it was cloudy, so the radiance in Troitsk was observed only in 2003.

Such storms are once or twice during the solar cycle. The storms of 2003 - 2004 took place in the last cycle of solar activity, and so we waited for such a storm in this cycle. Now we need to wait when we fall into a minimum of solar activity, then we will wait for the maximum, and somewhere again on the decline, not earlier than ten years after 2014, one more similar magnetic storm can be expected.

- Returning to the last magnetic storm, is it possible to say that the three factors worked coherently?

-Yes, yes, yes, that’s exactly. It turned out that the ratio of speeds was such that one indignation caught up with another and they coincided in space and in time.

If we talk about some examinations, such as killer electrons, sprinkled from radiation belts and disabled satellites, there were no reports of accidents. We will wait, perhaps they hide them, no one wants to be extreme.

- Thank you very much for the comment. Further success in the field of space forecasting.

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- What caused the phenomenon of polar radiance at the latitudes unusual for them?

Vyacheslav Burov : Magnetic indignation, which was expressed in stunningly beautiful pictures of polar radiance in the Moscow region, as well as in Tomsk, Novosibirsk and a number of other regions of the northern latitudes, was due to the emission of the coronal mass from the solar atmosphere.

Why were the polar radiance visible on low latitudes so much and so brightly? Two circumstances developed here: firstly, on March 14 there was a relatively small outbreak of class C9-this is a very small flash with the emission of the coronal mass towards the Earth, but it cannot be said that the emission of the coronal mass was giant.

But a few hours later, already on March 15, near the Central Meridian of the Sun, the coronal mass of rare power occurred, and it was directed precisely towards the Earth. And apparently, these two emissions of the coronal mass when interacting with each other at different speeds reached the magnetosphere of the Earth and led to a giant geomagnetic outrage, which turned out to be the strongest in the current, 24th solar cycle. Such an event is really unique and rarely observed.

- That is, in fact, there were two emissions from the sun?

- Yes, exactly, and the first emission was due (or accompanied, as you like), a small flash, a small, class C9. It is amazing that in the place of the second emission there was no solar outbreak - this is a very rare occurrence.

- And since the emission was more powerful, then caught up with the previous one?

-Yes, yes, he caught up with the previous one, and, apparently, together they distorted our magnetic shell so that they moved the oval of polar radiance towards low latch. Whether such emissions will be in the near future, it is difficult to say, but I think that the sun already pleases us with its manifestations. On Friday on March 20, we observed a solar eclipse - again, a complete set of pleasures for residents of the European part of Russia.

- Thanks for the comment.

Magnetic stormy data on March 17, 2015 can be viewed on the page of the Institute of Applied Geophysics http://ipg.geospace.ru/storm-20150318.html