Daily Geomagnetic Storm Watch with a Quiet Sun

[Brigit]

The quiet sun is an opportunity to watch Earth's geomagnetic disturbances, and track the various reasons given for these storms.

Solar Activity for the year 2020 so far:

[Brigit]

Solar activity flat:





A couple of bumps:



And so on:

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Catching up to today:

[Brigit]

Geomagnetic activity on the 5th and 6th was slight, but here is what spaceweather com reports:

AURORA SURPRISE: No geomagnetic storm? No problem. On Jan. 4th, auroras filled the sky over Ringvassøya, Norway. "What a lovely surprise!" says Gunnar Hildonen, who photographed the outburst:

"I was outdoors removing the snow from my driveway when the clouds parted and Lady Aurora put on a crazy beautiful show... out from nowhere," he says. "The solar speed was low, so this was a really big surprise.. "

Indeed, auroras were not in the forecast for Jan. 4th. Solar wind speeds were low, and no geomagnetic activity was expected. What happened? A relatively small crack in Earth's magnetic field opened--and it stayed open for many hours. Slow-moving solar wind percolated through the gap, eventually providing the fuel for a beautiful outburst of auroras. Similar displays were seen in Finland and Iceland.

~Jan 5th

We see this a lot. But is really the case? I have never been able to determine from the POTD if, in EU Planetary Science, the earth's magnetic field has small cracks that open.

• Even if it does, I think there are other possible causes of both geomagnetic storms and their auroras. I personally suspect that small electrically charged objects (NEOs) coming within one lunar distance of earth causes some of these storms, but it is very difficult to tell which ones.

[Brigit]

Spaceweather com, Jan 6th:

UNEXPECTED AURORAS: With no warning, a stream of solar wind hit Earth's magnetic field on Jan. 5th, nearly causing a geomagnetic storm. The unexpected impact sparked bright auroras around the Arctic Circle. Rayann Elzein sends this picture from Utsjoki, Finland:

"A faster-than-expected solar wind stream sparked bright and fast auroras tonight in northern Finnish Lapland," says Elzein. "Standing on the shore of the Teno River, which marks the border between Finland and Norway, we observed in awe the beautiful lightshow, which included quick-moving needles of light and, at one point, a purple fringe."

Three thousand km away in England, the impact of the solar wind was felt in a different way. "My backyard magnetometer recorded vibrations in our local magnetic field," reports Stuart Green, who sends this chart recording of the unrest:

The squiggles in Green's chart represent changes in ground-level magnetic fields caused by the buffeting of solar wind high overhead. "The sensor is buried in my garden about 0.5 meters below the surface in an East/West orientation," he explains. "This allows very sensitive (sub nanotesla) measurements of magnetic declination during geomagnetic storms. The plot shows the change in magnetic flux density in nanotesla occurring between readings every few minutes."

More vibrations are in the offing on Jan. 8th and 9th when another stream of solar wind is due to arrive. The gaseous material is flowing from a minor hole in the sun's atmosphere. Arctic sky watchers may expect bright green auroras mixed with nearly full moonlight. Aurora alerts: SMS

This time, the sun is quiet, but "gaseous material is flowing from a minor hole in the sun's atmosphere." Now we have Reason #2 for energetic auroral displays, even though the solar stream does not appear in any of the measurements I use.

Alright, let's give it three days to get here, and this is the Sun on the 3rd:


There is a spot but it doesn't look geoeffective to me.

Now let's go see what other Reasons there are for these powerful storms while the Sun is quiet.

[Brigit]

Spaceweather com, Jan 7th:

ELECTRICITY SURGES THROUGH THE SOIL OF NORWAY: Yesterday, Jan. 6th, something unexpected happened in the soil of northern Norway. "Electrical currents started flowing," reports Rob Stammes, who monitors ground currents at the Polarlightcenter geophysical observatory in Lofoten. This chart recording shows the sudden surge around 1930 UT:



"It seemed to be some kind of shockwave," says Stammes. "My instruments detected a sudden, strong variation in both ground currents and our local magnetic field. It really was a surprise."

NASA's ACE spacecraft detected something as well. About 15 minutes before the disturbance in Norway, the interplanetary magnetic field (IMF) near Earth abruptly swung around 180 degrees, and the solar wind density jumped more than 5-fold. Earth may have crossed through a fold in the heliospheric current sheet--a giant, wavy membrane of electrical current rippling through the solar system. Such crossings can cause these kind of effects.

While currents flowed through the ground, auroras filled the sky. Rayann Elzein photographed the corresponding outburst of lights from Utsjoki, Finland:



"What a surprise!" says Elzein. "The auroras were sudden and dynamic, with fast-moving green needles and several purple fringes!"

The auroras and ground currents were caused by the same thing: Rapidly changing magnetic fields. High above Earth's surface, magnetic vibrations shook loose energetic particles, which rained down on the upper atmosphere, creating auroras where they struck. Just below Earth's surface, magnetic vibrations caused currents to flow, triggering Rob Stammes' ground sensors.

"We couldn't see the auroras in northern Norway because of cloud cover," says Stammes, a little ruefully. "We had to be satisfied with the electricity underfoot."

After this, they kind of drop it, but there are still aurorae. They want to talk about Betelgeuse now.

[Brigit]

With a quiet Sun, and no geomagnetic storms, we have gorgeous auroral displays -- including pink and purple which I think requires higher energies -- and electric currents flowing in the ground, as far south as the UK.

Causes:

• a crack in the magnetic field allows very slow solar wind in

• a hole in the Sun's atmosphere slings particles our way

• we cross a fold in the heliospheric current sheet

Somehow the Kp index barely registered over a 3. Calm.

[Brigit]

The sun continued to be wonderfully quiet through the end of January and the month of Febuary up to today:

[Brigit]

Coronal holes, from which electrons and protons sometimes stream towards the earth, were hard to come by for the last week-and-a-half of January:


Jan 22, 2020 example

And on the 26th, there was a little action...


but no solar flares from the spot.

[Brigit]

Nevertheless, there were some mild, mild geomagnetic disturbances on the 30th and the 31st of January:



This is good because it shows that the instruments are on. (But I am not sure that all of them are.)

There were some beautiful auroral displays and upper atmosphere phenomenon (polar stratospheric clouds), on Jan 27th through the 31st:

SMALL CRACK IN EARTH'S MAGNETIC FIELD: Last night, a small crack opened in Earth's magnetic field. Solar wind poured in to fuel a quiet display of auroras over Canada. Catalin Tapardel sends this picture from Worsley, Alberta:


28jan20/Catalin-Tapardel via space weather com

"I spent few hours staring at the green glowing band," says Tapardel. "Other than a few shy pillars, there were no major developments in the aurora's structure. Just the usual solar minimum business...."

The crack developed on Jan. 28th when the interplanetary magnetic field (IMF) near Earth tilted south. This partially canceled our planet's north-pointing magnetic field, creating a gap through which solar wind could flow. During Solar Minimum (happening now), we rely on such cracks and gaps to "stoke the fires" of aurora borealis without the usual support of sunspots and solar flares.

The following day, there were these aurorae:

A NEW TYPE OF AURORA--"THE DUNES": A new type of aurora is rippling across Arctic skies. Citizen scientists who discovered it nicknamed it "The Dunes" because of its resemblance to desert sand dunes. A paper published in the Jan. 28th issue of AGU Advances describes the new form and the unexpected physics that causes it.

Woops, I have to leave!

[Brigit]

cont'd

Above: Aurora dunes over Latilla, Finland, on Oct. 7, 2018. Credit: Pirjo Koski. [more]

Dune-shaped auroras form in a narrow altitude range 80 km to 120 km above Earth's surface. Turns out, this is an extremely hard-to-study layer of Earth's atmosphere. It's too high for weather balloons, and too low for rockets.
"Due to the difficulties in measuring atmospheric phenomena between 80 and 120 km, we sometimes call this region 'the ignorosphere'," says Minna Palmroth, Professor of Computational Space Physics at the University of Helsinki and the lead author of the study.

Sky watchers in the Arctic have been seeing Dunes for years without understanding what they were. A breakthrough came on Oct. 7, 2018, when multiple groups photographed the dunes from widely separated locations in Finland. Maxime Grandin, a postdoctoral researcher in Palmroth's team, analyzed the images, using triangulation techniques to decipher the Dune's geometry.

Conclusion: Dunes are located ~100 km high--smack-dab in the middle of the ignorosphere--and have a pure, monochromatic wavelength of about 45 km.


Above: An artists' concept of a mesospheric bore trapped in a high-altitude waveguide. [more]

The research team believes the Dunes are a "mesospheric bore"--a type of atmospheric gravity wave that springs up from the surface below and gets caught in a thermal waveguide ~100 km high. When solar wind particles rain down on the bore, they illuminate its rippling structure.

The discovery of Dunes may allow researchers to study the ignorosphere as never before. Monitoring Dunes can reveal previously waves and waveguides at the boundary between Earth and space. Aurora photographers, have you seen a Dune? Submit your photos here.

via space weather com

Now I would like to show you what I see:

[Brigit]

Here is a list of Near Earth Objects which came within +-1 lunar distance during late January.

• Asteroid
  Date(UT)
  Miss Distance [unit is lunar distance]
  Velocity (km/s)
  Diameter (m)

• 2020 BN3
  2020-Jan-27
  6.9 LD
  28.9
  31
  
  2020 BA13
  2020-Jan-27
  0.5 LD
  10.3
  6
  
  2020 BY4
  2020-Jan-27
  6.9 LD
  21.2
  21
  
  2020 BK13
  2020-Jan-28
  1.5 LD
  9.9
  7
  
  2020 BO2
  2020-Jan-28
  10.5 LD
  10.7
  19
  
  2020 BJ7
  2020-Jan-28
  1.2 LD
  20.2
  8
  
  2020 BG13
  2020-Jan-28
  2.2 LD
  8.5
  10
  
  2020 BJ14
  2020-Jan-28
  8.5 LD
  15.4
  52
  
  2020 BG9
  2020-Jan-28
  12.5 LD
  10.2
  17
  
  
  2020 BZ13
  2020-Jan-29
  0.3 LD
  24.4
  4
  
  2020 BT14
  2020-Feb-03
  .5 LD
  8.4
  10

I think that these Near Earth Objects should be considered as potential candidates for the causes of the late January 2020 auroral and upper atmosphere activity. The case is very very difficult to make, but I will give reasons and I will address several serious objections.

[Brigit]

5 Reasons Why NEOs May Cause Geomagnetic Disturbances/Aurorae

1. A small charged body coming too near a large charged body induces a spark.

2. The small charged body, if it has a magnetic field, may induce current as it moves near Earth.

3. Depending on the latitude on the globe at which the small body grazes the Earth's magnetosphere, it may or may not show up on the instruments used to report a geomagnetic storm. The readings for the geomagnetic activity at each point are all averaged together, so one instrument which "felt" a very large disturbance would be averaged out by the lack of signal on the other instruments. But near the poles, could these localized geomagnetic disturbances cause an aurora?

4. The sizes of NEOs may be inaccurate because they are determined by magnitude (brightness), and most NEOs that come within 1 LD are always reported as tiny. Is this accountable? Also, not all NEOs are actually detected, and it does appear that they swarm by in groups.

5. A small charged body passing by the earth could possibly disturb either the inner or the outer Van Allen Belt, which may cause a discharge, ie a "rain of particles".
1 LD=238,900 mi
inner belt = 620-3700 mi
outer belt = 8100-37,300 mi

[Brigit]

I will offer this caution:
There may be geomagnetic storms, and no apparent NEOs or solar activity, and
there may be plenty of NEOs, and no auroral activity and no geomagnetic storms.

I have tried to address the problems with detection, measurement, and reporting on NEOs. After years of suspecting that asteroids -- because they are electrically charged bodies just like comets -- can disturb the Earth's magnetosphere, I found that just as often as not, like the flip of a coin, there is no observable effect of a near-passing asteroid.

But I showed at the beginning of the year that there may be some problems with the instruments used to detect geomagnetic storms, because there were some spectacular aurora and underground currents, yet no geomagnetic activity was measured. Is this right? Are one or two or even three of these instruments turned down, or turned off?

Some of these NEOs may indeed be very small, less than 10 meters, but what if their magnitude fluctuates? Why is it that no 1 LD NEO is ever very big? Are we that lucky?

Some NEOs may swing by and not be detected at all. I can say that after years of watching, sometimes they are detected and reported days after their near approach. I will give a February 2020 example of this.

[Brigit]

Are you alright Sun?



This is a lovely 3-day solar activity gif I get from tallbloke's. And it shows that we have even more signs of life for the instruments detecting geomagnetic storms.


And for such a trifling investment of geomagnetic disturbances, we got blue aurorae: