Solar, Space, & Geomag Weather part IV and Other Stuff

by Stephanie Osborn
http://www.stephanie-osborn.com

As I sit and sip my cafe au lait made from Cafe du Monde's signature chicory blend, I must note that I've been recalcitrant in posting lately. Sorry about that; I can only plead that I have been in the depths of a writing jag, and turning out word counts that are both consistent and high. I also totally hosed my reckoning of days of the week for this past week, thanks to the fact that Monday was a holiday.

So I am very late on this post. Please forgive me.

The latest installment of the Solar, Space, and Geomagnetic Weather series went up on Sarah Hoyt's blog, According to Hoyt, on schedule on Thursday. It's here:
https://accordingtohoyt.com/2016/09/08/solar-space-and-geomagnetic-weather-part-iv-by-stephanie-osborn/

An announcement of my title, Sherlock Holmes and the Mummy's Curse, having won the Silver Falchion Award went up on Wednesday's Mad Genius Club, here:
https://madgeniusclub.com/2016/09/07/sherlock-holmes-and-the-mummys-curse-wins-silver-falchion-award-stephanie-osborn/

To purchase a copy in print or ebook, go here:
https://www.amazon.com/Sherlock-Holmes-Mummys-Stephanie-Osborn-ebook/dp/B017IX33NW/ref=asap_bc?ie=UTF8#nav-subnav

I'm still answering comments on both blogs, so feel free to pop over to either of those, or both, or leave comments here.

In addition, solar activity has been fairly quiet, this week-and-a-half into September that we are. Sunspots have been seen throughout, but they are somewhat sporadic and all clustered in the equatorial regions (as would be expected at this point in the solar cycle). There have been a few flares, but nothing of great significance, and no coronal mass ejections have been produced, though there was a "prominence eruption" on the 6th. A few coronal holes have generated enhanced solar wind streams that have produced minor to moderate geogmagnetic storming, and some high-latitude auroras.

And that's it. There really hasn't been any solar/space weather news of significance so far this month. Things remain quiet, but not unusually so, in the solar mechanisms.

Other items:

Happy 50th birthday to Star Trek!

Condolences to SpaceX on the loss of their craft on the 1st.

We finally found the remains of the Philae comet lander:
http://www.space.com/33971-lost-philae-comet-lander-finally-found-photos.html

And that's about all I know, folks.

-Stephanie Osborn
http://www.stephanie-osborn.com

Solar/Geomagnetic Activity!

by Stephanie Osborn
http://www.stephanie-osborn.com

HEADS UP, SPACE FANS!

Earth is currently experiencing a GEOMAGNETIC STORM! These occur when a sudden influx of plasma (a gas cloud of charged particles) enters Earth's magnetic field from outside, most often from solar activity (a coronal mass ejection aka CME, or an enhanced wind stream from a coronal hole). They can be mild, strong, or severe, depending upon how dense the plasma cloud is.

Okay, for those of you just tuning in, let's work on explaining some terms.

~~~

      We are also sitting inside the atmosphere of the Sun, which is called the corona. Yes, we are, even at 93 million miles distant. It generates a wind, usually coming out from the Sun and spiraling away – yeah, the “solar wind.” Granted, the corona isn't very dense, but it's dense enough to create some effects, and we're working on using it to our benefit, like in solar sails and such, which can use the solar wind as much as light pressure (different topic) to maneuver around the Solar System like the spaceborne clipper ships of old. 

      But when the Sun gets... agitated, we'll say... the solar wind can get a lot denser. Coronal holes tend to move gradually from the poles down to lower latitudes, and the Sun's face develops an astronomical case of acne. This usually occurs around the time of solar maximum.

~The Weather Out There Is Frightful, Stephanie Osborn, ©2011

~~~

Now, a coronal hole is just a place in the magnetic field where the field lines stretch out to infinity, rather than looping back around, like the poles of a bar magnet. That means that the plasma can channel outward along those field lines, deep into the solar system.

This is an image of the inner corona of the Sun, taken by the Solar Dynamics Observatory on August 2, 2016, at a wavelength of 211 Angstroms. The dark regions are the coronal holes, which show up nicely at this spectral region.

If Earth happens to run into one of these "enhanced solar wind streams," as they're called, if it's strong enough, it slams into our magnetic field like a bow wave from a ship. This compressed the magnetic field on the sunward side, and stretches out the "tail" on the anti-sunward side. If the tail is stretched enough, it can snap off, and "magnetic reconnection" occurs, when the field lines reattach closer in. But magnetic reattachment itself generates a HUGE surge of energy, which is fed back into Earth along our own poles.

~~~

      So what are the effects of coronal hole winds and Coronal Mass Ejections (CMEs)? 

      They can actually raise the temperature of the outer layers of the Earth's atmosphere (the thermosphere, aptly named) sufficient to cause it to expand. This affects us, because that increases drag on satellites and spacecraft, and can cause the orbits of satellites to decay and re-enter well before they were intended... 

     Disruption of the Earth's magnetic field can be a problem. It can disrupt radio communication (including cell phones) rather severely. It can damage satellites that remain in orbit. It can generate “induced current” in any lengthy conductor...And it causes the aurorae. Most of you reading this have heard of the Northern Lights, properly termed the Aurora Borealis, but there are also the Southern Lights, the Aurora Australis. These are actually ovals that circle the magnetic poles of Earth (and most other planets with magnetic fields, by the way. They've been photographed on Jupiter.) They are where the charged particles that have been caught up from the solar wind or CME into the geomagnetic field follow the field lines down into the atmosphere. The gas molecules become excited into a higher energy state, then discharge that extra energy as light. This is very similar–in fact, essentially the same–as a fluorescent light bulb, only natural and not contained. The colors are determined mostly by the main gas that is fluorescing. Carbon dioxide produces white light; nitrogen, pink or red; oxygen, green or blue. (It can also generate ozone.)

~The Weather Out There Is Frightful, Stephanie Osborn, ©2011

~~~

So what we've got, space fans, is a big ol' coronal hole generating an enhanced solar wind stream, and the Earth ran smack into it. Currently the planetary K-index (a rough measure of the strength of the disturbance in the planetary mag field) is oscillating between 5 and 4, and at 5, we start geomagnetic storming. It's minor, so far, but it's there. So we are under an official NOAA GEOMAGNETIC STORM ALERT for MINOR GEOMAGNETIC STORMING.

This in turn means that there will be some heating of the upper atmosphere, and it can induce some currents in conductive materials near the poles. Communications may be affected in high latitudes, and migratory animals may briefly become confused.

But what it ALSO means is that we have an AURORA ALERT for high latitudes! Now, NOAA doesn't put out aurora alerts. But I do! My followers on Facebook know that whenever conditions are right, I issue an aurora alert, and give a heads-up to the regions who can reasonably expect to see one. This is not a guarantee that you WILL, only that the probability is GOOD. Therefore --

Residents of Canada, Greenland, extreme northern Russia, Finland, Sweden, Norway, Iceland, possibly extreme northern Scotland, Antarctica and the islands in the Antarctic oceans, Australia's state of Tasmania, the southern tip of New Zealand's south island, and the northern regions of the following USA states: Maine, Michigan, Minnesota, parts of North Dakota, and essentially all of Alaska --

Keep an eye to the skies tonight! You just might see an aurora!

~Stephanie Osborn
http://www.stephanie-osborn.com

Space Weather - The Carrington Event

In August of 1859, during historic Solar Cycle 10, something very strange began to happen. The Sun, as it neared solar max, grew unusually active. It produced prolific numbers of sunspots and flares, some of which were visible to the naked eye. This continued through the end of the month, until, just before noon on September 1, British astronomer Richard Carrington, just 33 and already acknowledged as one of England's premier solar astronomers, observed an incredibly brilliant solar flare – a flare that was easily visible to the naked eye. In later times, this single flare became known as The Carrington Super-Flare. In his own words from his scientific records:

“...Within the area of the great north group [of sunspots]...two patches of intensely bright and white light broke out...My first impression was that by some chance a ray of light had penetrated a hole in the [projection] screen...for the brilliancy was fully equal to that of direct sun-light; but by at once interrupting the current observation, and causing the image to move by turning the R.A. [right ascension, an astronomical coordinate akin to longitude] handle, I saw I was an unprepared witness to a very different affair...The instant of the first outburst was not 15 seconds different from 11h 18m Greenwich mean time, and 11h 23m was taken for the time of disappearance [from the telescope's view]. In this lapse of 5 minutes, the two patches of light traversed a space of about 35,000 miles...”

British amateur astronomer Richard Hodgeson also observed it; Balfour Steward at the Kew Observatory noted a “crochet” effect on the observatory's magnetometer. (A “crochet” is also sometimes called a Sudden Ionospheric Disturbance, or SID. It is when a solar event produces an abnormally high plasma density – remember, plasma is like the stuff in your fluorescent lights – in one layer of the ionosphere. This in turn creates literal electric currents running through the ionosphere, which magnetometers pick up. It creates something of an invisible lacy pattern in the atmosphere, hence, I suppose, the term “crochet.”)

And all of the previous flares and coronal mass ejections had fairly effectively cleared the interplanetary medium between the Sun and Earth.

The enormous coronal mass ejection produced by the super-flare slammed into Earth in only 17 hours.

The resulting effects lasted several days.

What kind of effects?

Worldwide aurorae for starters. These aurorae were most noted in the Caribbean, where they had never been seen before. Colorado gold miners, awakened by the brightening skies, got up and began cooking their breakfasts, because they thought it was dawn. In Europe and the northeastern United States, newspapers could be read by the light of the aurorae.

Speaking of newspapers, the Baltimore American and Commercial Advisor spoke of the ongoing event in poetic terms. “Those who happened to be out late on Thursday night had an opportunity of witnessing another magnificent display of the auroral lights. The phenomenon was very similar to the display on Sunday night, though at times the light was, if possible, more brilliant, and the prismatic hues more varied and gorgeous. The light appeared to cover the whole firmament, apparently like a luminous cloud, through which the stars of the larger magnitude indistinctly shone. The light was greater than that of the moon at its full, but had an indescribable softness and delicacy that seemed to envelop everything upon which it rested. Between 12 and 1 o'clock, when the display was at its full brilliancy, the quiet streets of the city resting under this strange light, presented a beautiful as well as singular appearance.”

Those dealing in the business of telegraphy did not think so highly of the display. The incredibly intense event, a maximal G5 and S5 by any definition, created induced currents in telegraph wires that were simply impossible to control. Lines and pylons threw sparks, telegraph batteries were blown, telegraphers received severe shocks, and telegraph “flimsy” paper burst into flames.

And yet some telegraph systems continued to function, despite having no batteries to power them. The induced current was simply that strong.

This was the Carrington Event, the most powerful solar/geomagnetic storm ever to occur in recorded history. It was before the advent of electricity, or electronics, or integrated grids and networks, save for telegraph systems, with which it wreaked havoc. Imagine what effect it would have today.

Dibs on the story.    ;-)

-Stephanie Osborn

http://www.stephanie-osborn.com

Solar-Earth DefCon Levels, Part 2

Now, while all of this stuff is going on in the geomagnetic field, what's happening in space? Hard radiation, and lots of it, that's what. After all, that's basically what's causing the disturbance in the geomagnetic field.

And of course NOAA has another scale that relates to that, called the solar storm scale, and represented by – you guessed it – S.

There's not a direct correlation that I've ever been able to find between the G scale and the S scale, because the S scale is determined by the number of protons of a given energy that passes through, say a square meter in a second. This number is called the proton flux. (In the case of the S scale, the energy of the protons must be greater than or equal to 10MeV, where MeV is mega-electron-volts. An electron volt is very tiny, only 1.6x10^-19 joules. So an MeV is an energy of 1.6x10^-12 joules. It's not big, but when you're talking about something as small as a proton, it's big enough.)

So at S1, our proton flux is 10 protons per second per steradian per square centimeter. (This is not a very big area. The bigger the number of protons passing through, the bigger the radiation dose.) An S1 is a minor solar storm. According to NOAA, the effects are as follows, “Biological: none. Satellite operations: none. Other systems: minor impacts on HF radio in the polar regions.” This happens a lot, but not quite as often as a G1 – an S1 occurs about 50 times per solar cycle.

An S2 is a moderate solar storm. It requires a proton flux of 100, and occurs half as often as an S1. Effects: “Biological: passengers and crew in high-flying aircraft at high latitudes may be exposed to elevated radiation risk. Satellite operations: infrequent single-event upsets possible. [A single-event upset, or SEU, is when the bit of a computer is accidentally reset to its opposite condition by a proton or electron impact.] Other systems: small effects on HF propagation through the polar regions and navigation at polar cap locations possibly affected.”

S3 is a little stronger still; it's a “strong” solar storm, with a proton flux of 1000. (Note that the solar storm scale is a logarithmic scale like the Richter scale, with each step of the scale having 10x greater proton flux than the previous.) Only 10 of these typically occur per solar cycle, but they aren't pleasant. “Biological: radiation hazard avoidance recommended for astronauts on EVA; passengers and crew in high-flying aircraft at high latitudes may be exposed to radiation risk. Satellite operations: single-event upsets, noise in imaging systems, and slight reduction of efficiency in solar panel are likely. Other systems: degraded HF radio propagation through the polar regions and navigation position errors likely.”

Stepping up to an S4, a severe solar storm, we have a proton flux of 10,000. They are pretty rare, with only about 3 per solar cycle occurring. “Biological: unavoidable radiation hazard to astronauts on EVA; passengers and crew in high-flying aircraft at high latitudes may be exposed to radiation risk. Satellite operations: may experience memory device problems and noise on imaging systems; star-tracker problems may cause orientation problems, and solar panel efficiency can be degraded. Other systems: blackout of HF radio communications through the polar regions and increased navigation errors over several days are likely.”

And finally the granddaddy of solar storms, the S5, the extreme storm. It has a proton flux of 100,000 protons per second per steradian per square centimeter. Simply put, a flood of 100,000 protons is striking every square centimeter (less than half an inch each way), every second. These are very rare, and may or may not occur in any given solar cycle. But they can be devastating. “Biological: unavoidable high radiation hazard to astronauts on EVA (extra-vehicular activity); passengers and crew in high-flying aircraft at high latitudes may be exposed to radiation risk. Satellite operations: satellites may be rendered useless, memory impacts can cause loss of control, may cause serious noise in image data, star-trackers may be unable to locate sources; permanent damage to solar panels possible. Other systems: complete blackout of HF (high frequency) communications possible through the polar regions, and position errors make navigation operations extremely difficult.”

We're fortunate those don't occur very often at all.

But even the typical description of a G5 or S5 doesn't match the strongest geomagnetic storm in history.

-Stephanie Osborn

http://www.stephanie-osborn.com

Solar-Earth DefCon Levels, Part 1

As I told you last week, NOAA has a scale of geomagnetic activity that ranges from G0 to G5, where G0 is quiescent, and G5 is the worst geomagnetic storm around. Now, we've already talked a little bit about what geomagnetic storms do...

No, we didn't, you say?

Ah, but we did. Back when I told you about all the effects that Coronal Mass Ejections can have. (Solar, Space, and Geomagnetic Weather, Part 4.) Because those sorts of things are what cause the geomagnetic storms.

But probably the best way I can tell you about the effects is simply to quote from NOAA's scale itself (which can be found here: http://www.swpc.noaa.gov/NOAAscales/#GeomagneticStorms).

As I mentioned last week, a G0 is the normal, quiescent geomagnetic field. This holds until the Kp index reaches 5, and then we begin minor geomagnetic storming, with the scale hitting G1. According to NOAA, “Power systems: weak power grid fluctuations can occur. Spacecraft operations: minor impact on satellite operations possible. Other systems: migratory animals are affected at this and higher levels; aurora is commonly visible at high latitudes (northern Michigan and Maine).” These are fairly frequent, with on average close to 2000 per 11-year solar cycle.

At Kp=6, G2 is considered a moderate storm. “Power systems: high-latitude power systems may experience voltage alarms, long-duration storms may cause transformer damage. Spacecraft operations: corrective actions to orientation may be required by ground control; possible changes in drag affect orbit predictions. Other systems: HF radio propagation can fade at higher latitudes, and aurora has been seen as low as New York and Idaho (typically 55° geomagnetic lat.).” These are a little less frequent than G1, but still occur at a rate of about 600 every solar cycle.

When Kp=7, G3 is a strong geomagnetic storm. “Power systems: voltage corrections may be required, false alarms triggered on some protection devices. Spacecraft operations: surface charging [static electricity buildup; this can lead to arcing]may occur on satellite components, drag may increase on low-Earth-orbit satellites, and corrections may be needed for orientation problems. Other systems: intermittent satellite navigation and low-frequency radio navigation problems may occur, HF radio may be intermittent, and aurora has been seen as low as Illinois and Oregon (typically 50° geomagnetic lat.).” These are less frequent still, with on average 200 per solar cycle. Also, as the geomagnetic storms increase in strength, their likelihood of occurrence tends to concentrate around solar maximum, though this is not a hard and fast rule.

At Kp=8, G4 is a severe geomagnetic storm. “Power systems: possible widespread voltage control problems and some protective systems will mistakenly trip out key assets from the grid. Spacecraft operations: may experience surface charging and tracking problems, corrections may be needed for orientation problems. Other systems: induced pipeline currents affect preventive measures, HF radio propagation sporadic, satellite navigation degraded for hours, low-frequency radio navigation disrupted, and aurora has been seen as low as Alabama and northern California (typically 45° geomagnetic lat.). These are rarer still, with only about 100 seen per solar cycle.

And then there's the big boys. Kp=9 means a G5 extreme geomagnetic storm. “Power systems: widespread voltage control problems and protective system problems can occur, some grid systems may experience complete collapse or blackouts. Transformers may experience damage. Spacecraft operations: may experience extensive surface charging, problems with orientation, uplink/downlink and tracking satellites. Other systems: pipeline currents can reach hundreds of amps, HF (high frequency) radio propagation may be impossible in many areas for one to two days, satellite navigation may be degraded for days, low-frequency radio navigation can be out for hours, and aurora has been seen as low as Florida and southern Texas (typically 40° geomagnetic lat.).” These are the rarest of all, but still occur on average 4 per solar cycle.

-Stephanie Osborn

http://www.stephanie-osborn.com

Solar Activity and the Activity Indices

Okay, back to bar magnets again. Because the Earth has one. But of course it's three-dimensional, not like our iron filings on paper example. Imagine picking up the bar magnet with the iron filings and paper attached, and rotating it 360º, letting the iron filings remain in the areas they move through. Now you have an image of what a three-dimensional dipolar (2-pole) magnetic field looks like – sort of like a giant pumpkin. With the solar wind (which is probably the largest influence on the interplanetary magnetic field) pushing on it from the Sun direction, the side of the pumpkin facing the Sun tends to smush in, but the side away from the Sun tends to stretch out and form a long tail. (You can see a really good animation of how this works here: http://en.wikipedia.org/wiki/File:Animati3.gif) This is all to say that you HAVE to think of the geomagnetic field three-dimensionally. And if it is three-dimensional, then each part of the field has an x-, a y-, and a z-coordinate component.

Let's simplify for a minute. Let's say that we're going to look at the component of the geomagnetic field that is running horizontally to the Earth's surface at any given point. Now because the Earth is curved, this is a tangent line that is continually changing as you move around the Earth. Now let's look at the disturbances from normal, caused by solar weather – coronal holes, CMEs, what have you.

So we have these variations, that are going to be different for different parts of the Earth for the same event. How do we measure it? It's a little like a Richter scale for geosolar storms. It runs from zero to nine, and there's a special formula that enables it to be calculated regardless of the location of the observatory, just like the Richter magnitude of a quake can be determined from seismographs on the opposite side of the globe. This scale for solar-induced geomagnetic activity is called the K-index. Zero is essentially no activity; anything above 5 is considered a storm level of activity. The bigger the number, the greater the effects seen on the ground, and the farther south the auroral oval can be seen. At a K=9, the aurora can be seen...in the TROPICS.

(Just for the sake of more information, the letter K was derived from the German word “kennziffer,” which apparently means “characteristic number.” Us scientists, we love our imaginative names, you know?)

Now if we reference the Kp index, we're talking about the interplanetary K index, not the geomagnetic K index. This is an average of all the K indices from all of the observatories, weighted as appropriate (remember, you won't get the same measurements from the various observation sites, so you have to factor that in, as well as the fact that the geomagnetic field is constantly changing). This gives us an indication of what the interplanetary magnetic field (IMF) is doing. BUT – not all of the stations report in at the same time. So then scientists have to calculate something called the “estimated Kp” which is just what it sounds like – an estimate for those stations that haven't reported in yet. This can sometimes be a very good predictor of what the magnetic field is going to do, and sometimes not so much. We're still very much learning this particular science.

But we're not done with indexes. There's also something called the a index. This is based on the AMPLITUDES (yep, there's the reason for using an a) of the deviations from geomagnetic normal, taken over a three-hour period. Then there's the A index, which is an AVERAGE (yep, that's where the A came from) of all the a-indices for a 24-hour period.

One more index we need to look at is the G scale, which is the National Oceanic and Atmospheric Administration's (NOAA) way of quantifying the strength of the geomagnetic disturbance. For any K index of 4 or less, the scale shows G0. At K=5, we jump to G1 – minor storming. For K=6, we have G2. For K=7, G3. At K=8, we have a storm level of G4, and at the maximum K=9, we have maximum storming of G5. Think of it like the Earth's solar DefCon level.

Next week we'll go into those DefCon levels in detail.

-Stephanie Osborn

http://www.stephanie-osborn.com

Solar, Space, and Geomagnetic Weather, Part 2

But wait! There's more!

At Solar Max, the coronal holes move away from the Sun's poles and group in with the sunspots, spewing high-speed solar particles out into the plane of the solar system.

At the end of every 11-year cycle, the magnetic orientation of the spots...flips. The end that was North becomes South, and the end that was South becomes North. It takes a whole 'nother cycle to get back to the way it started out. So that's a second solar cycle, the 22-year cycle.

In addition there are longer cycles that we are still working on figuring out, because they're hundreds of years long, and it's hard to get data that goes far enough back to chart those.

Now, sunspots look dark not because they're cold, but because they're just a bit cooler than the surrounding plasma of the photosphere (which is the visible “surface” of the Sun). If the photosphere is about 5,800°K (~10,500°F), then the sunspots are about 3,000-4,500°K (4,900-7,600°F). Still plenty hot enough to fry your turkey, but still several thousand degrees cooler than their surroundings. They can be teeny-tiny (relatively speaking, of course) or they can be huge things (80,000km/50,000mi – not too shabby when you consider the Earth is about 13,000km/8,000mi diameter) big enough to be seen by the naked eye (but don't do that – we like having eyesight.)

So you might reasonably expect that during a solar max the Sun would be cooler, and send less energy out into space, right? Well, at first glance you might think so, but that isn't really how it works. Remember, a sunspot is a big magnetic snarl. And the plasma around it follows the lines in that snarl. So we get all those great big loops – prominences and flares and things like that. Occasionally, like a snarl in your hair, the lines break – but unlike your hair, they reattach, producing really spectacular flares.

And then there are the CMEs. Coronal Mass Ejections.

I'm never quite sure how to best anthropomorphise a CME. Are they solar belches, or sneezes? Suffice it to say that all of that magnetic field mess around the sunspot group causes some sort of explosion. (No, we don't know exactly why. We do know it's really, really complicated.) And it is like a giant nuclear bomb, blowing a big bubble of plasma away from the Sun at high speeds.

So between the coronal holes increasing both the speed and density of the solar wind, and these CMEs exploding into the solar system, the most active time for the Sun is in fact solar max, and that is when it's pumping more energy into the solar system, not less.

I know, I know - that doesn't make sense. Let's talk about the details next week.

Stephanie Osborn
http://www.stephanie-osborn.com