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

Excerpt: The Case of the Displaced Detective:The Arrival

This is the prologue to the first book in my Displaced Detective Series, The Case of the Displaced Detective: The Arrival, a science fiction mystery. Books 1 and 2 (The Case of the Displaced Detective: At Speed) are in release, ebook and treebook; book 3, (The Case of the Cosmological Killer: The Rendlesham Incident) will be released later this year. You can purchase both in pretty much any format you like through my website, www.stephanie-osborn.com. Hope you enjoy this excerpt.

~~~

Prologue—Objects, Subjects, and Beginnings

A tall, dark figure, clad in formal Victorian eveningwear, strode briskly down the shadowed street, casually swinging his silver-embellished walking stick. No carriages had passed in the last half-hour, and only one hansom cab had wandered by ten minutes before, its horse’s hollow hoofbeats echoing between the buildings. The gas street-lamps were long since lit, but between them were patches of deep darkness, patches entirely too broad for comfort in these circumstances. Beneath the brim of his silk top hat, eagle-sharp grey eyes darted about, studying the shadows, alert and aware. For well this man knew that danger lurked in the gloom this night, danger peculiar to him alone; and he was alone. So very alone.

But not for long. He was headed to a specific destination. To the one man he knew he could trust, the one man who would stand at his side regardless of danger—for had he not done so, many times before? Was not this the reason for the deep, if largely unspoken, bond of friendship between them?

His friend would help. There was no doubt in his mind on that point. Already today two attempts had been made upon his life, and well did this man need help.

"Not far now," the words breathed past thin, pale lips. "Almost ther—"

The words died on said lips.

A hulking, brutish shadow materialised from the alleyway in front of him. The elegant man in the top hat ducked just in time to avoid the lead-weighted bludgeon that swung through the space his head had occupied fractions of a second before. Instead, the silk hat took the brunt of the blow, flying across the sidewalk and into a puddle in the gutter, its side crushed. Flinging up his cane and grasping each end in his hands, the gentleman dropped into an Oriental horse stance, and prepared to do battle.

"’Ere, now," the other figure said, in a coarse growl. "Hit’s th’ end o’ you, it is. Me superior won’t be ‘arvin’ it, an’ Oi means t’ see ‘e don’t ‘arve ta."

"You can try," the gentleman replied, calm. "But better men than you have tried, and here I stand."

A guttural, angry sound emerged from the assailant, and the cudgel swung again, this time with enough force to crush bone. Deft, the gentleman caught it with the center of his cane, but to his chagrin the walking-stick, his weapon of choice in many a similar street altercation, chose that moment to give up the ghost. It snapped in two, splintering and cracking. He snarled his own irritation, and flung the pieces aside when he realised there was not enough left to use as a decent weapon.

Then he began to flit and weave as the other man smirked and lunged at him, swinging the club repeatedly, as hard as he could. It was a dance of death, and one wrong move by the gentleman would have serious, possibly fatal, consequences.

But the man in the evening dress was not without weapons; no, his best weapons were permanently attached to his person. The alert grey eyes watched, looking for some opening; and when he saw his chance, he struck like lightning. A fist shot out at the loutish face, catching the hit man squarely in the mouth just as he realised his danger and started to shout for help. All that came out was a grunt, however, and the assassin fell to the pavement as if pole-axed, with both lips split.

The gentleman hissed in pain, grabbing his fist with his other hand for a moment to let the worst of the discomfort pass before examining the damage.

"By Jove, he has sharp teeth for such a troglodyte," he murmured, peeling off the ruined black kid glove to expose the bloody knuckles beneath. "Completely through the leather and into the flesh. I shall have to have this disinfected, for certain. No time for that now. Go, man!" He turned swiftly to resume his journey.

A crack resounded from the brownstone close at hand, and the man felt a spray of stone chips strike the side of his face. He flinched, and a sharp curse left his lips. He took to his heels and rounded the corner of the street, then disappeared into shadow.

* * *

Not ten feet away from the gentleman, though invisible to him, an elegant blonde woman in a white lab coat stood between tall, electronic towers. Behind her, concentric rows of computer consoles were manned by two dozen scientists, engineers, and technicians. Surrounding all of them was a huge, domed room carved from solid pink granite.

The woman stood for long minutes, silent, watching.

Finally one of the technicians broke the electronic silence.

"So, Doc, whaddaya think?"

"What do you think, Jim? How were the readings?" The woman turned toward him.

"I’ve got bang-on, Dr. Chadwick," Jim noted, glancing down at his own console, brown eyes darting about as he surveyed his readouts. "But I can’t say for everybody else."

"Rock steady at Timelines," someone else called.

"Sequencing looks good…" another said.

"Software’s running nominally."

"Hardware’s humming right along…"

On it went, from console to console. Finally the woman nodded.

"Perfect," she purred in deep satisfaction. "We’ve got our subject. Page Dr. Hughes and have her come down."

"On it, Doc," Jim grinned, reaching for the phone.

~~~

For more, or to purchase this and more books in the series, go to my website, www.stephanie-osborn.com.

Solar, Space, and Geomagnetic Weather, Part 4

So what the heck are CMEs?

Coronal Mass Ejections are gigantic explosions that occur, usually in the vicinity of particularly active sunspot groups (though not always). We're still discovering what they are, how they occur, and why they do what they do. It seems to get into some complicated electromagnetic physics and something called “magnetic reconnection.”

Think about it like this. Suppose you have two bar magnets, lying near each other but, say, perpendicular to each other. Each has its own magnetic field, with field lines that go out from one pole and arc around to the other pole (remember our discussion of iron filings a couple weeks ago?), but now we've got them close enough that those magnetic fields interact.

Suppose – just suppose – a field line broke away from its parent magnet and attached the opposite end to the other magnet? Now suppose a whole SEGMENT of field lines did that. Those bar magnets would start dancing a whirligig, and the magnetic field would go crazy.

Now suppose that the bar magnets are swirling plasma gases, and the field lines are running through more swirling plasma.

THAT is magnetic reconnection. The end result is that a whole bunch of energy gets transferred from the field into kinetic energy. This heats up the plasma AND accelerates it, and, at least on the surface of a star like our Sun, a titanic explosion is the result. A great big blob of plasma goes flying out into space, and that blob is a “coronal mass ejection,” because a big mass of the corona just got ejected from the Sun. (Imaginative name, huh?)

The vast majority of them aren't THAT big, and aren't even Earth-directed. The chances of one smacking Earth aren't that big. But because there are a lot of them, especially at solar max, it happens fairly often. Sometimes it's just the edge of the expanding bubble, but sometimes it whacks Earth upside the head. And when they come in, they're coming fast.

So what are the general parameters of a CME? Depends on where in the solar cycle you are. If you're near solar minimum, they occur about one every 5 days or so. If you're around solar max, expect one every 6 or 7 hours. How big are they? If you're talking volume, that's gonna depend on how far out from the Sun they are, and how well the interplanetary medium is allowing them to hold together. If you're talking how massive, well, on average they're about 3,520,000,000 lb (1,600,000,000,000 kg). That's over three and a half trillion pounds of plasma. On average, their speed is about 304 mi/s or 1.1 million mph (490km/s). IF, however, one follows close on the heels of another, so that the first one has swept most of the interplanetary medium out of the way (decreasing drag), the speed can increase to 2,000 mi/s or 7.2 million mph (3,200 km/s). And with the Sun 93 million miles away, that means a fast CME can reach Earth in just under 13 hours.

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