*Sorry, I had this scheduled to go this morning and in a brilliant move scheduled it for 7 pm. Sorry Stephanie. And yes, I can totally hear you say “Bless your heart.”-SAH*
Solar, Space, and Geomagnetic Weather, Part VI: Solar-Earth DefCon Levels
By Stephanie Osborn
“Interstellar Woman of Mystery”
Rocket Scientist and Novelist
As I told you last time, 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. And yes, that honkin’ big one we had in 2003 was one of these.
By the way, this also affects our astronauts. Per Australia’s ABC News, “Astronauts aboard the space shuttle Atlantis were aloft during a solar storm in October 1989, and ‘reported burning in their eyes, a reaction of their retinas to the solar particles,’ according to the book Storms from the Sun: The Emerging Science of Space Weather, by Michael J. Carlowicz & Ramon E. Lopez. [https://books.google.com.au/books?id=RJO_IsMDiccC&q=1882&hl=en#v=onepage&q=1989&f=false]
“‘The crew was ordered to go to the “storm shelter” in the farthest interior of the shuttle, the most shielded position. But even when hunkered down inside the spacecraft, some astronauts reported seeing flashes of light even with their eyes closed,’ the book notes, adding that if the astronauts had been on a deep-space mission or working on the Moon, there was a 10 per cent chance they would have died.”
Somewhat related to the geomagnetic storm index is the radio blackout index. This tells us the specific effects of a flare on radio communications. However, these are caused, not from the impact of a CME, but from the x-rays produced by the originating flare! So instead of taking hours to days for the effects to reach us, we feel the effects only 8.3 minutes after the flare occurs — at the same time we SEE the flare. Consequently, the strength of the comm effects can provide us an early warning to later geomagnetic effects.
An R1 radio blackout is considered minor. “HF Radio: Weak or minor degradation of HF (high frequency) radio communication on sunlit side, occasional loss of radio contact. Navigation: Low-frequency navigation signals degraded for brief intervals.” They occur on average 2,000 times per solar cycle.
An R2 radio blackout is “moderate.” “HF Radio: Limited blackout of HF radio communication on sunlit side, loss of radio contact for tens of minutes. Navigation: Degradation of low-frequency navigation signals for tens of minutes.” We get approximately 350 of these per solar cycle.
An R3 radio blackout is starting to get serious; it’s “strong.” “HF Radio: Wide area blackout of HF radio communication, loss of radio contact for about an hour on sunlit side of Earth. Navigation: Low-frequency navigation signals degraded for about an hour.” They happen 175 times per solar cycle.
Then we have an R4 Severe radio blackout. “HF Radio: HF radio communication blackout on most of the sunlit side of Earth for one to two hours. HF radio contact lost during this time. Navigation: Outages of low-frequency navigation signals cause increased error in positioning for one to two hours. Minor disruptions of satellite navigation possible on the sunlit side of Earth.” Fortunately, they only occur, on average, about 8 times in any given solar cycle.
And then there is the gut-buster. It’s an R5 Extreme radio blackout. This one can be bad, folks. “HF Radio: Complete HF radio blackout on the entire sunlit side of the Earth lasting for a number of hours. This results in no HF radio contact with mariners and en route aviators in this sector. Navigation: Low-frequency navigation signals used by maritime and general aviation systems experience outages on the sunlit side of the Earth for many hours, causing loss in positioning. Increased satellite navigation errors in positioning for several hours on the sunlit side of Earth, which may spread into the night side.” Fortunately, we get one or less of these per solar cycle.
But stop and think for a few minutes about the potential ramifications of one of these. An ENTIRE HEMISPHERE is without radio communications for entire blocks of time. ALL SHIPS AT SEA are out of comm with land, and each other. ALL AIRCRAFT are unable to communicate with each other and all flight controllers. Worse, THEY HAVE NO IDEA WHERE THEY ARE. Navigational systems have been hosed — yes, I’m talking GPS here — and they are now relying on eyeballs and dead reckoning to get from point A to point B.
Also realize that the largest ever in modern record-keeping was caused by a solar flare on Nov. 4, 2003, associated with the same solar activity that produced the Halloween Geomag Storm of 2003. This one was so strong, it actually pegged the measurement meters, and was originally believed to be “only” an X28…until further analysis revealed its true strength: X45. The last time we had one of these (that I’m aware of) was in 2006, but it was only an X9 and the blackouts lasted about 10 minutes.
But for the 2003 flares (it was really a series, and therein lies another danger — these things rarely pop off just once and then shut up), GPS was still a relative novelty in the civilian world, and this was before GPS was standardly included on everything from cars to cell phones. Given that our naval forces have stopped using, or even teaching, celestial navigation, and that we have, at any given time, thousands of commercial airline passengers IN THE AIR, this has the potential to be catastrophic beyond belief.
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 — the letter 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 1.6×10-19 joules. So an MeV is an energy of 1.6×10-12 joules. It’s not big, but when you’re talking about something as small as a proton, it’s plenty 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. In fact, there have been only 6 in the last century and a half, most of which were in the latter half of the 20th Century: 1972, 1989, 2000, 2003, and 2009.
But even the typical description of a G5 or S5 doesn’t match the strongest geomagnetic storm in history. The Carrington Event tops the charts by all measures.
Comet Tales blog/Osborn Cosmic Weather Report: http://stephanie-osborn.blogspot.com/