Posts Tagged ‘Sun’

Wishing Upon A Star



My love for radio began at an early age when I first started to tune the shortwave bands at age eleven. Little did I know then, that I was listening near the peak of the strongest solar cycle in recorded history, monster Cycle 19.



I thought that what I was hearing was normal for shortwave and that it would always be this way ... and it was, for a number of years.

As the solar cycle slowly declined, I began to take a deeper interest in propagation and its relationship with the Sun. After obtaining my licence and getting on the air, the reality set in with the arrival of a rather dismal Cycle 20. Following the vagaries of propagation became almost a hobby in itself, trying to correlate what I was observing with what the Sun was doing and even getting comfortable with predicting what might happen next.

It was particularly exciting during the stronger Cycles (21-23), to watch the dramatic effect of solar radiation on the F layer during the peak winter years of these cycles. With a major interest in 50MHz, watching the solar flux became a daily ritual, along with the fascinating daily rise of the F2 MUF as the Sun peaked over the horizon.

On normal mornings, around sunrise, the MUF would typically start close to 28MHz and slowly begin to rise over the next few hours. Often it would slow and settle-in between 38 and 42MHz, stay there for most of the day and then slowly recede as darkness approached.

I found myself looking forward to and wishing for more solar flares, along with the solar flux boost that inevitably followed.

On these mornings, the MUF would often be at 35MHz or higher, right at sunrise ... and begin climbing. Some days it would shoot-up like a rocket and in a matter of minutes would be at 50MHz or above, bringing thundering signals from the east coast not long after dawn. On other mornings it would climb much more slowly, receding and then advancing again, surging higher and then lower, as it teased its way towards the magicband. It was as if the ionosphere was a living breathing entity, as the solar radiation danced a slow tango with the critical frequency of the moment. Often it would stop at around 48 or 49MHz, stay there for several hours and then collapse ... no 6m excitement that day.

A nice bonus of watching this live interaction between the Sun and our ionosphere, was listening to the communications in the range between 28MHz and 50MHz as I followed the rising MUF. This was, and still is to a lesser extent, utilized on FM by paramedics, fire and police services throughout the U.S. It was not uncommon to hear mobile units enroute to an emergency, with sirens blazing in the background. Southern drawls usually meant that any 6m openings would begin in the southern states or the Caribbean, while Boston or New York accents, would herald an opening to New England or the possibility of trans-Atlantic openings to Africa or Europe. I became even more familiar with the daily interaction of the solar wind and how it affected radio ... and found it fascinating.

But just as the Sun affects propagation so positively, I was recently soberly reminded of how 'unfriendly' it can be ... as it has been in the past and will be again in the future. An article in this month's 'Astronomy', by Bob Berman, discussed threats to global welfare and in particular, a modern day repeat of the Carrington Event of 1859.

This was a double mega-flare and CME, taking only 19 hours to reach earth, compared to the normal 3-day trip. It was the strongest impact on earth ever recorded and one that will be repeated ... and is almost, statistically 'overdue', unless we dodged it in 2012 when a storm of similar magnitude missed the earth.

In Berman's words:

"What would a Carrington-level event do today, with our ubiquitous power lines, transformers, and more than a thousand operational satellites? In 2008, the U.S. government convened a panel of experts, who concluded that such a storm would completely destroy our electric grid. It would require two to 10 years to repair and cost about $2 trillion. We'd be knocked back to the stone age.
That panel panel called Carrington a "low frequency/high consequence" event - the kind humans typically ignore until it happens."
 

We quickly release how dependent on the hydro system we have become, when our power goes out for a few hours or even a day or two, following a severe weather event. Such an event is certainly 'inconvenient' but soon forgotten when the power returns. Going without power, and its trickle-down effects on our depended-upon infrastructures for several months or longer, would not be just 'inconvenient'. It would be a life-altering.

courtesy: http://www.solen.info/solar/
The Carrington event happened during Cycle 10, on the upward climb to the peak of an average-sized cycle. Solar scientists, for the most part, now predict a general decrease in solar activity over the next few cycles ... a spotless sun may become more the norm. Perhaps it is a good thing that the likelihood of a mega-flare event will be reduced but it seems that a repeat, at some point, is inevitable.

Maybe I'd better stop wishing for flares.

Thirty Minutes of Dazzle: The Sun in UHD 4K by SDO (NASA)

Take a front-seat view of the Sun in this 30-minute ultra-high definition movie in which NASA SDO gives us a stunning look at our nearest star.

This movie provides a 30-minute window to the Sun as seen by NASA’s Solar Dynamics Observatory (SDO), which measures the irradiance of the Sun that produces the ionosphere. SDO also measures the sources of that radiation and how they evolve.

SDO’s Atmospheric Imaging Assembly (AIA) captures a shot of the sun every 12 seconds in 10 different wavelengths. The images shown here are based on a wavelength of 171 angstroms, which is in the extreme ultraviolet range and shows solar material at around 600,000 Kelvin (about 1 million degrees F.) In this wavelength it is easy to see the sun’s 25-day rotation.

The distance between the SDO spacecraft and the sun varies over time. The image is, however, remarkably consistent and stable despite the fact that SDO orbits Earth at 6,876 mph and the Earth orbits the sun at 67,062 miles per hour.

Scientists study these images to better understand the complex electromagnetic system causing the constant movement on the sun, which can ultimately have an effect closer to Earth, too: Flares and another type of solar explosion called coronal mass ejections can sometimes disrupt technology in space. Moreover, studying our closest star is one way of learning about other stars in the galaxy. NASA’s Goddard Space Flight Center in Greenbelt, Maryland. built, operates, and manages the SDO spacecraft for NASA’s Science Mission Directorate in Washington, D.C.

Charged particles are created in our atmosphere by the intense X-rays produced by a solar flare. The solar wind, a continuous stream of plasma (charged particles), leaves the Sun and fills the solar system with charged particles and magnetic field. There are times when the Sun also releases billions of tons of plasma in what are called coronal mass ejections. When these enormous clouds of material or bright flashes of X-rays hit the Earth they change the upper atmosphere. It is changes like these that make space weather interesting.

Sit back and enjoy this half-hour 4k video of our Star!  Then, share.  🙂

73 dit dit

 

Stunning Ultra-HD View; Sun Timelapse 2015 NASA/SDO

This video is ten minutes of coolness.

This cool time-lapse video shows the Sun (in ultra-high definition 3840×2160 – 4k on YouTube) during the entire year, 2015. The video captures the Sun in the 171-angstrom wavelength of extreme ultraviolet light. Our naked, unaided eyes cannot see this, but this movie uses false-colorization (yellow/gold) so that we can watch in high definition.

The movie covers a time period of January 2, 2015 to January 28, 2016 at a cadence of one frame every hour, or 24 frames per day. This timelapse is repeated with narration by solar scientist Nicholeen Viall and contains close-ups and annotations. The 171-angstrom light highlights material around 600,000 Kelvin and shows features in the upper transition region and quiet corona of the sun.

The first half tells you a bit about the video and the Sun, and you can see the entire year 2015 rotate by.  The second half is narrated by a NASA scientist.  It is worth watching all ten minutes.  And, then, sharing!

The sun is always changing and NASA’s Solar Dynamics Observatory is always watching.

Launched on Feb. 11, 2010, SDO keeps a 24-hour eye on the entire disk of the sun, with a prime view of the graceful dance of solar material coursing through the sun’s atmosphere, the corona. SDO’s sixth year in orbit was no exception. This video shows that entire sixth year–from Jan. 1, 2015 to Jan. 28, 2016 as one time-lapse sequence. Each frame represents 1 hour.

SDO’s Atmospheric Imaging Assembly (AIA) captures a shot of the sun every 12 seconds in 10 different wavelengths. The images shown here are based on a wavelength of 171 angstroms, which is in the extreme ultraviolet range and shows solar material at around 600,000 Kelvin (about 1 million degrees F.) In this wavelength it is easy to see the sun’s 25-day rotation.

During the course of the video, the sun subtly increases and decreases in apparent size. This is because the distance between the SDO spacecraft and the sun varies over time. The image is, however, remarkably consistent and stable despite the fact that SDO orbits Earth at 6,876 mph and the Earth orbits the sun at 67,062 miles per hour.

A blending of an entire year, 2015, of the Sun as seen by NASA SDO at EUV 171 Angstroms

A blending of an entire year, 2015, of the Sun as seen by NASA SDO at EUV 171 Angstroms

Why This is Important

Scientists study these images to better understand the complex electromagnetic system causing the constant movement on the sun, which can ultimately have an effect closer to Earth, too: Flares and another type of solar explosion called coronal mass ejections can sometimes disrupt technology in space. Moreover, studying our closest star is one way of learning about other stars in the galaxy. NASA’s Goddard Space Flight Center in Greenbelt, Maryland. built, operates, and manages the SDO spacecraft for NASA’s Science Mission Directorate in Washington, D.C.

For us radio enthusiasts, the study of the Sun helps us understand the dynamics of radio signal propagation.  And, that aids us in communicating more effectively and skill.

Thanks for sharing, voting, and watching.  More information and live Sun content can be accessed 24/7 at http://SunSpotWatch.com

You can also get the Space Weather and Radio Propagation Self-study Course at http://SunSpotWatch.com/swc

 

Carrington Probabilities


K7RA's 'Solar Update' in this week's ARRL News, mentions Jeff Foust's recent article in 'The Space Review', reminding us again of the dangers posed by a modern-day 'Carrington Event', also known as the 'Solar Storm of 1859'. A large solar flare in late August, hurled a monster-sized CME towards earth, making the 93 million mile journey in just 17.6 hours compared with the more normal rate of several days.

Huge auroras soon lit up the sky as far as central Mexico, Hawaii and the Caribbean. The aurora was so bright, it was reported that Rocky Mountain goldminers awoke in the middle of the night, and thinking morning had arrived, started to prepare breakfast. Telegraph lines and equipment burst into flame while some circuits continued to be usable with power supplies completely disconnected. The 1859 event still remains the most geoeffective solar storm since records have been kept.

Such an event today, of course, would wreak much more havoc ... probably having devastating consequences for decades and causing trillions of dollars of damage.

From Foust's article:

Was that, though, just a fluke event? .... Pete Riley, senior research scientist at Predictive Science Inc., offered a probabilistic forecast for the likelihood of another Carrington-like event, based on that storm’s estimated strength and measurements of the actual strength of solar storms over the last few decades. “If you the (sic) time between events, you can calculate the probability of the next event occurring within some unit of time,” he explained. 

His estimate of the probability of another Carrington event is surprisingly high: about a 10 percent chance of such an event occurring over the next decade. “Ten percent is very, very high,” said William Murtaugh, assistant director for space weather at the White House’s Office of Science and Technology Policy (OSTP) ... “A one-percent probability over the course of the next one hundred years of a storm with an impact of that magnitude is considered very, very high and will motivate action.”

Interestingly, for this prediction, the actual strength of the solar storm of 1859 can only be estimated. If it was actually twice as strong as thought, then the probabilities drop from a (decade) 10% probability to just a 1% chance.

The U.S. government has recently set up a NASA multi-million budget funding proposal to study the likely effects of future large scale impacts and possible “response and resiliency capabilities” but it's not known if these will carry over to any new administration.

“Fortunately in space weather there’s no real politics,” Murtaugh said. “Both sides of House, both sides of the Senate, Republicans and Democrats, are both keen to work together to do something about this issue.”

The article has brought some interesting 'food for thought' comments, among them:

I think it is excellent that there are steps being taken to improve our understanding of the probabilities and predictive accuracy of such solar events, but I'm concerned that it isn't entirely clear how that information will translate into major investments in civil engineering that will make us less vulnerable to them. As for asteroidal impact threats, it's one thing to have a observations and research that will provide predictive information, and another to prevent tragedy. In both cases, it's about how we'll actually prevent such destructive effects once predicted. Prevention is a LOT more expensive than prediction, and is thereby ripe for threat denialism, which seems to be an emotion that has thoroughly infected at least the leaders of our nation.

It's a little funny about how much energy is being spent advocating human spaceflight for colonization and settlement as a means to save the species, but so little is being devoted to specific threats to the species, and to individuals in particular. I could get killed in an asteroidal impact or a severe geomagnetic storm, but sending a shipload of people to Mars sure isn't going to protect me. 

I am a member of Infragard, which is dedicated to supporting efforts to protect us from risks to our electrical grid and other critical infrastructure. A novel "One Second After" by William R. Forstchen accurately illustrates the effects of a similar intentional attack on our grid and how it creates a cascading collapse of our society. Gas stations cannot pump gas, food rots in the stores, more food cannot be delivered to all the needed locations, and the people who know how to fix things cannot reach where they are needed and also starve to death. The result of a severe Carrington event with no effective preparation or protection for the giant transformers could thus cause most of our population to starve in a few months. This risk is about 1% to 0.5 % per year and is like having everyone playing Russian roulette once a year with 200 pistols where just one is loaded. 

A modern day 'Carrington repeat' does indeed give pause for thought but perhaps the generally predicted upcoming 'grand solar minimum' will buy scientists some extra time to come up with solutions for what will eventually occur ... and, one more thing's for certain ... it'll be a heck of an aurora!

Aurora On The Move



A recent posting to the Pacific Northwest VHF Society's reflector brought my attention to an interesting article describing the southward migration of the auroral zone.




According to the research paper published in the Proceedings of the National Academy of Sciences, the earth's magnetic field is gradually growing weaker, thus affecting its interaction with the solar wind.

The paper indicates that our present, abnormally high magnetic field, forces this interaction (auroras) to higher latitudes and as the field strength gradually weakens to more long-term average levels, auroras will be seen further south than we have been used to. The field has already weakened by about 10% over the past two hundred years and will continue to do so. Apparently it's all related to the regular 'flipping' of our magnetic field, with the most 'recent' flip taking place about 780,000 years ago.

So what does this mean for radio amateurs? Probably not a lot, in the immediate future but the unwanted effects to disturbances in the geomagnetic field will eventually be felt further and further to the south. Radio propagation in southern British Columbia has always been particularly sensitive to even very small disturbances in the field, particularly on the LF and MF bands. I am constantly amazed at how regions only 150 miles to the south or southeast of me are so much less affected than here, in the southern fringes of the auroral zone. VE7's don't claim to be in radio's 'black hole' without good reason.

LF Improving

courtesy: http://sdo.gsfc.nasa.gov/

After more than a week of horrendous geomagnetic activity, due mainly to coronal-hole streaming, it looks as if things are starting to settle down once again. One would never know it from looking at the sun's image as the source of the streaming is largely invisible in the visible light spectrum. Viewing at a different wavelength however, reveals the source of the disruption, now about to rotate out of view for a few weeks.

courtesy: http://sdo.gsfc.nasa.gov/

courtesy: http://wdc.kugi.kyoto-u.ac.jp/dst_realtime/presentmonth/index.html

courtesy: http://www.noaa.gov/
With the DST heading upwards and the planetary K numbers dropping it looks like we are returning to a good place and just in time ... October is often one of the best months of the year for LF propagation.

Quiet Sun Not Enough


courtesy: http://sdo.gsfc.nasa.gov/
Conditions on LF have been rather dismal for the past week and a half. Here in western Canada as well as most regions running along the southern edge of the auroral zone, the nightly visible auroras have been wreaking havoc on normal LF propagation as well as dampening HF during the day but ...





... the sun has been deathly quiet, as can be seen in yesterday's solar disk image.

It seems that just the 'normal' solar wind can disrupt things all on its own, without any solar flares or coronal mass ejections. In the late 70's, 'cracks' in the earth's magnetosphere were first observed... cracks that allowed even a quiet solar wind to actively interact with the earth's (normally protected) upper atmosphere. Apparently this is the present condition that has been disrupting normal propagation for the past many days.

The spaceweather.com web site has a nice explanation of how these cracks allow the Sun's Interplanetary Magnetic Field (IMF) to interact with the earth's field:

"Earth has a magnetic field, too. It forms a bubble around our planet called the magnetosphere, which deflects solar wind gusts. (Mars, which does not have a protective magnetosphere, has lost much of its atmosphere as a result of solar wind erosion.) Earth's magnetic field and the IMF come into contact at the magnetopause: a place where the magnetosphere meets the solar wind. Earth's magnetic field points north at the magnetopause. If the IMF points south -- a condition scientists call "southward Bz" -- then the IMF can partially cancel Earth's magnetic field at the point of contact.

When Bz is south, that is, opposite Earth's magnetic field, the two fields link up," explains Christopher Russell, a Professor of Geophysics and Space Physics at UCLA. "You can then follow a field line from Earth directly into the solar wind" -- or from the solar wind to Earth. South-pointing Bz's open a door through which energy from the solar wind can reach Earth's atmosphere!"


Earth's Bz has been pointing south during this entire period of poor propagation. Heavy ionization of the daylight D-layer, normally an 'absorber' of LF signals, has allowed reception of several NDB signals normally only heard at night. In fact, one of my favorite NDB propagation indicators, 25-watt YLJ in Meadow Lake, Saskatchewan, has been heard all day long on 406KHz for the past week as its signal skirts along the underside of the dense D-layer. These auroral conditions however, often enhance the path to the south Pacific and several western BCB DXers have reported excellent propagation to Australia and New Zealand in the pre-dawn hours.

Another indicator of LF propagation disturbance is the DST or Disturbance Storm Time index. This number gives an indication of the severity of the weakness in the magnetosphere, with numbers going further and further negative as the charged particles trapped in the magnetosphere increase in numbers.


courtesy:http://wdc.kugi.kyoto-u.ac.jp/dst_realtime/presentmonth/index.html

The DST has been having a rough ride since the beginning of the month and as these numbers grow more positive and remain there, propagation will return to normal. With late September and October often being among the best months of the year for LF propagation, and with the sun now doing its part by remaining quiet, let's hope that the earth's magnetosphere will also co-operate and seal-up those propagation-killing cracks.

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