The Ionosphere and who invented it? In 1902 Oliver Heaviside ( glad you don't have that last name huh! ) suggested the existance of a upper layer of the atmosphere that was accounting for the long distance radio communications that Marconi had made the year before. By 1925 a guy name Ed Appleton wrote a paper about this and decided to break the atmosphere down to several layers. He used the letter "E" as the first letter ( for electrons) to designate the strength of the electric field in the upper atmosphere. Two years later he added the letter "F" to designate a higher region of the atmosphere. This of course led to the letter "D" for the lower section of the atmosphere. As other scientists started to believe in this theory, there was talk of a letter "C". However Mr. Appleton would have none of it. He made this stuff up in the first place and no one was gonna steal his thunder, he insisted the final lower level be called the "D" level. Well after dozens of scientific papers, this worked. Thats what it has stayed to this day. Talk about defending your turf, Mr. Appleton was on it. However the term Ionosphere itself was coined by a guy named Robert Watson who called it by that name even before Appleton. However Appleton is the guy who came up with the layers part of it.
When I first got into amateur radio, one of the first things I heard about was Sunspots. We apparently need them for good dx propagation. Every once a month a number would be reported in ham radio magazines, telling you what the sunspot number was and whether it was predicted to go up or down. Basically Sunpots = Good........ No Sunspots = Bad. This was the beginning of what we now call Space Weather.
This space weather information although welcomed, was hardly indicative of what one might expect daily when on the radio. Since then things have improved somewhat. Although I must say : Noted Scientists who have studied the Sun and its Sunspots for years do not completely understand everything that happens on the Sun. In fact I'd say were just scratching the surface of what is known to be true about the sun.
The Sun throws out radiation of all kinds, from way below Ham radio frequencys all the way past the X-ray region. A lot of the radiation ends up emitted as heat. The Sun also is constantly throwing out hot material from its surface in all directions into space. This makes up the so-called solar wind Sunspots are actually relatively cool areas that appear as dark spots. Think of them as big storms here on earth. Once telescopes were invented, sunspots got noticed and were documented shortly after that. After a few decades it was noticed that the number of sunpots went from high to low in an 11 year period, almost to the month. It was here that early astronomers realized the the Sun had its own space weather. And maybe this could be predicted?
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So in regards to amateur radio, it was noticed in the 1950's especially that more sunspots led to better long distance radio propagation, and in fact predictions about ham radio propagation could be made via sunspot counts. This method got refined over the years from Sunspot Numbers to SSN..... Smoothed Sunspot Numbers..... to now Solar Flux. Solar Flux is a measure of overall energy recieved from the sun and is calculated every few hours. This so far is the best way to gauge total solar energy coming towards the earth.
Again I am going to state that the Sun is very unpredictable. We basically know Squat about it. An example, Did you ever sit around a campfire drinking beer with your girlfriend, family or buddies, and your looking at the fire and thinking "like wow man" . Then all of a sudden a big flame or spark jumps out of the fire and heads in your direction? Was that predictable? No. Thats kind of like the Sun , its up there burning day and night and no one knows whats going to happen next. So even if the Solar flux report looks crappy, that doesn't mean you should turn off the radio, because you just never know what will happen next.
Radiation from the Sun creates regions of ionization in the atmosphere. Ok so whats that mean? Ionization is the process by which ions are formed by gain or loss of an electron from an atom or molecule. If an atom or molecule gains an electron, it becomes negatively charged and if it loses an electron, it becomes positively charged. These " Free " electrons are what make long distance DX communication possible. The resulting electrically charged atom or molecule is called an ion. The more of these free roaming electrons there are the more the the upper atmosphere, particularly the highest "F" layer starts to act like a reflector or a mirror of sorts. Able to reflect radio signals from 10-80 meters or so back to earth. You may think you never heard of Ionization before but you probably have.
Even hear of Ionized salt? This is created when sodium and chlorine are combined to make salt, the sodium atom gives up an electron resulting in a positive charge, while chlorine gets the electron and becomes negatively charged as a result. You might have heard about salt water being a good conductor of electricity. When you put salt in water, the water molecules pull the sodium and chlorine ions apart so they are floating freely, increasing the conductivity. These ions are what carry electricity through the water with an electric current. In short, saltwater (water + sodium chloride) can help to maintain electric currents running across it.
I am going to define what some of the more popular happenings on the sun are, so when we get into the numbers you'll hopefully better understand what is happening on a daily basis.
Solar Flares: Solar flares happen when a Large amount of energy erupts from the sun, shown in the photo above. These are sometimes as large as the entire Earth! These happen most often near the PEAK of the sunspot cycle. When they are heading towards Earth, they hit the atmosphere in about 9 minutes, disrupting every form of radio communications, including HF. what it specifically does is cause the lowest part of the Earth's Ionosphere ( The "D" layer ) to increase greatly, so that it absorbs all HF radio signals and does not let them pass through this layer into to the upper Ionosphere to be reflected back down to Earth like on normal days ( no skip or dx ). If these are really big and they hit the Earth at the right angle (dead on) then all communications stop. No Noise, No Static, No signals. This can last quite a few hours until the Earths atmosphere has a chance to first absorb this radiation and then dissipate it. This can kill communication satellites as well. Nasty. There are small flares all the time on the sun, but they have much smaller effects, like increased HF noise on the band.
Corona Holes: This is a "hole" just above and in the center of a big sunspot. Think of the eye of the storm scenario in hurricanes. These happen most often during a declining or lowest part of the sunspot cycle. They also... when facing the correct angle to hit earth, eject lots of junk in our direction. This junk is moving incredibly fast and increases the total solar wind heading towards us. It will also disrupt communications for a few days on Earth. In fact it may even happen repeatedly as the sun spins around and the suspect corona holed sunspot comes back into view of earth. So every month at the same time, communications can be disrupted.
Sudden Disappearing Filaments ( SDF's ) & Ionospheric Storms : These are similar to solar flares in that it is a large sudden explosion on the sun that is ejecting material towards Earth. These can be seen on Earth as Aurora. This is when the magnetic field of the Earth itself gets affected. Scientist use magnetometers to study these things and let you know when and where you might see Aurora in the sky. Despite the name, these are not as bad as the first two disturbances mentioned. These will increase the noise level on HF and, may sometimes make DX signals get a hollow or echo sound to them. The higher bands on HF like 10-15 meters get affected more by these then on 20 meters and lower.
OK, lets go over todays current solar report. These are provided by N0NBH and there are many other contributors as well, all found on QRZ.com You can even get one of these for your own QRZ.com page.
The most important information I feel is the SFI the A index and the K index. Most of the rest of the info is all based on the same magnetometer readings and is similarly interpreted.
These are the basic parameters that tell us if there’s enough ionization to refract/reflect a signal back to Earth.
The SFI index: This it is a gauge of how many solar particles and magnetic fields are reaching our atmosphere. The higher the number the better. So far so good. Its an overall picture but as you will see does not provide all the detail you need. For instance high SFI numbers do not influence 40-160 meters all that much. The Solar Flux Indexed is measured by how much radio noise is coming from the sun at 2800 mhz. The higher the solar flux number the higher the MUF or maximum useable frequency is to make long distance contacts via the ionosphere.
SFI number less than 70....propagation probably crappy for DX.
SFI number between 80-90....propagation better on 20 meters, but not affecting 10-15 meters that much. There still can be openings on 10 meters for DX but it's hit or miss.
SFI number between 90-100....propagation becomes decent but not spectacular on all HF bands
SFI number between 100-150...propagation is pretty good, 20 meters great, other bands also going well through 10 meters.
SFI number over 150.... propagation is great but could be very noisy as well. Can you say Pileup? 10-20 meters on fire.
SN (sunspot numbers): This is the old way that was used to determine propagation. The higher the Sunspot number the higher the SFI generally. The SFI number takes into consideration the Sunspot Numbers, but is a really complicated formula with many other variables.
These are the basic parameters that tell us if the Earth’s magnetic field is disturbed meaning its more noisy than it should be.
The A Index: This is daily average of all magnetometer stations around the world in the past 24 hours. It is an average of individual K index numbers from around the globe. The lower the numbers the better. In other words this is yesterdays information. Numbers can typically go from 1-30, but ocassionally can go alot higher during solar storms.
Between 1 and 5: Good quiet lower noise conditions on the HF bands. 1 is significantly better then 5
Between 6 and 9: Average conditions but increased noise probably on the HF bands. 6 somewhat noisy but 9 really noisy.
From 15 and above: Lots of noise on the HF bands. Although conditions are good. Some parts of the earth could have better conditions. But usually high numbers here mean if conditions in your part of the globe are good, they probably won't be in a few hours from now.
The K Index: (or the Boulder Colorado Index) is a gauge of geomagnetic activity relative to a totally quiet-day. These numbers change every 3 hours. Falling numbers mean improving conditions and better propagation particularly in northern latitudes. If you see a value above 7 or 8 this indicates our planet going thru a major solar storm of very high intensity. In others words, were all screwed. But it also has a bright side. If you are into Aurora the larger the numbers here, the lower in Latitude you will see Aurora. So A High K index means a geo magnetic storm is happening in the atmosphere and communications on HF are likely to be crummy. The K index is more useful than the A index. Look for low numbers, it generally means quieter conditions. This combined with a high 120+ SFI is the best situation as far as getting that rare island DX expedition station. Be aware that these numbers are measured at Boulder colorado, and may be different where you live. Look at them as a general guide.
From 0 to 1: Best conditions for the HF bands. LOW Noise.
From 2 to 3: Good conditions for the HF bands. Some noise and static but okay
From 4 to 5: Fair conditions for the HF bands. Typically somewhat higher static levels, You need a good beam antenna here to get rid of the some noise. Minor solar storm in the atmosphere, conditions variable.
From 5 to 9: Noisy Static conditions for the HF bands. Major Storm in the atmosphere
Be aware that just because the SFI Index isn't stellar, does not mean the conditions are crummy. More important many times is the noise level. If the A and K indexes are showing Zero's and One's as conditions and the SFI is only at 75. The A and K indexes are indicating LOW NOISE levels and this will be the difference in you hearing that station in Indonesia on 20 meters from North or South America and not hearing it, than when the SFI numbers are higher but so is the noise. Graphs of the past index numbers from the A , K and SFI indexes are most useful.
And Vice Versa, If the SFI is over 140, but the noise levels on the A & K index are high, you'll find its not going to be wonderful as you might think. This means that the upper layer of the atmosphere has disruptions in it, and is not a smooth even electrically charged layer, so communication may be spotty and noisy. Although this certainly can change on a dime. To be honest no one can predict when different conditions on the Sun are going to effect our atmosphere, these measurements are all after the fact.
X-Ray Index: This is the amount of X-Rays penetrating the lower atmosphere and how much it is affecting the D layer absorption. Lower letters and numbers are better. The letter A means minimal effects on the D layer. The letter B slightly more, Letter C about average. Letters M & X mean lots of Absorption so DX conditions are not optimal no matter what the SFI says. Signals cannot pass through this lower layer of the atmosphere and therefore cannot bounce off the upper layers. Thats means no dx on any band.
304A Index: this is taken by measurements in the upper atmosphere ( not magnetometers ). It is the total solar radiation measured by these high tech in atmosphere instruments and thus related to the SFI index. However these are updated hourly. So they are reported much faster. However just because you see a spike in numbers here does not mean the band where you are located is going to be hopping. So following them hourly and looking at the SFI numbers gives you a good idea where propagation is headed ....up or down.
Ptn Flx and Elc Flx : This believe it or not is a measure of the density and the amount of protons and electrons in the upper atmosphere. The F layer. It usually reads unknown. But sometimes has numbers attached to it. when it does higher numbers (< 1000) means the upper atmosphere is very well charged. I wouldn't worry about these two readings too much.
Aurora: This is another sketchy measurement of how confident scientists are of they're measurements about whether or not we will get an Aurora and above what Latitude. Below 2 means they think they're measurements are good.
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The rest of the measurements are pretty self explanatory. It is nice to glance at, but the SFI, A, K Indexes is where it's at.
Be aware that Sporadic E, may provide sky-wave propagation on the 6 and 10-meter bands, especially during the late spring and summer. The reason for this mode of propagation has nothing to do with any of these indexes, and Sporadic E is not predictable, but it can offer exciting DX opportunities especially on these upper bands at any time. Sporadic E is an local Ionized cloud of electrons floating around up there that is capable of reflecting the upper HF signals. The lower HF bands, such as 80 and 40 meters, are less susceptible to sunspot activity, and can provide good propagation possibilities even at the "bottom" of a cycle. In fact if higher sunspots do anything to these bands.... it's to create more noise on them. These lower HF bands do best in the winter time where there are no Sunspots and Thunderstorms in your hemisphere.
Here's something you may not know: The sun itself actually rotates around its axis every 27 days! , one day shorter than the moon does. Since the sun is not solid around the center the suns rotation takes 25 days, while at the poles it takes 35 days. Sunspots mostly appear near the equator or middle area of the sun. SO if you have great conditions on March 1st of the year, they may in fact come back on March 28th of the same month, as that part of the sun is now facing you again. This of couse isn't guaranteed, buts it's a something thats really not known widely.
There you go, now you know what those bunch of numbers actually mean. And some stuff about the sun! Tell your friends, tell your mom, your neighbors, tell Everyone.
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