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Posted by: Paul Harden, NA5N Posted On: 12/13/06 Subject: Today's solar report explained Message Posted: Hopefully, this post will only show up ONCE today. Must have been those protons or something :-) Gang, I am adding commentary to help explain "how to read" the reports I hope some of you find helpful. >Joint USAF/NOAA Report of Solar and Geophysical Activity >IA. Analysis of Solar Active Regions and Activity from 12/2100Z Normally, a solar flare causes radio emissions to begin in the 300-1000MHz range, then sweeps downward into HF. On especially strong flares, emissions can occur higher, at 10cm or 2880MHz where the Canadian Pentictin Observatory measures the hourly solar flux. The solar flux is the normalized energy output of the sun - thus, when a flare causes radio emissions at that frequency, it contaminates the daily flux reading. Pentictin removes the flare effect, such that the daily solar flux does NOT include the radio energy due to the flare. The 44000 sfu (solar flux units) is a large value and likely highly contaminated the flux readings. This statement is basically telling you the flare was a very energetic event to extend all the way to 10cm/2880 MHz, and informing you the daily solar flux reading is the "best guestimate" after removing the effects of the solar flare. What's important for QRPers to understand is this extra dose of solar flux, while meaningless to most people, means the E and F layers also got an extra dose to make them more reflective and elevated the MUF. Unfortunately, there are no "numbers" to tell you this, since the effect is removed from the daily solar flux readings. So, just remember that when a fairly large solar flare occurs, an hour or so afterwards until sundown is a good time to expect an improvement in the higher bands due to the MUF and E/F reflectivity. Normally, this enhancement ends when the sun goes down. The higher bands remained in good shape today (unexpected 10M openings) due to the persistence of the energetic proton event. >Type II (1534 km/s) and Type IV radio sweeps were associated with As the coronal mass ejection (CME) is blown away from the surface of the sun, it punches through the magnetic field lines of the disturbance causing radio bursts. Very near to the sun, these bursts will be in the above mentioned 300-1000MHz region. As the shockwave travels farther away from the sun, the radio bursts occur at lower and lower frequencies (due to the electron density of the sun's atmosphere getting less). These radio bursts, starting at high frequencies and "sweeping" to lower frequencies are the Type II bursts. Of particular importance is by measuring the time the bursts occur at one frequency vs. a lower frequency, one can calculate the velocity of the shockwave. In this case, the Type II sweeps indicated the CME was leaving the sun at 1534 km/s. It is interesting to note that with all the neat fancy satellites and ground based solar instruments, the shockwave is still measured by following the radio bursts from VHF to HF at various observatories. Once the CME is far out into space, the SOHO satellite can often see the movement of the plasma wave, and hence calculate the velocity of the CME. Unfortunately, these SOHO instruments are currently not operational to do this. So, good old radio is the only indication that this CME is a fairly fast one. > as well as a fast moving CME (estimated plane of sky speed of 1500 km/s). To be honest, with SOHO down, I don't know how they estimated the CME unless through mathmatical manipulation of the radio Type II sweep (like the 85% rule I used last night to estimate arrival time). The "sky speed" means the speed of the CME once it has escaped the sun's influence and traveling along the plane of the solar wind (or, the ecliptic). > Region 930 has a strong delta configuration in the southern penumbral area Large sun spots develop magnetic field lines between them called a beta configuration. When these magnetic field lines get very strong and complex, they are called a delta configuration. The majority of major flares occur from a delta region, though not all delta groups produce flares. This is basically telling you the delta group in region 0930 still has the capability of producing another major flare. NOAA's prediction below of a 60% chance of an M-class flare, and a 35% chance for another X is simply based on this "strong delta configuration" that still remains. Therefore, the fun may not be over yet. The penumbra are the small hair-like structures that extend outward from a sunspot. One belief is the darker "hairs" are painting a picture of the magnetic field lines around that particular sunspot. Sunspots in a delta group, with strong magnetic fields, tend to have a pronounced penumbra. >IB. Solar Activity Forecast: Solar activity is expected to reach Again, just based on the persistence of the strong magnetic delta group. >IIA. Geophysical Activity Summary 12/2100Z to 13/2100Z: The proton event is due to the X-class flare. The higher the energy level (MeV), the higher the ionizing radiation. PFU=proton flux units, a measure of the ionizing radiation due to the protons. >A greater than 10 MeV proton event started at 13/0250 UTC, and reached a Ditto for the 10MeV protons (less ionization than the 100MeV) >The greater than 2 MeV electron flux at geosynchronous orbit reached high This is a warning to those who operate satellites that the ELECTRON flux (not proton) is high, which can cause various problems to satellites. One effect is when the stream of electrons flows past the satellite, it can cause a large voltage differential to occur from one side of the satellite to the other (usually only a few feet). This can cause damage to the internal electronics. Some satellite operators will bring in their solar arrays, initiate an intentional spin, etc. to reduce the hazards. >IIB. Geophysical Activity Forecast: The geomagnetic field is In last night's post, a purely mathematical approach based on the Type II sweep speed was used to predict impact of the CME with Earth about 1000UTC on 14DEC (early morning EST). NOAA's prediction seems to be about two hours later than this. It is comforting to know they, too, are now predicting a severe geomagnetic storm. The point of that exercise, of course, was to demonstrate the methodology QRPers can use to estimate when a geomagnetic storm may occur following a major solar flare when you don't have your own personal SOHO satellite. Of course with this flare, neither does NOAA! Sometime tomorrow morning, we'll find out who's right ... >Major to severe storm conditions are expected to continue early into 15 >December. This is based primarily on the fact that a severe geomagnetic storm usually persists from 18-24 hours. >The greater than 100 MeV and 10 MeV proton events now in progress are >expected to continue for the next 24 to 48 hours. For QRPers, this is telling us a couple of things. Second, the influx of protons will continue to fuel the Polar Cap Absorption event, keeping our QRP friends in the higher latitudes in a state of perpetual HF blackout for a few more days. >III. Event Probabilities 14 Dec-16 Dec The delta configuration suggests further M or X class flare activity. >IV. Penticton 10.7 cm Flux The observed 10.7cm flux, again, is with the flare effects removed to show a normalized day-to-day change. >V. Geomagnetic A Indices Yikes! An estimated A-index of >100! That is definitely a severe geomagnetic storm, translating to a K-index of 7 to 8, and noise levels in the S8-S9 range. Of course, there is no precise correlation between these "numbers," just a general indicator. Also, on HF, the effects of a geomagnetic storm get worse the lower in frequency you go. If 40M is totally wiped out, noise levels on 20M may be manageable. >VI. Geomagnetic Activity Probabilities 14 Dec-16 Dec A greater than 50% chance of a major-severe geomagnetic storm. Also note the chances are greater in the higher latitudes, as is always the case, as the closer you are to the poles, the solar electrons and protons trapped in the Earth's magnetic field lines will be closer to the Earth's surface, and because our magnetic field, being disturbed, is weaker at the poles. For those interested in some illustrations on the beta and delta groups, or a table estimating K vs. A indices, etc., the handout I used at Rochdale is now online at: Sorry to be so long winded, but this may be the last opportunity to study a major flare event for many moons to come. Three X-class flares from the same region at the bottom of the solar cycle is indeed quite rare. 72, Paul NA5N PS -- For those who might be in the shack when the shockwave hits, it would be very interesting to monitor WWV at 5MHz or a shortwave station 5-6MHz with a tape recorder running. The onset of a high velocity CME can be very astounding. I'm sure thousands of QRPers would love to hear it if you are lucky enough to catch it. I'll bet a handful of those PhD type astronomers would love it too. |
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