+++++++++++++++++++ Date: Wed, 04 Jun 2003 18:32:01 -0600 From: na5n at zianet.com To: qrp-l at lehigh.edu Cc: k5di at zianet.com Subject: [151851] Re: Good Band Conditions Indicator Karl F. Larsen (k5di at zianet.com)wrote: > I used Google and put in WWV and got the web page that gives > Flux A and K numbers and a hint about solar activity. But I can't find > anyone who is willing to lodge a smart guess for conditions on Field Day > which is June 28,29. > > If you know of a place to get this guess data I would like the > URL for it. Thanks. Karl and others, This is actually a good question, and a chance to explain a few things for those new to the list. NOAA and other organizations do provide long term predictions of solar flux and the geomagnetic indices (A- and K-index), but those are based strictly on mathmatical averages. We have crossed the solar maximum and on the decline, for which the 11-year solar cycle flux can be estimated from month-to-month. On top of that, you have the variation in solar flux due to the 28-day period of a solar rotation. This causes the solar flux to go up and down, making a sine wave, over the 28-day Carrington rotation of the sun. This too can be mathmatically modeled and added to the month-to-month solar flux of the solar cycle. Using the above process, the estimated solar flux for June 28 Field Day will be about 110-115. However, this does not take into account things like major solar flares and coronal holes, which can not be predicted with much accuracy. Flares are almost impossible to predict, short of 24 hours prior to a major flare occuring, and coronal holes can sometimes be predicted with some accuracy, as they tend to remain at the same place on the sun for several rotations. Therefore, a large coronal hole, which is spewing out solar mass that can trigger minor geomagnetic storms when it reaches earth, can reappear at the same spot 28-days later to shower the earth again. For a coronal hole to effect the earth, it needs to be positioned approaching the center - to the center - of the sun for the outflow to reach the earth's geomagnetic field. It is fortunate that you asked this question today, because Field Day is a bit more than 28 days away. So in terms of solar flux and coronal holes, Field Day could appear very similar to what we were experiencing on June 1st. And that a solar flux around 110 and A-indices around 20 due to the ending of a coronal hole stream. However, June 1st also saw horrible conditions, major to severe geomagnetic storms, due to the major M and X class flares occuring over several days. We were being hit by the shock waves and the proton events from these large flares. That condition likely WILL NOT reoccur for Field Day, as the occurance of major flares are not predictable. But, the active region of the sun that caused all those flares, could survive a solar rotation and re-emerge a day or two before Field Day. If it does produce a major flare, it could effect Field Day. The window to watch would be 2-3 days BEFORE Field Day. It takes 2-3 days for the shockwave of a major flare to reach the earth. It is the shockwave that smacks into our geomagnetic field and causes the major to severe storms. So watch the NOAA site (http://www.sec.noaa.gov) for major flare activity on wednesday or thursday. If no major flares, and no large coronal holes, our geomagnetic field should be fairly quiet, defined as A index 12 or below, or K=1 or 2. Should a major flare occur DURING Field Day, it could interrupt HF propagation but ONLY for the DURATION of the flare and perhaps an hour or two afterwards. This is not from a geomagnetic storm, as the shock wave won't hit earth for another 2-3 days, but from the arrival of the speed-of-light, and near speed-of-light electrons hitting the earth. These may penetrate the E and F layers and travel into the D-layer, where they will cause enhanced ionization of the D-layer. The D-layer is the absorption layer, that is, it absorbs a portion of our QRP signals as it travels through to the E/F layers, and again on the bounce back to earth. If the D-layer gets highly ionized from the arriving electrons from a flare, it will cause the D-layer to highly attenuate HF signals for a couple of hours, until the ionization bleeds off to normal levels. During this time, signals will appear to be very weak, or perhaps sound like a radio blackout - no signals at all. But the good news, this condition is temporary and will exist only a couple of hours. In the meantime, work as many stations as you can on GROUND WAVE :-) One last thing to remember ... Solar flux effects the maximum usable frequency (MUF). The higher the solar flux, the higher the MUF. Right now, with solar fluxes around 100, 10M is barely open and the MUF is around 20-24 MHz ... making even 15M open for a short time of the day. Solar flux does NOT effect frequencies BELOW the MUF. Therefore, low MUF's will not effect 40/80M for example. Noisy conditions due to the after math of a flare generally do not extend below 10MHz. So again, 20M to 10M is only bothered by the solar flux phenomenon. Geomagnetic storms effect the lower frequencies more than the higher ones. Should a geomagnetic storm be in progress, this will effect the lower bands only. It takes a severe geomagnetic storm to cause problems much above 10MHz. So a geomagnetic storm does not particularly bother 20M. So for solar activity, geomagnetic storms and general propagation of the HF bands, it is ALWAYS pretty good practice to start out saturday noon with the highest band that is opened. Likely, 10M will beable to support long skip propagation from noon to late afternoon, local time. 15M will be in similar condition, except open before noon up until sundown or a little after. 20M will be open 14-hours, although with the lower flux, a bit weaker and fluttery in early evening to about midnight, when the night time atmosphere finally becomes stable. These bands will NOT be effected much should a geomagnetic storm be occuring on Field Day. Then at night, as the lower solar flux drops the MUF down to 18MHz or so, 20M will remain open, and skip on 40 and 80M will be starting late afternoon until sunrise sunday. The conditions on 80 and 40M have NOTHING to do with the solar flux or flares going on. Unless a major flare is tossing electrons and protons down to the surface of the earth, known as a GLE (ground level event). Let's worry about that scenario if it happens -hi. I mean that ionizing radiation is flying through your body at that point. Working Delaware should be the last of your worries! At night on 80-40M, the biggest concern is NOW the condition of our geomagnetic field. This is when the lowest A-index or K-index is very important. The higher the 3-hourly K-index, the higher the noise level below 10MHz. This will make the difference between a S-3 or S-4 noise level (K=1 or 2), or with K>3, noise levels pushing that S-meter to S5, 6 or 7. But the good news, by Field Day, you should know whether or not geomagnetic storming is likely ... due to either a coronal hole stream forecast, or a major flare occuring on wednesday or thursday. If those two situations do not occur, then 40-80M on Field Day saturday night should be a fairly good shape. So start with the highest band you hear activity on (15M, possibly 10M), and work down to 20M when you milk them out. Around sundown, work 15 or 20 for 30 minutes or so to pickup some good north-south propagation due to the grey-line, then hit 40M a bit after sundown, then 80M when you milk out 40M or your dupe sheet gets blown away in the wind :-) My guestimate for Field Day: Solar flux 110 +/- 5 and A-index <15 Unless of course a major flare occurs wednesday or thursday. 72, and CU on FD/QRP Paul NA5N PS - Even hoping to work Karl this year. You know, it's hard to work your fellow NM QRPers from the short local ground waves due to the mountains and skip tossing your signal too far. +++++++++++++++++ Date: Wed, 04 Jun 2003 20:06:57 -0600 From: "James R. Duffey" To: k5di at zianet.com, QRP-L Subject: [151862] Re: Good Band Conditions Indicator Karl - From NOAA'a 28 day predictions: 2003 Jun 26 115 25 5 2003 Jun 27 110 15 3 2003 Jun 28 115 15 3 Doesn't look too bad, barring any turbulent events on the Sun. 10 M probably won't be open except for sporadic E, but 15 M should open long. 20 M will be the workhorse. Paul's Prognostications look pretty good. - Dr. Megacycle KK6MC/5 ______________________ James R. Duffey KK6MC/5 Cedar Crest NM 87009 DM65 +++++++++++++++++