10, 12 and 15 meter openings? The secrets of solar data.


Many amateur radio websites show the Solar Terrestrial Data “ticker” from N0NBH. However, many HF radio enthusiasts just look at the SN (solar spot number) and perhaps the K index. The truth is that the SN does not necessary say too much about the current radio conditions. So what should you look at to check the current conditions (more realtime information)? solarvhf.php Here is the secret: I have personally found that the SFI and the 304A as well as the X-Ray values are very good realtime clues. One example is from 21.Oct.2012. This Saturday in October 2012, the 10 meter band was wide open from early morning even as far north as Oslo, Norway. The conditions on 12 and 15 meters was also fantastic. A screenshot of the N0BNH “ticker” shows SFI well above 120, 304A well above 140, K like zero and A like three as well as an X ray index of B9,9. Note that SN (sunspots) is not near abnormally high at around 112 (keep in mind we are closing in on sunspot maximum in cycle 24 so the SN will likely be around 100 all the time). One could expect average conditions by just looking at the SN. However the conditions was nothing like average. They were very very good. What was notable from that day is the following: SFI was well above 120 so there was a strong flux, K was zero so the mag field was still undisturbed, A was 3 so the mag field had been holding undisturbed for some time, X-Ray was B9,9 and this meant that there was quite strong X ray radiation coming in, 304A was 172,5 and this meant there was also quite strong UV radiation coming in, Aurora was 1 so there was practically no Aurora activity. The conditions was fantastic on this date on all bands above 7 Mhz. So again here is the secret: don’t just look at the SN for realtime information about the HF radio conditions.

NOAA solar wind prediction tool

NOAA has a nice tool that can be of utility for radio amateur operators that are interested in how the geomagnetic field will be affected and how strongly it will be affected. It is now possible to see when there is a high likelihood that the K and AP indexes will rise.


By processing the data from the STEREO satellites that are positioned “behind” and to “the side” of the sun, it is possible to plot the solar winds that are emitted from the sun.
You can check it out here: http://www.swpc.noaa.gov/wsa-enlil/cme-based/
The sun and the earth as well as the two STEREO satellites are seen from above in the circular images above. The green spot is the earth. The yellow spot is the sun. The grayish spot is the stereo satellite that sees the emissions from the sun before any active areas has rotated towards the earth. The red spot is the stereo satellite that sees the emissions from sun after any active area has rotated thru the earth direction.

The fan shaped images to in the center of the image above is the sun and earth seen “from the side”. It is possible to check if the emissions from the sun will propagate above, below or towards the earth. The AZ images on the left alone are not enough, because a particle emission may have the direction of the earth in zimuth (seen from the sun) but may have too high an elevation or too low an elevation to hit the earth.