The NW7US Beacon

Another Sunspot, Following Active Sunspot Region 1302…

Though it appears smaller when compared with the highly active sunspot region, NOAA 11302 (or, just 1302), there is a ‘new’ sunspot region just now rotating into view on the solar northeastern limb.  This will add to the overall solar activity and EUV (extreme ultraviolet) levels.

The high 10.7-cm radio flux of 190, reported for September 24, 2011, was likely enhanced by all of the back-to-back x-ray flare activity that occurred throughout September 24th. The flux at the official recording site has since fallen back to the upper 160s. However, the story is not yet over.

The active region, 1302, is not yet fully facing Earth. And, we have more sunspots coming into view, possibly. At least, we have this new, smaller one, which will add to the existing source of the ionizing EUV that contributes to the propagation of radio waves via the F2-region of the ionosphere.

Remember, the 10.7-cm radio flux is used to give us a general idea of the level of solar activity that affects the ionosphere. The higher the 10.7-cm radio flux, the ‘better’ the ionospheric F2 propagation. A better, more direct measure is actually the Background X-ray (1 to 8 Angstroms) level. And, we know that those levels are now in the C-class range, for a number of days, now. That’s pretty much a first, for this new Cycle 24. We’ve had moments of C-class background x-ray energy, but not consistently, as we’re now having.

Here’s the Background X-ray Level (1-8 Angstroms), Last Six Days: Sept 24, 23, 22, 21, 20, and 19 2011: C1.6, C1.3, C1.4, C1.0, B7.1, B8.0.

As you can see, the background x-ray level for September 24th was the highest of the last six days. This is the true indication of how energized is the ionosphere.

More about Background X-rays

The hard X-ray energy present from the wavelengths of 1 to 8 Angstroms provide the most effective ionizing energy throughout all of the ionospheric layers in our atmosphere. The GEOS satellites measure these wavelengths and the resulting measurements are reported as the ‘background X-ray level’ throughout the day. A daily average is reported, as well.

Just like X-ray flares, the background hard X-ray level is measured in watts per square meter (W/m2), reported using the categories, A, B, C, M, and X. These letters are multipliers; each class has a peak flux ten times greater than the preceding one. Within a class there is a linear scale from 1 to 9.

If one records the daily background X-ray levels for the course of a sunspot cycle, one would discover that the background X-ray levels remained at the A class level during the sunspot cycle minumum. During the rise and fall of a solar cycle, the background X-ray energy levels remained mostly in the B range. During peak solar cycle periods, the background energy reached the C and sometimes even M levels.

Armed with this information, can we discover any clues as to the current status of Sunspot Cycle 24? Below is a graph plotting the background hard X-ray energy reported by the GEOS satellites since the end of Sunspot Cycle 22. Clearly, we see a noticeable rise in Cycle 24 activity. We’re seeing the energy mostly in the B level more often, supporting the view that Cycle 24 is alive and moving along toward an eventual sunspot cycle peak in several years.

Overall, the monthly average background ‘hard’ X-ray level is rising (as seen by the following plot), showing a change from deep solar cycle minimum. We are certainly in the rising phase of Sunspot Cycle 24. While it has been a slow up-tick over the last eighteen months, I expect to see a more rapid rise during mid to late 2011.

Back to this weekend’s high solar activity…

So, even if we see the 10.7-cm flux level fall a bit from this new record high of 190, if the background x-ray level stays in the C-class range as I expect that it will, plan on enjoying higher F2-region Maximum Usable Frequencies (MUFs) on most HF (high frequency, or shortwave) propagation paths. Combine that with the seasonal enhancement for long-range DX, and we’re in for a great season.  That is, when we’re not dodging the momentary radio blackouts during those solar x-ray flares, or dealing with the periodic geomagnetic storms that accompany the coronal mass ejections sometimes triggered by these flares.  That’s all “par for the course” during these excellent days of high solar activity—the good with the bad.  I’ll take it all.  Happy DXing!

73 de NW7US