Thursday, March 6, 2014

The Verdict is In

Ever since the sun started to perk up back in 2009 I've seriously pondered the question: "From our location under the auroral oval is the increased solar activity a good thing or a bad thing?"

At the bottom of the 11-year solar cycle, with days on end of zero sunspots, the bands would open and close like clockwork, depending on the auroral activity.  20m would come to life most days and (especially during the spring and fall equinoxes) provide reasonable propagation to anywhere on earth. The lower bands would open any time there was no aurora and with low solar activity that also happened on a fairly regular basis. The upper bands didn't even exist. Some weak activity on 15m once in a while in the middle of the afternoon and nothing to be heard ever on 10m. The only thing that stirred up the aurora was high solar wind speeds caused by coronal holes. These would come around every 27 days like clockwork allowing fairly accurate predictions of whether band conditions would be good or bad on any particular day.

Now, with the continuing solar maximum, things are very different. Streams of solar nastiness from flares and CMEs pour into the polar regions wiping out the bands for days at a time. The aurora is omnipresent, and the K-index rarely dips below 2. Now it is the lower bands turn to be non-existent. Nothing to be heard from here on 80m or 160m. 40m can go either way. Heavily affected by the D-region absorption it stays mostly quiet but on occasion low auroral activity will allow it to perk up somewhat. The upper bands provide the best communications. 20m and 15m stay open for hours on end and when the solar flux gets high enough the 10m band can push through the aurora with strong enough signals to overcome the heavy absorption. It is still very much hit and miss, though. You just never know from one day to the next whether there will be anything at all on the radio.

So what to make of all this? I have finally reached the conclusion that any solar activity is better than none.  I've been having just as much fun working DX on the higher bands as I used to on the lower bands. Recently, I had been listening for Elmo, 3C0BYP, on Annobon Island off the west African coast.  Yesterday evening he finally popped up on 20m in the middle of his night time. I had no trouble working him for an all-time-new-one. This morning, still somewhat pleased with myself for the previous day's DX, I got up and turned on the radio again. As I sipped my coffee and tuned through the bands I heard many European stations coming over the pole on 10m. This alone doesn't really excite me anymore (it sure did last fall though!) but while I was listening a 10m DX spot came up for Carson, ZS8C, on Marion Island in the far south Indian Ocean. About half way between South Africa and Antarctica, this is one of the most distant DXCC entities from here at 11,000 miles away. I had listened for ZS8C many times in the past but had never before heard even a whisper on any band. This time I could hear a whisper. Down in the noise and not quite strong enough for 100% copy but audible nonetheless. I called a few times but soon had to turn off the radio to get ready for work. A half hour later I had a few extra minutes before I left for the day and decided to quickly fire up the radio again and take another listen. This time ZS8C was perfect copy peaking at S5 and five minutes later he was in the log for another new one. On 10m no less! That decided the question for me right then and there. Working Marion Island on 10m easily makes up for many days of no signals at all.

Now I'm ready to begin the search for an answer to my new question: "To get into 'Ham Heaven' do you need to 'work 'em all' (all 340 DXCC entities) AND have '5-band DXCC' too or is either one by itself good enough for admission...?"

Monday, March 3, 2014

The Missing Link

For years and years I tried to understand HF propagation from the Arctic.  At my location just above the Arctic Circle it was fairly easy to figure out when it would be bad.  The sun throws off high energy protons from the solar wind or solar energy particle events like flares and coronal mass ejections. The charged particles interact with the earth's geomagnetic field and the north and south poles of this magnetic field attract the particles just like iron filings on a magnet.  When the particles get dense enough to collide with molecules in the upper atmosphere they emit light energy visible at night as the aurora (although its still there in the daytime, just not bright enough to be visible).  Extreme levels of aurora tend to reflect higher radio frequencies (like 6m and VHF) back in the general direction of their source.  This can be great if the auroral oval is just to the North (or South) of you, not so great if you're right in the middle of it!  Radio frequencies in the HF range are scattered by the aurora and lose most of their energy with the majority of the attenuation occurring on the lower HF bands.

The auroral oval goes right over my head and most of the time we're right in the middle of it.






















If the K-index was high that would indicate auroral activity and I knew to expect poor conditions. The 160 and 80 meter bands would go completely dead and usually 40 meters as well.  Sometimes the higher bands held up a bit better but as the aurora becomes more intense the degradation increases in frequency.  It was a simple matter to take a peak at the K-index and I knew at a glance how bad things would be.  

What I had a much harder time understanding, though, was why it happened frequently that the auroral activity numbers would suggest things should probably be ok but, in fact, HF propagation would be lousy.  Then I discovered the D-RAP.  "D Region Absorption Predictions" are provided by NOAA and they opened up a whole new world of understanding about what's going on up there in the ionosphere especially at high latitudes.   In the context of amateur radio, the lower ionosphere is cited as the reason the low bands are only open at night.  The sun causes it to absorb low frequencies during the daytime.  What is actually happening is that the same aurora-causing high energy protons given off by the sun tend collect in a specific region of the upper atmosphere known as the D Region.  Since the earth's magnetic field tends to concentrate these particles towards the poles we have this layer overhead almost all the time.  What the D-RAP predictions do is to quantify exactly what the effect of the particles (and x-rays as well) will have on any specific frequency at any particular point on the Earth.  It takes the solar wind strength into account and also measures the effects of other solar particle events like flares and coronal mass ejections. 


The little chart on the right side of the image breaks down the amount of attenuation in the red areas. Click on the image for a larger version.















The NOAA D-RAP site  provides the data in a pretty easy to understand set of graphics that show the level of absorption (in dB) at specific frequencies.  Now its easy to see the piece of the puzzle that had been eluding me for so long.  Solar particle events throw off huge amounts of charged protons and if they are directed towards the earth they stream into the upper atmosphere for days afterwards.  A quick check of the data at any time will show which bands are affected and how much.  By combining this lowest usable frequency (LUF) data with the maximum usable frequency (MUF) calculated by the solar flux index one can instantly know which is the optimum HF band for paths from (or through!) the Arctic in real time.  Unfortunately for me and the other high-latitude operators, periods of low solar activity tend to lower the MUF.  When a solar particle events occur right after or during these quiet times the net result of a low MUF and a high LUF is no HF propagation from up here on any band!  The trick is being on the air at the just right time to catch those opportune moments when the flux is high enough to support propagation on the upper bands but with low attenuation from the D Region.  That happens just often enough keep me tuning the bands waiting for these interesting opportunities to communicate.

ARRL DX SSB VE8EV SO Unlimited HP

ARRL DX Contest, SSB

Call: VE8EV
Operator(s): VE8EV
Station: VE8EV

Class: SO Unlimited HP
QTH: Inuvik, NT
Operating Time (hrs): 40

Summary:
 Band  QSOs  Mults
-------------------
  160:    0     0
   80:    0     0
   40:    6     4
   20:  254    58
   15:  374    81
   10:  298    79
-------------------
Total:  932   222  Total Score = 620,712

Club: 

Comments:

The big X-class solar flare earlier in the week sure knocked the heck out of the bands up here. On Thursday evening 160-10m was completely dead but 24 hours later at the beginning of the contest things had at least improved enough to let the higher bands start to open up. Even then the absorption was strong enough all weekend that I was never able to get a decent run going anywhere, save for a couple of hours on 10m and 15m over the pole in the middle of the night on Friday. The low bands were a total washout, nothing heard at all on 80m and 160m, and only a tiny handful of "nearby" mults on 40m after midnight Saturday.

Highlights:

- Finally being able to prove my theory that the best time for 10m to Europe from here is in the middle of the night. I sensed a considerable amount of skepticism from the other side but WFWL happily prevailed.

- On three separate occasions someone in a pileup with me got through to the DX station and after making their contact told them to "listen up, there's a VE8 calling you". I was humbled each time but of course wasn't paying enough attention to catch their calls. Thanks for the multipliers!

- Collecting enough entities on 10m to push my DXCC total on that band to well over a hundred. Now I can stop worrying about missing out on 10m at the top of the solar cycle and start working on how I'm going to live long enough to work a 100 on 80m for 5BDXCC...


Other than stellar/dismal band conditions (depending on your perspective) the only lowlight was trying to tell guys wanting to pass me down to 20m in the middle of the afternoon that "Sorry, I've got no propagation on that band." Strange days, indeed!

Depending on my travel schedule this might be the last contest operation from here until CQWW in October. If so, see you then!

73
John VE8EV