[Elecraft] OT: K-index=2, But Bands Deader Than Doornail?

[Bill W5WVO]

Steve,

Terrific summary, thanks for contributing that.

It is also interesting to note that, since this period of unstable space 
weather started, there has been little to no sporadic-E propagation on 6M --  
this during a seasonal period when one would expect (based on past history) 
fairly regular openings.

I've read in a number of places over the years that mid-latitude sporadic-E 
propagation does seem to be inhibited by large-scale geomagnetic 
disturbance, just as HF propagation is --  albeit perhaps by a different 
mechanism. If the mechanism is indeed different (and it seems to me it would 
almost have to be), I'm not aware of any theory on how it might work. I have 
a few home-grown hypotheses on the matter, but nothing I'm willing to admit 
to in public.  :-)  Anyone know of any science on the relationship between 
mid-latitude sporadic-E propagation and geomagnetic disturbance?

Bill / W5WVO


Stephen W. Kercel wrote:
> Jeff:
>
> It is a perfectly reasonable topic, and one I've been wondering about
> myself.
> Since Thanksgiving, we've had astoundingly bad conditions with lots
> of flares and storms.
>
> There are three mechanisms of disruption indicated on the NOAA Web
> site, radio blackouts due to X-rays which are mostly felt on the
> sunlit side of the Earth and dissipate in a matter of hours, "solar
> storms" which are bursts of heavy particles (protons, as I recall),
> and the solar wind (a stream of electrons).
>
> As I understand the numbers, K is a "near real time" (reported every
> 3 hours) indication of disruption of propagation due to the
> geomagnetic fluctuations caused by fluctuations in the solar wind.
> With each value of K there is an associated value of a, with a pseudo
> logarithmic relationship between K and a, such that k=1 => a=3, and
> k=9 => a=400. A is the average of the last 8 a values, and thus is an
> indication of the cumulative effect of the solar wind on the
> geomagnetic field over the past 24 hours.
>
> It is important to realize that A and K are statistical measures that
> correctly describe propagation most of the time, but not always.
>
> A=9 is not low. It is usually an indication of "marginal but somewhat
> useful" conditions.
>
> My guess is that when the atmosphere takes a series of severe hits,
> as has happened over the past week, it takes much more than 24 hours
> (suggested by formula for the A index) for the atmosphere to "heal"
> itself, irrespective of the low A and K values currently being
> reported.
> It is my observation over recent months that once we've had a
> geomagnetic storm it requires two continuous days of both K and A <=
> 2 before one sees the return of good conditions.
>
> The problem is aggravated by the low sunspot numbers, and consequent
> low MUFs. I've noticed that most nights lately from New England, one
> hears practically nothing from Europe on 40 m (although one can hear
> Caribbean stations running European pileups). The reason is that the
> MUF between NE and EU most nights is about 6 MHz. 40 is dead but 80
> (in between storms) can be very lively.
>
> Anyway, given the low MUFs, most HF bands are dead much of the time,
> and 80 is only usable when the noise (partly induced by geomagnetic
> activity) dies down.
>
> I'd be curious what other list members know about this.
>
> 73,
>
> Steve Kercel
> AA4AK
>
>
>
> At 03:53 PM 12/19/2006, Jeff wrote:
>> My apologies for going off-topic, but I'm learning to interpret the
>> various solar parameters, such as the A- and K-indexes, and I'm a
>> bit confused.  The K-index is only 2 at 2045 UTC on Dec. 19, but I
>> can't hear ANY CW signals on any band, which, until recent weeks,
>> was a very unusual state of affairs. The A-index is 9, which I
>> believe is also relatively low.  Shouldn't I be hearing at least a
>> couple of signals, or is it just that everyone is still at work?
>>
>> Thanks & Happy Holidays,
>> Jeff
>> WB5GWB
>> Long Island, NY
>>
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