[K3PZN-List] Fwd: [QRP-L] Solar MINIMUM here?

[Curt Milton]

I thought everyone may be interested in these
scientific propagation observations from someone who
works for the gov't watching the sun.  Meanwhile enjoy
low band DX (and note his interesting observations on
sources of local noise).  

73, curt

--- na5n at zianet.com wrote:

> From: na5n at zianet.com
> To: qrp-l at mailman.qth.net
> Date: Wed, 18 Apr 2007 01:27:51 -0600
> Subject: [QRP-L] Solar MINIMUM here?
> 
> Gang, 
> 
> It appears we are at, or nearly at, the solar
> minimum.  Look at the solar 
> flux chart at:
> http://www.dxlc.com/solar 
> 
> The solar flux varies over the 28-day rotation of
> the sun, going from some 
> minimum value to a maximum.  During more active
> days, this 28-day cycle 
> produces variations in the solar flux running, from
> say, 90 to 150, making 
> more a less a 28-day sinewave when plotted.  For the
> past two solar 
> rotations, the 28-day variation in the solar flux
> has been between about 70 
> and 75, or a variation of only 5 counts. 
> Statistically, this is a virtual 
> “flat line.” 
> 
> The solar flux average over the past 90 days is 75;
> for the past several 
> days, it has been 69 with the forecast for the next
> few days at 70.  Thus, 
> solar flux is varying only by a few counts.  Solar
> flux in the 60-70 range, 
> with almost no 28-day variation, and the complete
> absense of sunspots, are 
> indications we may have hit the solar minimum. 
> 
> However, we won’t know for 2-3 more months.  In
> fact, there is no way of 
> knowing when we are at the actual solar minimum
> until AFTER it happens.  
> This is because the solar flux can do one of three
> things over the next few 
> months.
> 1) It can remain flat, pretty much as it is right
> now, if this is the 
> minimum.
> 2) Solar flux can actually drop a bit more, if the
> minimum is yet to come.
> 3) Solar flux can begin to rise, indicating we’re
> coming out of the 
> minimum. 
> 
> Only historical data will tell us when the minimum
> actually occured. 
> 
> There are several models of the solar minimum. 
> These models show the solar 
> minimum occuring around now, some say this summer
> (June-July), others later 
> this autumn.  Present indications suggest we are
> either at the solar minimum 
> right now, or very close to it. 
> 
> Not that it makes much difference.  Even if the
> solar flux begins to rise a 
> bit over the next few months, from our present 70 to
> 75, then 80, it will 
> hardly make a difference in the propagation we’ve
> been experiencing.  For 
> the good old days, with the 28-day solar flux
> varying between 100 and 150, 
> with solar activity shooting it above 200, is still
> a few years away. 
> 
> More specific to ham radio, the solar minimum
> represents the minimal amount 
> of ionizing radiation the sun delivers to the earth.
>  As a result, our E and 
> F layers are not being well ionized right now, and
> thus not very reflective. 
> And, once the sun goes away at local sundown,
> recombination of the free 
> electrons is very swift.  This is why 20M shuts down
> pretty much right at 
> dusk, compared to staying open into the wee hours of
> the night when the 
> solar flux is >100, or around-the-clock at the solar
> maximum.  When the 
> ionizing radiation from the sun stops at sundown,
> the MUF drops to around 
> 10-12 MHz right now, shutting down 20M.  During the
> more active sun, the MUF 
> seldoms drops below 18MHz - allowing 20M to be open
> 24 hours a day. 
> 
> Ionizing radiation from the sun, over the past two
> solar cycles (22 years), 
> has been measured by the x-ray radiation received on
> earth from the sun.  
> Or, near the earth.  Since x-rays do not normally
> penetrate our ionosphere, 
> x-ray radiation is measured by sensors on satellites
> in orbit above our 
> ionosphere.  This is shown at: 
> 
> http://www.sec.noaa.gov/today.html 
> 
> You’ll notice the x-ray radiation from the sun is
> virtually flat-lined 
> right now as well, below the “A” level.  For
> comparison, it takes a 
> “D” class, or “D” level flare to effect HF
> propagation.  Right now, 
> solar radiation is way down in the noise ... around
> 10^-9 ... or a mere 
> nano-watt per square meter. 
> 
> Prior to satellites, the x-ray radiation from the
> sun was measured by 
> sensors on high altitude balloons or small rockets. 
> Of course, this 
> provided only a few minutes of data for each rocket
> launch, and a few hours 
> of data on a balloon platform.  It has only been
> over the past two solar 
> cycles that almost continuous real-time x-ray data
> has become available.
> Even more astounding is how quickly that data became
> available not only to 
> scientists, but to us via the internet.  In the
> 1970s-80s, when I first 
> started working at the VLA observatories, our
> professional astronomers would 
> have killed to have access to the data that is
> available to us all today 
> courtesy the internet. 
> 
> What about the solar wind?  You can see what the
> solar wind and density has 
> been doing lately at: 
> 
> http://umtof.umd.edu/pm/ 
> 
> The escape velocity from the sun is generally
> believed to be around 320-350 
> km/sec.  Notice that is what the solar wind has been
> for some time ... 
> barely enough to escape the sun.  Another indication
> of the minimal solar 
> activity.  The spikes in solar DENSITY are due to
> the earth flying through 
> coronal hole streams, not changes in the solar wind
> SPEED. 
> 
> This minimal solar wind is good news for the lower
> bands, particularly 80M 
> and 40M.  Solar wind buffeting the earth is what
> causes noise on the lower 
> bands.  Sure, these bands are noisy.  They’re
> always noisy.  But, not all 
> of that noise is due to the sun.  Right now, those
> low sodium vapor lights 
> at your nearby Wal-Mart parking lot is contributing
> more noise than the sun! 
> At my QTH in Socorro, NM, the largest source of 40M
> noise is the Burger King 
> sign.  Too bad there’s not a plot for that :-)  In
> other words, what you 
> are
> hearing on 80/40M right now is about as good as it
> gets.  When the sun wakes 
> up, it will only get worse. 
> 
> Whether we are legally at the solar minimum or not,
> 20M is the daytime band, 
> and 40M the night time band.  And, if lucky,
> sporaidic daytime openings on 
> 15M and 10M.  The solar flux has little effect on
> 30M, 40M, 80M or 160M.  
> And, that’s just how it’s going to be for the
> next year or two. 
> 
> If you’re a purist, keep your eye on the solar
> flux plots.  It could be 
> we’re seeing the solar minimum right now, or it
> may be another month or 
> two away.  Regardless, we’re close enough to it we
> can taste it ... or 
> more precisely, hear it - from the lack of
> significant HF propagation.  I 
> would expect an official announcement from NOAA in a
> couple of months. 
> 
> But, don’t let the solar minimum thing discourage
> you.  It’s an even 
> playing field - every ham is experiencing the same
> thing.  Get on the air, 
> 20M daytime, 40/80M night time, and have a QSO or
> two now and again.  Or, 
> get on the air for the contests.  Contests are a
> good time to get on because 
> more ops tend to be on at the same time, and of
> course, exchanges are short 
> in case conditions are rough.  If you’ve never
> done a Run to the Bacon 
> thing or ARCI Sprint thing, give it a try.  I’m
> sure they’d like to hear 
> you on during these days of the doldrums.  And, of
> course, QRP To The Field 
> (QRPTTF) coming up on Sat. April 28th. 
> 
> The rules this year allows you to work the Taco Bell
> (TB) stations 
> repeatedly, such as once an hour.  The reason for
> this is to provide plenty 
> of activity on the otherwise “dead” bands. 
> Nobody wants to go to the 
> field and setup with hardly nobody to work ... or
> long spells of finding 
> somebody new during these days of the solar minimum.
>  So this QRPTTF feature 
> ensures you won’t have to sit there too long
> lurking for someone new to 
> work.  Every hour or so, run through the band(s) and
> work the TB stations 
> again.  For us
> QRPers anyway, it will be like old Sol is shining a
> bit stronger than it 
> really is.  With this feature, activity should be
> higher than normal to keep 
> us all busy (particularly if you’re a TB station).
>  Maybe this year I'll 
> break last year's blistering record of 12 Q's! 
> 
> The good news ... is this is as low as it gets. 
> We’ve hit rock bottom.  
> It will start the upward swing into the new solar
> cycle (#24) shortly, 
> though it will be awhile before we notice any
> significant improvement. 
> 
> 72, Paul NA5N 
> 
> 
>
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