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Date: Fri, 18 Jun 2010 01:05:51 -0500
From: Mike-WE0H <we0h@gmx.com>
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Subject: LF: Re: Changing solar conditions
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Good morning Dave,

But why on some days of active solar conditions do I find high 
absorption on 600 meters with stations out to 250 miles? On normal days 
they are coming in clear easy copy CW, but some days when the Density 
and the A & K indexes are above normal, those same stations are either 
barely audible or completely gone. I have followed that Density number 
and noticed a range that made 600m signals really stronger than normal. 
I'd like to say that range was about 5 to 11. That has been seen in 
daylight conditions and also night conditions so different D layer 
conditions. It's a strange thing that I am likely to never fully understand.

I haven't done any studies on the effects of a LF signal with differing 
A, K & Density figures. Only 600m studies so far. On the Velocity 
figure, I notice higher numbers above ~400 show a higher noise floor on 
bands from 600 meters on up into the HF bands. Again I haven't checked 
the LF bands to see what affect the Velocity has on their noise floor.

Alan's mention of the DST figure has me wondering if he is talking about 
the Proton Density or? This solar data can be useful and also can be 
confusing. hi hi...

Mike
WE0H



Dave S wrote:
> On 18 Jun 2010 at 0:04, Alan M wrote:
> 
>> You have found that Kp and A are not good indicators of propagation
>> conditions at LF. 
> 
> And it is worth also remembering that although the K instance is 
> 'instantaneous' and updated every 3 hours, the A index the average of 
> all the individual K indices over the past 24 hours. To that extent the 
> A index indicates what YESTERDAY's conditions were, the K index is the 
> only one that really shows what is happening NOW. A K index of 2 is a 
> fairly low level, the 5 it got up to earlier in the day is edging on a 
> significant storm. But in any case with a SN of 0 and a flux of 70/72 
> the sun is effectively dormant. I don't think the geomagnetic 
> disturbance mentioned was even worth mentioning.
> 
> I see this morning the flux remains at 70 but they have identified a 
> few speckles invisible to the human eye as 'spots' so the SN is now 14 
> (ie 4 speckles in one group, not 14...). K remains at 2. Nothing 
> significant happening there.
> 
> Remember also we are largely talking about tests by groundwave, 
> certainly so for Roger's ground electrode tests, and not transatlantic. 
> In these what is going on in the ionosphere is totally irrelevant, 
> groundwave does not go anywhere near the ionosphere...
> 
> 73 Dave G3YMC
> 
> http://www.davesergeant.com
> 
>