Re: [IRCA] WWV Solar Report

[Russ Edmunds <wb2bjh@xxxxxxxxx>]

Briefly, The K index is more immediate - it is measured and reported a
4-hour intervals. The A index is a logarithmic derivative of the values of
K over a longer preceding period. Therefore you
will see the K spike in response to geomagnetic activity several hours
before you will see the corresponding increase in the A index.

Typically auroral conditions will manifest themselves as the K increases.
Usually it take a change in the K of 2 units or more to be notable.

Except for the fact that the K is still leading the A timewise, the reverse
is true as the activity wanes. Here though, the residual auroral activity
takes longer to decay than it took to rise so the decline in the A index
may be more reflective of what's actually happening with reception.

A K index of 4+ indicates watching the bands, although one isolated 4-hour
period at that level isn't significant. A single isolated period may be
indicative of an auroral substorm, which may create moderate auroral DX
conditions which will fade more quickly.

An A index over 20 may or may not lead to auroral DX conditions, however an
A index of 30+ usually does. A really serious auroral storm resulting in
strongly auroral conditions may have an A index value of anywhere from 50
to 150, which may persist for a few days.

The longer the duration of the high activity, the more the conditions can
be impacted, and therefore the longer it will take to decay. Many times the
best auroral conditions are found after the peak and early in the decay
phase.

Any questions ?  :-}



Russ Edmunds
15 mi NW Phila
Grid FN20id
<wb2bjh@xxxxxxxxx>

AM: Modified Sony ICF2010's (4) barefoot w/whip
FM: Yamaha T-80 & T-85, each w/ Conrad RDS Decoder;
Onkyo T-450RDS; Tecsun PL-310 ( 4);
modified Sony ICF2010's (3) w/APS9B @ 15';
modified Sony ICF2010 w/whip


On Wed, Oct 5, 2016 at 10:06 PM, <Mark4@xxxxxxxxxxxxxxx> wrote:

> Colin, I for one (of many?) would appreciate a refresher on what to expect
> with varying indices of A and K.
>
> For example...the comment below is useful...and borne out by CX this
> morning.
>
> Thanks in advance!
>
>
> Mark Durenberger
>
> -----Original Message----- From: R. Colin Newell
> Sent: Wednesday, October 05, 2016 3:30 PM
> To: Mailing list for the International Radio Club of America ; Paul Walker
> Subject: Re: [IRCA] WWV Solar Report
>
> Although the A index has trended upwards, the K is trending downward -
>
> For those that do not pay a lot of attention to these charts, that is an
> indicator of potentially improved listening conditions.
>
>
> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Trends -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>> Date 04   04   04   04   04   04   04   05   05   05   05   05   05   05
>> UTC  0000 0300 0900 1200 1500 1800 2100 0000 0300 0600 0900 1200 1500 1800
>> SFlx 88   88   88   88   88   88   93   93   93   93   93   93   93   93
>> A-in 14   14   14   14   14   14   25   26   26   26   26   26   26   26
>> K-in 3    4    4    4    4    2    3    4    4    4    3    3    2    2
>> Current Solar information available at http://www.am-dx.com/wwv.htm
>>
>>
>>
>>
>> --
> Colin Newell - Editor and creator *of *Coffeecrew.com
> <http://www.Coffeecrew.com> and DXer.ca <http://www.DXer.ca> -
> VA7WWV | Twitter @CoffeeCrew | Victoria - Canada
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