Topband: solar wind, auroral oval images, D-region bite-outs

[N1BUG]

On 01/23/2013 09:17 PM, k9la at frontier.com wrote:
> I would think that there's a high correlation between the
> polarity of the IMF and the K/A indices, so this polarity may not
> tell us any more than the K/A indices.

Absolutely there is a very strong correlation. I suppose it comes 
down to what one wants to know and how soon one wants to know it. A 
index is a 24 hour value so it will usually not show much increase 
until a disturbance has been going on for many hours, even a day. K 
index (measured at Earth) is a 3 hour value but still looking at the 
previous 3 hour period so there is a lag. Suppose a disturbance 
starts at 0000 UTC. It won't be reported in K index derived from 
Earth based magnetometers until 0300. It won't show up officially in 
the A index until the following day, though SWPC does "estimate" the 
daily A index starting at 1800 UTC if I recall correctly.

There is, however, a K index model which attempts to forecast K 
index a few hours into the future using solar wind data as input:

http://www.swpc.noaa.gov/wingkp/

Raw solar wind data is more of an early warning system. It will show 
what is coming some 30 to 60 minutes before any Earth based 
magnetometer, depending on solar wind speed. It also shows what is 
coming sooner than the Wing Kp model. For the average MF/HF DXer I 
suppose the Wing Kp or even the previous 3 hour data of measured K 
index at Earth is quite sufficient. For catching VHF auroral 
propagation it most definitely is not enough, and I suppose years of 
that have biased me toward monitoring the earliest information 
available - even if it is in a raw state and requires considerable 
experience to appreciate. I pretty much always have an eye on the 
ACE plot:

http://www.swpc.noaa.gov/ace/MAG_SWEPAM_24h.html

NOTE, however, that following solar proton flares, the ACE data can 
become severely corrupted and useless. This affects all downstream 
models that depend on it, such as the Wing Kp and the much beloved 
(by me :) OVATION models.

73

-- 
Paul Kelley, N1BUG
RFI Committee chair,
Piscataquis Amateur Radio Club
http://www.k1pq.org