[Lowfer] SIDs

[jrusgrove at comcast.net]

Here's what the 1550z event looked like here ...

http://www.w1vd.com/SID021123.jpg

Jay W1VD


----- Original Message -----
From: Garry <k3siw at sbcglobal.net>
Reply-To: Discussion of the Lowfer \(US, European, & UK\) and MedFer bands <lowfer at mailman.qth.net>
To: <lowfer at mailman.qth.net>
Sent: 2/11/2023 3:56:09 PM
Subject: [Lowfer] SIDs


I've 
been monitoring VLF trnasmitter signal strengths in the daytime for 
awhile, looking for sudden ionospheric disturbances (SIDs). Using 
Spectrum Lab software signal strength - versus - time graphs have been 
created each day for four VLF stations: (1) NPM, Hawaii, 21.4 kHz; (2) 
NAA, Maine, 24.0 kHz; (3) NLK, Washington, 24.8 kHz; and (4) NML4, ND, 
25.2 kHz. GOES x-ray flux spikes in time indicate such events (see 
https://www.swpc.noaa.gov/products/goes-x-ray-flux) but so far here the 
impact on VLF signal strength has generally only been a few dB. But 
today around 1550Z a very large event occurred, followed around 1722Z by 
a typical event.

73, Garry, K3SIW, EN52ta, Elgin, IL