I am posting this as an update to my post a few days ago with regards the X-4.9 solar flare and the resulting CME that came from active region AR 1990 on the Sun. Today, as expected, it gave Earth a glancing blow, resulting in a moderate geomagnetic storm. Furthermore, we are now, and have been for a few days, experiencing an S1 solar radiation storm since protons from the Sun arrived after the solar flare, causing the storm. My goal in this post is twofold; I want to explain what a solar storm is and discuss its implications, and I want to discuss in limited detail some of the graphics from the SWPC and what information they are giving us.
Let’s first start talking about solar radiation storms. I have attached a graphic, Figure 1, which shows the proton flux measured by the GOES satellite, essentially the number of protons per centimeter squared per second. Notice how there is a spike in the proton flux around 21:00 UTC. Whenever this flux spikes, we can expect the possibility of a solar storm. Following the scales given by the SWPC, the region between 10 and 100 particles per centimeter squared per second that we are in now constitutes an S1 solar radiation storm. If you follow the link to the SWPC website, you can see that there is basically no harmful effects on humans or our equipment on Earth, except for certain devices in the polar regions, from these S1 solar storms.
So that is what I have to say about solar radiation storms for now, let’s discuss the glancing blow and the associated geomagnetic storm. There are two graphics I have here from the SWPC. Figure 2 is showing us a plot of the parallel component of Earth’s magnetic field. I am still rather unfamiliar with this graphic and what all the components mean. What I do know is that the red line and the blue line seem to follow a cosine wave pattern and when a geomagnetic storm hits, that pattern goes nuts and forms a crude zig-zag rather than a wave. Note in the figure how these is that nice transition between the wave and zig-zag.
The other figure I have, figure 3 is the Kp graphic, one of the easier to understand of the SWPC graphics. This graphic shows a measurement of the instability of the horizontal component of Earth’s magnetic field. The values are integers that range from one to 9. If you are unfamiliar with space weather and just want to know if you have a shot of seeing the northern lights, this is the only graphic you really need. The way you use this is to first find out what the threshold Kp is for your region. Google is a great place to look for this value. The threshold Kp is essentially the smallest Kp value that you need in order to see the northern lights from a location. For my location, Columbus, Ohio, there needs to be a KP value of at least an 8. As you can see from the graphic, the current Kp is a 5, so it has dropped a bit in the last few hours, and needs to rise a bit in order for me to be able to see the Northern lights tonight. According to the scales for geomagnetic storms, a Kp of 5 dictates a G1 geomagnetic storm, so we will probably be downgraded to a G1 storm soon. Note that previously the value was a 6, creating a G2 geomagnetic storm.