Big space weather news this week: measurements of the “radiation belts” made by the Global Positioning System satellites are now available to space weather researchers. This is a huge deal for several reasons, but let’s start by unpacking that sentence:
One of the ongoing research projects here at the University of Michigan’s Climate and Space department is computer simulations of eruptive events from the solar atmosphere into the solar system. “Eruptive events” are explosions of material (mostly super-hot hydrogen gas) and magnetic fields into space. The atmosphere of the sun is locked in a delicate balance between gravity, which holds the atmosphere down, and the expansive force of the super-hot atmosphere, which pushes it away. On top of this are complicated magnetic and electric forces. When the balance breaks down, you get an explosion of material into space. These are known as “coronal mass ejections”, or CMEs. Simulating these events is incredibly difficult because the physics behind CMEs is only tenuously understood.
Here at CLaSP, scientists have had a breakthrough with their new EEGGL model- the Eruptive Event Generator: Gibson-Lowe model. This model has had great success in reproducing solar storm observations, which is the first step towards prediction of these storms before they arrive at Earth. NASA has recently highlighted this new science, so be sure to give that article a read.
There are a few reasons for the recent dearth of posts here, but prominently,
- The weather in space has been especially boring as of recent,
- The end of each year is marked by the American Geophysical Union’s Fall meeting.
The latter, known colloquially as “the AGU meeting” by frequent attendees, is an annual gathering of more than 20,000 scientists, spanning many specialties, at San Francisco’s Moscone Center. At this meeting, there are thousands of presentations, talks, discussions, and meetings. It occurs every December and has a penchant for consuming participants- both during and well before the event itself. This is because it requires a great amount preparation before and endurance throughout: you will run from session to session, talk to talk, poster to poster, meeting to meeting, from very early to very late. It is an extremely important week where your colleagues, competitors, funders, and managers will all be present, so you must be “on” at all times.
This year’s AGU meeting saw a huge increase in sessions dedicated to space weather, with some very exciting talks and discussions. Continue reading “Space Weather at AGU’s Fall Meeting”
Here we go again! NOAA SWPC has issued another storm watch for a G3 level geomagnetic event. Right now, we’re already at G2 level. My guess is that we’ll hit G3 if the interplanetary magnetic field turns southward, so keep an eye on the real-time solar wind conditions. Because the storm has already started, I doubt that this will drive any visible aurora over the United States- by the time nightfall hits, the storm will have subsided again. But keep your eyes peeled just in case.
Check out my previous storm watch post for an idea of what values to watch as the storm progresses.
The outstanding feature in the solar wind during this storm is the long period (near 18 hours!) of southward Interplanetary Magnetic Field (IMF). This is seen in the red line in the top frame starting shortly after Oct. 13th and lasting into the next day. Southward IMF conditions are when the solar wind most efficiently transfers energy to the magnetosphere and Earth’s atmosphere, so the storm looks promising on these terms alone. IMF BZ (the component of the field that is oriented north- and southward, shown in the red line in the plot) reaches a value of almost -30nT! Values of -10nT are good enough to give us a strong response on the ground; -30nT is approaching what we would expect during a very strong storm.
Now, let’s jump down to the bottom two frames, which show the geomagnetic activity indices KP and DST. The former is an index of the global space weather activity at Earth and ranges from 1 to 9. The latter is an index of how much energy is stored in the “ring current” of the magnetosphere, a region that extends out to around 8 Earth radii (around 28,000 miles altitude.) The more negative DST, the more energy stored. In my previous post, we had hoped that this storm would intensify from “G2” to “G3” status, or a KP of 7 from 5 or 6; DST had already reached -100nT as I frantically typed. Unfortunately, my post came during the maximum of activity: both DST and KP recovered after that point. These are moderate values; this is a typical and relatively uninspiring event. Browsing the community-driven aurora monitoring website, Aurorasaurus, there is evidence of a light show reaching the northern United States, but not much further south than that.
So what happened? This is a time where the southward IMF values needed a little more help from the solar wind. The solar wind was relatively slow for a space weather storm (yellow line), staying around 400-500 km/s. During strong events, we expect much faster values- 600, 800, or even 1000 km/s. Next, we want a dense solar wind- tens of particles per cubic centimeter. When the IMF was southward, the solar wind was the least dense: <10 per cubic centimeter. The IMF was just right, but it didn’t get the help it needed to make this a very exciting space weather storm.
Finally, in the bottom frame, we see a strange discontinuity in the predicted DST as it jumps from -125nT back to zero. We see a similar jump in the KP plot. What could’ve happened here? This is a cold restart of the Space Weather Modeling Framework- something went wrong, and the code needed to be restarted from scratch. The problem could have happened anywhere in the predictive chain: in the processing of real-time solar wind data, a hardware glitch in the supercomputing environment, or an issue with the SWMF software itself. This is disappointing, but not completely unexpected- the real-time simulations at SWPC are brand new, and we – the researchers and code developers at the University of Michigan as well as the team at NOAA – will use this event to make the entire system more robust for future storms.
As a scientist, this storm will still be important. Every storm gives us an opportunity to make new observations of the sun-Earth system. With our sparse and ever-changing fleet of satellites taking measurements, each storm has the potential for something new to be discovered, even if it is not a record-setting event. This storm is one of the few that has happened in the lifetime of the young Magnetosphere Multi-Scale (MMS) satellite mission, so I expect some exciting observations to come from that.