Marcel de Bont Posted June 20, 2014 Share Posted June 20, 2014 SpaceWeatherLive Report Filament eruption June 19, 2014 A filament eruption occurred near S01E12, yesterday during the afternoon. The gorgeous eruption that spirals away from the Sun like a huge vortex was clearly visible on SDO AIA imagery and triggered a C4 solar flare from sunspot region 2093. A partial halo CME can be seen on SOHO/LASCO which is less than 180 degrees wide. We expect that the CME will head east and not arrive at Earth. This eruption was nonetheless a very nice event to watch! d426ed0fd6927f2506d4ffa7a343dd45 Source: SOHO/SDO/Nariaki Nitta/LMSAL Link to comment Share on other sites More sharing options...
Marcel de Bont Posted June 21, 2014 Author Share Posted June 21, 2014 SpaceWeatherLive Report Filament eruption - analyses explanation June 21, 2014 The NOAA SWPC has issued a minor G1 geomagnetic storm warning for June 22 following the filament eruption from June 19. The composition image attached to this post shows NOAA’s ENLIL model with the Coronal Mass Ejection (CME) that is expected to arrive at Earth late on June 22. We concluded yesterday that this CME is likely not traveling on the Sun-Earth line. An understandable question we get every now and then is: why is our opinion different than those from official organizations like the NOAA SWPC? In this post and with the help of the attached image we like to explain why we make our own analyses and why we occasionally do not agree with the official space weather forecasters. Let us first take a look at the two most important tools that we use and what they tell us: There are a number of tools that we have to determine if a CME is likely to reach Earth or not. Coronagraphs are among the most important ones. A coronagraph shows CMEs as they leave the Sun and expand in space. We can make a pretty good judgment how the CME is traveling with these images from SOHO as they show the CME from Earth’s perspective. With the STEREO coronagraphs we can determine if a CME was a backside or frontside event. A CME that is traveling towards Earth shows up as an expanding cloud covering the entire field of view as it travels further. This is called a full halo CME. The tricky part are CMEs that are not full halos, the so-called partial halo CMEs. CMEs that do not cover the entire field-of-view as they expand from the Sun. The CME that NOAA predicts to arrive at Earth was a so called partial halo CME. It did not cover the full 360 degrees, you can see this yourself in the attached bottom left image. In fact, the halo did not even cover 180 degrees, which suggests the CME is indeed heading east and away from Earth. Another tool that is important to use is the ACE EPAM plot (see bottom right image) which shows low-energy protons and electrons. A rise in these parameters often indicate that there is a CME on the Sun-Earth line. If we take a look at the ACE EPAM plot right now we see that all the values are at background level, indicating that there is likely no CME on the Sun-Earth line. We still advise our visitors to remain alert for a possible shock passage tomorrow as we have seen crazy things in the space weather field but with the data that we've got access to, there is no reason to believe that there is a CME heading towards Earth, let alone that we could see a G1 geomagnetic storm. Space weather in the near Earth environment will likely be calm in at least the coming 3 days. Feel free to leave a comment below if you have questions, comments or concerns! Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.