In this part, we will detail the means used to predict solar storms and thus be better prepared.
Before going further, it is necessary to give a definition of space weather: this is how solar activity may have unwanted effects on technology or human activity, on space or on the ground floor.
In other words, space weather encompasses conditions and space phenomenon which are likely to damage equipment on earth as well as in space.
Scientists use a variety of imaging systems and sensors on the ground to monitor the activity of the sun at different levels of the atmosphere. Radio or magnetic interferences emitted during a solar storm are spotted thanks to many devices. These radiations can be detected by telescopes: they use emitters and receivers which detect these radiations in the solar wind. Moreover, particle detectors allow to assess the presence of ions, electrons or protons. Finally, the magnetometers record magnetic field changes.
The latest spaceship SOHO allows scientists to detect CME (thanks to a special treatment of its images) not only if they are seen from aside but also if they are heading straight towards Earth. It is located close to DSCOVR, at the Lagrange L1 point.
However, these sensors at Earth aren’t very helpful compared to DSCOVR (http://www.nesdis.noaa.gov/DSCOVR/), a satellite sent in 2015 by NASA in order to have a better understanding of these solar storms. It is located at the Lagrange L1 point. It allows scientists to be informed half an hour before the coronal mass ejections reach the Earth. Unfortunately, this lapse of time isn’t important enough knowing the effects of a solar storm like Carrington. Therefore, there’s a great interest in increasing the prevention time. For example, NASA is considering to position a satellite in the upstream position which is closest to the sun.
The scientist Michael Hesse (Director of the Heliophysics Science Division, NASA) reports that some tools can currently follow the path of solar storms in their advance towards the earth in 3D. This 3D reconstruction is possible thanks to the twin STEREO satellites. Located on either side of the Sun, these satellites have enabled NASA to determine the direction and speed of CME.
While DSCOVR allows for the estimation of the power of a CME, STEREO satellites enable one to determine the trajectory of a CME and therefore if it will touch the earth.
The radiations that are emitted by the solar flare as well as the SEPs are hard to predict. Indeed, they travel at the speed of light or close to it. Predicting the hour of a solar flare and SEPs isn’t possible yet, even if there are services that give out probabilities on these events. Included in the SEPs, the protons and ions are damaging the Earth. However, they strike Earth ten minutes after the electrons which have lower impacts. (Arik Posner Report) (Figure 19) In the future electrons could be a search track for the prevention of solar flares.
As the radiations and SEPs are traveling too fast to let a reaction time. The solar flares’ forecast must be based on factors that precede them.
Expecting the CMEs (coronal mass ejections) arrival is easier than expecting SEPs arrival. Indeed, CMEs need several days to arrive on Earth. Now it is possible to forecast the time of arrival of a CME with an error margin of around 7 hours thanks to STEREO (although the Stereo satellites are now behind the sun from the Earth and therefore totally useless to observe CMEs directed toward Earth). However, it is impossible to judge the power of the impact of CME before it reaches DSCOVR . Its effects on the Earth would therefore be estimated half an hour before impact.
In order to improve these forecasts, several organizations are actively working on this subject, such as SWPC, who has published numerous reports.The setting up of artificial intelligence and the improve of modelling methods could allow to predict sooner the strength of a solar storm, thanks to the sunspots.
Radiations of the Carrington event created nitrates and beryllium 10 in the upper atmosphere. These elements have ended frozen in the ice in Greenland, which has allowed scientists to estimate the amount of nitrates. Nitrates researches under the ice have shown that the earth’s atmosphere was kicked by 18.8 billion per cm2 by high energy protons in 1959 (refer to figure 20). Moreover, beryllium revealed that the energy of these protons was very important.
As shown in Figure 20, the event of Carrington was the most important in terms of protons. This kind of researches based on previous events studies should allow us to understand in a better way this phenomenon and have a better preparation.