Final Report Summary - WILISCME (The relationship between white light and in situ observations of coronal mass ejections)
Summary of results:
This project resulted in a new understanding of the propagation, 3D structure and global appearance of “solar storms” (or “coronal mass ejections”, CMEs) between the Sun and the Earth, by using observations from multiple spacecraft in the solar wind. Remote images of the solar wind from the Heliospheric Imager instrument on the twin spacecraft STEREO mission were used, in conjunction with in situ solar wind data from various spacecraft, situated in the space between the Sun and 1 AU. Using these diagnostics the relationship between white light and in situ observations of CMEs was studied.
Results of the project include:
1. A first reconstruction of the global shape of interacting CMEs, with data from multiple missions in the solar wind and at Mercury, Venus and Earth.
2. The development of new techniques for analysing the physics of how CMEs travel from the Sun to the Earth, with self-similar expanding circles, in both single-spacecraft and stereoscopic versions.
3. The application of this and other techniques showed a general picture of how fast CME propagate between the Sun and the Earth. It can be formulated into three phases: an impulsive acceleration, then a rapid deceleration, and finally a constant speed propagation.
4. The compilation of a master list with 22 events for connecting CME observations seamlessly from the Sun to 1 AU, to serve as a starting point for benchmarking any kind of CME forecasting model.
5. We tested the newly developed forecasting methods for the accuracy of predictions of arrival time, speed and direction of CMEs. We were able to optimize the predictions and found accuracies in the arrival times on the order of 5-8 hours and the arrival speeds on the order of < 100 km/s, both for a prediction lead time of about 1 day.
6. We pinned down characteristics (e.g. kinematics, deflections and shock signatures) of CME-CME interactions in unprecedented detail.
Conclusions and impact:
This project resulted in an enhanced understanding of the physics of the CME propagation, their interactions with other coronal and heliospheric structures, and their global 3D configuration between the Sun and the Earth. These results are useful for improving space weather prediction, in particular for a future mission similar to STEREO but positioned on a fixed angular separation to Earth. The results of this project show that such a mission holds great promise in enhancing real-time space weather predictions. We also developed and tested new methods to calculate CME speeds, arrival times, and directions, with an advance warning time of 1-3 days.
Socio economic impacts:
Results from this project are basic principles to enhance the reliability of forecasting models for space weather. Such models are used to prolong the advance warning time for a potentially threatening solar eruption, in line with central aims of the new ESA Space Situational Awareness programme. The results form a basis to develop a dedicated space weather mission to the Lagrangian point L5 in the Sun-Earth system. A Heliospheric Imager is also planned for the upcoming ESA Solar Orbiter mission to the inner heliosphere, and the techniques newly developed in this project will form excellent tools to be used for this mission. Our new master list of CME events, seamlessly observed from the Sun to 1 AU, serves as a basis for various new research projects on solar eruptions. The results of this project are related to basic research, but future real-time applications could impact policy makers for natural disasters.
Project website:
http://physik.uni-graz.at/en/astrophysik/marie-curie/(se abrirá en una nueva ventana)