During the last years, alerts of solar storms on their way to Earth have been frequently sent out by the media.
Solar storms or so-called coronal mass ejections (CMEs), are formations consisting of charged particles and an embedded magnetic field structure. While slow CMEs need three to five days, the fastest can reach the Earth’s magnetosphere within one day or less, having impact speeds of up to 10 million kilometers per hour.
The consequences of these impacts are geomagnetic storms, which can damage satellites as well as lead to large-scale power outages on the ground, to name only two possible effects.
Accurately predicting arrival times and speeds of CMEs is quite difficult. Because of limited observational possibilities, errors in the arrival time of 10–20 hours are common. Besides the high prediction errors, false alarms are an even more important issue. False positive alarms are alerts where CMEs predicted to arrive Earth actually miss, false negative alarms are CMEs that are not predicted to arrive but actually hit.
The goal of this project is the enhancement of a CME prediction tool, that currently assumes an elliptical shape of the CME front and a uniform, unstructured background solar wind, which causes a deceleration or acceleration of the CME. The basis of this prediction tool are observations from the NASA mission “Solar TErrestrial RElations Observatory” (STEREO) and its heliospheric imagers. These heliospheric imagers are wide-angle cameras that provide a side view on the CME during its journey through interplanetary space. The aim of this project is to uncouple the tool from the rigid ellipse shape and to include a variable background solar wind speed. By allowing a variation of the CME shape during propagation, possible influences of high speed solar wind streams or other CMEs can be taken into account when forecasting a CME arrival. Another important improvement is the applicability of the tool to observations of polarized light that can be directly related to the shape of the CME, which is further incorporated into the prediction utility.
We expect a significant reduction of the prediction errors in CME arrival time and speed at Earth as well as a decrease of today’s false alarm rate.