Predicting the magnetic vectors within coronal mass ejections arriving at Earth
Abstract
The process by which the Sun affects the terrestrial environment on short timescales is predominately driven by the amount of magnetic reconnection between the solar wind and Earth's magnetosphere. Reconnection occurs most efficiently when the solar wind magnetic field has a southward component. The most severe impacts are during the arrival of a coronal mass ejection (CME) when the magnetosphere is both compressed and magnetically connected to the heliospheric environment, leading to disruptions to, for example, power grids and satellite navigation. Unfortunately, forecasting magnetic vectors within coronal mass ejections remains elusive. Here we report how, by combining a statistically robust helicity rule for a CME's solar origin with a simplified flux rope topology the magnetic vectors within the Earth-directed segment of a CME can be predicted. These magnetic vectors can be incorporated into forecasting procedures to predict the global response measured by the Kp index more reliably. In particular, false predictions of strong geomagnetic events made without magnetic field information are considerably reduced. As an example, the forecast strength of a geomagnetic storm following a CME on 7 January 2014, is reduced from G3 (strong) to G1 (minor) on the NOAA scale when magnetic vectors are taken into account.
- Publication:
-
Solar Heliospheric and INterplanetary Environment (SHINE 2014)
- Pub Date:
- June 2014
- Bibcode:
- 2014shin.confE.164S