Predicting the Time-of-Arrival of Coronal Mass Ejections at Earth Solely
From Heliospheric Imaging Observations
Abstract
The Time-of-Arrival (ToA) of coronal mass ejections (CME) at Earth is a
key parameter due to the space weather phenomena associated with the CME
arrival, such as intense geomagnetic storms. Several approaches to
estimate the ToA based on kinematical parameters derived from single-
and multi-viewpoint white-light coronagraph observations have been
proposed and implemented, particularly in the last decade. Despite the
incremental use of new instrumentation and the development of novel
methodologies, ToA estimated errors remain above 10 hours on average.
Here, we investigate the prediction of ToA of CMEs using observations
solely from heliospheric imagers, i.e., from heliocentric distances
higher than those covered by the existent coronagraphs. To that aim, we
analyse 14 CMEs observed by the heliospheric imager HI-1 onboard the
twin STEREO spacecraft to determine their front location and speed.
Outside the field of view of the instruments, we assume that the
dynamics of the CME evolution is controlled by the aerodynamic drag, a
force that comes from the interaction with particles from the background
solar wind. We found a CME ToA error mean value of 0.4+-7.3 hours ToA
and a mean absolute error of 6.1+-3.6 hours in a set of 14 events. The
results we found here illustrate that observations from HI-1 allow us to
estimate the ToA with similar errors than observations from
coronagraphs.