Collection, Collation, and Comparison of 3D Coronal CME Reconstructions

Abstract

Predicting the impacts of coronal mass ejections (CMEs) is a major focus of current space weather forecasting efforts. Typically, CME properties are reconstructed from stereoscopic coronal images and then used to forward model a CME's interplanetary evolution. Knowing the uncertainty in the coronal reconstructions is then a critical factor in determining the uncertainty of any predictions. A growing number of catalogs of coronal CME reconstructions exist, but no extensive comparison between these catalogs has yet been performed. Here we develop a Living List of Attributes Measured in Any Coronal Reconstruction (LLAMACoRe), an online collection of individual catalogs, which we intend to continually update. In this first version, we use results from 24 different catalogs with 3D reconstructions using Solar Terrestrial Relations Observatory observations between 2007 and 2014. We have collated the individual catalogs, determining which reconstructions correspond to the same events. LLAMACoRe contains 2,954 reconstructions for 1,862 CMEs. Of these, 511 CMEs contain multiple reconstructions from different catalogs. Using the best‐constrained values for each CME, we find that the combined catalog reproduces the generally known solar cycle trends. We determine the typical difference we would expect between two independent reconstructions of the same event and find values of 4.0° in the latitude, 8.0° in the longitude, 24.0° in the tilt, 9.3° in the angular width, 0.1 in the shape parameter κ, 115 km/s in the velocity, and 2.5 × 1015 g in the mass. These remain the most probable values over the solar cycle, though we find more extreme outliers in the deviation toward solar maximum.

On the Mesoscale Structure of Coronal Mass Ejections at Mercury’s Orbit: BepiColombo and Parker Solar Probe Observations

“…We have focused on characterizing and comparing properties of the interplanetary shock, sheath region, and magnetic ejecta as measured by the two spacecraft. Overall, we have found some similarities but also some profound differences between the two sets of in situ data that, although resulting from flank encounters with the structure as a whole, are characterized by a relative nonradial angular separation (∼5°) that is smaller than the typical errors associated with 3D reconstructions of CMEs based on remote-sensing data-for example, Verbeke et al (2023) found minimum uncertainties of 6°in latitude and 11°in longitude using the GCS model, and Kay & Palmerio (2024) estimated a typical difference of 4°in latitude and 8°in longitude between two independent reconstructions of the same event.…”

Updating Measures of CME Arrival Time Errors

“…The DONKI values should be used for the NASA GSFC predictions and should be similar to what was used by others, but each forecaster likely has their own coronal CME reconstruction that then use to drive their model. Coronal reconstructions are notoriously uncertain (e.g., Kay & Palmerio, 2024;Verbeke et al, 2023) so we expect there could be significant variation between the inputs used by different models. We have no means of comparing with the specific values used for each prediction, but suspect we may find more significant correlations if we could.…”

“…The model inputs include both the reconstructed CME properties and the background solar wind through which the CME propagates. We know that CME reconstructions can be affected by large uncertainties (e.g., Kay & Palmerio, 2024;Verbeke et al, 2023) and that these can translate into AT errors of the order of 10 hr (e.g., Kay et al, 2020). This alone is sufficient to mask the effects of any background SW effects or inadequacies in the models.…”