Collaborative Research: Reconciliation Between In-situ and Remote Sensing Analyses

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Eruptions on the Sun eject clouds of electrically charged gas and strong magnetic fields called coronal mass ejections into space. Some of these clouds are harmless while others can penetrate into and disrupt the space environment around Earth in space weather events called geomagnetic storms. Understanding the solar disturbances that produce storms is important because severe space weather can damage satellites orbiting around Earth, endanger astronauts, and even disrupt power grids on the Earth?s surface. Accurate forecasting of strong magnetic storms is hindered by the fact that the features of a coronal mass ejection observed near the Sun do not remain constant but continually evolve as it moves through the background heliosphere on its way to Earth even interacting with other solar disturbances and with large scale magnetic fields and plasma structures in interplanetary space. Major storms have occurred due to changes in the structure of the coronal mass ejection during its propagation to Earth. In an effort to understand and eventually better predict the impacts of coronal mass ejections on the Earth?s space environment, this project takes a detailed look at the changes in the characteristics of coronal mass ejections as they move through the heliosphere, and at the physical mechanisms responsible for those changes, by combining remote-sensing and in-situ observations and comparing to large scale simulations. As an outcome of the project, a large database of events and associated observations will be made available online for the broader scientific community. Results will be disseminated in scientific publications, and through presentations at workshops and conferences. The project supports the training of a post doctoral researcher who will be based at the University of New Hampshire but will spend time working with co-investigators at both NASA Goddard Space Flight Center and the Naval Research Laboratory. Support of this postdoctoral researcher also serves to broaden the participation of an underrepresented group in a STEM field. In addition, the project will contribute to the training of an undergraduate student each year during the summer months through involvement in high-impact research at NASA Goddard Space Flight Center.This project takes advantage of a suite of satellites currently observing the inner heliosphere with remote-sensing and in-situ instruments to answer fundamental questions about transient solar disturbances (in particular, coronal mass ejections) and how they change during propagation. These satellites include Wind, ACE, Messenger, STEREO, SOHO, and SDO. Remote-sensing instruments view the coronal mass ejection as it lifts off the Sun while in-situ instruments measure its internal structure as it sweeps by on its way outward through the heliosphere. The characteristics of coronal mass ejections are inferred from each type of measurement using previously tested models. A key requirement is a consistent and robust methodology for combining these two very different types of data, which will be applied to some 100 events. As part of the development of the methodology, the discrepancies in the inferred characteristics of the coronal mass ejection from the various data sources will be reconciled. When combined with large-scale magnetohydrodynamic simulations a study of the underlying physical mechanisms will be made albeit restricted to a limited number of these cases. Issues to be investigated include: the identification of unclear solar sources, undefined expansion rates, evidence of longitudinal/latitudinal deflections in the propagation, evidence for modifications of the coronal mass ejection due to collisions with solar wind structures or other transient events, and identification of magnetic flux-rope rotations.