Multi-viewpoint Coronal Mass Ejection Catalog Based on STEREO COR2 Observations

Abstract

We present the first multi-viewpoint coronal mass ejection (CME) catalog. The events are identified visually in simultaneous total brightness observations from the twin SECCHI/COR2 coronagraphs onboard the Solar Terrestrial Relations Observatory mission. The Multi-View CME Catalog differs from past catalogs in three key aspects: (1) all events between the two viewpoints are cross-linked, (2) each event is assigned a physics-motivated morphological classification (e.g., jet, wave, andflux rope), and (3) kinematic and geometric information is extracted semi-automatically via a supervised image segmentation algorithm. The database extends from the beginning of the COR2 synoptic program (2007 March) to the end of dual-viewpoint observations (2014 September). It contains 4473 unique events with 3358 events identified in both COR2s. Kinematic properties exist currently for 1747 events (26% of COR2-A events and 17% of COR2-B events). We examine several issues, made possible by this cross-linked CME database, including the role of projection on the perceived morphology of events, the missing CME rate, the existence of cool material in CMEs, the solar cycle dependence on CME rate, speeds and width, and the existence of flux rope within CMEs. We discuss the implications for past singleviewpoint studies and for Space Weather research. The database is publicly available on the web including all available measurements. We hope that it will become a useful resource for the community.

Fitting and Reconstruction of Thirteen Simple Coronal Mass Ejections

“…However, since measurements of the expansion speed are performed at 1 AU, they do not necessarily give information on the past behavior of the CME (regarding if and how it expanded) and this may explain why we find a significant number of elliptical cross-sections, even for events specifically selected for the small magnitude of the expansion speed at 1 AU. Another reason might be that CMEs start with an elliptical cross-section already in the corona, although some evidence from EUV and coronagraph images point to circular cross-sections (Vourlidas et al, 2017).…”

Modeling inner boundary values at 18 solar radii during solar quiet time for global three-dimensional time-dependent magnetohydrodynamic numerical simulation

“…The occurrence frequency of CMEs ranges from ~0.6/day to ~4/day [e.g., Wu, Lepping, and Gopalswamy, 2006] or to ~6/day [Wang and Colaninno, 2014;Hess and Colaninno, 2017;Vourlidas et al 2017], depending on the phase of the solar cycle. When a CME/ICME/Shock propagates from the Sun to the Earth, the solar wind can vary a lot, depending on the size/speed of the CME.…”

Forecasting the Structure and Orientation of Earthbound Coronal Mass Ejections

“…In other cases, an ICME and resulting geomagnetic storm may be unexpected, resulting in forecast “misses,” such as when a CME is observed remotely to be slow and faint, but the ICME magnetic field is unexpectedly strong enough to drive a storm (e.g., Nitta & Mulligan, ; Tsurutani et al, ). In other examples, limited coronagraph observations, or narrow and faint CMEs, can result in Earth‐directed CMEs being missed in observations (Kilpua et al, ; Webb & Howard, ; Vourlidas et al, ) and therefore never forecast. Some CMEs also leave the Sun without any noticeable surface signatures (e.g., Nitta & Mulligan, ; Robbrecht et al, ).…”

“…Recent studies have emphasized a range of morphologies (Vourlidas et al, ); for example, in addition to the above‐described three‐part structure there are loop‐like CMEs that have a bright front, but no cavity nor core, and jet‐like CMEs lacking clear substructure. The morphology depends strongly on the viewing angle and is subject to projection effects (Cremades & Bothmer, ; Vourlidas et al, ). For example, the absence of a cavity is thus likely due to the viewpoint, not due to the lack of the presence of a flux rope.…”