30 Jan 2026
| 30 Jan 2026
Status: this preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
"Corotating Interaction Region (CIR)", "Interaction Region", "Stream Interaction Region (SIR)", which term should be used?
Abstract. We discuss the history of quasiperiodic ~27-day recurrent geomagnetic activity and the origin of the names "interaction region", "corotating interaction region" and "stream interaction region". The latter three names have an identical meaning. We recommend the most commonly used name "corotating interaction region" or CIR for sole usage in the literature to avoid confusion.
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I understand the authors’ concern on the terminology confusions, as some authors use these two terms interchangeably (Waugh and Jardine, 2025). However, I’m not convinced with the authors’ current narratives. According to the modern studies, CIRs (coronating interacting regions) are used as subsets of SIRs (stream interacting regions). Allen et al. (2020) stated, “After a complete solar rotation, the SIR is classified as a corotating interaction region (CIR)”. Richardson (2018) uses “the general term “stream interaction region”, while being aware that some authors (e.g., Jian et al. 2006) use this term to distinguish a stream that is observed on only one solar rotation from a “corotating” interaction region that is seen on more than one rotation.” If the scientific community stops using the term of SIR, how would we call the CIRs that did not persist as long as one solar rotation? It’s straightforward to understand CIRs as a subset of SIRs.