Data-Driven Classification of Coronal Hole and Streamer Belt Solar Wind
| Autor: | Clare E. J. Watt, Leland McInnes, Mathew J. Owens, Téo Bloch, Allan R. Macneil |
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| Rok vydání: | 2020 |
| Předmět: |
Physics
010504 meteorology & atmospheric sciences Meteorology F300 Astrophysics::High Energy Astrophysical Phenomena Coronal hole Astronomy and Astrophysics Classification scheme 01 natural sciences Latitude Data-driven Solar wind Space and Planetary Science Physics::Space Physics 0103 physical sciences Cluster (physics) Astrophysics::Solar and Stellar Astrophysics Entropy (information theory) Unsupervised learning 010303 astronomy & astrophysics 0105 earth and related environmental sciences |
| Zdroj: | Solar Physics. 295 |
| ISSN: | 1573-093X 0038-0938 |
| DOI: | 10.1007/s11207-020-01609-z |
| Popis: | We present two new solar wind origin classification schemes developed independently using unsupervised machine learning. The first scheme aims to classify solar wind into three types: coronal-hole wind, streamer-belt wind, and ‘unclassified’ which does not fit into either of the previous two categories. The second scheme independently derives three clusters from the data; the coronal-hole and streamer-belt winds, and a differing unclassified cluster. The classification schemes are created using non-evolving solar wind parameters, such as ion charge states and composition, measured during the three Ulysses fast latitude scans. The schemes are subsequently applied to the Ulysses and the Advanced Compositional Explorer (ACE) datasets. The first scheme is based on oxygen charge state ratio and proton specific entropy. The second uses these data, as well as the carbon charge state ratio, the alpha-to-proton ratio, the iron-to-oxygen ratio, and the mean iron charge state. Thus, the classification schemes are grounded in the properties of the solar source regions. Furthermore, the techniques used are selected specifically to reduce the introduction of subjective biases into the schemes. We demonstrate significant best case disparities (minimum ≈8%, maximum ≈22%) with the traditional fast and slow solar wind determined using speed thresholds. By comparing the results between the in- (ACE) and out-of-ecliptic (Ulysses) data, we find morphological differences in the structure of coronal-hole wind. Our results show how a data-driven approach to the classification of solar wind origins can yield results which differ from those obtained using other methods. As such, the results form an important part of the information required to validate how well current understanding of solar origins and the solar wind match with the data we have. |
| Databáze: | OpenAIRE |
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