What drives space weather and what has helicity
- Slides: 20
What drives space weather and what has helicity got to do with it? . . . or assorted thoughts and questions of a confused Ph. D student 19/03/2019 Reko Hynönen 1 1 Aalto-yliopisto Reko. Hynonen@aalto. fi
Purpose of this talk 16. 6. 2021 2
Solar features - Strong magnetic flux - Active regions: simple and complex - Flares - Flux of magnetic helicity? 16. 6. 2021 3
Solar features - Strong magnetic flux - Active regions: simple and complex - Flares - Flux of magnetic helicity? - Open field lines - High-speed solar wind streams Ø With high Alfvénicity / cross helicity - CH: Relation to helicity? 16. 6. 2021 4
Solar features - Strong magnetic flux - Active regions: simple and complex - Flares - Flux of magnetic helicity? - Flares and coronal mass ejections - Transfer of magnetic helicity? - Open field lines - High-speed solar wind streams Ø With high Alfvénicity / cross helicity - CH: Relation to helicity? 16. 6. 2021 5
Solar wind structures 16. 6. 2021 6
Solar wind structures Slow, high-density solar wind • High velocity shear typically low cross helicity • Origin unclear: v One of the source regions: helmet streamers 16. 6. 2021 7
Solar wind structures Slow, high-density solar wind • High velocity shear typically low cross helicity • Origin unclear: v One of the source regions: helmet streamers Fast, low-density solar wind • Low velocity shear typically high cross helicity v Origin: Coronal holes 16. 6. 2021 8
Solar wind structures Slow, high-density solar wind • High velocity shear typically low cross helicity • Origin unclear: v One of the source regions: helmet streamers Fast, low-density solar wind • Low velocity shear typically high cross helicity v Origin: Coronal holes 16. 6. 2021 9
Space weather events Energy! Energy! 16. 6. 2021 10
Energy! Re co nn e ct io n! Space weather events Energy! io ct ne n co Re Energy n! 16. 6. 2021 11
Energy! Re co nn e ct io n! Space weather events Dungey cycle Energy! io ct ne n co Re Energy n! 16. 6. 2021 12
Space weather events Energy! Re co nn e ct io n! Dungey cycle Energy! io ct ne n co Re Energy n! 16. 6. 2021 13
Energy! Re co nn e ct io n! Space weather events Dungey cycle Energy! io ct ne n co Re Energy n! 16. 6. 2021 14
events Energy! Re co nn e ct io n! Geomagnetic storms Space weather • Enhancement of ring current • Equatorial, global activity • Measured by storm disturbance indices, like Dst Dungey cycle Energy! io ct ne n co Re Energy n! 16. 6. 2021 15
Re co nn e ct io n! Geomagnetic storms Space weather events • Enhancement of ring current • Equatorial, global activity Substorms • Measured by storm • Activity of auroral region disturbance indices, like Dst (both poles) • Local phenomena • Measured by substorm / Energy! electrojet current indices, like AE Dungey cycle Energy! io ct ne n co Re Energy n! 16. 6. 2021 16
Measuring Dst index Space • Four magnetic stations around equator 16. 6. 2021 weather events 17
Space weather events 16. 6. 2021 18
Space weather events 16. 6. 2021 19
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