1. Solar cycle variation of the heliospheric magnetic field
Mathew Owens
10 September 2012

2. Overview Photospheric magnetic field (briefly) Ulysses
Configuration of the heliospheric magnetic field
R2 |BR| invariance
Near-Earth observations
Variation in total heliospheric flux
Geomagnetic reconstructions
Adding/removing heliospheric flux
Suprathermal electron observations
Relation to Solar Orbiter

3. Photospheric extrapolations Top: Riley et al, 2006 Bottom: Eclipse photograph, Carlos & Espenak, 1995.
HMF observations are single-point measurements
PFSS (etc.) provides invaluable global context
BUT:
Steady state (over 27 days)
Minimum energy state of corona

4. Open Solar Flux (OSF) Unsigned Flux, FU=  |BR| r2 cos() dd
Flux threading the coronal source surface
Unsigned Flux,
FU=  |BR| r2 cos() dd
r = heliocentric distance
BR = radial field
 = solar latitude
 = solar longitude
+/2 2
-/2 0
“closed” field line
“open” field lines

5. PFSS solutions Magnetic field polarity at coronal source surface

6. HCS location e.g., Smith el al., 2003

7. Ulysses e.g., McComas et al, 2003; Jones et al, 2002.

8. BR invariance |BR| ecliptic d R Earth
Balogh et al., 1995; Smith et al., 2001; Lockwood et al., 2000 d
|BR|
ecliptic
Earth R
|BRE|
Ulysses showed that everywhere |BR|(d/R)2 = |BRE|
Thus total unsigned magnetic flux leaving the sun = 4R2 |BRE|

9. Heliospheric magnetic flux Owens et al., 2008

10. Total HMF

11. Geomagnetic reconstructions Svalgaard & Cliver, 2010; Lockwood & Owens, 2011

12. Note: Total HMF != OSF e.g., Wand & Sheeley, 1995; Lockwood and Owens, 2009; Erdos & Balogh 2012;

13. Suprathermal electrons e. g. , Feldman et al, 1975; Gosling et al
Suprathermal electrons e.g., Feldman et al, 1975; Gosling et al., 1987; Crooker et al., 1998

14. Adding/removing OSF Solanki et al, 2000
OSF can be modelled as a continuity equation
Source: New closed loops. Sunspots or CMEs
Loss: Disconnection of magnetic flux. ???
Owens and Crooker, JGR, 2006
Owens and Crooker, JGR, 2007

15. Solar wind at 1 AU (Simple classification of ACE suprathermal electron data)

16. Closed HMF - new OSF e.g., Gosling et al, 1987; Low 2001

17. Closed HMF in magnetic clouds Shodhan et al,, 2002; Crooker et al, 2002; Crooker et al, 2008
1 AU
5 AU

18. OSF transport by CMEs Owens & Crooker, 2007
CMEs project the Hale cycle into the heliosphere
Changes in PFSS solutions are associated with CME locations (e.g., Luhmann et al, 1998)

19. Inverted HMF – OSF removal

20. OSF loss and HCS tilt Owens et al, JGR, 2011

21. Solar Orbiter Close to Sun, combined remote and in situ observations, heliospheric imaging, etc.
Quantify the relation between OSF and HMF measured at 1 AU (and beyond)
Observe newly created and destroyed OSF before it evolves in transit to 1 AU
What are the solar signatures of these processes?
What fraction of the corona is undergoing these processes at any one time?
Are there newly emerged loops in the absence of CMEs?
How does this relate to the source of the slow solar wind.

22. PFSS - OMNI

23. PFSS -Ulysses

24. Ulysses Perihelion passes
(Fast Latitude Scans)
 1st - near sunspot min  2nd - near sunspot max

25. A rotating dipole?

26. Ulysses