Mathew Owens 1 Space and Atmospheric Electricity group Department of Meteorology HMF big Questions that I probably wont answer today What are the physical processes by which the the heliospheric magnetic field HMF evolve ID: 629975
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Slide1
Evolution of the heliospheric magnetic field
Mathew Owens
1
Space and Atmospheric Electricity groupDepartment of MeteorologySlide2
HMF: big Questions
(that I probably won’t answer today)
What are the physical processes by which the the heliospheric magnetic field (HMF) evolve?
What is the relation to solar wind release and acceleration?How do long- and short- time scales couple, and does this result in any
long-term predictability?
How can these processes be used to diagnose the solar dynamo?
What are the implications for
stellarspheres and stellar winds?
2
The HMF magnetically couples the Sun and planets, channels SEPs, shields from GCRs and can be reconstructed over millennia, providing the strongest constraints on the solar dynamoSlide3
Context: HMF variability
3Slide4
3D structure of HMF
ULysses
4Slide5
PFSS solutions
Magnetic field polarity at coronal source surface
5Slide6
OPEN SOLAR FLUX
Flux threading the coronal source surface
F
U
= |
B
R
|
r
2
cos()
dd
+/2 2
-/2 0
“closed” field line
“open” field lines
e.g.,
Balogh
et al., 1995Slide7
Open solar flux
view of the ecliptic
7
OSF
Total HMFSlide8
In-situ measurements
8
Owens et al., JGR, 2008Slide9
Inner Heliosphere
SamplingA strong case for orbiter (% Probe)!
9Slide10
Space-age variations
10Slide11
Suprathermal electrons
Tracers of HMF topology
[
Stverak
et al., 2009]
[Hammond et al., 1996]Slide12
OSF evolution
relating in situ and remote observations
12
Owens and Crooker, JGR,
2006
Sheeley
et al., 2007Slide13
Closed HMF
Primarily ICMEs aT
1 AU
13Slide14
Suprathermal electron
scattering
see poster by georgina
grahamSlide15
Non-CME closed flux?
15
Closed flux outside CMEs close to the Sun (but not identifiable at1 AU)?
HELIOS data (e.g., Owen,
Mattini
, Graham,
Stansby
, Salem)
Unique, but not ideal for these kinds of study
Remote observations of rising loops?
SunSlide16
HMF inversions
in-situ observations
16Slide17
Aside: Flux excess
[Lockwood et al., 2009]
Flux at R – Flux at L1
R [AU]Slide18
Coronal source
18
c.f. “Q parameter”Slide19
Pseudostreamers
interchange reconnection and the slow wind
19Slide20
Slow wind source
Latitudes accessible to orbiter
20
[Owens et
al.,
2014]Slide21
Orbiter?
Coordinated observations…….Between Orbiter instruments: Remote sensing and in
situHow “representative” is a single-point measurement?How can we interpret 2D images of 3D structures?…With
other spacecraft (Probe, DSCOVR) Remote and in-situ obsMulitpoint in-situ obs
Mulitploint remote
obs
Sample range of heliocentric distances
Disentangle structures of solar origin and those formed in transitHigh latitude (>20 degrees) observations
21Slide22
Extra slides
22Slide23
HMF inversions
e.g., Crooker et al., 2004
23Slide24
Photospheric flux
Top: e.g., David Hathaway, MSFCSlide25
Modelling the corona
Left: Riley et al., 2006
Right: Eclipse photograph, Carlos &
Espenak, 1995.Slide26
ULYSSES
Balogh
et al., 1995; Smith et al., 2001;
Lockwood et al., 2000
ecliptic
Ulysses showed that everywhere |B
R
|(d/R)
2
= |B
RE
|
Thus total unsigned magnetic flux leaving the sun = 4
R
2
|B
RE
|
|B
RE
|
R
d
|B
R
|Slide27
Flux ropes
Q: Does the CME flux rope form in transit or exist prior to launch?CME initiation mechanisms
SWx forecasting implicationsQ: How much flux/helicity is transported from the corona by CMEs?Role of CMEs in solar cycle evolution of heliosphere
Compare flux/helicity in AR with that in ICME. Compare composition with ICME with coronal flux systems
27Slide28
Non-cloud icmes
Q: What are non-flux rope ICMEs?Eruption without FR?
FR destroyed in transit?FR not encountered?Is there a increase in the fraction of non-FR ICMEs with distance?
Do structured CMEs result in FRs in situ?28Slide29
Large-scale structure
ICMEs remain (partly) magnetically connected to SunCritical for the “open flux” contribution of CMEs
Q: Is connectivity affected by pre-launch topology?Q: What is the extent of the “identifiable” ICME?Q: Over what length-scales are similar signatures seen?
29Slide30
Small-scale transients
Q: How do “blobs” relate to CMEs?Spectrum of similar phenomenon or fundamentally different beasts?
What do “blobs” look like before solar wind processing?Are small flux ropes present that can’t survive to 1 AU?Do they contain
counterstreaming electrons which are subsequently lost?
30Slide31
ICME kinematics
Q: To what extent are CMEs deflected from radial propagation?Primarily in corona by CH flux?
What about by fast wind in heliosphere?True centre of mass deflection or distortion of CME edges?Q: Where and how does the bulk of ICME deceleration occur?
CMEs tend towards solar wind speedBut evidence of deceleration in HI field of view is weak (or model dependent).
31Slide32
Shocks and SEPs
Q: What controls SEP production?Fundamental difference in impulsive and gradual SEPs?
Properties of near-Sun shocksExistence of suprathermal seed particles
Transport/release of SEPsShock connectivity
32Slide33
Requirements (?)
“Low” resolution (~minutes) in situ data (plasma, B, suprathermal electrons, composition) sufficient for most “transient” science?
Low res data throughout mission (including cruise) preferable to high resolution data over limited periodsExceptions: Shocks. Blobs. How to predict timing of these? Radio-based event trigger? Streamer belt encounter?
High cadence in situ observations need not be coordinated with high cadence remote sensing?Schedule remote sensing observations for quadrature with L1, etc.How can we address the questions I’ve mentioned?
What are the major science questions I omitted?
33