Title: MotivationCoronal signatures
1(No Transcript)
2Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
3Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
4the solar wind
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
natural turbulence laboratory
- We aim to
- Compare turbulence in plasmas and neutral fluids
so that we can learn more about the universal
aspects of turbulent flows - Specific understanding of plasma turbulence
phenomenology and modeling of space weather - Learn more about the conditions in the solar
corona from which the solar wind originates.
High magnetic Reynolds number 105
5the solar wind
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
natural turbulence laboratory
- We aim to
- Compare turbulence in plasmas and neutral fluids
so that we can learn more about the universal
aspects of turbulent flows - Specific understanding of plasma turbulence
phenomenology and modeling of space weather - Learn more about the conditions in the solar
corona from which the solar wind originates.
High magnetic Reynolds number 105
6the solar wind
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
natural turbulence laboratory
- We aim to
- Compare turbulence in plasmas and neutral fluids
so that we can learn more about the universal
aspects of turbulent flows - Specific understanding of plasma turbulence
phenomenology and modeling of space weather - Learn more about the conditions in the solar
corona from which the solar wind originates.
High magnetic Reynolds number 105
7self-similarity
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
Change scale from t to bt AND scale y to bHy
8self-similarity
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
Change scale from t to bt AND scale x to bHx
If the statistics of bHy is the same as y then
process is statistically self-similar
Hurst exponent H
9Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
x(t,?) y(t?) - y(t)
?
10Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
x(t,?) y(t?) - y(t)
?
probability density function (pdf)
11pdf collapse
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
12pdf collapse
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
13moment scaling
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
pdf scaling implies scaling of moments AND
monoscaling implies a linear increase in the
scaling of the moments with moment order p
?(p)Hp
14moment scaling
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
pdf scaling implies scaling of moments AND
monoscaling implies a linear increase in the
scaling of the moments with moment order p
?(p)Hp
15Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
16Lévy processes
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
For Levy H1/?
17heavy-tails
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
18finite-size effects
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
From extreme value theory (EVT)
19finite-size effects
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
From extreme value theory (EVT)
gradient1/?
20Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
K. Kiyani, S. C. Chapman and B. Hnat, Phys. Rev.
E 74, 051122 (2006)
21multifractals
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
non-linear
Why does this happen?
22multifractals
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
non-linear
Why does this happen?
23digression
Nigel Goldenfeld. Roughness-induced criticality
in a turbulent flow. Phys. Rev. Lett. 96,
0445031-4 (2006)
24Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
real-world data
25solar cycle change
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
- In situ data from solar wind monitors ACE WIND
around the Sun-Earth L1 point (R. Lepping, K.
Ogilvie) - To study solar max (2000) and solar min
(1996)
- Probe in detail the scaling of B2 - magnetic
field energy density
26Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
Monofractal Lévy process
Multifractal p-model
27results
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
2000 - Solar max
1996 - Solar min
?(p)
?(p)
Moment p
Moment p
H 0.44 0.02
K. Kiyani, S. C. Chapman, B. Hnat and R. M.
Nicol, Phys. Rev. Lett 98, 211101 (2007)
28Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
_at_ 1
1 year (2000 solar max) ACE 64 seconds calibrated
magnetometer data (R. Lepping)
2 hrs
5 mins
log10(Sp)
K. Kiyani, S. C. Chapman, B. Hnat and R. M.
Nicol, Phys. Rev. Lett 98, 211101 (2007)
29pdfs
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
Functional form of pdf different at solar max and
min
Power law tail at solar maximum reminiscent of a
Lévy process
B. Hnat et. al. , Geophys. Res. Lett. 34, L15108
(2007)
30Lévy?
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
H1/? for a Lévy process
Measured values H0.44 ? 1/?0.71
31Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
All epistemological value of the theory of
probability is based on this that large scale
random phenomena in their collective action
create strict, non-random regularity. (Gnedenko
and Kolmogorov, Limit Distributions for Sums of
Independent Random Variables)
32limit theorems
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
Central Limit Theorem (De Moivre, Laplace,
Lyapunov)
33limit theorems
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
Central Limit Theorem (De Moivre, Laplace,
Lyapunov)
Generalized Central Limit Theorem (Lévy)
34Joseph effect
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
Introduce memory via Mandelbrots notion of
Joseph (memory) and Noah (large events) effects
using
Linear fractional stable motion (lfsm)
Memory parameter d H - 1/?
tail parameter ?
dgt0 gt persistence dlt0 gt anti-persistence
self-similarity parameter H Hurst exponent
35lfsm
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
fft based algorithm obtained from S. Stoev and M.
Taqqu (fractals 2004)
36finite-size scaling
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
37finite-size scaling
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
?(p)
Moment p
38Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
2000 - Solar max
lfsm H0.44 ?1.4
?(p)
?(p)
Moment p
Moment p
39conclusions
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
- We find a unique monofractal signature in the
solar wind at 1 AU in the ecliptic at solar
maximum. - Use of a robust statistical estimator which
operationally excludes a small percentage of
poorly represented extreme events. - Solar Max -- Complex topology larger events gt
are we seeing remnants of solar activity? - To obtain a more complete picture it is
necessary to take into account non-Markovian
effects -
Possible signatures of the processes driving the
turbulence?
- Outlook - look to different spacecrafts to scan
interplanetary solar wind to study the evolution
of its turbulence. Check for detailed solar cycle
dependence.
40references
Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary
- Self-similar scaling of B2
- K. Kiyani, S. C. Chapman, B. Hnat and R. M.
Nicol, Phys. Rev. Lett 98, 211101 (2007). - B. Hnat, S. C. Chapman, K. Kiyani, G. Rowlands
and N. W. Watkins, Geophys. Res. Lett. 34,
L15108 (2007). - Conditioning extreme events
- K. Kiyani, S. C. Chapman and B. Hnat, Phys. Rev.
E 74, 051122 (2006). - Applications to anomalous transport
- G. Zimbardo, Plasma Phys. Control. Fusion 47
B755-B767 (2005). - D. F. Escande and F. Sattin, PRL 99, 185005
(2007). - Reading on stable processes
- Samorodnitsky Taqqu, Stable Non-Gaussian
Random Processes.
41Motivation Coronal signatures Scaling Introducin
g memory Heavy-tails Summary