Solar Physics & upper-Atmosphere Research Group Robert Erdélyi University of SheffieldPPARC ASSSP...

University of Sheffield

Solar Physics & upper-Atmosphere Research Group

Robert Erdélyihttp://robertus.staff.shef.ac.uk

PPARC ASSSP 200631 Aug – 4 Sep 2006, Mallorca





www.iaus247.org

LOC contact: Cesar Mendoza-Briceno (Venezuela)

SOC contact: Robertus Erdélyi (UK)




The structure of the lower The structure of the lower solar atmospheresolar atmosphere

Robert Erdélyi

[email protected], Department of Applied Mathematics,

The University of Sheffield (UK)

http://robertus.staff.shef.ac.uk





Lower atmosphereLower atmosphere

• Very highly structured and dynamic; challenge for magnetic seismology via inversion

Three outstanding topics:

• Atmospheric/coronal heating.

• Influence of magnetic atmosphere, i.e. magnetic carpet, on oscillations.

• Role of p modes in the dynamics of the lower atmosphere! (Not yet explored.)

• Photosphere – chromosphere – TR (– corona are) magnetically coupled.





Lower atmosphere: Lower atmosphere: couplingcouplingWavelength T (C)

Visible 5000

Magnetic Field 5000

UV 1600 A 8000

Hydrogen H 15,000

Helium EUV 50,000

Iron 8/9 EUV 1 million

Iron 11 EUV 1.5 million





What is the motivation?

• Understand atmospheric structures (spicules, prominences, loops, plumes, etc.)

• Source of atmospheric heating; solar wind/particle acceleration

Lower atmospheric Lower atmospheric seismologyseismology

Observationsspectroscopic

imaging

Wave properties (speed, amplitude, spectrum)

Geometric properties of waveguides (structuring, shape, curvature)

Atmospheric diagnostic parameters (temperature, density)

Atmospheric physical parameters (B, fine structure, transport coefficients)

Coronal (Roberts et al. 1984) /Atmospheric seismology (Erdélyi 2006)





Solar interior

• Global oscillations

• p/f/g-modes

Unifying feature of variety of solar atmospheric oscillations

• Waveguide concept

• MHD description

Solar atmosphere

• More local oscillations

• Sunspot oscillations, prominence oscillations, coronal loop oscillations, plume oscillations

• Moreton & EIT waves

Oscillations ubiquitous in Sun

Objects: atmospheric Objects: atmospheric oscillationsoscillations





Global oscillationsGlobal oscillations

¤ Red curve : l = 75

¤ Yellow curve : l = 25

¤ Green curve : l = 20

¤ Blue curve : l = 2

¤ White curve : l = 0

ν= 3mHz





Global oscillationsGlobal oscillations

¤ n=14 (radial nodes)

¤ m=16 (poloidal nodes)

¤ l=20 (spherical harmonic degree)

¤ The frequency of this mode determined from the MDI data is 2935.88 0.2 µHz.





Solar interior


• p/f/g-modes



• MHD description

Solar atmosphere










Sunspot oscillationsSunspot oscillations





Solar interior


• p/f/g-modes



• MHD description

Solar atmosphere










Standing kink (transversal) modesStanding kink (transversal) modes• TRACE: Loop oscillation excited by M4.6 flare (14 July 1998)

Movie in TRACE 171 A

Occurrence rate: 17/255 flares with transverse oscillation

Schrijver et al. 2002





Solar interior


• p/f/g-modes



• MHD description

Solar atmosphere










Moreton waves • Seen in H in the chromosphere at 10000 K (Moreton ’60)

• Propagation speeds 450-2000 km/s, away from a flare site

• Propagate almost isotropically; confined to an arc rarely exceeding 120º

• Have been identified as the intersection of coronal shock waves (due to a flare) with the chromosphere (Uchida ‘68; ‘74)

• Are not seen to decelerate

• The generation mechanism has not been made clear yet

Moreton and EIT wavesMoreton and EIT waves





• M

oret

on w

aves

on

diff

eren

ce

imag

es a

fter

sol

ar e

rupt

ion






Solar interior


• p/f/g-modes



• MHD description

Solar atmosphere










Low atmosphere

• Ph, Ch, possibly TR

• Isolated flux tubes

• Effect of stratification

Stratification leads to the Klein-Gordon effect

Higher atmosphere

• TR, Corona

• Magnetic environment

vA

vA

(Roberts 1981, Rae & Roberts 1982, Erdélyi(2005)


Atmospheric Atmospheric oscillationsoscillations

(Review: Erdélyi, Roberts, Ruderman, Thompson 2006; Erdélyi 2006)





The Klein-Gordon wavesThe Klein-Gordon wavesStratified atmosphere (g=const)

Webb & Roberts, Sol. Phys, 56, 5 (1978); Ulmschneider and co’s, may papers in A&A; Review by Roberts (2003); Erdélyi & Hargreaves

(2005)Erdélyi (2006); De Pontieu & Erdélyi (2006)

• Equilibrium:

• Scale height:

• 1D, sound waves:

• Introduce

)()( 0'0 zgzp

0

0)()( 22

22

2

2

Qzz

Qzc

t

QSS

),()(),( tzQzftzu ),( tzu

)](21[4

)( '02

0

22 z

cz S

S





The Klein-Gordon wavesThe Klein-Gordon waves

De Pontieu, Erdélyi & James (2004); De Pontieu, Erdélyi & De Moortel (2005); De Pontieu & Erdélyi (2006)

Leakage of photospheric motion into LA

• Sound, slow, Alfvén waves

• γ=5/3 1

• Non-adiabatic plasma

• Inclination of magnetic wave guides

Isothermal atmospheres

acS c

g

2

Photosphere: νac= 4.8 mHz P = 210 s

(acoustic cut-off frequency)

Corona: νac= 0.18 mHz P = 91.7 min





Coupling scales and elementsCoupling scales and elements

¤ Magnetic fields

¤ Flow fields

Manifestations of presence of solar atmosphere:

Organised flows (meridional; differential rotation, etc.)

Random flows (granulation, convection, etc.)

Coherent global fields (e.g. canopy)

Random fields (magnetic carpet)





Solar acoustic oscillationsSolar acoustic oscillations

¤ Separated ridges of power predicted: Ulrich (1970), Leibacher & Stein (1971)

¤ Separated ridges of power observed: Deubner (1975)

MD

I ob

serv

atio

ns

gkm

nn

212





Differences in sound speedDifferences in sound speed





Internal structure vs BCs?Internal structure vs BCs?

¤ EVP with proper BCs

¤ “Surface term” = ALL the atmospheric physics included!!

¤ Inversion should include (magnetic) solar atmosphere





Problem: “solar cycle effects”Problem: “solar cycle effects”

¤Time dependent ridges of power observed: systematic frequency decrease (0.42 μHz 0.14 μHz) of low spherical (l) degree p-modes from maximum (1980) to minimum (1984) activity (Woodard & Noyes)

¤Most obvious theoretical candidate for interpretation: magnetic field (Ledoux & Simon 1957; Goossens et al. 1972, 1976; Biront et al. 1982 in stellar context)

(Campbell & Roberts 1989; Evans & Roberts 1990, 1991, 1992; Jain & Roberts 1993, 1994abc; Miles & Roberts 1992; Erdélyi & Taroyan 2000, 2001, 2002a-c, 2005; Erdélyi, Kerekes & Mole 2005; Erdélyi & Pintér 2005; Shelyag, Erdélyi & Thompson 2005; Petrovay, Erdélyi & Thompson 2005 Erdélyi, Taroyan & Barlow 2006, etc. in solar context)





Problem: frequency differenciesProblem: frequency differencies

¤Strong dependence of frequency shifts on the frequency and degree of the mode

Libbrecht & Woodard 1975





GONG observations of line-widthGONG observations of line-width

¤ Variation of Г with magnetic activity for a single multiplet (l = 50, m = 9)

¤ Magnetic flux (dashed line)

¤ Sunspot number (dotted line)

¤ Komm et al., ApJ, 531, 1094, 2000





BiSON observation of line BiSON observation of line width variationwidth variation

¤ Changes in LW of low-angular degree p-modes during fall of SC22

• Averaged over 2.6 to 3.6 mHz

• 24 3% mean increase in the modal line width from activity minimum to maximum

• Chaplin et al., MNRAS, 313, 32, 2000





An example: line-widths (GONG)An example: line-widths (GONG)

Surface gravity(f) modes

Acoustic(p) modes

Dziembowski and Goode, ApJ 2005





Model ConceptModel Concept

¤ Magnetic fields

¤ Flow fields

Manifestations of coupling scales:

Organised flows (meridional; differential rotation, etc.)

Random flows (granulation, convection, etc.)

Coherent global fields (e.g. canopy)

Random fields (magnetic carpet)






¤ Global modes interact (e.g. resonantly ) with local MHD modes

¤Dissipation

¤ Damping of global oscillations

Steady state

¤ Global oscillations influenced by atmosphere






Manifestations of presence of solar atmosphere:





Simple-minded solar modelSimple-minded solar model corona

chro

mos

ph

eric

tr

ansi

tion

al

laye

r (L

)

photospherexzy g solar interior

B(z)

canopy (h)





EigenmodesEigenmodes





Frequency spectrum (Frequency spectrum (L=0, B=0L=0, B=0))

¤ Role of atmosphere: cut-off frequencies υI and υII

scI kv

1

2

sc

II v

g

2

g

vHkH SC

2

,1

1kH

gvsc

I

1

SCII kv





Eigenmodes (Eigenmodes (L=0, B=0L=0, B=0))





Frequency spectrum (Frequency spectrum (LL0, B=00, B=0))

¤ Role of chromospheric transitional layer (L0): chromospheric g-modes

¤ Modes below Brunt-Väisälä frequency

)(

)(ln)(

2

20

zv

g

dz

zdgz

sBV

Uchida 1965, Thomas et al. 1971, Deubner & Gough 1984, Clark & Clark 1989, Braun & Fan 1998, Pintér et al. 1998

g1





Eigenmodes (Eigenmodes (LL0, B=00, B=0))

g-modes are trapped in the transition layer where ωBV>0





Frequency spectrum (Frequency spectrum (L=0, B L=0, B 0 0))






¤ Two-layer model

¤ Polytrop interior

¤ Isothermal atmosphere

¤ vA=cst β=cst (C&R89)

¤ B=cst (E&R90)

¤ No Alvén/slow continua






leaky modes

leaky modes

quasi-modes

eigenmodes

eigenmodes





Eigenmodes (Eigenmodes (L L 0, B 0, B 0 0))





Resonant coupling (Resonant coupling (L L 0, B 0, B 0 0))

The The coefficient coefficient functions:functions:





• Driven problem ω is prescribed• Eigenvalue problem ω is searched for

constC

B

TCBiP

B

Cgi

A

A

Ax

ABz

sgn2

sgn

21

2

Jumps are independent of dissipative coefficient






• Inhomogeneous plasmas: natural behaviour

• Easy wave energy transfer resulting in heating

• Condition to occur: ωdriver = ωlocal

• Could/may/viable to explain:

- local/atmospheric heating

- power loss of acoustic waves in sunspots

- damping of standing waves coronal loop oscillations

- damping of helioseismic (p/f/g) eigenmodes

- energisation of MHD waves in magneto/heliosphere






Eigenmodes (Eigenmodes (L L 0, B 0, B 0 0)) ¤ Three-layer model


¤ Magnetic transitional layer resonances damping

¤ Isothermal magnetic upper atmosphere

¤ Presence of Alvén/slow continua

¤Tirry et al. 1998, Pintér et al. 1999





¤ Three-layer model





¤ Erdélyi and Pintér 2005

l = 100L = 2 Mm

Δν

(μ

Hz)

Bc (G)

p3

p8

p4

f

Bc (G)

p1 p2

l = 100L = 2 Mm

Im ν

(nH

z)Eigenmodes (Eigenmodes (L L 0, B 0, B 0 0))






¤ Three-layer model





¤ Non-parallel propagation

¤Pintér, Erdélyi & Goossens 2005






¤Pintér, Erdélyi & Goossens 2005






¤ Pintér, Erdélyi & Goossens 2005

¤ Poster by Erdélyi & Pintér





¤ Erdélyi, Pintér & Goossens 2005






Observations of Observations of sub-surface flowssub-surface flows The order of the observed velocity of a poleward meridional flow is 10 m/s.

Values of U’ for each data set, averaged over both hemispheres. The triangles indicate the SOI-MDI observations and the squares show the GONG observations.

Braun & Fan 1998





Observations of Observations of sub-surface flowssub-surface flows

Residual angular velocity as function of time. Each 1-month-wide stripe represents one 3-month dataset, so that adjacent strips are not independent.

Howe R., Komm R., Hill R., Sol. Phys. 192, 427, 2000





Physical processPhysical process

Variation of damping

Temporal variation of a sub-photospheric flow

?





Revised solar modelRevised solar model

Space & Atmosphere Research Center

B(z)

corona

chro

mos

ph

eric

tr

ansi

tion

al

laye

r (L

)

photospherexzy g solar interior v

canopy (h)





Flow effects on frequency spectrumFlow effects on frequency spectrum






Can be done analytically in small wavelength limit…






Erdélyi & Taroyan 2002a,b

Cyclic frequency shift

Δν=ν(l,B,V)-ν(l,B,0)

in µHz for the f-mode

Cyclic frequency shift

Δν=ν(l,B,V)-ν(l,B,0)

in µHz for the n=1 p mode





Flow effects on line widthFlow effects on line width

Pintér, Erdélyi & New R., A&A, 2001





Rotational splitting of sectoral modesRotational splitting of sectoral modes

Pintér B., New R. & Erdélyi R., Astron. Astrophys., 378, 1, 2001

• v = 2 km/s

with n1 = n2, l1 = l2 and m1 = l, m2 = -l

• Sectoral modes:

n1,l1,m1 & n2,l2,m2

• Rotational splitting of sectoral modes:

n,l,l n,l,l - n,l,-l





Rotational splitting of sectoral modesRotational splitting of sectoral modesP

inté

r B

., N

ew R

. & E

rdél

yi R

., A

&A

, 378

, 1, 2

001

Relative increase of n,l,l : 0.41%

&

GONG & MDI - observational error: 0.25%

The effect is ~detectable.

More realistic models are required.





Model improvementModel improvement

Dowdy et al. (1986)Solar Phys., 105, 35





Random field effects: Random field effects: magnetic magnetic carpetcarpet, granular motion, granular motion

mixed polarity network almost everywhere on the solar surface 95% of the photospheric flux closes low down in the magnetic carpet continuous emergence and disappearance of flux the magnetic concentrations follow the dominant flow patterns

Magnetic carpet Magnetic carpet

Full disc magnetogram by SOHO/MDI, 1998 June 13.





The origin of quiet Sun so far unexplained:

smaller loops from below the convection zone the product of local field generation due to small-scale shearing processes in the sub-surface layers

Mean absolute flux density ~2GaussReplacement time ~40 hs10 hsMean total flux / event1016 (obs. limit) - 1019 Mx

Ob

serv

ed f

eatu

res

Ob

serv

ed f

eatu

res






Demo: Random magnetic field & the surface-mode

z

xz=0 B (x, z), 2 (atmosphere)

field-free interior, 1

Basic assumptions2D Cartesian geometrytime-independent random fieldincompressible media no coherent background fieldno flow







Basic assumptionsatmospheric magnetic field:

B0=[B1(x, z), 0, B3(x, z)] in z0

Bi(x, z)=0 ensemble average

B0(x, z)=A0(x, z)

A0=[0, A, 0]= zexp( 2z)b(x)

b(x)=0 2 decay factor






Dimensionless dispersion relation (K<<1):

a) thick layer (H=500 km)

b) thin layer(H=100 km)

relative freq. diff. (%) (H=200 km)

2=10-4 kg/m3

=0.20=10 Gg =274 m/s2







Conclusions I.Conclusions I.

• Widths and frequencies are sensitive to atmospheric magnetic fields, to resonances with MHD waves and to sub-photospheric flows.

• In the observed range of l, widths and frequencies vary

-- with observed activity (magnetic field, canopy height, T)

-- approximately linearly with flow

• Variation in splitting of sectoral (m=+/-l) eigenmodes due to sub-surface flow changes





Possible challenges…Possible challenges…

So far “only”: 1D model

organised magnetic field random emerging flux?

turbulent granulation (see Murawski et al. 1996, 2001; Mole, Erdélyi & Kerekes. 2005)

meridional flows, differential rotation?

radiation/conduction?Dowdy et al. (1986)Solar Phys., 105, 35





Model improvementModel improvement





2D-simulation of a flux tube embedded in photospheric granulation (radiation-MHD) [Steiner et al. (1997) ApJ 495, 468]

Domain: 2400 km x 1400 km, Time: 18 min

LA: LA: oscillations & dynamicsoscillations & dynamics





Low atmosphere: Low atmosphere: role of underlying driverrole of underlying driver

LA: LA: oscillations & dynamicsoscillations & dynamics

Rut

ten,

R.,

AS

P-C

S, 1

84, 1

81, 1

999





Two types of observed oscillations can be distinguished

1. Propagating waves (Ofman et al. 1997, DeForest & Gurman 1998, Berghmans & Clette 1999, De Moortel et al. 2000, 2002a,b,c, Robbrecht et al. 2001, King et al. 2003, Marsh et al. 2003, Marsh & Walsh 2006)

2. Standing waves

SOHO/TRACE examples (mainly TR and higher)

i) Standing kink-mode oscillations by TRACE (Aschwanden et al. 1999, 2002, Nakariakov et al. 1999, Schrijver & Brown 2000, Schrijver et al. 2002, )

ii) Standing slow-mode oscillations by SOHO/SUMER (Kliem et al. 2002; Wang et al. 2002, 2003a,b)

Reviews by Aschwanden (2003), Wang (2004)

Atmospheric Atmospheric oscillationsoscillations





Source of coronal (longitudinal) oscillations

1. The TRACE oscillations in sunspot fans and associated loops seem related to the 3 min oscillations in the umbral chromosphere and TR seen with CDS (e.g., Brynildsen et al., 1999; Fludra, 1999).

2. However, the 5 minute oscillations in coronal loops anchored in plage are mysterious. Perhaps they are related to the photospheric 5 minute oscillations? If so, how they propagate from the photosphere to TR and corona is unclear.

Unresolved issues:

Lower atmospheric Lower atmospheric oscillationsoscillations





The Klein-Gordon wavesThe Klein-Gordon wavesStratified atmosphere (VALIIIC, g=const)





The Klein-Gordon wavesThe Klein-Gordon wavesStratified atmosphere (VALIIIC, g=const)

driver

p-modes

40°50°

0°





Angle of field lines to horizontal (e.g. AR 68512)

Tendency for somewhat more horizontal field lines at location of moss oscillations ?






Leakage of photospheric oscillations into the solar atmosphere:

driving chromospheric spicules (and coronal waves)





Dynamics:Dynamics: Solar spicules Solar spicules

Earth

Earth Pet

er &

von

der

Lüh

e (

199

9)

Imag

e cr

edit

: H. P

eter





Lower atmospheric moss Lower atmospheric moss oscillationsoscillationsBright reticulated layer of EUV emission consisting of 1 - 3 Mm bright elements with dark “holes” (jets): 1 MK upper transition region at footpoint of hot 3-5 MK loops above unipolar plage

(Berger et al., Fletcher & De Pontieu, De Pontieu et al., 1999, Martens et al, 2000)





Not steady waves but wave trains of finite duration. Oscillations usually last for 32±7 mins or 3 to 7 cycles (just like p-modes): rarely continue for more than 40 min.

Wav

elet

ana

lysi

s us

ing

Mor

let w

avel

et (

k=6)

Lower atmospheric Lower atmospheric moss oscillationmoss oscillation

Oscillations usually suddenly start and stop.





Some good correlations between171 Å and C IV 1550 Å: no delaytime within resolution (42 s).

If waves were driven from belowand passed through low TR first (C IV), and then to upper TR

(171),no delay is expected: TR is verythin (~ a few 100 km) and phasevelocity of slow magnetoacousticwaves is of order 100-200 km/s.






Sometimes photospheric vertical velocity (MDI Dopplergram)shows correlation with mossoscillations, with significant timedelay of order 100 s.






P-mode driven P-mode driven spiculesspicules (and coronal (and coronal oscillations)oscillations)






For location towards center of plage Leakage of evanescent oscillations,

(including granulation!) is dominated by ~200 s periods

Leaked photospheric signal shocks in low chromosphere because of density stratification

Rebound shocks form as a result of oscillating wake following passage of driven shocks

Chromospheric dynamics dominated by 200-250 s

Vertical Velocity for = 0°






P-mode driven motions form spicules For different location, at edge of plage,

where H shows highly inclined fibrils Substantially more leakage and

propagation than for = 0° Shocks merge, usually rebound shock

(weaker) is caught up by driven shock Longer periods (~300 s) dominate

chromospheric dynamics

Vertical Velocity for = 50°






Ver

tical

flu

x tu

be

Incl

ined

flu

x tu

be (

50°)

Chromospheric dynamics in inclined flux tubes are dominated by five minute periods because of significantly increased leakage of photospheric p-modes into the atmosphere






= 0°

Observed spicule occurrence isgiven by the negative of theTRACE 171Å intensity, since EUV brightness changes aredominated by spicule occurrence.

Varying spicule filling factors leadto mismatch in amplitude






= 50°

The match between predicted spicule occurrence and observed spicule occurrence is good, especially considering the limitations of the numerical model





P-mode driven (spicules) and P-mode driven (spicules) and coronal oscillationscoronal oscillations

Many observations of intensity oscillations inTRACE 171 Å loops, identified as propagating MAW in 1 MK plasma.

TRACE 171 Å

Fro

m D

e M

oort

el e

t al.

(200

2)





Moss/coronal oscillations similar?Moss/coronal oscillations similar?Moss Oscillations

P=200-600 s, avg= 349±60 s

P changes with time

I/I = 10 ±3 %

I/I not constant in time

Wave form not sinusoidal

Wave trains of finite duration

Often at periphery of plage

Limited to 1-2 arcseconds

Coronal Oscillations (Plage)

P=200-600 s, avg= 321±74 s

P changes with time

I/I = 4.1±1.5% (filling factor)

I/I not constant in time

Wave form not sinusoidal

?

Often inclined (~45°)

Limited to ~2-4 arcseconds

=





For photospheric location below loop of case 16b of De Moortel et al. (2002), with MDI driver from 12-Jun-2001 from 07:25-08:05 UT

P-mode driven shocks form spicules, then propagate into corona

Shocks in corona are weak, average Mach number is 1.2±0.1

Propagation speeds are of order 145 ±10 km/s (for 0.8 MK corona)

Ver

tical

Vel

ocity

for

=

40°

tim

e

height

P-mode driven (spicules) and P-mode driven (spicules) and coronal oscillationscoronal oscillations





P-m

ode

dri

ven

(sp

icu

les)

an

d

P-m

ode

dri

ven

(sp

icu

les)

an

d

coro

nal

osc

illa

tion

sco

ron

al o

scil

lati

ons

Wavelet power for observations

Intensity oscillations from observations

Wavelet power for simulations rebinned to emulate resolution of data (30 s, 2 arcsec)

Intensity oscillations from simulations(rebinned to emulate resolution of data)




• 2-D model solar atmosphere based on the VALIIIc temperature profile and the condition of hydrostatic equilibrium

• Applied vertical velocity perturbations to this atmosphere under hydrodynamic equations.

2D leakage of photospheric acoustic waves into non-magnetic atmosphere

Erdélyi & Malins (2006)





• 30 second period.

• This driver has a frequency well above the acoustic cut-off frequency in the lower solar atmosphere,

• Waves propagate well through the lower atmosphere and then through the transition region into the corona.

• Series of images at 25 second intervals showing velocity perturbations propagating into the corona, with a relatively low level of reflection at the transition region

High frequency driver





• 300 second driver

• Just above the acoustic cut-off in the lower atmosphere (and slightly below it at the temperature minimum)

• Experience strong reflection at the transition region standing wave formation in the vertical direction

• Drives the development of the horizontally propagating surface waves

Low frequency (5 min) driver





• Vertical velocity along the central vertical axis alongside the full 2-D velocity structure

• Clear (left) stratification driven amplification and clean propagation of the high frequency 30 second wave with height

• The generation (right) of a standing wave form with a node between the driver and transition region which are anti-nodes

Propagation versus cavity modes





Time-distance image of the propagation of vertical velocity signals across a line drawn at a height of 1.3Mm

Standing waves in the lower atmospheric cavity (5 mins)

The power spectrum shows clearly a fundamental mode at the driver frequency, but also a set of higher harmonics





P-mode driven spicules: 2-DP-mode driven spicules: 2-D





Moss oscillations






• Numerous examples of waves and oscillations by SOHO and TRACE in lower solar atmosphere structures

• Lower atmosphere has back-reaction of global oscillations

• (M)HD theory seems to be a satisfactory description

• Atmospheric seismology provides us information about: magnetic field, transport coefficients, fine structures, etc.

• Coupling of photospheric motions (p-modes, granular, etc.) to lower atmosphere (and above)

• Stratification has significant effect

SummarySummary





•Further challenges:

• What are the details of p mode coupling to LA (2/3D)?

• What are the exact consequencies of stratification??

• Atmospheric magnetic field effects on time-distance analysis?

• Role of global oscillations (coupling)?

• Role of Transition Region (spicules)?

• Effect of non-uniform temperature

• Effect of radiation (hot loops!); include proper chromosphere (leakage)

• Work out inverse problem for coronal structures (fine scale)

SummarySummary





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Solar Physics & upper-Atmosphere Research Group Robert Erdélyi University of SheffieldPPARC ASSSP...

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Transcript of Solar Physics & upper-Atmosphere Research Group Robert Erdélyi University of SheffieldPPARC ASSSP...