Transcript Solar Radiation Physical Modeling (SRPM)
Solar Radiation Physical Modeling (SRPM)
J. Fontenla June 30, 2005a
SRPM Objectives
•
Diagnosis
of the physical conditions through the solar atmosphere, and in particular the radiative losses that must be explained by mechanical heating.
•
Evaluating
the role of proposed physical processes in defining the solar atmosphere structure and spectrum at all spatial and temporal scales.
•
Synthesizing
the solar irradiance spectrum and its variations in order to understand the physical processes behind the observations and improve the models.
•
Computing
the effects of until now unobserved conditions on the Sun by applying physically plausible hypothesis and knowledge of other stars.
2
SRPM Scheme
n lev , S, κ, , …(x,y,z) Intermediate Parameters Emitted Spectrum I( λ,μ,φ,t) T,ne,nh,U,...(x,y,z) Physical Models Observed Spectrum I( λ,μ,φ,t) 3
Basic Equations Mass Conservation:
t
U
0
Momentum Conservation:
U
t
p
UU
Γ
F
P Energy Conservation:
t
p
U
F
H
q
Q
Particle Conservation (or Statistical Equilibrium):
n
il
t
n
il
V
il
U
R
il
n
I n
Radiation Transport:
I n
R n
n
' '
I n
' '
d
'
d
'
MHD Version of Maxwell’s Equations:
B
0
E
; 1
c
B
t
B
4
c
;
J
i
J
σ
i
E
V
i
U
B
c
4
Technology
• Modular structure (currently 5 services) • Use of relational SQL database storage: – Atomic and molecular data – Physical models and simulations – Intermediate data (e.g., level populations) • Object Oriented C++ (currently ~300 classes) • I/O interfaces to NETCDF and HDF5 • Parallel computing + 3rd party libraries 5
New Developments In SRPM Version 2
1. Constantly improving atomic and molecular data 2. Constantly improving physical models 3. Detailed non-LTE for all species 4. Abundance variation and non-local ionization due to diffusion and flows 5. 3-dimensional non-LTE radiative transfer extension of Net Radiative Brackett Operator 6. MHD simulation based on standard Adaptive Mesh Refinement 6
Heritage
• Extensive work by many people on observations, radiative transfer, non-LTE, and modeling.
• Net Radiative Brackett Operator (NRBO) multilevel non LTE method developed by JF for modeling solar prominences in the 70s.
• Energy balance and particle diffusion developed by JF for the transition-region in the 80s.
• Fontenla, Avrett, and Loeser (FAL) series of papers from the early 90s, the last paper (FAL4).
(They used JF earlier methods and PANDORA.) • Solar irradiance modeling C++ code from the late 90s (RISE).
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Magnetic Features on the Sun
Sunspots Active Regions Network Coronal Loops Prominences •Medium spatial resolution structures produced by the magnetic fields are observed on the Sun.
•Effects of magnetic fields on the energy-transport and magnetic heating at various layers are not well known.
•Physical processes responsible for the observed structure and spectra from these features are a major topic of SRPM research.
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0.02
Models try to describe a range of spectral characteristics
Histograms of brightness distribution in Ca II K3 and Ly alpha images of quiet Sun and active region 0.02
0.015
0.015
0.01
0.01
0.005
0.005
0 0.8
1 Active Region Quiet Region 1.2
1.4
1.6
Ca II K3 Intensity (arbitrary units) 1.8
2 2.2
0 0 1 2 Active Region Quiet Region 3 4 5 6 7 8 Ly alpha Intensity (arbitrary units) 9 10 11 12 9
Models of Representative Features
Quiet Sun C – quiet Sun cell center E, F – Regular and active network Active Sun H, P – Plage and Faculae R, S – Sunspot penumbra and umbra 10
V1.5 1-dimensional Models
Line profiles Spectral irradiance Model C - CLV Contrast - CLV Physical model 11
V1.5 Computed and Observed Lines
4 6 3 10 6 2 10 6 1 10 6 0 5888 5889 5890 Model C Observed Kitt Peak 5891 5892 5893 5894 5895 Wavelength (A) 5896 5897 5898 5899 5900 5901 3 10 6 2.5
10 6 2 10 6 1.5
10 6 1 10 6 5 10 5 0 6560 6561 6562 Model C Observed Kitt Peak 6563 6564 6565 Wavelength (A) 6566 6567 6568 6569 12 6570
V1.5 Computed and Observed IR Irradiance Spectra for Quiet Sun
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E F H P R S
Power Delivered by each Model at 1 AU (W/m
2
)
Model 0.4-5 μ 0.4-0.5
μ 0.5-0.6μ 0.6-1 μ 1-5 μ C 1297 186 196 485 430 1293 1294 12944 1341 269 1079 185 185 185 199 7 131 195 195 195 204 13 153 483 483 483 504 83 407 430 430 4302 434 167 388 14
Spectral Irradiance Synthesis
PSPT red band image Solar Features Mask on 2005/01/15 PSPT Ca II K image C 0.789
E 0.146
F 0.041
H 1.45e-2 P 6.44e-3 R 3.45e-3 S 9.03e-4 15
Spectral Irradiance Synthesis
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Critical Next Steps
• Adjust photospheric models and abundances – Low first-ionization-potential (FIP) contribute to ne and photospheric opacity – High FIP are needed for upper layers • Re-think lower chromosphere – Account for radio data showing T min <4200 K – Account for UV continua from SOHO-SUMER showing high T min – Account for molecular lines (CN, CH, CO) showing low T min • Re-think upper chromosphere with current abundances and observations • Re-compute transition region with updated abundances, atomic data, diffusion and flows, and energy-balance • MHD, full-NLTE, 3D simulations of chromospheric variations 17