Solar Radiation Physical Modeling SRPM

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Solar Radiation Physical Modeling (SRPM)

• J. FontenlaJune 30, 2005a

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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.

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SRPM Scheme
nlev, S, ?,?,(x,y,z)
I(?,µ,f,t)
T,ne,nh,U,...(x,y,z)
I(?,µ,f,t)
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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

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New Developments In SRPM Version 2

• Constantly improving atomic and molecular data
• Constantly improving physical models
• Detailed non-LTE for all species
• Abundance variation and non-local ionization due
  to diffusion and flows
• 3-dimensional non-LTE radiative transfer
  extension of Net Radiative Brackett Operator
• MHD simulation based on standard Adaptive Mesh
  Refinement

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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
Prominences
Sunspots
Active Regions
Network
Coronal Loops

• 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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Models try to describe a rangeof spectral
characteristics
Histograms of brightness distribution in Ca II K3
and Ly alpha images of quiet Sun and active region
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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
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V1.5 1-dimensional Models
Line profiles
Spectral irradiance
Model C - CLV
Contrast - CLV
Physical model
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V1.5 Computed and Observed Lines
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V1.5 Computed and Observed IR Irradiance Spectra
for Quiet Sun
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Power Delivered by each Model at 1 AU (W/m2)
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Spectral Irradiance Synthesis
PSPT red band image
Solar Features Mask on 2005/01/15
PSPT Ca II K image
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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 Tmin
• Account for UV continua from SOHO-SUMER showing
  high Tmin
• Account for molecular lines (CN, CH, CO) showing
  low Tmin
• 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