Solar Radiation Physical Modeling (SRPM)

1. Solar Radiation Physical Modeling (SRPM) J. FontenlaJune 30, 2005a

2. 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. • Synthesizingthe 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.

3. SRPM Scheme nlev, S, κ,,…(x,y,z) I(λ,μ,φ,t) T,ne,nh,U,...(x,y,z) I(λ,μ,φ,t)

5. 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

6. 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

7. 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).

8. 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.

9. 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

10. 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

11. V1.5 1-dimensional Models Line profiles Spectral irradiance Model C - CLV Contrast - CLV Physical model

12. V1.5 Computed and Observed Lines

13. V1.5 Computed and Observed IR Irradiance Spectra for Quiet Sun

14. Power Delivered by each Model at 1 AU (W/m2)

15. Spectral Irradiance Synthesis PSPT red band image Solar Features Mask on 2005/01/15 PSPT Ca II K image

16. Spectral Irradiance Synthesis

17. 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<4200 K • 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