Solar Radiation Physical Modeling (SRPM) J. Fontenla June 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. 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.

3 SRPM Scheme Emitted Spectrum Observed Spectrum Physical Models Intermediate Parameters I(λ,μ,φ,t) T,ne,nh,U,...(x,y,z) n lev, S, κ, ,…(x,y,z)

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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 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

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 SunspotsActive Regions NetworkCoronal 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.

9 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

10 Models of Representative Features C – quiet Sun cell center E, F – Regular and active network H, P – Plage and Faculae R, S – Sunspot penumbra and umbra Quiet Sun Active Sun

11 V1.5 1-dimensional Models Model C - CLVContrast - CLV Line profilesSpectral irradiance 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/m 2 ) Model0.4-5μ μ μ0.6-1μ1-5μ C E F H P R S

15 Spectral Irradiance Synthesis PSPT red band image PSPT Ca II K image Solar Features Mask on 2005/01/15 CEFHPRS e-26.44e-33.45e-39.03e-4

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 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