Spectral Solar Irradiance Sources
Space Measurements
(UARS, SUSIM, SORCE, SOLSPEC, etc)
Ground Measurements
(Labs & Neckel, etc)
Stellar Theoretical
Models
Semi-Empirical
Solar Models
|-------- Solar Radiation Physical Modeling (SRPM) ---------|
Seeks not to replace these, but rather to integrate them
in a consistent physical model that matches the observations.
1
SRPM Flow Scheme
Carbon Ionization and Mass FLow
......... Static case (w/dif)
_____ Upflow case (w/dif)
IonizationFraction
0.8
0.6
0.4
0.2
0.0
4
10
2
3
4
5
6
7
8
9
5
10
Temperature (K)
2
3
4
5
6
7
8
9
6
10
Intermediate
Parameters
nlev,nion,…(x,y,z,t)
Physical Models
& Processes
T,ne,nh,U,...(x,y,z,t)
Emitted
Spectrum
I(λ,µ,φ,t)
Observed
Spectrum
I(λ,µ,φ,t)
2
New Reference Spectrum (Quiet Sun)
7500
1 cm^-1 bin
10 cm^-1 bin
7000
Brightness Temperature (K)
6500
6000
5500
5000
4500
4000
3500
0
5000
1 . 10
4
4
1.5 . 10
2 . 10
4
4
2.5 . 10
3 . 10
4
4
3.5 . 10
4 . 10
4
4
4.5 . 10
5 . 10
4
Wavenumber (cm^-1)
• Option in MODTRAN at 0.01 to 10 cm-1 bins
• On AER web site at full resolution
3
Irradiance & Features on the Sun
Delta Brightness Temperature (K)
0
1
2
3
4
500
1000
1500
2000
2500
3000
Wavelength (nm)
Daily solar disk mask
Brightness temperature daily variation
Synotic mask of the whole Sun
Lyα flux
around the Sun
4
Next Steps
• Improve visible & IR continuum:
– Tune the model photospheres to fox the 3% excess
– Keep updating the atomic data with NIST V3.0
– Extend non-LTE to more species (e.g. Mg, Fe )
• Extend SRPM to the UV:
– Develop better model chromospheres
– Non-LTE for all species
• Extend SRPM to the EUV and XUV:
– Develop model corona and transition region
– Consider more ionization stages
5
References
•
•
•
•
•
•
•
Fontenla, J., & Harder, J., “Physical Models of Spectral Irradiance Variations”,
MmSAI, 76, 826-833 (2005)
Harder, J., Fontenla, J., White, O., Rottman, G., & Woods, T., “Solar Spectral
Irradiance Variability Comparisons of the SORCE SIM Instrument with
Monitors of Solar Acitivity and Spectral Synthesis”, MmSAI, 76, 735-742
(2005)
Fontenla, J.M., Avrett, E., Thuillier, G., & Harder, J., “Radiation-Effective Solar
Atmosphere Models. I. Quiet and Active-Sun Photosphere”, ApJ, 639, 441-458
(2005)
Fontenla, J.M., Harder, J., Rottman, G., Woods, T.N., Lawrence, D.M., &
Davis, S., "The Signature of Solar Activity in the Infrared Spectral Irradiance",
ApJ, 605, L85-L88 (2004)
Fontenla, J.M., Avrett, E.H., & Loeser, R., "The Energy Balance in the Solar
Transition Region. IV. Hydrogen and Helium Mass Flows with Diffusion", ApJ,
572, 636-662 (2002)
White, O.R., Fontenla, J.M., & Fox, P., "Extreme Solar Cycle Variability in
Strong Lines Between 200 and 400 nm", Sp. Sci. Rev., 94, 67-74 (2000)
Fontenla, J.M., White, O.R., Fox, P.A., Avrett, E.H., & Kurucz, R.L.,
"Calculation of Solar Irradiances I: Synthesis of the Solar Spectrum", ApJ, 518,
480-499 (1999)
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