Modeling the Solar EUV irradiance Margit Haberreiter PMOD/WRC, Davos, Switzerland IPC XI Sept 26 Oct 15, 2010.

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  • Slide 1
  • Modeling the Solar EUV irradiance Margit Haberreiter PMOD/WRC, Davos, Switzerland IPC XI Sept 26 Oct 15, 2010
  • Slide 2
  • Picard
  • Slide 3
  • Absorption of EUV in the Earths atmosphere Altitude-wavelength dependence of energy deposition from solar irradiance units of Log 10 (Wm -4 ) From Solomon and Qian 2005 Solar minimum conditions EUV varies by a factor of 2 and more!!
  • Slide 4
  • Peculiar Minimum 23/24 Claus Froehlich, PMOD TSI composite
  • Slide 5
  • Is there an EUV long-term trend? The SOHO/SEM measurements (36-34 nm) indicate a decrease in the EUV by15% Uncertainty ~ 6% Not explained by F10.7 or sunspot number What is the role of coronal holes? Solomon et al, 2010, GRL, 37, L16103 15% decrease
  • Slide 6
  • SDO/AIA image
  • Slide 7
  • EUV spectrum Wavelengths UV: 120 400 nm EUV: 10 120 nm Contribution from the Chromophere Transition region Corona
  • Slide 8
  • Solar Modeling (SolMod) Multi level atoms 373 ions, from H to Ni with ioncharge 25 ~14000 atomic levels ~170000 spectral lines Statistical equation is solved to get the level populations Chromosphere and transition region for ioncharge 2: full NLTE ( Fontenla et al., 2006; 2007; 2009) plus optically thin transition region lines Spherical symmetry Corona ioncharge >2 optically thin, i.e. collisions and spontaneous emission Line of sight integration accounts for opacity Spherical symmetry
  • Slide 9
  • Masks from Precision Solar Photometric Telescope Disk mask on 2005/9/12 obtained from PSPT data, Mauna Loa, Hawaii http://lasp.colorado.edu/pspt_access/ (R) Sunspot Penumbra (S) Sunspot Umbra (P) Faculae (H) Plage (F) Active network (D) Quiet network (white) (B) Intergranular Cells Determined by the contrast as a function of the position on the disk -Only possible with respect to a -normalized quiet Sun intensity Continuum, 607 nm (PICARD) Ca II 393.4, FWHM=0.27nm
  • Slide 10
  • Solar Chromosphere (Ca II) of quiet Sun Intergranular Cells Model B Quiet Network Model D Fontenla et al., 2009, ApJ s s Active Network Model F
  • Slide 11
  • Faculae Plage Active network Quiet network Intergranular Cells Fontenla et al., 2009, ApJ 707, 482-502
  • Slide 12
  • G-Band of CH molecular lines Fontenla et al., 2009, ApJ 707, 482-502
  • Slide 13
  • Violet CN Band Fontenla et al., 2009, ApJ 707, 482-502
  • Slide 14
  • Modeling the EUV e.g. Fe XV 284
  • Slide 15
  • Coronal models Coronal Models are based on temperature and densities given by Doschek (1997), ApJ, 476, 903 Singh et al., 1982, J. Astrophys. 3, 249 Cranmer et al, 2007, ApJS 171, 520
  • Slide 16
  • Spherical Symmetry Allows the calculation of intensities at and beyond the limb (e.g. Haberreiter et al. 2008) Account for corona over 2 x area of solar disk Adopted from Mihalas, 1978
  • Slide 17
  • Spherical symmetry
  • Slide 18
  • Optical depth Fe XV 17.1 nm: Disk center: max = 0.06 Limb: (r=1.02): max = 0.63 (~900,000K) Fe XV 19.5 nm: Disk center: max = 0.06 Limb: (r=1.02): max = 0.34 (~1,100,000K) Fe XV 28.4 nm: Disk center: max = 0.39 Limb: (r=1.02): max = 0.88 (~2,000,000K)
  • Slide 19
  • Spectrum from Corona, TR and Chromosphere
  • Slide 20
  • EUV spectrum Haberreiter, 2010, submitted to Solar Physics EVE rocket calibration flight: Chamberlin et al., 2009, GRL
  • Slide 21
  • EUV spectrum Haberreiter, 2010, submitted to Solar Physics EVE rocket calibration flight: Chamberlin et al., 2009, GRL
  • Slide 22
  • SOHO/EIT images He II 30.4 nm Fe XV 28.4 nm Fe IX 17.1 nm Fe XII 19.5 nm
  • Slide 23
  • EIT passbands Fe IX 17.1 nm Fe XII 19.5 nm Fe XV 28.4 nm He II 30.4 nm
  • Slide 24
  • EIT wavelengths SRPM EVE
  • Slide 25
  • Variability of solar activity features EIT 17.1nm 07/01/2005 EIT 19.5 nm 10/01/2002 EIT 28.4 nm 10/10/2003 EIT 30.4 nm 07/10/2006 coronal holes quiet Sun quiet coronal network active coronal network - hot loop super hot loop
  • Slide 26
  • EIT image analysis Radial dependence for outer corona Thresholds based on intenstiy histogram of the EIT images Maximum value of histogram varies with solar cycle (in particular for 284 ) Does the coronal hole/quiet Sun intensity changes with solar cycle identification of coroanl features not trivial
  • Slide 27
  • Does the quiet Sun intensity change Barra et al, 2009 already performed the analysis for 3 components.
  • Slide 28
  • Outlook: Shape of coronal holes influences strength of solar wind streams Gibson et al, 2009
  • Slide 29
  • Conclusions Good agreement between the synthetic spectra and the observed EVE quiet Sun spectrum Our calculations indicate that opacity effects have to be taken into account for some prominent lines, i.e. the EIT lines Challenge for feature identification: potential change of coronal hole and quiet Sun intensity Spectral reconstruction over a full solar cycle still to come....
  • Slide 30
  • Further plans Valicate the identification scheme of coronal holes, active regions Account for temporal variability changing distribution of features, e.g. coronal holes, active regions LYRA measurements very important for validation/comparison 1 TB/day from SDO/AIA and SDO/EVE....
  • Slide 31
  • References Cranmer et al, 2007, Self-consistent Coronal Heating and Solar Wind Acceleration from Anisotropic Magnetohydrodynamic Turbulence, ApJS 171, 520 Doschek (1997), Emission Mesaures and Electron Densities for the solar transition region, ApJ, 476, 903. Fontenla et al., 2009, Semi-empirical Models of the Solar AtmosphereIII. Set of NLTE Models for FUV/EUV Irradiance Computation, ApJ, accepted for publication Klimchuk (2006), On Solving the Coronal Heating Problem, Solar Physics 234, 41-77 Singh et al., 1982, Eclipse Observations of Coronal Emission Lines, J. Astrophys. 3, 249

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