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WG2 Topical Sessions

WG2 Topical Sessions. Origin and Evolution of the Solar Wind (Wed AM) Magnetic Data Input into Global Models (Thu PM). WG1/2 Session: Origin and Evolution of the Solar Wind. Invited Talks: Phil Isenberg (UNH): “Kinetic Mechanisms for Generation of the Fast Solar Wind”

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WG2 Topical Sessions

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  1. WG2 Topical Sessions Origin and Evolution of the Solar Wind (Wed AM) Magnetic Data Input into Global Models (Thu PM)

  2. WG1/2 Session: Origin and Evolution of the Solar Wind Invited Talks: • Phil Isenberg (UNH): “Kinetic Mechanisms for Generation of the Fast Solar Wind” • Uri Feldman (NRL): “The Source of the Solar Wind in Quiet and Coronal Hole Regions” • Scott McIntosh (SWRI): “Magneto–Convection Driven Spicules: Fast Solar Wind Origins and the Potential Impact on CME Propagation” • Tayeb Aiouaz (HAO): “The Supergranular Magnetic Network, its Expansion and Effects through the Solar Atmosphere” Contributed Talk: • Jason Gilbert (UM): “Applications of the Diffusive Equilibrium Mapping Technique”

  3. Phil Isenberg (UNH): “Kinetic Mechanisms for Generation of the Fast Solar Wind” Talk summary: • Fast SW is produced by strong perpendicular ion heating (at 2–6 RS). • Specific heating mechanisms must be modeled kinetically to determine their feasibility. • Detailed heating mechanism is necessary to correctly model the microphysics in global simulations of solar wind and CME behavior. • Recent work has indicated the possibility of a parallel turbulent cascade to resonant frequencies. • Some possible kinetic mechanisms for ion heating include: • Cyclotron resonant interaction of ions with oblique waves. • Proton heating by electrostatic waves – generated from electron beams and processed by ion cyclotron resonant scattering. • Preferential perpendicular heating of heavy ions by 2nd order Fermi acceleration. • Alpha particles are a major concern and will be a stringent test to any theoretical model! • Future UVCS observations will be important to constrain the models. • Solar Probe may also provide important in situ observations near the Sun to test the various models.

  4. Uri Feldman (NRL): “The Source of the Solar Wind in Quiet and Coronal Hole Regions” Talk summary: • SW composition and photospheric compositions are not always the same. • FIP Bias (coronal abundance / photospheric abundance) can be used to distinguish between fast and slow SW: • FIP Bias ~4 (Mg, Si, Fe) in slow SW; same for quiet Sun. • FIP Bias ~1 in fast SW. • Elemental settling in solar corona • Fe is depleted in height in the corona relative to Mg and Si. • Recent theories by Fisk and colleagues may explain this behavior. • SW originates at ~106 K (solar upper atmosphere): • Slow SW originates from the quiet Sun corona close to solar surface. • Fast SW is associated with coronal hole regions.

  5. Uri Feldman (NRL): “The Source of the Solar Wind in Quiet and Coronal Hole Regions” Sun at 106 K Sun at 105 K

  6. Scott McIntosh (SWRI): “Magneto–Convection Driven Spicules: Fast Solar Wind Origins and the Potential Impact on CME Propagation” From Wang (1998) & Priest et al. (2002)

  7. Scott McIntosh (SWRI): “Magneto–Convection Driven Spicules: Fast Solar Wind Origins and the Potential Impact on CME Propagation” Talk Summary: • SUMER results have provoked a simple analysis of long-duration (rare) SOHO/EIT 304Å data to test this hypothesis. • Study showed that observed spectroscopic, imaging, and wave signatures are all consistent with the ubiquitous driving of solar plasma by magneto-convection-driven reconnection. • The relentless emergence, advection, and eventual destruction of magnetic flux on supergranular scales is responsible for mass loading, heating and initial acceleration of plasma at the base of solar corona. • Local magnetic field conditions control the rate and scale of the energy release. • Global magnetic field topology controls how the energy is released and utilized by plasma: plasma heating versus bulk motions. • SW initiation and atmosphere plasma heating can be performed with one single process, where spicules are the basic building blocks of this process. • This model can explain a number of solar phenomena named differently because they are observed in different wavelengths.

  8. SUMER Ne VIII Intensity/Doppler Comparison Quiet Sun: Bulk blue-shift (4% of pixels) located at network “vertices.” No apparent correlation of blue-shift with rest of network cell pattern. Coronal Hole: LOTS more blue-shifted regions (22% of pixels). Considerable drop (40%) in emission. Still no apparent correlation of blue-shift with network cell pattern, but appear mostly on interior-side of cell boundaries.

  9. Tayeb Aiouaz (HAO): “The Supergranular Magnetic Network, its Expansion and Effects through the Solar Atmosphere” Talk Summary: • Unipolar vs. mixed polarities: • At low heights network loops affect expansion. • At higher heights cases converge. • BG vs. no BG case: • Reduced amount of network flux. • Internetwork field does reach the corona. • Reconnection at network boundaries. • Network vs. single-funnel expansion: • “Single-funnel” like network is obsolete. • There is variety of structures (open & closed) in network. • Work in progress: 3D MHD simulations of QS.

  10. Summary & Plans for Next SHINE • Modelers need additional observations to evaluate the significance of the existing mechanisms for the generation of fast SW (e.g., by turbulent heating, cyclotron resonant heating, etc.)? • Some observations, however, are unaccounted for in the models, or remain unexplained. • How do we fill the existing gaps to make further progress on this topic? • Another big questions is: • Is SHINE community interested in having the same topical session at the next meeting? • If so, what should we focus on? • Origin of fast solar wind again? • Discuss the messy slow solar wind? • Ideas are always welcome!

  11. WG2 Session: Magnetic Data Input into Global Models Invited Talks: • Luca Bertello (UCLA): “Mt. Wilson Magnetic Field Observations: Methods and Calibration” • Leif Svalgaard (ETK): “How Good/Bad Are the Inner Boundary Conditions for Heliospheric Solar Wind Modeling?” • Carl Henney (NSO): “SOLIS-VSM Magnetic Synoptic Maps” • Yang Liu (Stanford): “Synoptic Maps of Magnetic Field from MDI and WSO Magnetograms” • Igor Sokolov (UM): “Semi-Empirical MHD Modeling of the Solar Corona and Solar Wind” Contributed Slides: • K.D. Leka (CoRA): “With Two Hands on IVM Data”

  12. Luca Bertello (UCLA): “Mt. Wilson Magnetic Field Observations: Methods and Calibration” Talk summary: • Calibration of observables, center-to-limb correction, and saturation factor correction. • Observations in Fe I l5233Å provide reference magnetic field measurements unaffected by saturation effects. • Magnetic fields are compared point by point to get a saturation factor. • MWO data are used to fix the “zero point” in the calibration of MDI data. • There is no simple scaling factor, but a mask that needs to be applied. • Proper orientation of MDI m-gram is important.

  13. Leif Svalgaard (ETK): “How Good/Bad Are the Inner Boundary Conditions for Heliospheric Solar Wind Modeling?” Talk summary: • No matter how sophisticated a physics-based SW model is, it is no better than the quality of the magnetic map used. • WSO and SOLIS data show that the observed B field behaves as a simple projection of a radial field. • So are MWO data before the hardware upgrade in 1982. • To get the true magnetic flux, MWO data (collected after 1982) should be multiplied by:

  14. Old cycle New cycle 5 July 2006 (also observed 4th) 15 June 2006 (also observed 16th) 23 July 2006 (also observed 22nd) Carl Henney (NSO): “SOLIS-VSM Magnetic Synoptic Maps” Talk summary: • Transition from KPVT to SOLIS. • KPVT renamed to KP SOLIS Tower. • KPVT & SOLIS-VSM have similar characteristics. • Beta-testers are needed to input data into their models! • SOLIS-VSM provides vector B-field measurements on the whole Sun. • SOLIS-VSM has detected several new cycle bipolar magnetic regions starting in June 2006! • VSN status summary: • Transition from development phase to operations phase. • Operating 7 day/week. • Some VSM data processed in near real-time. • Started VSM requested observing.

  15. Yang Liu (Stanford): “Synoptic Maps of Magnetic Field from MDI and WSO Magnetograms” Talk summary: • Individual MDI magnetograms need: • Offset correction; and • Rescaling. • Remapping of individual MDI magnetograms yields a synoptic map. • Correction for differential rotation is needed. • Polar field correction is needed (7 techniques exist, but 2 work best). • Modelers have began using MDI data in their models. • How about WSO data? • High accuracy. • Excellent determination of the magnetic “zero level.” • Consistent 30-year time-series of low-resolution, large-scale B-field measurement without any significant instrumentation modification. • Community support needed to continue WSO operation!!!

  16. WSO Data Applications From Arge (2005) PFSS

  17. Igor Sokolov (UM): “Semi-Empirical MHD Modeling of the Solar Corona and Solar Wind” Talk summary: • Global MHD model is driven by a full-disk MDI magnetogram. • Using the Bernoulli integral, the semi-empirical values of the SW speed at 1 AU are related to the boundary condition for the “turbulent energy density” at the solar surface. • SW speed computed from WSA model. • To bridge from this boundary condition to the SW model in the solar corona, the varied polytropic index is used. • Modeled SW parameters at 1AU in good overall agreement with observations. • Modeled IMF is 4 times weaker though. • Scaling factor for MDI magnetogram needs to be applied.

  18. Summary & Plans for Next SHINE • We have learned about the variety of existing magnetic data that are available to the community (MWO, SOLIS, MDI, IVM, WSO, etc.) • We have learned how grapes are collected from the vineyard, processed, fermented, bottled, and delivered to the store to satisfy our fine taste. • We also learned about the quality control. • Now modelers are asked to do “wine tasting” and report on the variations in taste. • Observers are asked to supply cheese and crackers. • This means: • Pick a Carrington Rotation for which magnetic data exists from various observatories, and are of good quality. • Other data inputs are welcome (e.g., density maps). • Use these data to drive your simulations. • Report on the structure of the SW and IMF at 1AU, or at other locations for which in situ data exist. • Results of such investigation are very important. • Will modelers take the challenge? • Will observers provide cheese and crackers?

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