Hinode 5
Exploring the Active Sun

Invited Talk Abstracts

O. Steiner: Small-scale structure in the quiet solar atmosphere.
Abstract Author(s): Steiner, O. (1)
Institution(s): (1) Kiepenheuer-Institut für Sonnenphysik
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

With ever increasing spatial resolution due to larger telescope apertures, more powerful adaptive optics, refined image-restoration techniques, and observations from the space and the stratosphere, more and more substructure of the quiet Sun atmosphere becomes visible. At the same time, three-dimensional MHD-simulations have become more numerous and refined in spatial resolution, and a greater variety of initial and boundary conditions are considered. Magnetoconvection simulations are now also used for carrying out numerical experiments targeted at specific processes like the conversion of wave modes or seismic wave propagation.
A recent focus of interest concerns vortical flows. Signatures of variousvortical flows have been discovered by feature tracking and spectroscopicobservations in the photosphere and the chromosphere. These discoveriesare complemented with analyses of numerical simulations, which lead to new insights and predictions.
With respect to the magnetic field, observations with the Solar OpticalTelescope of the Hinode space observatory have revealed parts of thehitherto so called `hidden' magnetic flux and made it accessible toZeeman polarimetry. It was found that the magnetic field of the quiet Sun atmosphere is not homogeneously turbulent but that it shows structure in the form of tiny loops and flux concentrations and that it points predominantly in the horizontal direction. The origin of this field remains enigmatic. Is it all generated by the surface dynamo? To what extent does it consist of recycled field of decaying active regions? The propagation of magnetoacoustic waves in such a magnetically complex structured atmosphere atmosphere has just started to become subject ofintense research. It seems that conversion from slow, predominantly acoustic waves to fast, predominantly magnetic waves near the surface ofplasama-beta unity is responsible for the measured reduction of wavetravel-time in magnetic areas and for the so called magnetic shadow.

F. Hill: Recent progress in observing the emergence of magnetic fields
Abstract Author(s): Hill, F. (1)
Institution(s): (1) National Solar Observatory
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

Helioseismology allows us to probe below the visible photosphere, holding out the hope that we can forecast surface magnetic field behavior. If possible, such forecasts would be valuable for space weather and could help to mitigate the adverse effects of geomagnetic storms on society and technology. In this talk I will present four approaches that could lead to useful predictions. The first study uses global helioseismology to detect the large-scale zonal and meridional flows below the surface that appear to be intimately linked with the long-term behavior of the solar cycle. The second study uses local helioseismology to observe the temporal evolution of vorticity below active regions and associated flare production. The third study uses acoustic holography to detect active regions that emerge on the farside of the sun, which can be compared to STEREO observations. The final line of research uses local helioseismology to detect changes in vertical velocity and p-mode travel times associated with active regions before they emerge on the solar surface. The current status and prospects for these methods will be presented.

R. Ishikawa: Properties of transient horizontal magnetic fields; their implication to the origin of quiet-Sun magnetism
Abstract Author(s): Ishikawa, R. (1)
Institution(s): (1) National Astronomical Observatory of Japan
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

The origin and evolution of the quiet-Sun magnetic fields are not well understood. Hinode/SOT with high spatial resolution and high polarization sensitivity reveals that there are a lot of transient horizontal magnetic fields in the internetwork region and provides us with new insight to better understand the quiet-Sun magnetism. Exploiting the SOT data with careful treatment of photon noise, we reveal the enigmatic properties of these horizontal magnetic fields such as lifetime, size, position in terms of granular structure, occurrence rate, three-dimensional structure and so on. Comparing the properties of these horizontal fields between the quiet Sun and plage region, we conclude that they are generated by the local dynamo process due to the granular convective motion. Furthermore, we broaden our scope to clarify the origin and the properties of the internetwork magnetic fields, both vertical and horizontal, in a unified way, and reveal the clear positional association between the vertical and horizontal magnetic fields. We also investigate the relationship of these magnetic fields with the meso- and super-granulations. Based on the observational results, we conjecture that internetwork magnetic fields are formed by the emergence of small-scale horizontal magnetic fields with bipolar footpoints, and the vertical magnetic fields of the footpoints are advected by the supergranular flow, and eventually form the network fields.

R. Casini: The Magnetic Diagnostics of the Quiet-Sun Chromosphere
Abstract Author(s): Casini, R (1)
Institution(s): (1) HAO
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

This decade will offer tremendous new opportunities to deepenour understanding of the Sun's magnetism. Both ground-basedand space-borne instruments currently being developed (ATST, EST, Solar-C) are specifically designed to deliver spectro-polarimetric data of unprecedented quality. The spatial and temporal resolutions offered by these instruments will be adequate to attain critical observations that can realistically constrain the sophisticated modelings of the time-varying solar atmosphere, which are also being developed at this time. In particular, the magnetic diagnostics of the quiet-sun chromosphererepresents the next big challenge, in order to bridge our picture ofthe Sun's magnetism from the deep layers of the photosphere into thelower solar corona. In this talk we focus our attention on theidentification of target spectral lines in the solar chromosphere, the magnetic regimes that they would help unveil, and the diagnostictools needed for their interpretation.

S. Kamio: Quantitative study of microflares
Abstract Author(s): Kamio, S. (1)
Institution(s): (1) MPS
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

Microflares are small transient brightenings in the corona, which are often observed in X-ray and EUV. Although the scale is different, they share common characteristics with ordinary flares in active regions. One of the advantage of studying these small-scale events is that they are frequently observed and show simple structure. First, we review the properties of microflares observed by X-ray and EUV telescopes. We also present the temporal evolution of flaring bright points captured by EIS and XRT. The lightcurves at different temperatures can be interpreted as a cooling of small flare loops. Coronal jets and dimmings associated with the bright points reflects the magnetic field structures in the surrounding.

R. Kitai: Ellerman bomb as a manifestation of chromospheric fine scale activity
Abstract Author(s): Kitai, R. (1)
Institution(s): (1) Kwasan and Hida Observatories, Kyoto University
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

Since their findings in 1917, Ellerman bombs have been studied as one of the small scale chromospheric activities in active regions. As their wide H-alpha emission profiles resemble those of flare kernels, these bombs have been believed to be driven by similar mechanism as solare flares. However, the atmospheric structure and dynamic state of these fine scale structure have not observationally been cleared due to the atmospheric degradation in ground-based observations. Recent instrumental developments in ground-based and space observations, such as SOT/Hinode, have considerably advanced our understanding of the magnetohydrodynamic states in Ellerman bombs. With spectroscopic and monochromatic imaging observations, we now have a view that Ellerman bombs are driven by intermittent magnetic reconnection in upper photosphere or in lower chromosphere. A review of our study and present understanding of Ellerman bombs will be given in this paper.

M. Carlsson: Modeling the solar chromosphere
Abstract Author(s): Carlsson, M, (1), Hansteen, V. H. (1), Gudiksen, B. V. (1)
Institution(s): (1) Institute of Theoretical Astrophysics, University of Oslo
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

The enigmatic chromosphere is the transition between the solar surface and the eruptive outer solar atmosphere. The chromosphere harbors and constrains the mass and energy loading processes that define the heating of the corona, the acceleration and the composition of the solar wind, and the energetics and triggering of solar outbursts. In spite of its importance, the chromosphere is arguably the least understood domain of solar physics. All at once it represents the transition from optically thick to thin radiation escape, from gas-pressure to magnetic-pressure domination, from neutral to ionised state, from MHD to plasma physics, and from near-equilibrium ("LTE") to non-equilibrium conditions. Its physics is so complex that traditional methods relying on analytic analysis or simplified mechanisms do not work. It has become abundantly clear that only ab-initio numerical simulation, built on the same fundamental non-linear physics equations that the Sun obeys, and explicitly accompanied by sufficiently deep subsequent analysis of what occurs within each simulation, can deliver physical insight to understand how the chromosphere works.We here report on recent results from such numerical simulations with the Bifrost code. The 3D radiation MHD equations are solved for a computational region extending from the convection zone into the corona for various initial magnetic field configurations. We include conduction along magnetic field lines, optically thin radiative losses in the corona, non-LTE radiative losses in the chromosphere, heating from incoming radiation from the corona and full radiative transfer including scattering in the photosphere. Effects of the hydrogen ionization balance being out of equilibrium are also discussed.

A. Winebarger: The Magnetically Closed Corona: A Review of the Coronal Loops Workshop
Abstract Author(s): Winebarger, A.R. (1)
Institution(s): (1) NASA/MSFC
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

Coronal loops are the magnetically closed structures that direct the flow of hot plasma in the solar atmosphere. The observational properties of loops, including their lifetime, evolution, and temperature indicate that there are different classes of loops and that the different classes have different heating magnitudes and timescales. The classes of loops can be related to the loop length and magnetic field strength, with shorter loops associated with stronger magnetic field being hotter and steadier than longer loops associated with weaker field. There has been significant effort to model the observational properties of loops with both 1-D and 3-D hydrodynamic models and 3-D magneto-hydrodynamic models, however no model has been able to well reproduce all the observations. In this talk, I will review the latest observations, simulations, and theoretical models of coronal loops presented at the Fifth Coronal Loops workshop held in Palma Mallorca, Spain in June 2011.

M. Zhang: Coronal mass ejections as a result of magnetic helicity accumulation
Abstract Author(s): Zhang, M. (1)
Institution(s): (1) National Astronomical Observatory of China
Session: Instabilities, Transients and Eruptions

Coronal mass ejections (CMEs) are a major form of solar activities. A CME takes away a body of plasma from the low corona into the solar wind and disturbs the near-Earth space if the CME is earth-directed. Here we summarize our understandings and reasoning that lead us to conclude that CMEs are the unavoidable products of magnetic helicity accumulation in the corona. Our study puts the formation of magnetic flux rope and CME eruption as the natural results of solar coronal evolution. Our study also gives insights into the observed associations of CMEs with the magnetic features at their solar surface origins.

L. Fletcher: Solar flares: Energy release, transport and radiation
Abstract Author(s): Fletcher, L. (1)
Institution(s): (1) School of Physics and Astronomy, University of Glasgow
Session: Instabilities, Transients and Eruptions

Magnetic free energy in a flaring active region is built up over timescales of many hours to days, and stored on large spatial scales. It is released on much shorter timescales during a rapid restructuring of the field and converted primarily into the kinetic energy of non-thermal particles and chromospheric radiation in the flare impulsive phase. The observationally determined properties of solar flares such as overall energy budget and distribution in space, time and energy of flare radiation, have improved enormously over the last cycle. This has enabled precision diagnostics of flare plasmas and nonthermal particles, informing and driving new theoretical modeling. The theoretical challenges in understanding this process are considerable, involving MHD and kinetic processes operating in an environment that is far from equilibrium, but progress is being made. New observations have also provided some challenges to long-standing models of flare energy release and transport. This talk will overview recent solar flare observational and theoretical developments, and highlight some important questions for the future.

S. Tsuneta: Solar-C mission with Solar-D on the horizon
Abstract Author(s): Tsuneta, S. (1), JAXA Solar-C WG (2)
Institution(s): (1) NAOJ, (2) ISAS/JAXA
Session: Future Needs - Observational, Theoretical and Computational

The purpose of the Solar-C mission is to reveal the magnetic and plasma structures of the whole solar atmosphere from the photosphere throughout the corona, and understand the mechanisms of chromospheric and coronal heating/dynamism and acceleration of the solar wind as a system. It is our understanding that small scale processes related to waves, shocks and reconnection play an important role in the global phenomena of the Sun and the heliosphere.
Our approach to implement this science goal is through high resolution imaging spectroscopy for the entire solar atmosphere without gaps in temperature coverage where plasma might escape detection because of lack of instrumental sensitivity. Hinode clearly showed that the combination of high spatial resolution and spectroscopy (including spectro-polarimetry) is critically important both in the photosphere and in the corona. The strawman instruments for the Solar-C satellite include a larger visible light telescope, which obtains magnetic and velocity maps for the chromosphere and the photosphere, a high-throughput UV imaging spectrometer covering the chromosphere through the corona, and an X-ray/EUV imaging spectrometer. The three instruments will seamlessly cover the photosphere through the corona. Such a wide spectroscopic coverage with high resolution is not available with any mission so far launched. The Solar-C instruments are characterized by high spatial and spectral resolution, high throughput, wide temperature coverage, and high time resolution, better than available from any existing missions.
An Interim Report of the mission is available now. The document describes the current state of development for the Solar-C mission concept. As the program progresses we will continue to solicit new ideas and improvements to the mission definitions, especially from our colleagues outside Japan. We recognize that Solar-C will only be realized with the enthusiastic participation of NASA and ESA in all phases of its development from the conceptual design of the instruments, through their construction, and in the science operation of the Solar-C mission.
Since plan A is as important as Solar-C for our future and it will require a long time to be ready for one mission, we desire to continue activities for plan A as a Solar-D program. This includes preparation of a mission called DESTINY (PI: Dr. Y. Kawakatsu, kawakatsu.yasuhiro@jaxa.jp, Department of Space Systems and Astronautics, ISAS/JAXA) for the ISAS small satellite announcement of opportunity to be expected in 2012: it is essentially a technology demonstration satellite for a large ion engine, a ultra-light weight solar paddle, autonomous onboard operation, and advanced orbit design and control, all to be used in Solar-D program. The plan is to launch DESTINY to L2 in 2016-2017 time frame. In parallel with the Solar-C development, ISAS/JAXA may allocate some resources to run the basic development program for the Solar-D mission.

B. De Pontieu: The Interface Region Imaging Spectrograph (IRIS) NASA SMEX
Abstract Author(s): De Pontieu, B. (1), Title, A. (1), Lemen, J. (1), Schrijver, C.J. (1), Tarbell, T.D. (1), Wuelser, J.-P. (1), Golub, L. (2), Kankelborg, C. (3), Carlsson, M. (4), Hansteen, V. (4)
Institution(s): (1) Lockheed Martin Solar & Astrophysics Laboratory, Palo Alto, CA, (2), Harvard Smithsonian Center for Astrophysics, Cambridge, MA, (3), Montana State University, Bozeman, MT, (4) Institute of Theoretical Astrophysics, University of Oslo, Norway
Session: Future Needs - Observational, Theoretical and Computational

The solar chromosphere and transition region (TR) form a highly structured and dynamic interface region between the photosphere and the corona. This region not only acts as the conduit of all mass and energy feeding into the corona and solar wind, it also requires an order of magnitude more energy to heat than the corona. Nevertheless, the chromosphere remains poorly understood, because of the complexity of the required observational and analytical tools: the interface region is highly complex with transitions from optically thick to optically thin radiation, from pressure to magnetic field domination, and large density and temperature contrasts on small spatial scales. The Interface Region Imaging Spectrograph (IRIS) was selected for a NASA SMEX mission in 2009 and is scheduled to launch in December 2012. IRIS addresses critical questions: (1) Which types of non-thermal energy dominate in the chromosphere and beyond? (2) How does the chromosphere regulate mass and energy supply to the corona and heliosphere? (3) How do magnetic flux and matter rise through the lower atmosphere, and what role does flux emergence play in flares and mass ejections? These questions are addressed with a high-resolution near and far UV imaging spectrometer sensitive to emission from plasma at temperatures between 5,000 K and 10 MK. IRIS has a field-of-view of 120 arcsec, a spatial resolution of 0.4 arcsec, and velocity resolution of 0.5 km/s. The IRIS investigation includes a strong numerical modeling component based on advanced radiative MHD codes to facilitate interpretation of observations. We will highlight some of the issues that IRIS is expected to help resolve, describe the IRIS instrumentation and numerical modeling, and present the status of the IRIS observatory development.

P. Testa: Solar and stellar X-ray activity and the solar-stellar connection
Abstract Author(s): Testa, P. (1)
Institution(s): (1) Harvard-Smithsonian Center for Astrophysics
Session: Solar-Stellar Connections

Magnetic activity similar to that of the Sun is observed in solar-like stars. The corona of our Sun is, to date, the only stellar corona that can be spatially resolved and studied at a high level of detail, and it is therefore often used as paradigm for the interpretation of the X-ray activity of other solar-like stars.Stellar astrophysics, on the other hand, allows us to place the Sun ina more general stellar context, and, by providing access to a wide range of stellar parameters (e.g., mass, age, rotation period, multiplicity), it allows us to investigate the characteristics of dynamo mechanisms in very different regimes, and the consequent differences in the properties of coronal emission. I will discuss recent advances and outstanding questions concerning our understanding of the Sun as a star and how far the solar analogycan be extended to other stars, with particular focus on the X-ray emission from the Sun and other stars, activity cycles, solar and stellar flares, and chemical fractionation in stellar outer atmospheres.

Contributed Talk Abstracts

P. Antolin: A rainy day on the Sun
Abstract Author(s): Antolin, P. (1), Rouppe van der Voort, L. (1), Verwichte, E. (1)
Institution(s): (1) Institute of Theoretical Astrophysics, University of Oslo
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

Observed in cool chromospheric lines such as Hα or Ca II H, coronal rain corresponds to cool and dense plasma falling from coronal heights. Considered rather as a peculiar sporadic phenomenon of active regions, it has not received much attention since its discovery more than 40 years ago. Yet, it has been shown recently that a close relationship exists between this phenomenon and the coronal heating mechanism. Indeed, numerical simulations have shown that this phenomenon is most likely due to a loss of thermal equilibrium ensuing from a heating mechanism acting mostly towards the footpoints of loops. In this work we show the important role it can play in the understanding of the coronal magnetic field. We start by presenting Hinode/SOT observations in the Ca II H line where in-phase transverse oscillations of multiple strand- like structures in a loop are put in evidence by coronal rain. Estimates of the coronal magnetic field and the energy flux of the waves are given through helioseismology techniques. We then present the first multi-wavelength high resolution spectroscopic observations of coronal rain, performed by the CRISP instrument at the Swedish Solar Telescope. The condensations composing coronal rain are observed to elongate and separate as they fall down to sizes as small as the diffraction limit resolution of the SST. At this resolution, coronal rain is observed to literally invade the entire field of view, implying that coronal rain may be a common phenomenon, and thus that thermal non-equilibrium is important for coronal heating. A large statistical set is obtained in which temperatures and dynamics of the condensations are derived. Simultaneous observations obtained with SDO provides a complementary picture of the ambient corona, thus allowing further insight into the local and global physical conditions.

H. He: Quantitative analyses of the 3-D coronal magnetic fields associated with the X3.4 flare event of the solar active region NOAA 10930
Abstract Author(s): He, Han (1), Wang, Huaning (1), Yan, Yihua (1)
Institution(s): (1) National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China.
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

The X3.4 flare event of the solar active region NOAA 10930 happened on 13 December 2006, which was captured by many space and ground telescopes. Based on the nonlinear force-free field (NLFFF) model and the photospheric vector magnetograms obtained by the Spectro-Polarimete (SP) of the Solar Optical Telescope (SOT) aboard the Hinode satellite, the 3-D coronal magnetic field distributions of NOAA 10930 before and after the X3.4 flare eruption were calculated by using the upward boundary integration computational scheme of the direct boundary integral equation (DBIE) NLFFF extrapolation method (He and Wang, 2008; He et al., 2011). To analyze the time series evolution of the 3-D coronal magnetic structures, six magnetograms within the time interval of 25 hours were selected for the NLFFF modeling, three for pre-flare and three for post-flare. Projection effect in the photospheric vector magnetograms was corrected prior to the extrapolation calculations, and the corrected magnetograms were co-aligned and cropped to a uniform 300" x 160" field of view (FOV). The pixel scale of the calculated 3-D coronal magnetic fields is 1"/pixel. The quantitative analyses of the 3-D coronal magnetic fields associated with the X3.4 flare event show that: (1) There exists a magnetic connectivity in the lower layers of the corona just before the flare eruption, the direction of the connectivity is parallel to the direction of the polarity inversion line (PIL) in the photospheric magnetograms. This connectivity is totally disconnected and separated after the flare eruption. (2) The total magnetic energy conserved in the modeling volume of the corona decreases remarkably after the flare eruption, the order of magnitude of the magnetic energy loss is $10^{32}$ erg. By comparing the 3-D magnetic energy density distributions before and after the flare eruption, it is found that the region of magnetic energy density decrease is located in the relatively higher layers of the corona, and the projection site of the energy density decrease region on the solar surface coincides with the location of the flare eruption.

T. Shimizu: Precursor of sunspot penumbral formation discovered with Hinode SOT observations
Abstract Author(s): Shimizu, T.(1), Ichimoto, K.(2), Suematsu, Y.(3)
Institution(s): (1) ISAS/JAXA, Japan, (2) Kyoto University, Japan, (3) NAOJ, Japan
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

Formation of sunspot penumbra and the period before its moment is poorly understood due to lack of high resolution, continuous observations on the early phase of sunspot formation. Particularly, the moments of penumbra formation have been reported only in a few papers (Leka & Skumanich 1998, Yang et al. 2003, Schlichenmaier et al. 2010), because the formation of a penumbra is a rapid phenomenon.
We succeeded to continuously monitor the development of an emerging flux region in 30-31 December, 2009, with Hinode SOT magnetogram and Ca II H observations. The observations cover from the start of emergence to the formation of a large well-developed sunspot pair, including the moment of the penumbral formation. We discovered a remarkable dark ring-like structure (3-5 arcsec in radial direction) surrounding the spot in Ca II H, which appeared soon after the pore formation and existed until the appearance of penumbra at the photosphere. Magnetic signal is fairly weak in the ring. The network flux pre-existed before the flux emergence (same polarity with the sunspot) were swept out to the outer boundary of the ring, and they kept 3-5 arcsec distance from the pore (umbra), although the umbra moved outward slowly as the flux emerged. Finally, the penumbra was formed to fill in the ring-like region.
What is this Ca II H ring before the penumbral formation? It is completely different from the moat, in which moving magnetic features move outward in radial direction. The ring can be well seen in chromospheric Ca II H images, whereas normal granules are only visible in photospheric G-band images. We infer that a canopy structure is already formed around the umbra in the chromospheric level, much before the formation of the penumbra at the photospheric level. The magnetic pressure by the canopy structure may act to keep the 3-5 arcsec distance from the pre-existing network elements. Therefore, the remarkable Ca II H ring structure is a chromospheric precursor of penumbral formation and, with this "precursory chromospheric penumbra," we can predict the size and area where the penumbra will be formed at the photosphere.

S. Tiwari: 3D Magnetic, Thermal and Velocity Structure of a Sunspot as Observed from Hinode (SOT/SP)
Abstract Author(s): Tiwari, S. K. (1), Lagg, A. (1), Solanki, S. K. (1)
Institution(s): (1) Max-Planck Institute for Solar System Research, Katlenburg-Lindau, 37191, Germany
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

Three dimensional (3D) structure of sunspots has been extensively studied for the last two decades by using advanced inversion codes on polarimetric observations. Reliable height dependent inversions of polarimetric observations are essential to understand the three-dimensional magnetic, thermal and velocity structure of sunspots. We perform such an inversion of a complete sunspot to retrieve magnetic, thermal and velocity parameters in three dimensions. The spectro-polarimetric observations of the sunspot, NOAA AR 10933, was taken from SOT/SP onboard the Hinode spacecraft. The sunspot was observed on the solar disk center during a normal scan mode of SOT/SP. We used the inversion code SPINOR to obtain the height stratification of magnetic field vector, temperature and velocity throughout the umbra and penumbra. The inversion is optimized to obtain the best solutions for the umbra (including umbral dots, light bridges and dark background), the penumbra (including dark and bright fibrils) and quiet Sun. Here, we present some of these results obtained at different optical depths. The excellent Hinode/SOT/SP data allow both the 3D large-scale and the 3D fine structure to be simultaneously determined. The spatially averaged magnetic field strength increases with depth in umbra and inner penumbra, and decreases in outer penumbra. Field inclination is almost constant with depth in umbra and inner penumbra and increases as one goes towards outer penumbra. Temperature shows its expected behavior: it increases with depth but the slope is significantly flatter in the umbra, in good agreement with umbral model atmospheres in the literature. Upflows in inner penumbra and downflows in outer penumbra are seen with increasing depth. The azimuth shows a global twist that increases outwards from center of spot. In addition, we also obtain the fine scale structure in umbra and penumbra as a function of depth.

A. Ortiz: Observations of supersonic downflows in pores
Abstract Author(s): A. Ortiz (1), L. Bellot Rubio (2) & L. Rouppe van der Voort (1)
Institution(s): (1) Institute of Theoretical Astrophysics, University of Oslo, Norway, (2) Instituto de Astrofisica de Andalucia-CSIC, Spain
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

We have investigated the velocity field of pores at a resolution of 0.14”. Our analysis is based on full Stokes spectropolarimetric measurements taken with the CRISP instrument at the Swedish 1m Solar Telescope. We find localized patches of supersonic downflows in some parts of the pore edges, with velocities reaching up to 7-8 km/s. We have determined the velocities and magnetic properties of these regions from a two-component Stokes inversion of the photospheric Fe I lines at 630 nm. The observations are compatible with inclined magnetic fields containing the strong downflows above a normal, field-free granulation pattern. In addition we performed full Stokes spectropolarimetric measurements in the Ca II 854.2 nm line, with a cadence of 1 minute. These observations reveal the presence of very strong chromospheric downflows at the position of the photospheric supersonic flows. Some of them show brightenings in Ca 854.2 nm and Ca II H line core images.

A. Savcheva: The Pre-eruption Behavior of an XRT Sigmoid - NLFFF models and an MHD simulation.
Abstract Author(s): Savcheva, A. (1), Pariat, E. (1), DeLuca, E. (1), van Ballegooijen, A. (1), Aulanier, G. (1)
Institution(s): (1) Boston University
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

Sigmoidal regions are known to be great storage places for magnetic free energy, which they can later release in a flare or CME event. The field of a sigmoid is characterized by highly sheared and twisted magnetic fields held down by a potential arcade. We present topological analysis of the 3D magnetic field structure of a sigmoid observed with Hinode/XRT in Feb 2007. The field is derived from a Non-Linear Force Free Filed (NLFFF) model, based on the flux rope insertion method. We compare the results of the NLFFF model with the dynamical MHD simulation of Aulanier at al. (2010). The comparison is based on quasi-separatrix layer maps and current distributions. We point out the similarities in the field line structure. We discuss the implications of the observed flux cancellation and conditions for the torus instability that are observed both in the NLFFF model and the MHD simulation. We show the presence of a hyperbolic flux tube at the flare location. All of the above point to a single coherent picture about the pre-eruption behavior of this sigmoid, which is also reproduced in the MHD simulation.

S. Toriumi: Numerical Simulation and the SOT Magnetogram Analysis on the Small-scale Magnetic Elements on the Solar Emerging Flux Region
Abstract Author(s): (!) Toriumi, S., (1) Yokoyama, T.
Institution(s): (1) The University of Tokyo
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

It is thought that solar active regions are formed by the risings of flux tubes from the convection zone. In this study, we aim to figure out the flux emergence from the interior to the atmosphere through the surface, by conducting a numerical simulation and a Hinode/SOT observation. First, we performed a three-dimensional magnetohydrodynamic (MHD) simulation on the flux tube emergence from -20,000 km of the convective layer. The initial tube has a field strength of 2.0x104 G, a total flux of 6.3x1020 Mx, and a twist of 5.0x10-4 km-1. As a result, the rising tube expands sideways beneath the surface to create a flat structure. As time goes on, the subphotospheric field rises again into the corona due to the Parker mode of the magnetic buoyancy instability. We newly found that the photopsheric magnetogram showed multiple separation events as well as shearing motions, which reflects the Parker instability of the subphotospheric field. This situation agrees well with Strous & Zwaan (1999)'s model: each emergence event occurs in a vertical sheet, while the sheets are aligned in a parallel fashion. We also confirmed that the wavelength perpendicular to the separations (the distance between vertical sheets) is approximately a few times the tube's initial radius. Secondly, we analyzed an SOT/FG magnetogram of an active region (AR 10926), and observed that the small-scale magnetic elements among the major sunspots make alignments with a certain orientation. The wavelength perpendicular to the alignments (the distance between the sheets) was found to be ~3,000 km. Comparing with the numerical results, we speculate that this active region observed by the SOT is created by the rising flux tube with a radius of the order of 1,000 km in the deeper convection zone.

D. Shiota: Yearly Variation of Magnetic Field in the Polar Regions Observed with Hinode
Abstract Author(s): Shiota, D. (1), Tsuneta, S.(2), Orozco Suarez, D.(2), Shimojo, M.(3), Sako, N. (4)
Institution(s): (1) RIKEN, Wako, Saitama, Japan, (2) National Astronomical Observatory of Japan, Mitaka, Tokyo, Japan, (3) Nobeyama Solar Radio Observatory, NAOJ, Nobeyama, Nagano, Japan (4) The Graduate University for Advanced Studies, Mitaka, Tokyo, Japan
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

The magnetic polarity of the global magnetic field of the Sun reversesduring the solar cycle maximum. The understanding of the magneticfield evolution in the polar region is important for the solar dynamoprocess, because the magnetic flux may be transported into the solarinterior due to the meridional circulation of the solar convectionzone and then become the seed of the magnetic flux in following solarcycles in some solar dynamo models. To make clear the process, wemonitored the polar region (HOP 81) since September 2008. We haveinvestigated the properties of the photospheric magnetic fields of the polarregions using data taken with the spectropolarimeterof the Solar Optical Telescope aboard the Hinode satellite.The magnetic field vector was inferred from the observed Stokes profilesusing a Milne-Eddington inversion code. We resolve the 180-degreeambiguity of the transverse magnetic fields assuming thatthe magnetic field is either vertical or horizontal. Then, we identified all the strong magnetic flux concentrations observed within the field-of-view and investigated the variationof their magnetic properties with solar cycle. The main results will besummarized in this contribution. Among them,we found that there exist a strong variation with the solar cycle of thedistribution of the vertical magnetic flux elements in the Northpolar region. The variation is smoother in the South polar region.

K. Otsuji: Statistical Study on the Nature of Solar Flux Emergence
Abstract Author(s): Otsuji, K. (1), Kitai, R. (2), Ichimoto, K. (2), Shibata, K (2)
Institution(s): (1) National Astronomical Observatory of Japan, (2) Kwasan and Hida Observatory, Kyoto University
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

We studied 101 flux emergence events ranging from small ephemeral regions to large emerging flux regions which were observed with Hinode Solar Optical Telescope filtergram. We investigated how the total magnetic flux of the emergence event controls the nature of emergence. To determine the modes of emergences, horizontal velocity fields of global motion of the magnetic patches in the flux emerging sites were measured by the local correlation tracking. Between two main polarities of the large emerging flux regions with more than around 2x1019 Mx, there were the converging flows of anti-polarity magnetic patches. On the other hand, small ephemeral regions showed no converging flow but simple diverging pattern. When we looked into the detailed features in the emerging sites, irrespective of the total flux and the spatial size, all the emergence events were observed to consist of single or multiple elementary emergence unit(s). The typical size of unitary emergence is 4 Mm and consistent with the simulation results.From the statistical study of the flux emergence events, the maximum spatial distance between two main polarities, the magnetic flux growth rate and the mean separation speed were found to follow the power-law functions of the total magnetic flux with the indices of 0.27, 0.57, and -0.16, respectively. From the discussion on the observed power-law relations, we got a physical view of solar flux emergence that emerging magnetic fields float and evolve balancing to the surrounding turbulent atmosphere.

A. Munoz-Jaramillo: Polar Faculae: A Proxy for the Evolution of the Solar Polar Field During the Last 100 Years
Abstract Author(s): Munoz-Jaramillo, A. (1), DeLuca, E. (1)
Institution(s): (1) Harvard-Smithsonian Center for Astrophysics
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

Apart from its mean 11-year periodicity, the solar cycle presents long-term modulations of its amplitude and period which remain poorly understood. However, grasping the mechanisms behind these changes becomes more important as more efforts are made to disentangle the role of solar variability on climate and predict solar cycle properties.Unfortunately, aside from sunspot properties, there are very few data-sets spanning the timescales necessary to understand long-term solar variability. Here we show how can we alleviate this deficiency by consolidating polar faculae data from four observational campaigns (1906-1964, Sheeley 1966; 1960-1975, Sheeley 1976; 1975-1990, Sheeley 1991; 1985-2007, Sheeley 2008) and combine it with polar field measurements taken by the Wilcox Solar Observatory (1977-2011) to estimate the polar field evolution since 1906. These data nicely complement polar field measurements using Hinode (Ito et al. 2010) and can be expanded by using SOHO/MDI and SDO/HMI magnetograms.This research is supported by NASA Living With a Star Grant NNX08AW53G to Montana State University/Harvard-Smithsonian Center for Astrophysics and the NASA Living With a Star Jack Eddy Postdoctoral Fellowship Program, administered by the UCAR Visiting Scientist Programs.

J. Martinez-Sykora: Comparison Of Observations And Advanced Numerical Simulations Of Type II Spicules
Abstract Author(s): Martinez-Sykora, J. (1,2) De Pontieu, B. (1) Hansteen, V. H. (2) Moreno-Insertis, F. (3) Pereira, T. M. D. (1)
Institution(s): (1) Lockheed Martin Solar & Astrophysics Lab, Palo Alto, CA, USA, (2) Institute of theoretical astrohpysics, University of Oslo, Norway, (3) Instituto Astrofisico de canarias, La Laguna, Tenerife, Spain
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

We have performed realistic 3D radiation MHD simulations of the solar atmosphere. These simulations show jet-like features that are similar to the type II spicules discovered with Hinode's Solar Optical Telescope. These type II spicules have been associated with so-called rapid blueshifted events (RBE's) on the solar disk, and with significant blueward asymmetries in transition region and coronal lines at the footpoints of coronal loops (discovered with Hinode's EIS). These observational results and their ubiquity suggest they may play a significant role in providing the corona with hot plasma. We will present a detailed comparison of the properties of the simulated jets, with those of type II spicules (observed with Hinode) and RBE's (with ground-based instruments). We will present analysis of a wide variety of synthetic emission lines from the simulations covering temperatures from 10,000K to several million K, and compare their intensities, velocities, line widths and asymmetry with those of the observed phenomena. We will also show how the formation mechanism of these jetscomplicates efforts to establish a firm link between observations of magnetic fields and of chromospheric flows, and suggests that magnetic field observations at chromospheric heights may be crucial to establish from observations how these jets are formed.

D. Williams: Non-thermal broadening of EUV lines in magnetic flux emergence
Abstract Author(s): Williams, D.R. (1), Lee, E. (2), Lapenta, G. (2)
Institution(s): (1) Mullard Space Science Laboratory, University College London, Holmury St Mary, Surrey, RH5 6NT, UK, (2) Centrum voor Plasma-Astrofysica, Katholieke Universiteit Leuven, Belgium
Session: Magnetic structuring of the Sun from beneath the photosphere through the corona

Understanding both large- and small-scale dynamics of the solar corona is a prime driver behind the use of spectrometers on modern solar missions; but an important mystery remains unsolved in the understanding of spectroscopic data. In coronal plasmas, if the ion kinetic energy distribution can be described by a Maxwellian (at least along the line of sight), then this Maxwellian will produce a Gaussian distribution of particle velocities about some mean, leading to the commonly-fit profile. This Gaussian has a standard deviation that is predictable from the characteristic temperature, but almost all EUV coronal emission lines exhibit a larger width than this prediction, even when instrumental effects are taken into account. This is even more true in active regions than in the quiet Sun. It is difficult to know how the population of electrons behaves, since we only directly measure emission from ions, but it cannot be ruled out that the former plays a key role in the energy transport.

In an effort to understand the source of this line broadening, this work builds on initial findings that show growth of a high-energy tail of non-thermal velocities in the core of an active region, following a case of flux emergence. We investigate a further case of flux emergence from its early phase, and examine in detail the variation of this tail over several days of observation. We do this at multiple coronal temperatures and multiple sites within the active region, and find that there is appreciable variation in behaviour with both of these variables, that the shape of the non-thermal distribution is time-dependent, and that this shape is not easily predicted from other observables.

H. Tian: Two components of the coronal emission revealed by both spectroscopic and imaging observations
Abstract Author(s): Tian, H. (1), McIntosh, S. W. (1), De Pontieu, B. (1), Martinez-Sykora, J. (1), Sechler, M. (1), Wang, X. (1)
Institution(s): (1) High Altitude Observatory, National Center for Atmospheric Research
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

Recent spectroscopic observations have revealed the ubiquitous presence of blueward asymmetries of emission lines formed in the solar corona and transition region. These asymmetries are most prominent in loop footpoint regions, where a clear correlation of the asymmetry with the Doppler shift and line width determined from the single Gaussian fit is found. Such asymmetries suggest at least two emission components: a primary component accounting for the background emission and a secondary component associated with high-speed upflows. The latter has been proposed to play a vital role in the coronal heating process and there is no agreement on its properties. Here we slightly modify the initially developed technique of Red-Blue (RB) asymmetry analysis and apply it to both artificial spectra and spectra observed by the EUV Imaging Spectrometer onboard Hinode, and demonstrate that the secondary component usually contributes a few percent of the total emission, has a velocity ranging from 50 to 150 km s−1 and a Gaussian width comparable to that of the primary one in loop footpoint regions. The results of the RB asymmetry analysis are then used to guide a double Gaussian fit and we find that the obtained properties of the secondary component are generally consistent with those obtained from the RB asymmetry analysis. Through a comparison of the location, relative intensity, and velocity distribution of the blueward secondary component with the properties of the upward propagating disturbances revealed in simultaneous images from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory, we find a clear association of the secondary component with the propagating disturbances.

I. De Moortel: 3D Simulations of Wave Heating; where is all the energy?
Abstract Author(s): De Moortel, I. (1), Pascoe, D. J. (1)
Institution(s): (1) University of St Andrews
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

Recently, observations have shown that transverse oscillations are present in a multitude of coronal structures. It is generally assumed these oscillations are driven by (sub)surface foot-point motions. Using fully 3D MHD simulations, we show that these footpoint perturbations generate propagating kink modes which couple very everciently into Alfven waves. We investigate the energy budget contained within such oscillations in various dirent ways. We compare the footpoint energy with the energy budget at higher altitudes and show the distribution of the temperature resulting from the phasemixing of the Alfven waves. Using an ensemble of randomly distributed loops, driven by footpoint motions with random periods and amplitudes, we compare the absolute energy in the numerical domain with the energy that is 'visible' when integrating along the line of sight. We show that this 'LOS energy' is only a small fraction of the actual energy provided by the footpoint motions.

H. Mason: Cambridge Active Region Studies
Abstract Author(s): Mason, H. (1), Tripathi, D. (1), Klimchuk, J. (1), Del Zanna, G. (1), O'Dwyer, B. (1)
Institution(s): (1) University of Cambridge
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

The Hinode EUV Imaging Spectrometer (EIS) provides us with an opportunity to determine the plasma properties of solar active regions, and hence to attempt to distinguish between different coronal heating mechanisms. Recent work by the Cambridge (UK!) group of moss and hot core loops favours the impulsive (nanoflare) models.

T. Pereira: Using Hinode/SOT to uncover the dynamics of spicules
Abstract Author(s): Tiago M. D. Pereira (1), Bart De Pontieu (2), Mats Carlsson (3)
Institution(s): (1) NASA Ames Research Center; (2) Lockheed-Martin Solar & Astrophysics Lab; (3) Institute of Theoretical Astrophysics, University of Oslo
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

Understanding the dynamic solar chromosphere is of paramount importance in solar physics. Spicules are an important feature of the chromosphere, connecting the photosphere to the corona, potentially mediating the transfer of energy and mass. While it is generally accepted that there is more than one type of spicule, their quick motions, small spatial scales, and short lifetimes have prevented a systematic study of their properties over different solar regions. In the present work we undertake such a study, using the unique view of Hinode/SOT's Ca H filtergrams to detect spicules at the solar limb. Looking at different magnetic field configurations (quiet Sun, coronal holes, active regions), we discuss how the properties of the spicules change, how the two spicule populations (type I and type II) are connected, and how spicules are related to other chromospheric phenomena such as dynamic fibrils.

M. Guarrasi: MHD modeling of the heating of coronal loops
Abstract Author(s): Guarrasi, M. (1)(2), Reale, F. (1)(2), Orlando, S. (2), Mignone, A. (3)
Institution(s): (1) Universita degli Studi Di Palermo, Palermo, Italy, (2) INAF Osservatorio Astronomico di Palermo, Palermo, Italy
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

It has been recognized that magnetic flux tubes must expand rapidly in the region between the high beta photosphere and the low beta corona. This loop expansion needs to be accounted in modeling the moss intensities. Anyway, this cross section variation with loop position is not included in a large part of numerical models of coronal loops. In all these models the emission measure from the transition region and from the lower corona is much higher than what is observed. We present a 2D MHD loop model that naturally accounts for loop expansion through the variation of the magnetic field from the chromosphere to the corona. Our model consistently includes plasma fluid and thermodynamic behavior, in particular the plasma thermal conduction along the magnetic field lines and the radiative losses. We present some 2D MHD simulations of the ignition and evolution of a loop under different kinds of heating and analyze the plasma structure and feedback on the loop expansion.

K. Olluri: Non-equlibrium ionization in 3D numerical models
Abstract Author(s): Olluri, K. (1), Gudiksen, B. (1), Hansteen, V. (1)
Institution(s): (1) Institute of Theoretical Astrophysics, University of Oslo
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

The chromosphere and transition region have for the last 20 years been shown to be quite dynamic layers of the solar atmosphere with timescales shorter then the equilibration timescales of many of the ions observed in the solar atmosphere. The fast change in the properties of the atmosphere and the long ionization- and recombination times, result in ions being unable to reach equilibration with their surroundings. A number of the spectral lines we observe can therefore no longer be expected to give us any information about the local density or temperature, since ions can now be found far from their equilibrium temperatures. Numerical modeling is essential to interpret the observations. Modeling of the ionization balance has earlier been done in 1D simulations, but due to many free parameters inherent in such modeling, led to incomplete results. We have studied the ionization balance closer by implementing the rate equations in the 3D numerical code Bifrost. We will present our implementation and a study of the carbon IV 1549 Å line and the iron XII 195 Å line, which is an important line in the Hinode EIS wavelength band, focusing on differences between statistical equilibrium and non-equilibrium ionization results.

L. Culhane: Active region plasma outflows and their contribution to the solar wind
Abstract Author(s): Culhane, J. L. (1), van Driel-Gesztelyi, L. (1, 2, 3), Baker, D. (1) Rouillard, A. (4), Démoulin, P. (2), Mandrini, C.H. (5), Opitz, A. (6)
Institution(s): (1) MSSL/UCL, UK. (2) Paris Observatory, LESIA, France. (3) Konkoly Observatory, Hungary. (4) NRL, Washington, USA. (5) IAFE, University of Buenos Aires, Argentina. (6) CNRS, CESR, Toulouse, France.
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

When active regions are adjacent to coronal holes, interchange reconnection often leads to significant evolution of coronal hole boundaries. Reconnection can also take place in regions with a large magnetic connectivity gradient – Quasi-Separatrix Layers (QSLs). Outcomes may include variability of active region-associated hot plasma outflows and the modulation of the solar wind flows on open field lines. In the interval 2 18 January, 2008, we studied a pair of opposite-polarity coronal holes at mid-latitudes on the Sun with two active regions located between them. The active regions are separated by the Heliospheric Plasma Sheet (HPS). We used the Hinode EIS instrument to locate active region-related outflows and measure their velocities. SOHO/EIT imaging was used to follow the evolution of the coronal hole boundaries. STEREO imaging and in-situ data were also employed as were ACE in-situ observations, to assess the resulting impacts on the interplanetary solar wind structure and composition. Results from the work so far will be reported.

R. Kano: What determines coronal-loop temperature?
Abstract Author(s): Kano, R. (1), Tsuneta, S. (1), Ueda, K. (2)
Institution(s): (1) National Astronomical Observatory of Japan, Tokyo, Japan, (2) University of Tokyo, Tokyo, Japan
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

Magnetic loops in active regions have widespread distribution in temperature as indicated by distinct difference between SDO/AIA and XRT images. One way to tackle the coronal heating problem is to reveal why and how such loop-dependent difference in temperature occurs. Cool loops emanate from both sunspot regions (SS regions; i.e. umbrae, penumbrae and pores) and non-SS regions, while most of hot loops from non-SS regions. We identify the photospheric footpoints of the hot and cool loops in the SOT/SP images, and obtain the magnetic fields and the horizontal velocities. We confirm that the footpoints of the cool loops in SS regions have higher magnetic filling factors than the footpoints of the hot loops (Katsukawa and Tsuneta, 2005). However, we find no difference between the hot and cool loops in any photospheric property including the magnetic filling factors in the non-SS regions. There is little correlation between the position-dependent photospheric magnetic properties obtained with SOT/SP and the associated coronal temperatures. Instead, we discover a clear anti-correlation between the loop temperatures and the loop length estimated with potential field approximation: If the loop length is larger, lower the temperature. The loop length (i.e. volume for unit cross-section) is somehow related to the temperature, suggesting the uniform heat input from the footpoints.

J. Okamoto: Propagating waves along spicules
Abstract Author(s): Okamoto, T. J. (1), De Pontieu, B. (2)
Institution(s): (1) NAOJ, (2) LMSAL
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

Propagating Alfvenic waves in the corona are thought to play an important role in coronal heating and acceleration of solar wind. Recent observations have shown the existence of such waves along chromospheric spicules, jets of plasma that protrude into the corona. Here we investigated the detailed and statistical properties of Alfvenic waves along spicules in the polar coronal hole using very high cadence observations of the Solar Optical Telescope onboard Hinode. We developed a technique for the automated detection of spicules and high-frequency waves in a time series of images. We detected 89 spicules, and obtained the following observational results: (1) We found a mix of upward propagating, downward propagating, as well as standing waves (i.e., with a phase speed of more than 500 km/s). The ratio is 59%, 21%, and 20%, respectively. (2) A gradual increase with height of the phase speed was observed. (3) Upward waves were dominant at lower altitudes, while standing waves were dominant at higher altitudes. (4) Standing waves were dominant in the early and late phases of each spicule, while upward waves were dominant in the middle phase. (5) In some spicules, we found direct observational evidence for a scenario in which waves along one spicule propagate upward (from the bottom of the spicule) and downward (from the top of the spicule) to form, through superposition, a standing wave in the middle of the spicule. (6) The medians of the (displacement) amplitude, period, and velocity amplitude were 55 km, 45 s, and 7.4 km/s, respectively. Assuming a plasma number density of 1010 /cm3, we would roughly estimate the Poynting flux to be 2.5x105 erg/cm2/s, if the filling factor were 1.
We speculate that upward propagating waves are produced near the solar surface (below the spicule) and downward propagating waves are caused by reflection of (initially) upward propagating waves off the transition region at the spicule top. The mix of upward and downward propagating waves implies that exploiting these waves to perform seismology of the spicular environment requires careful analysis and may be problematic.

T. Matsumoto: Self-consistent reconstruction of the solar corona and the solar wind under the Alfven wave scenario
Abstract Author(s): Matsumoto,T. (1), Suzuki, T. K. (1)
Institution(s): (1) Nagoya University
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

The solar corona is the outermost portion of the solar atmosphere that has extremely higher temperature compared with the cool surface (the photosphere). Above the corona, the supersonic solar winds blow into the interplanetary space. A key ingredient of the coronal heating and the solar wind acceleration is Alfven wave; transversal wave propagating along magnetic field lines. The energy of Alfven wave can be converted into thermal energy both through compressible or incompressible processes. In addition to gas pressure, the pressure of Alfven wave can accelerate the ambient plasma. However, which energy conversion processes can work effectively in the sun has not been elucidated yet. Here we present results of 2D magnetohydrodynamic simulations of Alfven wave propagation to reproduce both the solar corona and the solar wind above the coronal holes simultaneously. We found that shock heating is effective in the coronal bottom where the solar wind flow is subsonic. This implies that the mass loss rate from the sun is controlled by the shock heating process. In the solar wind acceleration region, both the shock waves and the Alfven turbulence are turned out to be important for the heating and the acceleration.

Abstract Author(s): N. Nishizuka (1), T. Nakamura, T. Kawate, K. A. P. Singh, and K. Shibata (2)
Institution(s): (1) ISAS/JAXA, (2) Kwasan and Hida observatories, Kyoto University
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

The Solar Optical Telescope on board Hinode has revealed numerous tiny jets in all regions of the chromosphere outside of sunspots. A typical chromospheric anemone jet has a cusp-shaped structure and bright footpoint, similar to the shape of an X-ray anemone jet observed previously with SXT/Yohkoh. In Ca II H broadband and Fe I 6302A narrowband filter images, chromospheric anemone jets are associated with the mixed polarity regions which are either small-scale emerging flux regions or moving magnetic features. This configuration has been well explained by the emerging flux-reconnection model. We examine various chromospheric anemone jets in the active region near the limb and the disk center, and study the typical features (e.g., length, width, lifetime, and velocity) of the chromospheric anemone jets. Statistical studies find that chromospheric anemone jets have: (1) a typical length 1.0�4.0 Mm, (2) a width 100�400 km, (3) a lifetime 100�500 s, and (4) a velocity 5�20 km/s. The velocity of the chromospheric anemone jets is comparable to the local Alfvén speed in the lower chromosphere (about 10 km/s). The observed relationship between the velocity and length of chromospheric anemone jets shows that the jets do not follow ballistic motion but are more likely accelerated by some other mechanism, e.g. shock acceleration. This is consistent with numerical simulations of chromospheric anemone jets and may give some model to explain coronal heating. The timescale of chromospheric anemone jets indicates faster reconnection than expected from the Sweet-Parker theory. Since the current sheet in the low Reynolds number atmosphere (106 in the lower chromosphere) is hard to get thin enough for microscopic instability to trigger localized anomalous resistivity, magnetic reconnection in weakly ionized plasma, i.e. the role of neutral particles and macroscopic dynamics such as turbulence, plasmoid ejections and fractal structure in the current sheet will be also discussed in this presentation.

M. Cheung: Magnetohydrodynamics of the Partially-Ionized Solar Atmosphere
Abstract Author(s): Cheung, M. C. M. (1), Cameron, R. H. (2)
Institution(s): (1) Lockheed Martin Solar & Astrophysics Laboratory, Palo Alto, CA, (2) Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

By incorporating important physical processes such as radiative transfer and magnetoconvection, recent numerical magnetohydrodynamics (MHD) simulations have provided key insights into the mechanisms underlying a plethora of solar atmospheric phenomena. Until now, however, such simulations have treated the plasma in the photosphere and chromosphere as fully ionized. When one takes into account that photospheric and chromospheric plasma are weakly ionized, new effects such as the Hall drift and ambipolar diffusion need to be taken into account. We present MHD simulations that use a generalized Ohm's law in the induction equation to take into account neutral-ion coupling in the solar photosphere. Ambipolar diffusion is responsible for the collapse of current sheets in weakly ionized plasma and the Hall effect is responsible for rotation of the plane of polarization of Alfven waves. The relative importance of these respective effects under certain thermodynamic regimes will be discussed.

T. Wang: Spectroscopic Diagnosis of Propagating disturbances in coronal loops: Waves or flows?
Abstract Author(s): Wang, T. (1,2), Ofman, L. (1,2), and Davila, J. M. (2)
Institution(s): (1) Catholic University of America, Washington, DC, USA, (2) NASA's Goddard Space Flight Center, Greenbelt, MD, USA
Session: Energy transport and dissipation through the solar atmosphere and into the heliosphere

Quasi-periodic intensity disturbances propagating upward along the coronal structure have been studied with EUV imaging observations for a long time. They were mostly interpreted as slow mode magnetoacoustic waves. However, it was recently argued that they are actually caused by a faint highly blueshifted quasi-periodic upflowing component of the order of 50-150 km/s. Here we present the analysis of multi-wavelength spectral properties of propagating disturbances (PDs) using the Hinode/EIS sit-and-stare observations. First we test the forward modeling of the Red-Blue (RB) asymmetry profiles for 6 EIS coronal lines for different Doppler velocities of the secondary Gaussian, and found that the derived velocity by the RB analysis is saturated when the secondary component is centered at offset velocities equivalent to the line width. This effect leads to a detection limitation of upflow velocity by the RB method to be above 50-60 km/s due to the broad instrumental width for EIS spectra (especially for the short-wavelength band). We then developed a different method to examine the spectral features for the PDs. By assuming that the excessive emission of the PD profile against the background (taken as the one prior to the PD) is caused by the hypothetic upflow, we derived the LOS velocities of the order of 10-20 km/s for the warm (1-1.5 MK) loops, in which the PDs are most prominent. This velocity size is much smaller than those inferred from the RB asymmetry analysis, and did not support the interpretation of the PDs by intermittent high-speed upflows, and therefore confirms the previous wave interpretation. However, the PDs seen in higher (about 2 MK) temperature lines appear to show different features. We discuss their origin based on the double Gaussian fits.

L. Harra: Spectroscopic observations of a coronal Moreton wave
Abstract Author(s): H., Sterling (1), Gomory (1), Veronig (1)
Institution(s): (1) UCL-MSSL
Session: Instabilities, Transients and Eruptions

We observe a coronal wave ('EIT wave') on 2011 February~16, using EUV imaging data from SDO/AIA and EUV spectral data from Hinode/EIS. The wave accompanied an M1.6 flare that produced a surge and ejected a Coronal Mass Ejection (CME). EIS data of the wave show a prominent red-shifted signature indicating line-of-sight velocities of ~20 km/s or greater. Following the main red-shifted wave front, there is a low-velocity period (and perhaps slightly blue-shifted), followed by a second redshift somewhat-weaker than the first; this progression may be due to oscillations of the EUV atmosphere set in motion by the initial wave front, although alternative explanations may be possible. Along the direction of the EIS slit the wave front's velocity was ~500 km/s, consistent with its apparent propagation velocity projected against the solar disk as measured in the AIA images, and the second red-shifted feature had propagation velocities between ~200-500$~km/s. These findings are consistent with the observed wave being generated by the outgoing CME, as in the scenario for the classic Moreton wave. This type of detailed spectral study of coronal waves has hitherto been a challenge, but is now possible due to the availability of concurrent AIA and EIS data.

M. Inomoto: Excitation of Low Frequency Electromagnetic Waves in Magnetic Reconnection Laboratory Experiment
Abstract Author(s): M. Inomoto, A. Kuwahata, S. Ito, H. Tanabe, Y. Hayashi, P. Copinger, T. Ii, B. Gao, T. Ito, T. Yamada, Y. Ono
Institution(s): The University of Tokyo
Session: Instabilities, Transients and Eruptions

Magnetic reconnection plays important roles in rapid eruption and structure formation events in magnetized plasmas. Fast magnetic reconnection is provided by large magnetic dissipation, or the anomalous resistivity in the diffusion region, which is induced by microscopic instabilities in the current sheet. One of the primary candidates of the microinstabilities is the lowerhybrid drift instability (LHDI), which is often observed in space and laboratory experiments. Recent three-dimensional particle simulation studies have pointed out that the drift kink instability (DKI) is triggered after the nonlinear saturation of the LHDI mode when the half-width of the current sheet decreases below the ion gyroradius, resulting in the reconnection enhancement and anomalous ion heating.
Local current sheet behaviors have been experimentally investigated by using toroidal plasma merging devices, in which self-organized magnetic reconnection events develops with small constraint from boundary conditions. Recently, excitation of low frequency electromagnetic waves was observed associated with the magnetic reconnection with a moderate guide field (about half of the reconnecting field). The waves have frequency in the range of ion cyclotron frequency and parallel wavelength in the order of several ion gyroradius. Enhancement of the effective resistivity in the current sheet was observed around the same time when the maximal wave amplitude up to 10 % of the reconnecting field was detected. These experimental results suggest that the DKI like current sheet modulation develops and enhances the reconnection rate.

A. Hillier: Simulations of the magnetic Rayeigh-Taylor instability in the Kippenhahn-Schluter pominence model
Abstract Author(s): Andrew Hillier (1), Thomas Berger (2), Kazunari Shibata (1) and Hiroaki Isobe (3)
Institution(s): (1) Kwasan and Hida Observatories, Kyoto University, Japan (2) Lockheed Martin Advanced Technology Center, Palo Alto, California, USA (3) Unit of Synergetic Studies for Space, Kyoto University, Japan
Session: Instabilities, Transients and Eruptions

Observations of quiescent prominences by the Solar Optical Telescope (SOT) on board the Hinode satellite show plumes of hot, underdense material rising through the prominence. These plumes form at the boundary between the prominence and low density bubbles, approximately 10 Mm in size, that appear beneath the prominence, and then rise through the prominence material at speeds of approximately 20 km/s and widths of approximately 1.5 Mm. The plume profile ranges from highly turbulent to smooth, suggesting that the prominence conditions, as well as those of the bubble, are important in determining the dynamics. To investigate this phenomenon, we perform simulations of the magnetic Rayleigh-Taylor instability in a local prominence model. The instability creates rising plumes of hot, underdense material that propagate through the prominence material at a velocity of approximately 6-7 km/s and widths of approximately 1.5 Mm, in rough agreement with the Hinode observations. Nonlinear effects, in which the interaction between plumes drives an inverse cascade process creating large plumes from smaller plumes, are found to be important. Increasing the magnetic field strength creates smoother plume structures. The addition of a strong guide field, which is suggested in some prominence models, does not hinder plume formation but does change the dynamic scaling. The Rayleigh-Taylor instability drives an upward flow of magnetic energy and a downward flow of mass. The results from the simulations well match the characteristics of the observed plumes, suggesting that the magnetic Rayleigh-Taylor instability could be important in determining prominence structure as well as changing the magnetic energy distribution in overlying coronal cavities which ultimately erupt as coronal mass ejections.

S. Imada: Imaging Spectroscopic Observation of Filament Eruptions by Hinode/EIS Flare Hunting Study
Abstract Author(s): Imada S. (1), Hara H. (1), Watanabe T. (1), Shimizu T. (1), Harra L. K. (1)
Institution(s): (1) ISAS/JAXA
Session: Instabilities, Transients and Eruptions

So far, Hinode/EIS observed several flares, and reveals the dynamical features associated with flows during the flare. On the other hand, the temporal resolution in most EIS flare observation is not enough to reveal the dynamical features associated with flare. Therefore, we have proposed the fast cadence Flare Hunting Study (~6 min) to concentrate observing the dynamical feature. From 2009 December to 2011 April, Flare Hunting Study produced the raster images more than 5000. We have processed 5000 raster scan data and checked the processed images (intensity, velocity, line width). We have identified the flare not by GOES class but the enhancement of FeXXIII or FeXXIV line intensity. After all, more than 30 individual flare associated events are found. We can observe many downflow signatures during the flares in the coronal emission lines (Te ~ 1MK). For example, redshifted post flare loop, strongly redshift near the footpoint of flaring loops during impulsive phase, and redshifted plasma associated with filament eruption.
In this talk, we concentrate the flow characteristics of erupting filament. We found a few filament eruption events associated with flare. We can clearly identify in OVI line. Actually, it seems that those filaments are once erupting and they fail back. EIS clearly observed the velocity signals of the filaments with 6min cadence. At the beginning of the eruption, some part of the filaments shows the blueshift (a few 10km/s) in FeXII and FeX. After 6 minutes later, FeXII and FeX show the clear redshifts in the leg of filaments, although the filaments seem to be still erupting. The downflow velocities are roughly 100 km/sec (almost sound speed) estimated by double Gaussian fitting. This result may suggest that the filaments loose their mass along the loop during the erupting phase. Further, the mass loss process may work as a positive feed back to the filament eruption (like Parker-Instability).

Y. Su: Observations and Magnetic Field Modeling of the Flare/CME Event on 2010 April 8
Abstract Author(s): Yingna Su (1), Bernhard Kliem (2), Adriaan van Ballegooijen (1), Vincent Surges (1), Edward Deluca (1)
Institution(s): (1) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA (2) Institute for Physics and Astronomy, Unversity Potsdam, Potsdam, Germany
Session: Instabilities, Transients and Eruptions

We present two studies on the flare/CME event that occurred in Active Region 11060 on 2010 April 8. This flare is well observed at multiple EUV and UV channels by SDO/AIA. The CME is observed by STEREO and SOHO/LASCO. We create a series of static magnetic field models, using the flux-rope insertion method developed by van Ballegooijen (2004). The boundary conditions for the magnetic fields are provided by line-of-sight magnetograms taken by SDO/HMI. The best-fit NLFFF model is constrained by the coronal loops observed by SDO/AIA and Hinode/XRT. We find that the axial flux in the best-fit pre-flare NLFFF model (Axi=4e20 Mx) is close to the threshold of instability (Axi=5e20 Mx). The unstable model (Axi=6e20 Mx) matches the flare footpoints and coronal dimmings as observed at the early phase of the event. We also produce scaled versions of these three models in Cartesian geometry, and use these models as realistic initial conditions for three-dimensional zero-beta MHD simulations (Torok & Kliem 2003, Kliem et al. 2004). These MHD simulations confirm that the model with axial flux of 4e20 Mx is stable, while the model with axial flux of 6e20 Mx erupts as a real CME. Detailed comparisons of the CME model with observations (e.g, dynamics, morphology, erupting direction of the CME) will be presented.

H. Hara: Observed Features of Magnetic Reconnection in 2007 May 19 Flare
Abstract Author(s): Hara, H.(1), Watanabe, T.(1), Harra, L. K.(2), Culhane, J. L.(2), and Young, P. R. (3)
Institution(s): (1) National Astronomical Observatory of Japan, (2) UCL-Mullard Space Science Lab., UK, and (3) Geroge Mason University, USA
Session: Instabilities, Transients and Eruptions

We report observed features that occurred near the loop-top region of a 2007 May 19 flare. We have found a loop-top hot source, a fast jet nearby, and an inflow structure to the hot source in the impulsive phase of the flare from the Hinode EUV Imaging Spectrometer. From the geometrical relationships and observed parameters of these phenomena, we conclude that they provide evidence for magnetic reconnection that occurs near the loop-top region. The reconnection rate estimated from the observed parameters is 0.05-0.1, which supports the Petschek-type magnetic reconnection. The presence of slow-mode and fast-mode MHD shocks is discussed with supporting evidence based on the observed quantities.

S. Shestov: Spectral diagnostics of flare and active region plasma based on EUV spectra from SPIRIT spectroheliograph aboard CORONAS-F
Abstract Author(s): S. V. Shestov, S. V. Kuzin, S. A. Bogachev, A. A. Reva
Institution(s): Lebedev Physical Institute
Session: Instabilities, Transients and Eruptions

EUV spectroheliograph SPIRIT aboard CORONAS-F satellite operated in orbit from 2001 till 2005. The spectroheliograph was built on slitless optical scheme with grazing incidence diffraction grating. Such a scheme provides full-Sun field of view with comparatively high spectral and spatial resolution. Spectral bands of the spectroheliograph 176-207 A and 280-330 A include lines corresponding to a broad range of temperatures: from cold Si VIII and Mg VIII (Tmax - 0.8 MK) to hot Ca XVII and Fe XXIV (Tmax - 10-15 MK). During the satellite operation several thousands of spectoheliograms were registered, including dozens of spectroheliogram with intense solar flares of M- and X-classes. The obtained spectra were used for temperature (DEM) and density plasma diagnostics in flares and active regions. We have found considerable amount of hot plasma in several active regions; for solar flares DEM has been obtained; since for some flares several spectra were registered during decay phase, DEM evolution has been obtained. EUV spectroscopic data from SPIRIT can be used for active region and flare plasma diagnostics, verification of atomic data, verification and evaluation of response functions of EUV telescopes.

S. Guidoni: A New Look at a Classic Flare Structure
Abstract Author(s): Silvina E. Guidoni, David E. McKenzie, Dana W. Longcope
Institution(s): Montana State University - Bozeman
Session: Instabilities, Transients and Eruptions

The M1.4 flare of Jan 28, 2011 has a remarkable resemblance to the famous Tsuneta flare of 1992. It was observed with Hinode/XRT, SDO/AIA, and STEREO (A)/EUVI, giving us higher resolution, more temperature coverage, and stereoscopic views of this iconic structure. We interpret these observations in terms of a newly develop model of retracting reconnected flux tubes. In this model, the retraction drives gas-dynamics shocks that heat and compress the plasma.
The high temperature images reveal a brightening that grows in size to form a tower-like structure above a post-flare arcade. We combine the images with a potential field source surface (PFSS) extrapolation to develop a complete picture of the magnetic field structure and the coronal plasma state variables. XRT provides accurate high temperature measurements of the plasma while the simultaneous high resolution and high-cadence observations from AIA allow us to map the evolution of the plasma. In addition, EUVI data is used to estimate the line of sight depth of the bright tower.

D. Baker: Forecasting a CME by Spectroscopic Precursor
Abstract Author(s): Baker, D. (1), van Driel-Gesztelyi, L. (1,2,3), Green, L.M. (1)
Institution(s): (1) Mullard Space Science Laboratory, University College London, UK, (2) Observatoire de Paris, Meudon, France, (3) Konkoly Observatory, Budapest, Hungary
Session: Instabilities, Transients and Eruptions

Multi-temperature plasma flows resulting from the interaction between a mature active region (AR) inside an equatorial coronal hole (CH) are investigated. Outflow velocities observed by Hinode EIS ranged from a few to 13 km/s for three days at the AR’s eastern and western edges. However, on the fourth day, velocities intensified up to 20 km/s at the AR’s western footpoint about six hours prior to a CME. 3D MHD numerical simulations of the observed magnetic configuration of the AR-CH complex showed that the expansion of the mature AR’s loops drives persistent outflows along the neighboring CH field. Based on these simulations, intensification of outflows observed pre-eruption on the AR’s western side where same-polarity AR and CH field interface, is interpreted to be the result of the expansion of a sigmoidal AR, in particular, a flux rope containing a filament that provides stronger compression of the neighboring CH field on this side of the AR. Intensification of outflows in the AR is proposed as a new type of CME precursor.

K. Kusano: Comparative Study of Solar Flare Onset Based on MHD Simulations and Hinode Observations
Abstract Author(s): Kusano, Kanya (1,2), Bamba, Yumi (1), Yamamoto, Tetsuya T. (1)
Institution(s): (1) Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 4648601, Japna, (2) Japan Agency for Marine-Earth Science and Technology, Kanazawa-ku, Yokohama, Kanagawa, 2360001, Japan
Session: Instabilities, Transients and Eruptions

Although solar flares are now widely believed to be driven by magnetic energy stored around sunspots, what triggers the onset of them is not well understood yet. Hypotheses for the flare onset mechanism includes the emerging flux model, in which magnetic reconnection caused by the emergence of magnetic flux from below the solar surface to the corona leads to solar flares. However, the condition for this process is still unclear. Here, we study what kind of emerging flux can cause the onset of solar flares based on the comparison between three-dimensional MHD simulations and the Hinode/SOT observation of pre-flare activities. First, in terms of simulations, we found that the small magnetic flux emerged into a sheared magnetic arcade is capable to trigger flare eruption, if and only if the azimuthal orientation as well as the amount of emerging flux meet some condition. In particular, the simulations indicate that there are two different parametric windows for the azimuth of emerging flux to trigger flares. Second, we analyzed the flux emerging activity of AR NOAA 10930 by comparing the Ca II H images and the longitudinal magnetogram taken by Narrowband Filter Imager of Hinode/SOT. As consequence of it, it was shown that some pre-flare brightening events coincide with the rapid emergence of small magnetic bi-polar system. Finally, we will show the geometrical structure of each flux emergence to examine the simulation results for the preferential azimuth of emerging flux to trigger flare.

S. Savage: Current Sheet and Reconnection Inflow-Outflow Observations During Solar Eruptions
Abstract Author(s): (1) Sabrina Savage, (1) Gordon Holman, (2) Kathy R. Reeves, (3) Daniel B. Seaton, (4) David E. McKenzie, (1) Yang Su
Institution(s): (1) NASA/GSFC, Greenbelt, MD; (2) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA; (3) Royal Observatory of Belgium, Brussels, Belgium; (4) Montana State University, Bozeman, MT
Session: Instabilities, Transients and Eruptions

Magnetic reconnection is widely accepted as a dominant source of energy during solar flares; however, observations of it have been indirect and/or incomplete. Using the suite of instruments available spanning wavelength space, we will provide observations and measurements of both the inputs and outputs predicted from reconnection in the form of inflows preceding outflows (i.e. supra-arcade downflows, supra-arcade downflowing loops, upflows, and disconnection events). We will also present evidence for current sheets through which reconnection is expected to occur and discuss current sheet motion during flare progression.

J. Trujillo Bueno: The Hanle Effect from Space for Measuring the Magnetic Fields of the Upper Chromosphere
Abstract Author(s): J. Trujillo Bueno, J. Stepan, L. Belluzzi, et al.
Institution(s): Instituto de Astrofisica de Canarias
Session: Future Needs - Observational, Theoretical and Computational

We present some theoretical predictions concerning the amplitudes and magnetic sensitivities of the linear polarization signals produced by scattering processes in some UV and FUV spectral lines of the upper chromosphere and transition region, such as Ly-alpha and Mg II k. To this end, we have calculated the atomic level polarization (population imbalances and quantum coherences) induced by anisotropic radiation pumping in semi-empirical and hydrodynamical models of the solar atmosphere, taking into account radiative transfer and the Hanle effect caused by the presence of organized and random magnetic fields. The amplitudes of the emergent linear polarization signals are found to vary typically between a fraction of a percent and a few percent, depending on the scattering geometry and the strength and orientation of the magnetic field. The results shown here encourage the development of UV polarimeters for sounding rockets and space telescopes with the aim of opening up a true diagnostic window for magnetic field measurements in the upper chromosphere and transition region of the Sun.

K. Kobayashi: The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP)
Abstract Author(s): Kobayashi, K. (1), Tsuneta, S. (2), Trujillo Bueno, J. (3), Bando, T. (2), Belluzzi, L. (3), Casini, R. (4), Carlsson, M. (5), Cirtain, J. (6), De Pontieu, B. (7), Hara, H. (2), Ichimoto, K. (8), Ishikawa, R. (2), Kano, R. (2), Katsukawa, Y. (2), Kubo, M. (2), Kim, T. (6), Manso Sainz, R. (3), Narukage, N. (2), Asensio Ramos, A. (3), Robinson, B. (1), Sakao, T. (9), Shimizu, T. (8), Stepan, J. (3), Suematsu, Y. (2), Watanabe, H. (8), West, E. (6), Winebarger, A. (6)
Session: Future Needs - Observational, Theoretical and Computational

We present an overview of the Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP), a proposed sounding rocket experiment currently under development as collaboration between Japan, USA and Spain. CLASP aims to measure the magnetic field in the upper chromosphere and transition region of the Sun through the detection and measurement of Hanle effect polarization of the Lyman alpha line. The Hanle effect (i.e. the magnetic field induced modification of the linear polarization due to scattering processes in spectral lines) is believed to be a powerful tool for measuring the magnetic field in the upper chromosphere, as it is more sensitive to weaker magnetic fields than the Zeeman effect, and also sensitive to magnetic fields tangled at spatial scales too small to be resolved. The Lyman-alpha (121.567 nm) line has been chosen because it is a chromospheric/transition-region line, and because the Hanle effect polarization of the Lyman-alpha line is predicted to be sensitive to 10-250 Gauss, encompassing the range of interest. Hanle effect is predicted to be observable as linear polarization or depolarization on the order of 0.1% to 1%. The experiment is proposed for flight in 2014.

Section Photo