Click on links to view session descriptions below.
1. Understanding the Origin and Transport of GLEs with Modern Observations (Ryan/Christian/de Nolfo)
2. Techniques for Connecting In-situ Observations with Solar Sources (Richardson et al.)
3. Ground based, remote sensing and in situ measurements- how to tie multi-platform information together to better address questions about CMEs and SEPs (Korreck/Schwadron)
4. When and Why Does Space Weather Forecasting Fail? (Mays/Richardson/ThmpsonNieves-Chincilla)
5. Physics of the relationship of ICMEs to their CME progenitors (Arge/White)
6. Coronal Magnetic Energy Estimation (Barnes/Leka)
7. Frontiers in modeling magnetic flux emergence and the development of solar eruptive activities (Linton/Fan)
8. Heavy Ion Composition in the Heliosphere (Zhao/Lepri/Landi)
9. What is the Role of non-Maxwellian Ion Distributions in the Solar Wind? (Klein/Verscharen)
10. The Role of Electron Thermodynamics for the Multi-Scale Evolution of the Solar Wind (Salem/Verscharen)
11. Accuracy of spacecraft measurements of solar wind plasma: Past, Present and Future (Podesta/Steinberg)
12. Plasma Turbulence in Solar Wind and Corona: from Fluid to Kinetic Scales (Matthaeus et al.)
13. The Turbulent Dissipation Problem in Weakly Collisional Plasmas: Moving the Challenge Forward (Parashar/Salem)
14. The Final Frontier of Kinetic Turbulence: Distribution Function Dynamics (Howes/Klein)
15. Challenges in understanding 3D magnetic reconnection in observations and simulations (Wyper/Guidoni)
|1. Understanding the Origin and Transport of GLEs with Modern Observations
J.M. Ryan, E.R. Christian, G.A. de Nolfo
The relative importance of solar energetic particle (SEP) acceleration close to the Sun through magnetic reconnection and higher in the corona through Coronal Mass Ejection-driven shocks is unclear. The uncertainty exists at the very lowest energies of SEPs observed in-situ and persists right through Ground Level Enhancements (GLEs) at high energies. The highest energy SEPs provide an improved case study in that the effects of transport are often minimal, and new measurements by the PAMELA and AMS experiments have extended in situ measurements of SEPs to energies that overlap with ground-based neutron monitors and muon telescopes.
|2. Techniques for Connecting In-situ Observations with Solar Sources
Ian Richardson,Robert Wicks, Leila Mays, Mari Paz Miralles, Steering Committee: G.A. de Nolfo, M. Zhang
In order to identify the precise source of solar energetic particles, it is sometimes necessary to understand the complex connectivity of the solar corona to 1 AU. Traditional techniques include identifying solar eruptive events, e.g., flares and coronal mass ejections, that are consistent with particle injection times based on measurements of in-situ particle event onsets. Modern instrumentation now makes it possible to determine solar sources using additional techniques including (removed repeat of particle onsets) radio and X-ray signatures, EUV and white light images, magnetic field modeling, and solar wind mapping. Using observations from STEREO A/B, sources on the far side of the Sun can be taken into consideration. The origin of many smaller events, or those with slow onsets or high ambient backgrounds,however, remains ambiguous. In order to identify the source of the smaller eventscorrectly, advances in the combination of imagery, in-situ data, and solar wind modeling, must be made.
- Are there reliable methods for improving estimates of particle onset times in problematic events?
3. Ground based, remote sensing and in situ measurements- how to tie multi-platform information together to better address questions about CMEs and SEPs
Using multiple observations to better constrain problems from CME evolution to solar wind sources to particle acceleration should aid in our understanding. In the coming few years, unprecedented access to heliospheric data from ground based, remote sensing and in situ observations will be come available with the commissioning of DKIST and the launch of Solar Probe and Solar Orbiter. Now is a good time to plan for those observations and to address any holes in modeling or data so that we can enable maximum science from those data sources. This session will focus on discussion of coordinated observations already used and those areas where coordinated multi-platform observations can be used.
Some of the questions for discussion include:
|4. When and Why Does Space Weather Forecasting Fail?
Leila Mays (CUA/GSFC), Ian Richardson (UMD/GSFC), Barbara Thompson (GSFC), Theresa Nieves-Chincilla (CUA/GSFC)
Space weather forecasting has made tremendous strides in recent years. Nevertheless, there are frequent mismatches between predicted and measured impacts. This session will discuss such failures, and assess whether they are due to limitations in observations, modeling, forecasting methods, or our understanding of the physics involved. We encourage contributions from the forecasting and research communities on all aspects of space weather predictions, including flares, energetic particle events, coronal mass ejections, high speed streams, and impacts to spacecraft and planetary environments. Discussion points may include:
To encourage participation in the discussion and the related poster session, some candidate events for study have been identified, including the large active region 12192 in Oct 2014 that produced many X-class flares but was unexpectedly CME and SEP-poor, and the CMEs on 7 Jan 2014, 10 Sep 2014, and 15 March 2015, where the resulting geomagnetic storm strength at L1 was far different from predictions. However, contributions focusing on other events, and other aspects of space weather forecasting, are welcome!
|5. Physics of the relationship of ICMEs to their CME progenitors
Coronal Mass Ejections (CMEs) are large eruptions of coronal plasma and magnetic fields that travel out into interplanetary space and dynamically interact with the background solar wind. Interplanetary Coronal Mass Ejections (ICME) are the heliospheric manifestations of these eruptions with structures that are often highly modified from their original form. It is well known that the strong magnetic fields that reside within ICMEs are a key driver of major geomagnetic storms when they have a sustained southward component. However, the physical evolution of CMEs into their ICME counterparts is still poorly understood, as is the relative importance of the various internal and external physical factors that transform CMEs into ICMEs. The goal of this session is to elucidate the physical processes that can play a role in changing the structure of a CME as it propagates through the solar wind.
Key questions concerning the origin of ICME structure and properties.
(1) How much of the original CME makes up the ICME that hits the Earth?
(2) What are the physical processes that control this and what is their relative importance?
-Overlying coronal fields.
|6. Coronal Magnetic Energy Estimation
G. Barnes, K.D. Leka
The energy to power solar energetic events must ultimately originate ator below the solar photosphere, and is likely to build up in the coronal magnetic field before release in an event. The objective of this session is to compare the energy estimates from a range of different approaches, applied to a single active region.
We invite estimates of the coronal energy for NOAA AR 11158 (HMI HARP 377) at four specific times: on 13 February 2011 at 17:12 and 18:24 UT (before and after the M6.6 flare), and on 15 February 2011 at 01:24 and 02:48 (before and after the X2.2 flare). Specifically, submissions should include 2 of the 3 following quantities: potential energy, free energy, total energy. Also of interest are estimates of the energy released during these events.
Techniques for energy estimation which have previously been applied to active regions include (but are not limited to):
--Tracking the Poynting flux of energy through the photosphere, using a velocity estimation technique applied to time series of vector magnetograms.
--Reconstructing the coronal magnetic field using extrapolation methods such as nonlinear force-free field (NLFFF) modeling from a single vector magnetogram.
--Using the magnetic virial theorem to estimate the energy from a surface integral over the photospheric field.
--Estimating the rate at which free energy is building up in the corona using a topological method.
Each of these techniques is subject to a different set of assumptions, with different strengths and weaknesses, so one of the key objectives of the session will be to estimate how accurate the results are. The spread in answers may give some insight into how accurate the estimates are, but because the energy in the solar corona is not known, it is impossible to determine which method performs best. We will therefore also encourage a discussion on how best to use simulated data, where the answer is known, to better evaluate how well each of the methods can estimate the coronal magnetic energy. Session discussion may include candidate regions/events for a follow-on session in 2016.
|7. Frontiers in modeling magnetic flux emergence and the development of solar eruptive activities
Mark Linton (NRL), Yuhong Fan (HAO/NCAR)
Significant advances have been made in recent years in modeling magnetic flux emergence on multiple scales and the consequent development of eruptive activities such as jets, flares and coronal mass ejections (CMEs). This session focuses on new results and insights obtained from the MHD models and comparisons with new observations from Hinode, SDO, and IRIS, and discusses challenges and approaches for future model development. We will explore the following 3 major questions/topics:
(1) How are flare and CME productive active regions (such as d-sunspot regions) formed, what are their subsurface origin and coronal structure/evolution?
(2) What are the underlying magnetic field structure and evolution for the development of homologous flares/CMES, and homologous, helical jets?
(3) Can model coupling be effectively used in numerical simulations of solar eruptive activities driven by magnetic flux emergence from the interior?
|8. Heavy Ion Composition in the Heliosphere
Liang Zhao, Sue Lepri, and Enrico Landi (University of Michigan, Ann Arbor)
In the Sun's atmosphere and heliosphere, heavy ions act largely as test particles. They can be directly affected physical processes, such as waves and instabilities, and respond to the properties of the environment around them. This response is primarily imprinted on their elemental abundance and charge states.
Twenty-three years after the first sophisticated solar wind ion composition spectrometer was launched on the Ulysses mission, we now have a wealth of information from Voyager, ACE, WIND, and STEREO indicating that heavy ions play a key role in improving our understanding of solar and heliospheric physical processes. At the same time, the fleet of remote sensing instrumentation (SOHO, STEREO, Hinode, SDO, IRIS) allows us to observe the source regions of the solar wind, and through propagation models or observed proxies they allow us to link in-situ measurements with remote observations of the Sun. The focus of this session will be to discuss the data, theory and modeling needed to understand the coupled solar corona-heliosphere system, in order to address the heating of the corona, the generation of the solar wind, the propagation of the solar transients, the advances made possible by the current instrumentation, and the opportunities offered by the upcoming Solar Orbiter and Solar Probe Plus missions, and the challenges before us.
By bringing together experts on in-situ measurements, remote-sensing observations, solar and heliospheric models, and solar and heliospheric theory, we will create a venue where specialists in each of these sub-disciplines can meet and discuss, and interact with students.
The focused questions addressed in this session include:
|9. What is the Role of non-Maxwellian Ion Distributions in the Solar Wind?
Kristopher G. Klein and Daniel Verscharen
The solar wind emanates from the solar corona and fills the entire heliosphere. A detailed description of this ubiquitous background medium is critical for our understanding of the solar-terrestrial system. One important characteristic of the solar wind is that the mean free path for binary particle collisions is typically of order the system size. Therefore, the solar wind is considered a collisionless plasma, which means that non-equilibrium structures can survive in particle distribution functions. In-situ ion measurements show that solar-wind distributions often deviate from the Maxwellian equilibrium. Two examples for such non-equilibrium structures are ion beams along the background magnetic field and temperature anisotropies with respect to the background magnetic field.
In the past, non-equilibrium distribution functions have been modeled as bi-Maxwellians, to some degree of consistency with observations. However, recent high-resolution observations have shown that the bi-Maxwellian description lacks a number of important characteristics of ion distributions in the solar wind. In particular, there exist a non-negligible number of observations with plasma parameters beyond the theoretical thresholds of micro-instabilities driven by ion beams and/or temperature anisotropies based on a bi-Maxwellian description. In this session, we will discuss the role of non-Maxwellian ion distribution functions and their implications for our overall understanding of the solar-wind.
Our session encourages an interdisciplinary discussion concerning theoretical models, numerical simulations, and in-situ observations of non-Maxwellian ion distributions in the solar wind. We focus on the following specific science questions:
- How do non-Maxwellian ion distributions affect wave dispersion relations and instability thresholds in the solar wind?
|10. The Role of Electron Thermodynamics for the Multi-Scale Evolution of the Solar Wind
Chadi Salem and Daniel Verscharen
The contribution of electrons to the generation and evolution of the solar wind is still a critical and unsolved problem in solar-wind physics. For the development of predictive, physics-based solar-wind models, a more accurate understanding of the contribution of electron physics is crucial.
The core, the halo, and the strahl contribute to the substantial electron heat flux in the solar wind and can significantly modify the properties of wave dispersion relations. These non-equilibrium structures can also represent a source of free energy for various micro-instabilities. In addition to these collisionless processes, binary Coulomb collisions among electrons and the ambipolar electric field play important roles for the evolution of the electron distribution function.
We invite contributions about the connections between small-scale and large-scale electron processes by means of observational, theoretical, and numerical investigations. We especially welcome contributions that compare the roles of collisional and collisionless processes. We would like to encourage discussions about the following questions:
- How can we understand the nature of the electron distribution functions in the inner heliosphere?
|11. Accuracy of spacecraft measurements of solar wind plasma: Past, Present and Future
John Podesta and John Steinberg
What is the accuracy or experimental uncertainty of spacecraft measurements of the ion density, ion bulk flow velocity, ion temperature, and ion distribution functions in the solar wind? For many spacecraft data sets, this is a question for which there is no straightforward documented answer. Nevertheless it can be crucial for doing good science. In this session we shall discuss and try to quantify the experimental uncertainties of spacecraft data used by the Shine community. Some of the questions to be addressed are the following.
1. How accurate are existing solar wind measurements? For example, how accurate are measurements of the ion bulk velocity and each of its vector components? What is the experimental uncertainty of these measurements?
2. How accurate are measurements of changes in plasma parameters at different times?
3. High accuracy, high time resolution measurements of both plasmas and fields are needed to advance knowledge and understanding of solar wind plasma processes. What accuracy and time resolution should be required for the next generation of spacecraft measurements?
4. To what degree must one sample the full 3D ion distribution function to obtain a prescribed accuracy for bulk plasma parameters (bulk velocity, density, temperature, etc.)? Under what circumstances would 1-D or 2-D scans suffice? What are the accuracy trade-offs among different instrumental techniques such as electrostatic analyzers and Faraday Cups?
5. What scientific investigations, questions and/or advances would become possible with higher accuracy, higher time resolution plasma data? Measurement of the scale dependent angle between the velocity and magnetic field fluctuations is one example.
|12. Plasma Turbulence in Solar Wind and Corona: from Fluid to Kinetic Scales
W. H. Matthaeus (with Jeffrey Tessein, Minping Wan, Michael Shay)
This session aims to follow up on similarly named SHINE sessions that have been successfully organized in the last several years. The goals remain to improve the plasma physics knowledge, the modeling endeavors, and observational interpretations of the turbulent solar wind energy cascade, energy dissipation, and related plasma heating. The emphasis will be on observations, theory and simulations that are relevant at fluid and/or kinetic scales, and especially studies that connect fluid and kinetic scales. This year we emphasize the following issues:
• How does the large magnetofluid scale cascade interact with small scale kinetic processes? Can we understand system size effects? Are couplings local or nonlocal?
• What controls partitioning of energy between electrons, protons, and minor ions? Are the kinetic cascade and dissipation processes local or nonlocal in scale? What are the relevant mechanisms? What controls variability of spectra in the kinetic range?
• What do we know about current sheet structure? What are the observational signatures of secondary island formation? Is there evidence for “hot spots” of dissipation, or can uniform plasma theories work? What is the significance of observed intermittency?
The session will cover the proposed topics in relation to coherent structures in the solar wind such as reconnection, current sheets, shocks, discontinuities, heating, and co-rotation interaction regions (CIRs), as well as to MHD and kinetic waves and instabilities. The topics are also relevant to suptrathermal particle acceleration and SEP transport. The aim is to attract physicists studying the solar wind from various perspectives and applying various tools. This approach supports SHINE’s
|13. Turbulence and Dissipation in the Solar Wind Plasma: Current Challenges and New Diagnostics
Tulasi Parashar & Chadi Salem
This session aims to follow up on similarly named SHINE sessions that have been successfully organized in the last couple of years. Our previous sessions were extremely successful and served as discussion platforms to propose and define the “Turbulent Dissipation Challenge”. The goal of this effort is to bring the community together to tackle, in a coordinated way, the central issues related to the particular problem of dissipation in weakly collisional systems like the solar wind. We defined a set of problems based on the outcome of our previous SHINE sessions.
We are now at a stage where we are performing the first set of simulations to compare different simulation models in different limits. The next stage will be to carefully design “critical community simulations” (very large, 3D, fully kinetic simulations) that can be analyzed by everyone in the community to address the problem of dissipation.
This year, the sessions will address key aspects of the challenge:
We will focus the discussion on the following points:
|14. The Final Frontier of Kinetic Turbulence: Distribution Function Dynamics
Gregory G. Howes and Kristopher G. Klein
Plasma turbulence occurs ubiquitously throughout the heliosphere, yet our understanding of how turbulence governs energy transport and plasma heating remains incomplete, constituting a grand challenge problem for the SHINE community. Turbulence connects mechanisms at large temporal and spatial scales to those at much smaller scales through a cascade of energy. But we have yet to determine definitively the kinetic physical mechanisms responsible for the damping of the turbulent electromagnetic fluctuations in the weakly collisional solar wind and the ultimate conversion of their energy into plasma heat. High resolution measurements of the particle velocity space distributions represent an important, yet largely untapped, potential source for discovery science.
Recently launched and upcoming missions, including the Magnetospheric Multiscale, Solar Probe Plus, and Solar Orbiter missions, boast unprecedented cadence and better velocity phase-space resolution for plasma measurements. Such resolution will be essential for determining definitively the kinetic mechanisms responible for the damping and dissipation of the turbulent electromagnetic fluctuations. The interpretation of these measurements arises as a new scientific challenge. Now is the time to employ kinetic plasma theory and kinetic numerical simulations to develop a theoretical framework for the interpretation of these valuable upcoming measurements.
The aim of this session is to bring observers experienced with spacecraft plasma measurements together with theoretical and numerical plasma modelers to address the following questions:
1) What features in the velocity distribution functions are associated with the turbulent dynamics?
2) What are the predicted signatures in the velocity space distribution of plasma particles associated with different collisionless damping mechanisms?
3) How can these predicted signatures be identified in high resolution measurements of particle velocity distributions from future missions? Ultimately, we hope to establish a community effort now to develop the tools necessary to exploit fully the scientific potential of upcoming in situ observations of solar wind velocity distribution functions.
|15. Challenges in understanding 3D magnetic reconnection in observations and simulations
Peter Wyper (NASA/GSFC - ORAU) & Silvina Guidoni (NASA/GSFC - CUA)
Magnetic reconnection is believed to be responsible for rapid restructuring of magnetic field in the Sun's atmosphere and the Earth's magnetosphere, involving processes at multiple scales with accompanying dynamics in three dimensions. Global dynamics advect flux and set the conditions for reconnection to take place on small scales. During this change in magnetic topology, energy is released into plasma heating, particle acceleration, radiation, and bulk flows, which in turn feed back on the global dynamics. Recent highquality observations in the solar corona, magnetopause, and magnetotail as well as laboratory experiments and stateoftheart simulations at kinetic and MHD scales, are paving the way toward understanding reconnection in true threedimensional terms. Although we have a relatively complete understanding of reconnection in two dimensions, there are still many unanswered questions when considering threedimensional systems.
This session follows on from last year's session "Magnetic reconnection and flux redistribution: multiscale and 3D dynamics", by discussing recent progress and new challenges of understanding 3D reconnection in various contexts. The following questions aim to structure the discussion:
1. What effects/physics is not captured by 2D modelling?
1. What reconnection related phenomena (such as solar flares and jets, substorms, and FTEs)
cannot be satisfactorily explained by 2D theories?
● How can we combine current and future remote and insitu observations, laboratory
experiments, and simulations to better understand the basics of 3D reconnection?