NASA LWS Workshop on Solar Dynamo Frontiers: Helioseismology, 3D Modeling, and Data Assimilation

Tuesday, June 9, 2015 to Friday, June 12, 2015

Group Photo image

The High Altitude Observatory at the National Center for Atmospheric Research
Boulder, Colorado

The last five years have seen substantial progress in our understanding of the solar dynamo, fueled by continuing advances in observations and modeling. With the launch of NASA’s Solar Dynamics Observatory (SDO) in 2010 came an unprecedented window on the evolving magnetic topology of the Sun, highlighting its intricate 3D structure and global connectivity. The Helioseismic Magnetic Imager (HMI) instrument on SDO in particular has provided potentially transformative yet enigmatic insights into the internal dynamics of the solar convection zone that underlie the dynamo. Attempts to detect subsurface convective motions from helioseismic inversions have yielded only upper limits on the large-scale convective amplitude, challenging our understanding of global solar convection. Yet, potential signatures of giant cells have been detected in photospheric Dopplergrams. Estimates of the meridional flow from HMI and complementary instruments (SOHO/MDI and GONG) have been equally tantalizing and enigmatic. Several disparate techniques, including local and global helioseismic inversions and correlation tracking of surface features, have yielded evidence of a multi-cellular meridional flow but they differ on the detailed flow structure and amplitude. This multi-cellular meridional flow has potentially profound implications for flux-transport dynamo models that previously assumed a very different structure with a single circulation cell per hemisphere.

From a modeling perspective, the last five years have seen dramatic advances in global convective dynamo simulations. These now exhibit magnetic self-organization of chaotic turbulent fields into cyclic mean fields that bear some similarity with solar cycle observations. These convective dynamos operate very differently than Babcock-Leighton dynamo models which require flux emergence in order to operate and which are also backed by some observational support. Which of these paradigms applies to the Sun? Answers may only come by bridging the gaps between the two by understanding how convective dynamos generate emerging magnetic flux structures. Progress on this front has also been made in recent years with the spontaneous generation of rising flux structures in convective dynamo simulations and with the advent of 3D Babcock-Leighton/Flux-Transport dynamo models. Increasingly sophisticated simulations of solar surface convection suggest that flux systems can coalesce into sunspot pairs after emergence. Furthermore, the efficiency of small-scale dynamo action in these surface convection simulations suggests that turbulent fields may permeate the convection zone and dominate the magnetic energy. Meanwhile, growing research on data assimilation into solar dynamo models promises to provide a powerful new means to calibrate models, to identify model biases, to distinguish between competing models, and to potentially forecast future solar activity.

The time is ripe for a careful assessment of these new observational and modeling results and their implications for solar dynamo research. This workshop will bring together observers, modelers, and theorists to determine which recent developments are most robust, to identify the most pressing and tractable challenges, and to suggest a path forward for further research. The format will include invited talks, contributed talks, and open discussion and participation will be open to the community.

List of the organizers:
Mark Miesch (co-chair: HAO/NCAR)
Junwei Zhao (co-chair: Stanford Univ.)
Allan Sacha Brun (CEA Saclay)
Paul Charbonneau (Univ. Montreal)
Arnab Choudhuri (IIS, Bangalore)
Mausumi Dikpati (HAO/NCAR)
Rudi Komm (NSO)
Alexander Kosovichev (BBSO)
Nagi Mansour (NASA ARC)
Markus Roth (Kiepenhauer Inst. Sonnenphysik)
Mausumi Dikpati (HAO/NCAR)
Wendy Hawkins (HAO/NCAR)
Mark Miesch (HAO/NCAR)

|**Scientific Program**| |**Abstract Booklet**|   Click on talk titles (below in blue) to open linked files.

Tuesday, June 9
8:15 AMBus departs from the Holiday Inn Express (arrival time 8:30)
9:00-9:10Welcome: Mark Miesch
9:10-9:55Keynote: David Hathaway, “Observational Constraints and New Frontiers for Solar Dynamos
 Session 1:  Solar Meridional Circulation and Differential Rotation: Observations
9:55-10:20Invited: Ruizhu Chen, “Comprehensive Measurement of Deep Solar Meridional Flow”
9:20-10:45Invited: Jason Jackiewicz, “Meridional Flows from GONG”
10:45-11:15Coffee Break and poster setup
11:15-11:40Invited: Martin Woodard, “Helioseismic detectability of Solar Meridional Flow”
11:40-12:00Contributed: Jesper Schou, “Results from Improved Analysis of MHD and HMI Global Mode Data”
12:00-1:15Lunch (NCAR Cafeteria, cash only)
 Session 1 (continued)
1:15-1:40Invited: Ariane Schad, “Helioseismic Measurement of Meridional Circulation and Differential Rotation from Mode Eigenfunction Perturbations”
1:40-2:00Contributed: Dean-Yi Chou, “Probing Magnetic Fields at the Base of the Solar Convection Zone with Meridional Flows”
2:00-2:45Open Discussion: Led by Rudi Komm, Markus Roth & Junwei Zhao
2:45-3:15Coffee Break and poster viewing
 Session 2:  Convection and Magnetism: Observations
3:15-3:40Invited: Shravan Hanasoge, “Seismic Constraints on Large-Scale Convection in the Sun
3:40-4:05Invited: Ben Greer, “Fast Convective Flows Throughout the Near-Surface Shear Layer”
4:05-4:25Contributed: Tom Duvall Jr., “Flows in the Convection Zone with Potential Relevance to the Dynamo
4:25-4:50Invited: Aimee Norton, “Joy’s Law: A Space-Age Update
4:50-5:10Contributed: Xudong Sun, “Polar Field Reversal and Surface Flux Transport of Cycle 24 Observed by SDO/HMI”
5:10-6:00Poster session
6:00-7:30Reception: NCAR Foothills Laboratory
7:30 PMShuttle departs to Hotels
Wednesday, June 10
8:30 AMBus departs from the Holiday Inn Express (arrival time 8:45)
 Session 3:  Modeling of Convection and Mean Flows
9:00-9:25Invited: Gustavo Guerrero, “Large-Scale Flows and Dynamo in Global Large-Eddy Simulations of the Sun and Solar-Like Stars
9:25-9:50Invited: Nicholas Featherstone, “Stratified Convection Driven by Internal Radiative Heating: Scaling Laws
9:50-10:10Contributed: Bradley Hindman, “Transport Properties of Stratified Convection in the High-Rayleigh Number Regime”
10:10-10:30Contributed: Nishant Singh, “Fanning out of the f-mode in Presence of Nonuniform Magnetic Fields and its Seismic Implications”
10:30-11:00Coffee Break and poster viewing
11:00-11:25Invited: Yuhong Fan, “Differential Rotation in Solar Convective Dynamo Simulations”
11:25-11:50Invited: Hideyuki Hotta, “Small- and Large-Scale Dynamo in the Solar Convection Zone
11:50-12:10Contributed: Nicholas Nelson, “Self-Organization and Solar-Like Differential Rotation Using a Plume Boundary Condition in Global Solar Convection Simulations
12:10-1:30Lunch (NCAR Cafeteria, cash only)
 Session 3 (continued)
1:30-2:15Open Discussion: Led by Mark Miesch & Mark Rast
 Session 4: Advances in Dynamo Modeling: Convective Dynamos
2:15-3:00Keynote: Axel Brandenburg, “Simulating and Understanding Large-Scale Dynamos
3:00-3:25Invited: Youhei Masada, “Organization of Coherent Magnetic Fields in Turbulent Thermal Convection”
3:25-3:55Coffee Break and poster viewing
3:55-4:20Invited: Jean-Francois Cossette, “Large-Scale Field Induction in Global MHD Simulations of Solar Convection
4:20-4:45Invited: Petri Käpylä, “Competing Dynamo Modes in Spherical Wedge Simulations of Turbulent Convection”
4:45-5:10Invited: Antoine Strugarek, “Benchmarking Convective Dynamos: Subgrid-Scale Modeling Effects
5:10-5:30Contributed: Jörn Warnecke, “Understanding Equatorward Migration of the Sun’s Magnetic Field”
5:30-6:15Open Discussion: Led by Matthias Rempel and Juri Toomre
6:45 PMShuttle departs to Hotels
Thursday, June 11
8:30 AMBus departs from the Holiday Inn Express (arrival time 8:45)
 Session 5:  Advances in Dynamo Modeling: Flux-Transport Dynamos and Flux Emergence
9:00-9:25Metcalf Award Lecture: Bidya Karak, “Flux Transport Dynamo Models: Fluctuations and Grand Minima”
9:25-9:50Invited: Andrés Münoz-Jaramillo, “Modeling Active Region Emergence in 3D Flux-Transport Solar Dynamos
9:50-10:10Contributed: Robert Cameron, “The Importance of Surface Magnetic Fields to the Solar Dynamo”
10:10-10:30Contributed: Gopal Hazra, “Is the Deep One-Cell Meridional Circulation Essential for the Flux-Transport Solar Dynamo?”
10:30-11:00Coffee Break and poster viewing
11:00-11:20Contributed: Alexander Kosovichev, “Dynamo Models with Double-Cell Meridional Circulation”
11:20-11:40Contributed: Alexandre Lemerle, “A 2DX2D Babcock-Leighton Dynamo Model
11:40-12:00Contributed: Maria Weber, “Magnetic Flux Tubes in the Turbulent Solar Interior: Linking Fibril Magnetic Fields with Active Regions”
12:00-1:15Lunch (NCAR Cafeteria, cash only)
 Session 5 (continued)
1:30-2:00Open Discussion: Led by Robert Cameron and Andres Munoz-Jaramillo
 Session 6: Data Assimilation in Dynamo Models
2:00-2:45Keynote: Alexandre Fournier, “Data Assimilation with 3D Models of the Earth’s Dynamo
2:45-3:10Invited: Olivier Talagrand, “A Few Basics about Data Assimilation: Principles and Methods”
3:10-3:35Invited: Laurene Jouve, “Variational Data Assimilation as a Tool to Better Understand Solar Magnetism
3:35-4:05Coffee Break and taking down posters
4:05-4:30Invited: C. Nick Arge, “Estimating the Global Solar Photospheric Magnetic Field Distribution using the ADAPT Model”
4:30-4:55Invited: Irina Kitiashvili, “Data Assimilation Approach for Prediction of Solar Activity Cycles”
4:55-5:15Contributed: Mei Zhang, “Helicity Observations as a Constraint on Solar Dynamo Models”
5:15-6:00Open Discussion: Led by Sacha Brun and Mausumi Dikpati
6:15 PMShuttle departs to Hotels
Friday, June 12
8:30 AMBus departs from the Holiday Inn Express (arrival time 8:45)
 Session 7:  The Solar-Stellar Connection
9:00-9:45Keynote: Moira Jardine, “Magnetic Activity of Intermediate and Low-Mass Stars
9:45-10:10Invited: William Chaplin, “Inferences on the Solar-Stellar Connection and Stellar Activity from Space-Based Photometry
10:10-10:35Invited: Tim Reinhold, “Rotation and Differential Rotation in the Kepler Era
10:35-10:55Coffee Break
10:55-11:20Invited: Kyle Augustson, “Superequipartition Convective Dynamos in Massive Stars”
11:20-11:40Contributed: Corrine Simard, “Non-Kinematic α2-Ω Mean-Field Dynamo Model”
11:40-12:45Lunch (NCAR Cafeteria, cash only)
 Session 7 (continued)
12:45-1:10Invited: Matthew Browning, “Magnetic Field Generation in Fully Convective Stars”
1:10-1:30Contributed: Patrice Beaudoin, “Double Dynamo Signatures in a Global MHD Simulation and Mean-Field Dynamos
1:30-1:50Contributed: Paul Bushby, “Convectively-Driven Dynamo Action in the Quiet Sun
1:50-2:10Coffee Break
2:10-2:50Open Discussion: Led by Ben Brown and Moira Jardine
 Session 8: Perspectives and Outlook
2:50-3:15Invited: Matthias Rempel, “The Future of Dynamo Modeling”
3:15-3:40Invited: Laurent Gizon, “Perspectives in Helioseismology”
3:40-4:20Open Discussion: Led by Paul Charbonneau and Jesper Schou
4:20 PMWorkshop Adjourns
4:30 PMShuttle departs to Hotels

Charles ArgeUSAF/AFRl
Kyle AugustsonHAO/NCAR
Patrice BeaudoinUniversité de Montréal
Amitava BhattacharjeePrinceton University
Axel BrandenburgMontana State
Matthew BrowningUniversity of Exerter
Allan Sacha BrunAIM/SAp - CEA Saclay
Paul BushbyNewcastle Universitym Mathematics/Statistics
Robert CameronMax-Planck-Institut fur Sonnensystemforschung
Bill ChaplinUniversity of Birmingham
Paul CharbonneauUniversité de Montréal
Ruizhu ChenStanford University
Dean-Yi ChouNational Tsing Hua University
Jean-Francois CossetteLASP/CU
Marc DeRosaLockheed Martin Solar and Astrophysics Laboratory
Tom DuvallMax-Planck-Institut fur Sonnensystemforschung
Zahida EhsanCOMSATS IIT Lahore
Yuhong FanHAO/NCAR
Nicholas FeatherstoneJILA, University of Colorado
Alexandre FournierInstitut de Physique du Globe de Paris
Yori FournierLeibniz-Institut für Astrophysik Potsdam (AIP)
Kinfe GebreegzabiharAddis Ababa University
Laurent GizonMax-Planck-Institut fur Sonnensystemforschung
Benjamin GreerJILA, University of Colorado
Gustavo GuerreroUniversidade Federal de Minas Gerais
Lee GundersonPPPL (Princeton Plasma Physics Laboratory)
Shravan HanasogeTata Institute of Fundamental Research
David HathawayNASA/Ames
Gopal HazraIndian Institute of Science
Bradley HindmanJILA, University of Colorado
Hideyuki HottaHAO/NCAR
Jason JackiewiczNew Mexico State University
Moira JardineUniversity of St Andrews
Laurene JouveIRAP, Observatoire Midi-Pyrénées
Petri KäpyläUniversity of Helsinki
Bidya Binay KarakNORDITA
Irina KitiashviliNASA Ames Research Center
Rudolf KommNational Solar Observatory
Alexander KosovichevNew Jersey Institute of Technology
Alexandre LemerleUniversité de Montréal
Sushant MahajanGeorgia State University
Valentin Martinez PilletNational Solar Observatory
Youhei MasadaNational Aichi University of Education
Bruce McDonaldNASA
Mark MieschHAO/NCAR
Andres MunozMontana State
Dibyendu NandiCenter of Excellence in Space Sciences
Nicholas NelsonLANL (Los Alamos National Lab)
Aimee NortonStanford University
Ryan OrvedahlJILA
Ethan PetersonUniversity of Wisconsin
Paul RajaguruIndian Institute of Astrophysics
Anthony RascaNaval Research Laboratory
Timo ReinholdInstitut für Astrophysik Göttingen
Matthias RempelHAO/NCAR
Markus RothKiepenheuer-Institut für Sonnenphysik
Phil ScherrerStanford University
Brigette SchmiederLESIA, Observatoire de Paris,CNRS
Jesper SchouMax-Planck-Institut fur Sonnensystemforschung
Ariane SchadKiepenheuer-Institut für Sonnenphysik
Corinne SimardUniversité de Montréal
Nishant SinghAstrophysics and Astrobiology
Philip SlaymakerSlaymaker Engineering and Research
 Robert SteinMIchigan State University
Andrey StejkoNew Jersey Institute of Technology
Antoine StrugarekUniversité de Montréal
Xudong SunStanford University
Olivier TalagrandLaboratoire de Météorologie Dynamique, CNRS
Michael ThompsonHAO/NCAR  (maybe for reception)
Juri ToomreJILA, University of Colorado
Lisa Upton 
S. Pavai ValliappanLeibniz Institute for Astrophysics
Virendra VermaUttrakhand Space Application Center
Junfeng WangGeorge Washington University & HAO/NCAR
Jörn WarneckeMax-Planck-Institut fur Sonnensystemforschung
Maria WeberUniversity of Exeter
Martin WoodardNorthWest Research Associates
Mei ZhangNatl. Astronomical Observatories & HAO/NCAR
Junwei ZhaoStanford University

The NASA LWS Workshop on Solar Dynamo Frontiers will be held at NCAR's Foothills Lab 2 (3450 Mitchell Lane) in the Main Auditorium. Registration will occur and posters will be exhibited in the Cafeteria Atrium nearby. Foothills Lab (FL) is located in Northeast Boulder, walking distance to HAO (Center Green).

For your convenience, lunch is available every day at the FL2 cafeteria:

You will need cash to purchase lunch. There is a variety of main dishes, soups, and a salad bar. Lunches typically cost from $4.00 to $8.00 depending on your meal choice. Cafeteria menu example.

Driving directions:


Airport ground transportation at the Denver International Airport:

Ground transportation desks are located at the top of the escalator after you exit the terminal train. Both shuttle services provide shared vans to hotels or requested drop-off locations. If you are coming directly to the workshop, have the driver take you to the FL2 (Foothills Lab 2) building, 3450 Mitchell Lane. If you are returning to the airport Friday after the workshop, you can arrange to be picked up at the same location.

Shuttle Services to/from DIA Airport (Please book your own shuttle online):
  • Scroll to bottom and click Make Your Reservation Now
  • Scroll to bottom and enter discount code “ncarucar” and GO
  • Pickup location – select FOOTHILLS LAB (BUILDING 2)
  • Fill out other information as appropriate and CONTINUE
  • Eventually you will be asked for a credit card
  • The link will take you directly to the Group Discount for NCAR. You will see the discount code “NCAR1” is already filled in.

Transportation to/from workshop:

We provide a bus from the Holiday Inn hotel to the workshop and back beginning Tuesday, June 9 through Friday, June 12. If you miss the shuttle, call Boulder taxi (303) 777-7777. For those of you staying at other Boulder hotels we are providing a map of the NCAR shuttle route and stops. You can walk to the nearest stop location. Link to NCAR shuttle schedule.

Shuttle Stops image

Parking at the workshop:
Free parking is available in front of the building at 3450 Mitchell Lane or in any of the surrounding parking lots; no permit is required. When you drive down Mitchell Lane, the building is straight ahead when you come to the stop sign at the t-junction.

For your return trip to the Denver Airport you can take a public Bus (RTD):

  • Take the free UCAR Shuttle to Table Mesa Park & Ride
  • At the Table Mesa Park & Ride, get on the& AB or ABA bus to DIA (Denver International Airport)
  • The bus is $13 cash EXACT CHANGE (the front desk may have change); no reservation is necessary

bus schedule