Research Highlights

Research Highlights

A selection of highlights culled from publications by HAO staff.

Erupting magnetic flux rope

Comprehensive Radiative MHD Simulations of Eruptive Flares above Collisional Polarity Inversion Lines

Matthias Rempel, Georgios Chintzoglou, Mark C. M. Cheung, Yuhong Fan, and Lucia Kleint present a new simulation setup using the MURaM radiative Magnetohydrodynamic (MHD) code that allows to study the formation of collisional polarity inversion lines (cPILs) in the photosphere and the coronal response including flares. In this scheme we start with a bipolar sunspot configuration and set the spots on collision course by imposing the appropriate velocity field at the footpoints in the subphotospheric boundary.

CR synoptic map are plotted as purple and green dots

The Polar Field Reversal Process over Five Solar Cycles

D. F. Webb, B. A. Emery, S. E. Gibson, I. M. Hewins, R. H. McFadden , T. A. Kuchar examine the process during which the solar magnetic field reverses polarity around solar maximum using the McIntosh Archive (McA) of solar synoptic maps over five consecutive solar cycles, SCs 19-23 or from 1955 to 2009. This data set permits us to track features such as filaments, polarity inversion lines (PILs), coronal hole (CH) boundaries and sunspots over many consecutive Carrington rotations and solar cycles.

Magnetic Reconnection

The Sun's Alfvén Surface: Recent Insights and Prospects for the Polarimeter to Unify the Corona and Heliosphere (PUNCH)

Sarah Gibson et al., review the properties of an irregularly shaped “Alfvén surface” surface and discuss its importance in models of solar wind acceleration, angular momentum transport, MHD waves and turbulence, and the geometry of closed coronal loops. We also review the results of simulations and data analysis techniques that aim to determine the location of the Alfvén surface.

WACCM-X Rayleigh-Taylor (R-T)

Quasi 6-Day Planetary Wave Oscillations in Equatorial Plasma Irregularities

N. M. Pedatella, E. Aa, and A. Maute explore the influence of atmospheric planetary waves on the occurrence of irregularities in the low latitude ionosphere is investigated using Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (WACCM-X) simulations and Global Observations of the Limb and Disk (GOLD) observations. 

Cycling magnetic behavior

Inflows towards Bipolar Magnetic Active Regions and Their Nonlinear Impact on a Three-Dimensional Babcock-Leighton Solar Dynamo Model

Kinfe Teweldebirhan, Mark Miesch, and Sarah Gibson investigate the role and impact of converging flows toward Bipolar Magnetic Regions (BMR inflows) on the Sun’s global solar dynamo. These flows are large-scale physical phenomena that have been observed and so should be included in any comprehensive solar dynamo model.

McInerney WACCMX climate observations

Climate Change in the Thermosphere and Ionosphere From the Early Twentieth Century to Early Twenty‐First Century Simulated by the Whole Atmosphere Community Climate Model—eXtended

Authors Joseph McInerney, Liying Qian, Han-Li Liu, Stanley Solomon, and Susan Nossal decided to apply the WACCM-X climate model to the upper atmosphere for the decades from the 1920s to 2010s. This type of modeling application will be useful to predict what will happen in the century ahead as greenhouse gases increase and humans make efforts to reverse the increase.

Residual mean meridional wind

Impacts of gravity waves on the thermospheric circulation and composition

Hanli Liu, Peter Lauritzen, and Francis Vitt use the high-resolution whole atmosphere model to study small-scale wave propagation from the lower atmosphere into the thermosphere. Using this high-resolution model, which can partially resolve the small-scale waves, they can directly quantify the force exerted by these waves on the general circulation in the thermosphere.

Mapping the Sun’s Alfvén Surface with PUNCH

Steven Cranmer, Rohit Chhiber, Chris Gilly, Iver Cairns, Robin Colaninno, David McComas, Nour Raouafi, Arcadi Usmanov, Sarah Gibson, Craig DeForest review the properties of Alfvén surface and discuss its importance in models of solar wind acceleration, angular momentum transport, MHD waves and turbulence, and the geometry of closed coronal loops. Simulations results and data analysis techniques are used to determine the location of the Alfvén surface.

Evolution of the magnetic fields (left) and helicity density (right) for AR 12673

Deciphering Pre-solar-storm Features Of September-2017 Storm From Global And Local Dynamics

B. Raphaldini, M. Dikpati, A. A. Norton, A. S. W. Teruya, S. W. McIntosh, C. B. Prior, and D. MacTaggart investigate how global toroid patterns and local magnetic field topology of solar active region AR12673 together can hindcast occurrence of the biggest X-flare of cycle 24. We infer that minimum-phase storms can be forecast only hours ahead, while flare-prone active regions in peak-phase can be anticipated at least a month ahead from global toroid patterns.