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Visualization Solves Solar Wind Mystery
What happens when high velocity (400 km/s) solar winds meet the magnetic field of the planet Mercury? Thanks to a visualization by University of Alberta researchers, powered by WestGrid computing resources, a phenomenom that has puzzled scientists for four years finally has an explanation.
University of Alberta doctoral student, Jan Paral, and University of Alberta Physics Professor, Robert Rankin, combined satellite data with observations from NASA’s MESSENGER spacecraft to create a one-of-a-kind simulation that explains a mysterious interaction between solar winds and the planet’s magnetic field. Their results were recently published in Nature Communications.
According to Paral and Rankin's study, MESSENGER first observed "sawtooth patterns in the magnetic field" on its approach to Mercury in 2009. Scientsts were puzzled by this solar wind behaviour, as it was unlike anything that happens around Earth's magnetic field.
Global kinetic hybrid simulations were used to explain the observations of large-scale vortices forming exclusively on the dusk side of Mercury's magnetosphere. The results show that vortices are excited by a Kelvin–Helmholtz instability near the subsolar point, which grows convectively along the dusk-side magnetopause. Virtual time series along a track approximating a flyby of the MESSENGER show correspondence with the satellite data; the data contain sawtooth oscillations in plasma density, flow and magnetic field, and exhibit the observed dawn–dusk asymmetry.
The study was published following four years of Paral working with the data -- writing and fixing code, harnessing massive computational power, and integrating advanced data visualization software.
“One of my bigger simulations needed more than three billion particles pushed step by step, followed in space and time, to get the kind of result you see on the animation,” Paral said. “You need an enormous amount of resources to do that, for several days.”
Paral even spent time at IBM’s T.J. Watson Labs in New York optimizing and debugging his code and was given access to IBM’s BlueGene supercomputer for a majority of these computationally complex runs. Paral used WestGrid’s Jasper and Lattice clusters for some of the later runs.
Chris Want, a WestGrid programmer / analyst, also assisted with the visualization component, using WestGrid computing resources to render some of the simulation's final animations.