Science Success Story
XSEDE Allocations Lead to Better Understanding of Geomagnetic Storm Research
UCLA Researchers Utilize SDSC Resources for Solar Wind Study
By Kimberly Mann Bruch, SDSC Communications
|Artist's concept of the Parker Solar Probe spacecraft approaching the sun. Launched in 2018, the Parker Solar Probe provides data on solar activity and makes critical contributions to the ability to forecast major space-weather events that impact life on Earth. Credit: NASA|
Both satellite and ground-based telecommunications systems can be impacted by geomagnetic storms, such as the one triggered by a powerful explosion on the surface of the sun that took down a Canadian power grid back in 1989. To better understand such strong, mysterious storms – which occur infrequently while other smaller storms occur more regularly – a team of scientists at UCLA recently completed a comparative study between satellite data collected by NASA's Parker Solar Probe and numerical simulations from Comet at the San Diego Supercomputer Center (SDSC) at UC San Diego.
The UCLA research team used XSEDE allocations on Comet to confirm that the shear between two solar wind streams of different speeds has a significant impact on the characteristics of turbulence, such as the energy levels and how the energy is distributed among different physical quantities. Importantly, their simulations on Comet agreed with satellite data collected by the Parker Solar Probe.
Recently published in Astronomy and Astrophysics and the Astrophysical Journal, the Comet-generated simulations help scientists better understand how solar wind is heated to such a high temperature (sometimes above one-million degrees) as well as how solar wind is accelerated to very high speeds (often faster than one-thousand miles per second). In turn, this information can help with solar wind forecasting.
"Our simulations not only agreed with the satellite data, but also provide detailed information not possible to obtain from the single-point satellite measurement," said Chen Shi, a postdoctoral scholar in the Earth, Planetary and Space Sciences Department at UCLA. "The Comet simulations can provide global information on most of the structures and processes happening in the heliosphere while the satellites only observe specific points in space. For example, the satellite gives us limited information while the simulations give us global information, which can lead to better insight on geomagnetic storms and allow us to forecast and prepare for those."
Our project helps answer the question of how plasma turbulence evolves in the solar wind and these studies are crucial to understanding a couple of the most fundamental physical processes in the field of heliophysics, such as Alfvénicity (a property of magnetohydrodynamic fluctuations in plasma physics), solar wind temperature and speed, and we are only able to accomplish our work with the help of supercomputers like Comet. — Chen Shi, postdoctoral scholar in the UCLA Earth, Planetary and Space Sciences Department
Shi further explained that the solar wind, when it impacts the Earth's magnetic field, can produce currents that flow in both outer space and on the ground. "If we can predict the fluctuations in the solar wind and how they interact with other solar processes, we can better prepare for magnetic storms caused by the turbulence that can interfere with satellite and ground-based telecommunications," he said. "Our project helps answer the question of how plasma turbulence evolves in the solar wind and these studies are crucial to understanding a couple of the most fundamental physical processes in the field of heliophysics, such as Alfvénicity (a property of magnetohydrodynamic fluctuations in plasma physics), solar wind temperature and speed, and we are only able to accomplish our work with the help of supercomputers like Comet."
Why is Alfvenicity Important?
|This Comet-generated figure shows the evolution of the fluctuation amplitude in the solar wind calculated by a 2D magnetohydrodynamic simulation run on Comet. The stream shears (at y'~0.25 and 0.75) deform the shape of the wavefront of the fluctuations and facilitate the dissipation of the fluctuation energies. Credit: Chen Shi, UCLA|
Alfvénicity, a term that defines the level of alignment between magnetic fluctuations and velocity fluctuations, was named in honor of UC San Diego Nobel Laureate Hannes Alfvén (1908-1995) – regarded by many as the father of the fundamental physics discipline coined magnetohydrodynamics, the study of plasmas in magnetic fields. Alfvén's studies were some of the first regarding magnetic storms, and turbulence forecasting has become more prevalent as scientists have come to realize that the solar wind not only can have a negative impact on satellites, space apparatus and even astronauts, but also can create magnetic storms that threaten ground electronics on Earth.
What would Alfvén think of the Parker Solar Probe, which was launched in 2018, so close to the sun that it is able to measure Alfvénicity in the very nascent solar wind? And, how did Shi's project show that faster solar wind has higher Alfvénicity?
"We found a more dominant outward propagating wave component and more balanced magnetic and kinetic energies in the solar wind with larger speed," Shi explained. "Meanwhile the slow wind that originates near the polar coronal holes has much lower Alfvénicity compared with the slow wind that originates from the active regions."
These findings lead to a deeper understanding of the processes that occur in solar winds and can help to improve the models and forecasts.
How XSEDE Helped
To accomplish this large-scale, high-performance computation project, Shi said that the team received a great deal of assistance from the XSEDE support team on ways to improve the scalability of their code. "The SDSC computational team gave us advice on improved ways to run our numerical simulations on Comet, which provided us with the necessary resources to conduct our study," said Shi. "More and more researchers are viewing numerical simulations as an extremely helpful and necessary method to study heliophysics and plasma physics – we are fortunate to have access to supercomputers like Comet alongside the support staff that allows us to accomplish our research goals."
Because the Comet-generated two-dimensional data closely agreed with the observations collected by the Parker Solar Probe, the team now has developed plans for additional studies that encompass three-dimensional simulations. And, while the Parker Solar Probe continues to lower its orbit toward the sun, the researchers have already started working on their next set of calculations and plan on using additional supercomputing resources to complete their future exploration of solar wind in both two-dimensional and three-dimensional illustrations.
This research was funded in part by the FIELDS experiment on the Parker Solar Probe spacecraft, designed and developed under NASA (contract NNN06AA01C) and the NASA Parker Solar Probe Observatory Scientist (grant NNX15AF34G). Computational work on Comet was completed via XSEDE (allocation TG-AST200031).
San Diego Supercomputer Center: https://www.sdsc.edu/
UC San Diego: https://ucsd.edu/
National Science Foundation: https://www.nsf.gov/
At a Glance:
- UCLA researchers used XSEDE allocations to run numerical simulations on SDSC's Comet to better understand geomagnetic storms.
- Data from NASA's Parker Solar Probe was validated with the supercomputer illustrations.
- Results were published in Astronomy and Astrophysics and the Astrophysical Journal.