In which direction is the solar wind blowing? Supercomputers improve space weather forecasting

(Top panel, left to right) July 12, 2012 Coronal mass ejection observed on the STEREO B Cor2, SOHO C2 and STEREO A Cor2 coronographs, respectively. (Bottom panel) The same images overlapped with the model results. Credit: Talwinder Singh, Mehmet S. Yalim, Nikolai V. Pogorelov and Nat Gopalswamy

Using supercomputers, researchers are developing new software to improve space weather forecasts.

The sun’s surface boils with energy and frequently ejects masses of highly magnetized particles plasma towards Earth. Sometimes these ejections are strong enough to pass through the magnetosphere – the natural magnetic shield that protects the Earth – damaging satellites or power grids. Such space weather events can be catastrophic.

Astronomers have studied the activity of the sun for centuries with increasing understanding. Today, computers are at the heart of the quest to understand the behavior of the sun and its role in space weather events.

The bipartite PROSWIFT (Promoting Research and Observations of Space Weather to Improve the Forecasting of Tomorrow) law, promulgated in October 2020, formalizes the need to develop better space weather forecasting tools.

“Space weather requires a real-time product so that we can predict impacts before an event, not just after,” said Nikolai Pogorelov, distinguished professor of space science at the University of Alabama in Huntsville, who used computers to study space weather for decades. “This topic – related to national space programs, the environment and other issues – has recently been taken to the next level.”

To many, space weather may seem like a distant concern, but like a pandemic – something we knew was possible and catastrophic – we might not realize its dangers until it’s too late.

“We don’t think about it, but electrical communications, GPS and everyday gadgets can be affected by extreme space weather effects,” Pogorelov said.

In addition, the United States is planning missions to other planets and the moon. All of this will require very accurate predictions of space weather – for designing spacecraft and for alerting astronauts to extreme events.

With funding from the National Science Foundation (NSF) and Nasa, Pogorelov leads a team that strives to improve the state of the art in space weather forecasting.

Threaded coronal mass ejection by magnetic field lines

The coronal mass ejection spun by magnetic field lines in the equatorial slice colored by the temperature of the plasma. Credit: Space Weather April 2020 (DOI: 10.1029 / 2019SW002405), American Geophysical Union

“This research, combining complex science, advanced computation and exciting observations, will advance our understanding of how the Sun determines space weather and its effects on Earth,” said Mangala Sharma, program director for space weather at the NSF Atmospheric and Geospatial Sciences Division. “The work will help scientists predict space weather events and build our country’s resilience against these potential natural hazards. “

The multi-institutional effort involves NASA’s Goddard and Marshall Space Flight Centers, the Lawrence Berkeley National Laboratory, and two private companies, Predictive Science Inc. and Space Systems Research Corporation.

To improve the models and methods at the heart of space weather forecasting.

Turbulence plays a key role in the dynamics of solar wind and coronal mass ejections. This complex phenomenon has many facets, including the role of the shock-turbulence interaction and the acceleration of ions.

“Solar plasma is not in thermal equilibrium. It creates some cool features, ”Pogorelov said.

Write in the Astrophysics Journal in April 2021, Pogorelov, with Michael Gedalin (Ben-Gurion University of the Negev, Israel) and Vadim Roytershteyn (Space Science Institute) described the role of return pickup ions in the acceleration of charged particles in the universe. Return ions, of interstellar or local origin, are captured by the magnetized plasma of the solar wind and move radially outward from the Sun.

“Certain non-thermal particles can be further accelerated to create solar energetic particles that are particularly important for space weather conditions on Earth and for people in space,” he said.

Pogorelov performed simulations on Frontera to better understand this phenomenon and compare it with observations from Voyager 1 and 2, the spacecraft that explored the far reaches of the heliosphere and now provides unique data from the local interstellar medium.

One of the main purposes of space weather forecasting is to correctly predict the arrival of coronal mass ejections – the release of plasma and the accompanying magnetic field from the solar corona – and to determine the direction of the magnetic field. that it leads. The study by Pogorelov’s team on repression ions contributes to this, as does the work published in the Astrophysics Journal in 2020 who used a flux cable-based magnetohydrodynamic model to predict the time of arrival on Earth and the magnetic field configuration of the coronal mass ejection of July 12, 2012. (Magnetohydrodynamics refers to magnetic properties and the behavior of electrically conductive fluids such as plasma, which plays a key role in the dynamics of space weather).

Simulation of coronal mass ejections

Configuration of the magnetic field line of the coronal mass ejection inserted at the inner limit R = 0.1 AU, shown with the red sphere. Credit: Talwinder Singh, Tae K. Kim, Nikolai V. Pogorelov and Charles N. Arge

“Fifteen years ago, we didn’t know much about the interstellar medium or the properties of the solar wind,” Pogorelov said. “We have so many observations available today that allow us to validate our codes and make them much more reliable.”

Pogorelov is a co-investigator on an embedded component of the Parker solar probe called SWEAP (Solar Wind Electrons, Protons, and Alphas instrument). With each orbit, the probe approaches the sun, providing new information about the characteristics of the solar wind.

“Soon it will penetrate beyond the critical sphere where the solar wind becomes ultra-fast magnetosonic, and we will have information on the physics of solar wind acceleration and transport that we never had before,” he said. -he declares.

As the probe and other new observational tools become available, Pogorelov anticipates a host of new data that can inform and drive the development of new models relevant to space weather forecasts. For this reason, alongside his fundamental research, Pogorelov is developing a flexible software framework that can be used by different research groups around the world and can integrate new observational data.

“There is no doubt that in the years to come, the data quality of the photosphere and the solar corona will be considerably improved, both because of the new data available and the new and more sophisticated ways of working with the data”, a- he declared. “We’re trying to create software in such a way that if a user comes up with better boundary conditions from new science missions, it will be easier for them to integrate that information. “

The references:

“Backstreaming Pickup Ions” by Michael Gedalin, Nikolai V. Pogorelov and Vadim Roytershteyn, April 2, 2021, Astrophysics Journal.
DOI: 10.3847 / 1538-4357 / abe62c

“A modified Spheromak model suitable for coronal mass ejection simulations” by Talwinder Singh, Mehmet S. Yalim, Nikolai V. Pogorelov and Nat Gopalswamy, May 5, 2020, Astrophysics Journal.
DOI: 10.3847 / 1538-4357 / ab845f

“Application of a Modified Spheromak Model to Coronal Mass Ejection Simulations in the Inner Heliosphere” by Talwinder Singh, Tae K. Kim, Nikolai V. Pogorelov and Charles N. Arge, April 23, 2020, Space weather.
DOI: 10.1029 / 2019SW002405


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