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Deng, Welling using $652K NASA grant to study space weather’s impact on power grids

Yue Deng, left, and Daniel Welling
Yue Deng, left, and Daniel Welling

A team led by University of Texas at Arlington physicists is studying the impact of space weather, particularly the effect that solar-induced phenomena can have on electrical power grids.

Yue Deng, UTA distinguished professor of physics, is principal investigator for the project, titled “Advances in numerical simulations for resolving multi-scale geomagnetic disturbances.” The work is being funded by a four-year, $652,409 grant from NASA through its Heliophysics Living With a Star (H-LWS) program. She is joined by Daniel Welling, UTA assistant professor of physics, and Sheng Cheng, a research engineer scientist in Deng’s lab.

Deng also recently secured an additional $1.5 million in funding to continue the Multidisciplinary University Research Initiative (MURI) project she is leading. The study, funded by the Air Force Office of Scientific Research, is titled “Next Generation Advances in Ionosphere Thermosphere Coupling at Multiple Scales for Environmental Specification and Prediction.” The original five-year MURI grant of $7.3 million was made in 2016, and the latest round of funding brings the project’s total to ~$9 million.

NASA Living With a Star project

The NASA project’s goal is to use a system of numerical computer models to allow scientists to better understand how space weather affects changes in the Earth's magnetic field.

Geomagnetically induced currents (GICs) can result from geomagnetic storms — a type of space weather event in which the Earth’s magnetic field is rattled by incoming magnetic solar material, creating geoelectric fields. Most GICs are caused by coronal mass ejections, which interact with the Earth’s magnetic field and cause it to shake. Rapid changes in magnetic fields create GICs through a process called electromagnetic induction.

“In our study we hope to improve modeling of geomagnetic disturbances and the geoelectric field during disturbed periods and to improve our understanding of the role of solar wind, magnetosphere, ionosphere and thermosphere in driving geomagnetic variation and the geoelectric field,” Deng said.

GICs can flow through any long metal structures, including railroad tracks, underground pipelines, and power grids. While usually they are not likely to cause widespread permanent damage to power grids, in extreme cases – such as during geomagnetic super storms – GICs can cause blackouts over large areas.

“While geoelectric fields are very weak and have no effect on you and me, if they align with long, ground-based conductors, such as power grid lines, it can produce strong DC currents, which are called GICs. The power grid was never meant to handle such currents and can be knocked out of service under the right conditions,” Welling said.

“Space activity is the driver of GICs, but a big factor is the Earth itself – the crust is a mix of conducting and resistive regions. How and where geoelectric fields and GICs form depends on the space driver and the profile of the Earth’s electric conductivity below a set of power lines. It’s a very complicated problem.”

In recent years, progress has been made in observations and simulations to improve scientists’ understanding of GICs. The ground conductivity model, which plays a crucial role in estimating the geoelectric field from geomagnetic disturbances, has been improved from a one-dimensional to a three-dimensional model. However, a thorough understanding of the impact of different processes on multi-scale geomagnetic disturbances is lacking.

In the course of their study, the researchers will address three topics. The first is determining the role of ionospheric and thermospheric processes in producing geomagnetic disturbances on the Earth’s surface. This will be accomplished through the use of magnetohydrodynamic (MHD)-general circulation model (GCM) numerical models with expanded coupling that includes thermospheric processes to examine disturbance generation and to compare with observations.

The second is discovering how the combined magnetosphere-ionosphere system produces geomagnetic disturbances of different spatial and temporal scales. This question will be studied using a high resolution MHD-GCM coupled model. This will explore processes leading to different scales of disturbances, including solar wind conditions, conductance and neutral-wind perturbations driven by atmospheric waves.

The third is finding out how magnetic perturbations manifest as geoelectric fields, and how much the Earth conductivity model affects this conversion. The team will examine the frequency dependence of geoelectric field conversion, break down the geoelectric field by its contributions from different geospace regions, and combine numerical results with one-dimensional and three-dimensional models of Earth’s conductivity.

The hot topic in the field is small-scale geoelectric fields: very strong, short-lived fields that are only observed within a region of around 200 km, Welling noted. These are difficult to predict because scientists don’t yet have a good understanding of how they are generated. They could be the result of small-scale activity in near-Earth outer space, small-scale structures in the high altitude atmosphere, the result of structures in the ground conductivity profile, or some combination of these.

“Our project looks to explore all of these factors at once through a system of numerical computer models,” Welling said. “We’re taking new steps to develop our computer models to not only resolve small-scale activity, but include feedback processes between near-Earth space and the upper atmosphere. Many of these steps have never been taken before, so we’re very excited at what we’ll find.”

The UTA team is collaborating with Los Alamos National Laboratory to better understand the role of the Earth’s crust in the calculations.

“It is essential to understand the magnetospheric and ionospheric processes responsible for geomagnetic disturbances during space weather events in order to improve the preparedness of society to the impact of space weather,” Deng said.

Added Welling, “In a nut shell, it all comes down to the impact of space weather – solar flares and coronal mass ejections – on the ground, particularly on the power grid. This is a huge and critical area of research. Being able to predict geoelectric fields and GICs is now an issue of national security. We’re improving models that are currently used to forecast space weather, but are not yet capable of forecasting small-scale structures reliably.”

“This study will help to make important advances in our understanding of how space weather affects processes on Earth that can have a critical impact on our infrastructure,” said Alex Weiss, professor and chair of the UTA Department of Physics. “This work by Dr. Deng and her colleagues is another example of the outstanding and growing role UTA’s physics department plays in the field of space weather.”

MURI space weather simulator project

The goal of the MURI project is to develop a next-generation space weather simulator capable of predicting how energy is distributed during events such as solar flares and magnetic storms.

Deng is lead investigator of the study, which includes space physicists from the University of California at Los Angeles; Johns Hopkins University; Massachusetts Institute of Technology; University of Colorado at Boulder; University of New Mexico; University of Texas at Dallas; and Penn State University.

“We have completed a robust description of mesoscale features and developed capabilities to specify and simulate those features,” Deng said. “Through that research, we identified new and interesting topics that can be achieved by applying our findings, and some tasks which need additional time to complete. Thus we proposed a one-year extension and received additional funds to support the new efforts, which will allow us to pursue consequences of new basic concepts of multiscale features that were previously discovered during the project and can substantially add to what was conceived in the original MURI proposal.”

One area of research which will be supported by the additional $1.5 million in funding is the study of new features discovered earlier in the project: dawnside auroral polarization streams (DAPS), and azimuthal expansion of a flow channel.

DAPS is a type of ionospheric plasma flow that may be important to the circulation of plasma in the magnetosphere, ionospheric heating, and energy transport in the magnetosphere‐ionosphere system. Azimuth refers to the horizontal angular distance from a reference direction; azimuthal expansion of a flow channel is a step in the growth of substorms – processes in the magnetosphere‐ionosphere coupled system where energy is stored and abruptly released.

Deng and her team will study these newly discovered phenomena using ground-based radar, two-dimensional auroral structural observations, and the Rice Convection Model-Global Ionosphere and Thermosphere Model (RCM-GITM).

“These phenomena would be expected to have a major impact on the ionosphere-thermosphere system that has not yet been evaluated from either models or observations,” Deng said.

The scientists will also develop deep learning techniques to detect and characterize the change of patterns in traveling ionospheric disturbances (TIDs), which will fill in major gaps in the description of multiscale features in TID patterns and represent a major breakthrough for measuring disturbances in motion in the ionosphere. Another goal is the creation of a new empirical model of the large-scale convective flows that extend beyond the auroral zone and into the plasmasphere.