Wang receives NSF grant to study effects of electromagnetic storms

Wednesday, Nov 13, 2024 • Greg Pederson :

Zihan Wang, UTA assistant professor of physics

A physicist at The University of Texas at Arlington is using a federal grant to study changes in the number of electrons in the upper atmosphere during solar flares to learn how to better mitigate the effect of solar flares on communication systems and navigation technology.

Zihan Wang, assistant professor of physics, received a three-year, $348,238 grant from the National Science Foundation Division of Atmospheric and Geospace Sciences for the project, which is titled “Collaborative Research: Evolution of the Global Total Electron Contents (TEC) during Solar Flares”. Two physics undergraduate students in Wang’s lab, Christa Sadeghian and Sudip Dhungel, are assisting with the project.

Solar flares are large eruptions of electromagnetic radiation from the Sun which can last from minutes to hours. They can cause enhanced ionization in the upper atmosphere on a global scale, and this can affect power grids, communication systems including satellites and radio systems, and global navigation systems.

The ionosphere is the layer of Earth’s atmosphere which is ionized by solar radiation. The Total Electron Content (TEC) is the total number of electrons present along a path between a radio transmitter and receiver. Radio waves are affected by the presence of electrons — the more electrons there are in the path of the radio wave, the more the radio signal will be affected. For ground to satellite communication and satellite navigation, TEC is a good parameter to monitor for possible space weather impacts.

Present understanding of solar flare variations is elusive and makes forecasting difficult, Wang said. The Sun’s activity level is measured in solar cycles, each of which lasts approximately 11 years. The present cycle is the 25^th since measurements began in 1755 with the recording of sunspot activity. Solar Cycle 25 started in 2019 and is approaching its maximum, when solar flares are more frequent and more intense.

“The project’s overarching science goal is to investigate the evolutions of the global ionospheric TEC during solar flares and to improve our ability to predict the responses of the global TEC to solar flares,” Wang said. “The results of this project will significantly deepen our understanding of flare-to-flare variations in the upper atmosphere and improve our predictability of the global upper atmosphere during solar flares.”

“The work Dr. Wang and his team are doing in this project has great potential to significantly improve our knowledge of solar flares and how they affect an array of technologies,” said Alex Weiss, professor and chair of the UTA Department of Physics. “This grant is further evidence of the strength of our space weather program and the stellar reputation it has in the science community.”

The project will specifically address three questions: (1) What is the temporal evolution of the global TEC during solar flares? (2) How do the different phases of solar flares impact the responses of the global TEC? (3) How can we predict the response of global TEC to solar flares using machine learning (ML) models?

The first question will be addressed by conducting detailed data analysis to investigate the responses of the TEC to solar flares using TEC data from worldwide Global Navigation Satellite System (GNSS) receivers. The solar spectral irradiance, or power per unit area received from the Sun, during solar flares will be derived from empirical models, such as the Flare Irradiance Spectral Model‐Version 2 (FISM2), or from observations such as the Solar Dynamics Observatory’s (SDO) Extreme ultraviolet Variability Experiment (EVE).

To answer the second question, the team will use state-of-the-art, physics-based numerical models, such as the Global Ionosphere-Thermosphere Model (GITM), to investigate responses of the TEC during different phases of solar flares, especially the extreme ultraviolet (EUV) late phase and coronal dimming. GITM is a three-dimensional model that allows scientists to simulate the near-Earth space environment using a stretched grid in latitude and altitude. It was created in 2006 by Yue Deng, UTA professor of physics, and Aaron Ridley, professor of climate and space sciences at the University of Michigan.

The third question will be addressed through the development of machine learning models which will predict the global TEC responses to solar flares.

“With this project, we will build the first-ever machine learning models to quantitatively predict the impact of solar flares on the global ionospheric TEC,” Wang said. “We will also improve current numerical models to investigate the effect of different phases of flares. This project can help mitigate the impact of solar flares on our technological society.”

Wang joined the UTA Department of Physics last fall after working as a postdoctoral research fellow at the University of Michigan from 2021-23. He earned his Ph.D. in Space Science from the University of Michigan in 2021.

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