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Welling using NASA grant to study changes in Earth’s equatorial electrical field

Dan Welling
Dan Welling

A physicist from The University of Texas at Arlington is collaborating on a project designed to discover the reasons for changes in Earth’s equatorial electrical field during periods of increased solar storm activity.

Dan Welling, assistant professor of physics, is a co-investigator for the study, titled “Quantifying the variability of equatorial electrodynamics during disturbed geomagnetic conditions using first-principle models” and funded by an $839,926 grant from NASA’s Living with a Star program. Welling received a $152,224 sub-grant for his work on the project.

Principal investigator is Tzu-Wei Fang, a research scientist in environmental sciences at the University Of Colorado at Boulder. The Living with a Star program focuses on the science necessary to understand aspects of the Sun and Earth's space environment that affect life and society.

“This study aims to extend our current understanding of equatorial electrodynamics, ionospheric changes, and neutral wind perturbation during geomagnetic storms,” Welling said. “The investigation will provide state-of-the-art models as powerful simulation tools to the focus team members.”

Previous studies have suggested that the tides and waves associated with terrestrial weather can contribute significantly to the day-to-day variability of the equatorial electric field under low solar activity and quiet geomagnetic conditions.

The project is using a coupled numerical modeling approach to study ionospheric conductance, which is a critical component of the Earth’s ionosphere-thermosphere (I-T) system. Conductivity is important in the study of the Earth-space environment because it influences the way that energy is deposited in the ionosphere and thermosphere.

The ionosphere is the layer of Earth's atmosphere that contains a high concentration of ions and free electrons and is able to reflect radio waves. It extends from about 50 to 600 miles above the Earth's surface.

“Our research team here at UTA will provide values from the magnetosphere-ionosphere system including radial current densities, estimations of precipitating particles and energy, and ionospheric electric potential,” Welling said. “We will obtain these values from the Space Weather Modeling Framework, a numerical modeling system developed and maintained by the University of Michigan with contributions from UTA. The simulations will be refined as necessary to improve agreement with observations.”

To better understand I-T system responses under storm conditions and their impact on equatorial electrodynamics, the researchers are seeking to answer four main questions:

(1) What are the temporal and spatial variations in equatorial electrodynamics under the impact of geomagnetic storms?

(2) What is the contribution of changes in ionospheric conductivity and thermosphere neutral winds in driving storm-time equatorial electrodynamics?

(3) How does lower atmosphere variability modulate the electrodynamic response to a geomagnetic storm?

(4) How well can we forecast the storm-time responses of the system using state-of-the-art models?

The team will use the Whole Atmosphere Model (WAM) and the Ionosphere Plasmasphere Model to quantify the relative roles of the disturbance dynamo and prompt penetration electric field. These will be combined with the Geospace model – which was created by the NOAA’s Space Weather Prediction Center and is driven by real-time solar wind data – to examine the forecast capability of predicting I-T conditions when geomagnetic activity increases.

By conducting WAM simulations under disturbed geomagnetic activity, the scientists will be better able to estimate the contributions of the disturbance dynamo and tides/waves from the lower atmosphere, and their impact on the equatorial electric field will be quantified. Simulated storm-time I-T changes and equatorial electrodynamics will be compared with observations from multiple satellites and ground-based measurements.

“Simulation results will provide a good estimation of storm-time electrodynamics and yield to a better understanding of the physics that connects the high-latitude drivers and low-latitude electrodynamics,” Welling said. “The comprehensive whole atmosphere-ionosphere model, combined with the well-described high-latitude electric field and energy inputs, will enable us to systematically analyze and quantify the impact of geomagnetic storms on the I-T system.”

Alex Weiss, professor and chair of the UTA Department of Physics, said that the study by Welling and his colleagues advances UTA’s commitment to data driven discovery, one of the main themes of the University’s Strategic Plan 2020.

“This project could expand scientists’ knowledge of how electromagnetic radiation from the sun can affect activity in Earth’s atmosphere and thus life on the planet,” Weiss said. “Dr. Welling’s work is another great example of the exemplary research being done in the Department of Physics.”

Welling came to UTA in Fall 2018 after spending six years as an assistant and associate research scientist in the Department of Climate and Space Sciences and Engineering at the University of Michigan at Ann Arbor. He earned a B.S. in Physics from Northern Michigan University in 2003 and a Ph.D. in Atmospheric and Space Sciences from the University of Michigan in 2009.