The College of Science is highlighting some of its Ph.D. students in honor of National Dissertation Day, which is April 26.
At the edge of the Earth’s atmosphere, where the planet gives way to space and satellites orbit, conditions are constantly shifting.
For Ben Martinez, that boundary is central to his research.
A Ph.D. candidate in the Clemson University Department of Physics and Astronomy, Martinez studies the upper atmosphere, a region that plays a critical but often invisible role in modern life. The conditions there can determine whether satellites stay in orbit, impact GPS navigation on Earth and disrupt space-based infrastructure.
Weather systems in the lower atmosphere, including storms on Earth’s surface, can alter conditions in the upper part of the atmosphere.
Weather predictions
Martinez’s research focuses on weather models that describe the lower atmosphere and couples them with ionosphere models of the upper atmosphere to extend weather predictions.
He was able to find a system that accurately predicted upper-atmosphere variance using lower-atmosphere models, and vice versa.
Martinez studied astronomy at Wesleyan University in Connecticut for his undergraduate degree but switched paths after realizing he wanted to work on research projects that had more direct applications.
“I wanted to have a more concrete impact, like, people need this,” he says.
Extensive collaboration
Forecasting is not a typical project at Clemson. Still, Martinez’s principal investigator, Xian Lu, an associate professor in the physics and astronomy department, helped him find a project that involved extensive collaboration with other institutions.
Lu describes Martinez as “an exceptionally creative and driven researcher who combines genuine curiosity, physical understanding and technical skills. It’s always been a pleasure working with him. He is a stellar example of how our program helps students develop into successful and independent researchers.”
While working on his Ph.D., Martinez met Nicholas Pedatella, a scientist at the National Center for Atmospheric Research (NCAR), a research and development center in Colorado sponsored and primarily funded by the National Science Foundation. He spent an average of three months a year in Colorado working with Pedatella, with the rest of the time in Clemson.
“It was nice because Clemson actually has a pretty big presence at NCAR. We send a lot of graduates, and we have good collaborations there,” he says.
Computational physics
To conduct his research, Martinez primarily uses computational physics to develop and refine numerical models that solve physical equations. He also works on data analysis, such as satellite data.
Martinez can test models using past radar and satellite observations to see whether the results and data from his model match real-life weather patterns.
“The idea being that, we know what’s happening now, and then if we solve the physics equations freely in time based on these initial conditions, it’ll evolve in time, and then we can compare that to what really happens,” he says.
Accurate models
This comparison shows how accurate a model is. When scientists look back in time and use a model to predict weather, it’s called hindcasting, not forecasting.
Once scientists determine they have an accurate model, they can choose specific parameters, such as the atmosphere’s composition and density, to help show conditions that could deorbit a satellite. Another example is electron density, the amount of charged particles in a portion of the atmosphere, which impacts GPS measurements.
After Martinez completes his Ph.D. in May, he plans to pursue postdoctoral studies at Utah State University.
