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Brian Breitsch is improving our understanding of the upper atmosphere in some of the most isolated places on Earth.��

A research associate in the Ann and H.J. Smead Department of Aerospace Engineering Sciences, Breitsch is leading an $840,000 U.S. Office of Naval Research project to study the ionosphere, which spans from roughly 50-1000 km (31-621 mi) in altitude above the Earth.

It is an area where solar flares and other space weather can wreak havoc with high frequency communications and radar signals.

“This region of the atmosphere is ionized due to the sun’s radiation. There are all these free electrons and ions floating around, otherwise known as plasma, and the structure of this plasma impacts radio signals that travel through it. We want to be able to better see what’s going on in this region,” Breitsch said.

Day-to-day ionosphere forecasting works fairly well over populated continents, thanks to a broad network of ground sensors. However, there is much less data covering areas over the ocean. Although few people live on the water, such regions are crucial to Naval communications and operations. It is this region, specifically at equatorial latitudes, where Breitsch’s work will focus.

“We don’t have many sensors at the surface here, since they’d have to be deployed on boats or buoys. Instead, we want to use satellite-based reflectometry, which roughly mimics the type of measurement geometry we’d get from ground receivers,” he said.

Breitsch is an alumnus of �鶹��Ѱ�����Boulder, earning his aerospace engineering sciences PhD in Professor Jade Morton’s lab in 2021. A leader in the remote sensing field, Morton is also involved in Breitsch’s grant.

The research process involves GPS satellites and other similar global navigation satellite systems (GNSS). The signals from these satellites continuously blanket the planet. When beamed down, some of that signal reflects off the surface and bounces back into space, where it can be picked up by other satellites in low Earth orbit.

When those signals travel through the ionosphere, they undergo subtle changes that can be used to measure the plasma structure.

“We’re at the forefront of processing those signals and using them to estimate the ionosphere. Reflectometry gives us geometries of measurement over the ocean that we wouldn’t otherwise have,” Breitsch said.

That data is already being collected and is available to researchers, but it is extremely difficult to analyze.

“We only get coherent reflections when the sea is calm. One of the main things we’re trying to do in this project is work with noncoherent reflections from rough seas. To do that, we need to analyze data over longer timespans. It’s much more challenging,” he said.

Over the next three years, Breitsch will work with graduate students to develop signal processing techniques to extract useful information from the data. They will also validate and integrate this data with other measurements from other sources, including radio occultation receivers, ground-based radars, and Android phone GPS receivers.

“This is a tough estimation problem, but the ionosphere and the science of it all is really cool. These techniques we’re working on might be the future of GNSS reflectometry for ionosphere observation,” Breitsch said.

In addition to Breitsch, researchers on the grant include PhD student Jiawei Xu and two co-investigators, Morton and Smead Aerospace Distinguished Professor Penina Axelrad.