An RMIT researcher has been recognised by the International Council for Science (ICSU) for his contributions to solar-terrestrial science.
RMIT’s Dr Brett Carter, from the School of Science and the RMIT SPACE Research Centre, was awarded the Distinguished Young Scientist Award by the ICSU Scientific Committee on Solar-Terrestrial Physics (SCOSTEP) for his innovative approach in his study of the occurrence of equatorial plasma bubbles (EPBs) and of geomagnetically-induced currents.
This prestigious award is given biannually to young scientists who have achieved considerable success in SCOSTEP science and who took an active part in SCOSTEP events.
Professor Kefei Zhang, Director of the RMIT SPACE Research Centre, said Carter had made significant advances in understanding the occurrence of EPBs, which are an ionospheric phenomenon near the Earth’s geomagnetic equator at night time.
"EPBs affect radio communications and navigation signals by causing random variations in the signals’ amplitude and phase, and this degrades the performance of Global Positioning System (GPS) applications," said Zhang.
"The problem of EPBs has been a hot research topic for decades, and has become an even more important issue now that society relies so heavily upon space-based navigation and timing signals, such as GPS."
Carter explained that the frequency of these ionospheric disturbances strongly depends on the season and location, similar to how rainfall in tropospheric weather varies around the world.
"In Northern Australia, the most common times for these disturbances are February to April and August to October, when plasma bubbles are expected on most nights," he said.
"Plasma bubbles can have dimensions of several 100 km and they form after dark when the sun stops ionising the ionosphere.
"The ions recombine at lower altitudes, forming a lower-density layer. This layer can rise through the more ionised layers and it makes a turbulent plasma bubble with irregular edges, which effectively scatters radio waves that pass through it."
Carter and his team of researchers developed and tested an EPB prediction capability that can be used to capture the daily variability in the occurrence of EPBs across multiple locations around the world.
Importantly, the new EPB prediction capability requires no ground infrastructure, only data from spacecraft upstream in the solar wind and an advanced upper atmosphere model.
He is currently working on translating this research finding into an operational product that will distribute forecasts for GPS, very high frequency (VHF) and ultra high frequency (UHF) users.
Carter has also significantly advanced research in geomagnetically induced currents (GICs) at equatorial latitudes. His team investigated the effects of shocks in the solar wind when they impact the Earth’s magnetosphere.
"When these shocks hit the magnetosphere, they cause magnetic field variations that can be measured on the ground all over the world," he said.
"These variations cause GICs, which change the flow of electricity in electrical power infrastructure.
"In our study, we found that these magnetic field variations are locally amplified at the magnetic equator by an ionospheric current called the ‘equatorial electrojet’.
"This has significant implications for nations located at the magnetic equator whose electrical power grids may not have been designed to cope with adverse space weather conditions.
"We discovered that we don't need huge geomagnetic storms to experience negative effects. They can also take place during what we might otherwise classify as 'quiet' periods of space weather.
"In other words, electrical disruptions in the equatorial region do not require severe geomagnetic storms, similar in scale to events that have crashed power grids in the past, most notably in Quebec in 1989 and in Sweden in 2003.
"Our findings are a sober realisation that Earth's equatorial regions are more susceptible to disruptive space weather than previously thought."
According to Professor Zhang, Carter is an excellent young scientist who has made very substantial contributions to the international solar-terrestrial and space physics community.
He joined research leaders from Boston College, the University of Sydney, Newcastle University, Brazil’s National Institute for Space Research and NASA Goddard Space Flight Center to nominate Carter for this international recognition.
Story: Petra van Nieuwenhoven