Multi-station GPS TEC and magnetometer observations of ULF waves in Antarctica

Ultra-low-frequency (ULF) waves, or magnetic pulsations, are frequently observed by ground-based magnetometers. Recently, ULF modulations of Global Positioning System (GPS) total electron content (TEC) measurements have also been observed. However, there are few prior reports of simultaneous ULF wave and TEC measurements from multiple stations. The Autonomous Adaptive Low-Power Instrument Platforms (AAL-PIP) include dual-frequency GPS receivers and magnetometers, forming a chain along the 40-degree magnetic meridian on the East Antarctic Plateau. This chain of closely spaced stations provides novel ULF wave TEC observations. A GPS TEC database and software tool have recently been developed to process the first-hand dual-frequency GPS data collected by AAL-PIP between 2013 to 2019 and analyze the characteristics of candidate ULF waves. As a case study, large amplitude, global ULF wave modulations of the GPS TEC and geomagnetic field on Feb 28, 2019, associated with a geomagnetic storm, were detected from multiple Antarctic stations. We examine spatial and temporal variation of wave properties using the multi-point observations, and discuss possible generation mechanisms for the TEC modulations as well as their possible impacts on space weather, HF radio, and GPS. This work is the first step toward implementing the Antarctic AAL-PIP GPS data for ULF wave studies and other space weather investigations.