As modern society grows more and more dependent on technology, researchers are becoming increasingly interested in space-weather phenomena that can interfere with our gadgets. Although they are still a long way from learning to predict these high-altitude disturbances, scientists are working to understand them better.The ionosphere is the strip of atmosphere 60–1000 kilometers above ground where molecules become ionized by solar radiation. When space weather events like solar or geomagnetic storms strike or when earthquakes, tsunamis, or hurricanes occur on Earth, they can trigger disturbances in the ionosphere’s electron density, called traveling ionospheric disturbances (TIDs). These disturbances can travel through the atmosphere for thousands of kilometers in the form of waves, which degrade radio signals and navigation systems.Scientists often use specialized ionospheric sounders, both in space and on Earth, to collect current information about ionospheric activities. Recently, they have become interested in the thriftier possibility of using conventional GPS satellites. However, the movement of the satellites, which orbit Earth every 12 hours, can affect their ability to collect reliable information.In a recent study, Penney and Jackson-Booth looked into the limitations of current techniques for using GPS satellites to monitor TIDs and crafted their own strategy: Over a period of 18 months, the team used a short-baseline, three-receiver array to gather TID data from all available GPS satellites. The study showed how to measure TID velocities using receivers spaced only 3 kilometers apart, so there was a delay of only 30 seconds or less between pairs of receivers observing the TID waveform.Overall, the researchers found that the new GPS method gave more reliable information about TIDs than existing methods. The small number of receivers meant less information, but with less to comb through, the researchers were able to discern more intricate details of the TID waves. A smaller data field also made it easier to focus on specific parameters, such as the rate at which the total electron content changes as a wave travels through the ionosphere. (Radio Science, doi:10.1002/2015RS005767, 2015)
—Shannon Kelleher, Writer Intern
Citation: Kelleher, S. (2016), New GPS satellite technique to monitor ionospheric disturbances, Eos, 97, doi:10.1029/2016EO047469. Published on 7 March 2016.