The Sun is much more than a vital source of warmth and light. In the region between it and Earth, which we call geospace, is a constant stream of charged particles called the solar wind. The solar wind flows out from the sun at hundreds of kilometres a second. Most particles are deflected by Earth’s geomagnetic field, but in polar regions some plunge into our atmosphere. These particles create auroras. The charged solar wind blowing past Earth also generates large voltages in the Antarctic atmosphere and forms huge convection cells (similar to a weather map's high and low pressure areas). These cells drive 7000 km/h winds in a region of the upper atmosphere called the ionosphere.
Occasionally, enormous eruptions on the sun blast billions of tonnes of matter into the solar wind. These can wreak havoc on Earth — knocking out communications and navigation, and generating huge magnetic storms that can destroy satellites and even power grids. At such times the auroras expand out away from the polar regions and can even be seen as far north as Brisbane.
Understanding and predicting all these effects falls into a category of science now called ‘space weather’.
Scientists from the Bureau of Meteorology and the Australian Antarctic Division have installed radars called ionosondes at each of our stations. Closer to home, the Tasman International Geospace Environment Radar (TIGER) in southern Tasmania looks out over the Southern Ocean and the Antarctic continent to get a broader perspective of space weather.
TIGER is an over-the-horizon radar system. Its beam yields data on the ionosphere over thousands of square kilometres to the shores of Antarctica. The location of the TIGER radar makes it ideal for keeping an eye on the auroral oval and polar convection patterns. This could potentially generate warnings of an approaching magnetic storm. TIGER can also measure upper atmosphere wind speeds and study irregularities there.
Observations made with ionosondes and TIGER will further our understanding of processes in the Earth’s geospace environment, and be of major importance in the forecasting of space weather.