Robust mapping of tropical cyclone wave fields using HF skywave radar

The prospect of obtaining real-time measurements of oceanographic and meteorological conditions over vast areas of the Earth´s oceans by means of HF skywave (´over-the-horizon´) radar has been the subject of many investigations over the past three decades. The remote sensing information is obtained by interpretation of echoes from the sea surface, whose time-varying geometry imposes a complex modulation on the radar signals. Depending on radar design and ionospheric conditions, a map spanning several million square kilometres may be acquired on a grid with resolution typically 10-20 km in less than 30 minutes. We describe methods developed in the Defence Science and Technology Organisation (DSTO) to overcome, or at least minimise, the deleterious effects of radio interference, disturbed ionospheric propagation conditions, scattering from very rough seas and the intrinsic complications of wave fields generated by intense weather systems. The goal is the integration of these various measures into a fully automated cyclone mapping system.