Plasma bubble monitoring by HF trans-equatorial arrival angle and propagation distance measurements

Demand for plasma bubble monitoring for global navigation satellite system users is increasing. Large-scale ionospheric structures associated with plasma bubbles are studied by measuring trans-equatorial propagation of HF radio waves from Australia to Japan. Propagation distance of the radio waves are simultaneously measured with two digital radio receiver, one near the radio transmitting site in Australia and the other at receiver site in Japan. The study shows that off-great circle trans-equatorial propagation of HF radio wave corresponds to plasma bubble and useful for wide-area plasma bubble monitoring. Propagation distance measurement helps improving the monitoring performance.