We propose to investigate the ionospheric plasma structures using two techniques: tomographic technique and scintillation technique. Each is summarized in the following. 1. Tomographic technique: Our simulation studies over the past several years, as well as several studies by others, have demonstrated the potential and capability of imaging ionospheric structures of horizontal scales from tens of kilometers to hundreds of kilometers. We propose to set up a network of stations to receive Doppler shifted signals from the navigation satellites NNSS for the purpose of imaging the equatorial ionosphere using the tomographic technique to learn about the dynamics of the equatorial anomaly region. This project has associated tasks in repair and modification of donated JMR geodetic TRANSIT receivers, development of a low-cost PC based data acquisition system, development of receivers at selected field sites, data management and processing, further development of computer algorithm, and data interpretation. 2. Scintillation technique: This project is concerned with analyzing already collected scintillation data at various sites of geophysical interests. One station (Spitzbergen, 77.00oN, 15.55o, geomagnetic dip 73.43oN) is a polar cusp station. The small structures observed by the scintillation technique can be related to the presence of auroras, the configuration of the interplanetary magnetic field, electromagnetic omissions, etc. In the Pacific-Asia region data from a network of stations have been collected to analyze the relation of scintillation with the traveling ionospheric disturbances. At equator the scintillation data can be correlated with the radar data to investigate the relation between ionospheric motions and the production of small ionospheric structures.
