Imaging of electron density troughs by tomographic techniques

摘要: Troughs in the latitudinal distribution of electron density are a well-known feature ionosphere from subauroral to polar latitudes. The location and depth trough minimum, width feature, horizontal gradients associated with walls all quantities interest or concern practical applications radio systems involving ionosphere. In practice, precise characteristics trough-like structures have been difficult monitor using ground-based methods. Ionospheric tomography represents new development that is maturing into technique ideally suited study troughs. Results presented variety observations made during tomographic campaigns northern Europe. A long-term investigation has main network stations United Kingdom. position minimum wall studied on diurnal basis images reconstructed measurements for succession passes Navy Navigation Satellite System satellites. With deployed more than 6 months, average behavior also studied. Examples shown extreme under very disturbed geomagnetic conditions, which continues yield while limitations ionosondes exposed. Studies narrow troughs steep seen at auroral latitudes used investigate some successes method. Measurements cap show depleted densities hole center dawn convection cell illustrate power method high Finally, dayside high-latitude boundary between corotating counterstreaming flux tubes afternoon sector revealed image extending over 30° latitude, chain six Scandinavia.