The interplanetary scintillation instrument measures the physical quantity of solar wind by observing the scintillation phenomena, which can be observed when a radio source in space passes solar wind particles. The primary data obtained from observing scintillation show fluctuations in signal intensity by time intervals. Accordingly, it is difficult to directly indentify the physical quantity of solar wind. Thus, by using the Fourier Transform, the scintillation is transformed into power components depending on observation frequencies. When the transformed power lines of the spectrum are applied to the existing model, fluctuations in velocity and density of solar wind can be calculated.
Since Manoharan and Ananthakrishnan from India suggested a model for calculating the physical quantity of solar wind, developing the model has been conducted mainly by scholars in Nagoya University, Japan. Models used in the interplanetary scintillation are based on previous research; however the application methods are changed depending on the instrument’s features and types. In order to calculate the physical quantity of solar wind, KSWC uses existing models in combination with optimal methodology appropriate to the instrument’s features and types.
The interplanetary scintillation measures variations in velocity and density of solar wind from each radio source's location. As a result of solar rotation, the solar wind spins as it heads toward the Earth. It is important to accurately forecast when the observed solar wind is expected to reach the Earth.
After measuring values through long term obser-vations of solar wind velocity and density at each chosen point in the solar system, a map on variations in solar wind velocity and density in the vicinity of the Sun and the Earth can be devised. These data can then be used as basic data for prediction.