[P-EM12] Study of coupling processes in solar-terrestrial system

[PEM12-07] Solar wind and heliospheric studies using the interplanetary scintillation observation

★Invited Papers

*Kazumasa Iwai¹, Munetoshi Tokumaru¹, Ken'ichi Fujiki¹ (1.Institute for Space–Earth Environmental Research (ISEE), Nagoya University)

Keywords:solar wind , Heliosphere, Coronal mass ejection, Space weather, Interplanetary scintillation, Phased array

The solar wind, which is a high-speed plasma flow from the Sun, forms the heliosphere that contains all planetary systems including the Earth. The solar wind sometimes generates great disturbances to the environment around the Earth. This disturbance can cause enormous damage to social infrastructure such as communication failures and artificial satellite failures. Interplanetary scintillation (IPS) is a radio scattering phenomenon caused by the turbulences in the solar wind. The IPS observation using ground-based radio telescopes has been an important technique to investigate the global structure of the solar wind in the heliosphere. Institute for Space–Earth Environmental Research (ISEE), Nagoya University have observed IPS to derive the solar wind velocity and density irregularities for several decades using large radio telescopes at 327 MHz. The derived solar wind velocity is used to understand the global structure of the heliosphere via the tomography technique. The amplitude of the IPS, so-called g-level, is also used to predict the arrival of coronal mass ejections (CMEs) in the recent space weather forecasts. On the other hand, it has become clear that more IPS observations are required to understand the acceleration process of the solar wind and to improve the accuracy of solar wind prediction. Now, a new project to develop the next generation IPS observation system is in progress. We consider a new ground-based radio observation system at 327 MHz by constructing a 2D flat phased-array antenna system consisting of multiple dipole antennas, and installing digital beam forming devices. The multidirectional simultaneous radio scintillation observation using this system enables the solar wind observation 10 times as much as the conventional radio instruments have been done. This project will greatly contribute to understanding the solar wind and improving the accuracy of space weather forecasts. In addition, its cooperation with various related projects can contribute to a comprehensive understanding of the heliosphere.