11:00 AM - 11:15 AM
[PEM15-02] Next generation solar wind observation system for investigating the heliosphere and coupling processes in solar-terrestrial system
Keywords:solar wind, coronal mass ejection, heliosphere, space weather, phased array, digital signal processing
The solar wind, which is a high-speed plasma flow from the Sun, sometimes generates significant disturbances to the environment around the Earth. This disturbance can cause enormous damage to social infrastructure such as communication failures and artificial satellite failures. Understanding the solar wind itself and the response of the planetary environments to the solar wind are essential to understand the coupling processes in solar-terrestrial system.
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 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 solar wind observation system is in progress. This project can contribute to understand the coupling processes in solar-terrestrial system through the improvement of the accuracy of IPS observations. 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. A small scall array system is under construction as a phase-I project. Dipole antennas or Yagi antennas were considered as candidates for the antenna elements of the array, and their prototypes were developed. Sixteen antenna elements are combined in an analog system, and the combined signal is digitized by an ADC. The digital signals are transmitted by optical fibers to a signal processing system composed of FPGAs. This system synthesizes 8 beams simultaneously.
This project aims to understand the acceleration process of the solar wind, the global structure of the heliosphere and its variations, and to improve the accuracy of space weather forecasting through IPS observations. In addition, this project will greatly contribute to understanding the coupling processes in solar-terrestrial system by cooperating with various projects for the magnetosphere, ionosphere, and atmosphere observations. Moreover, the phased array technique is common to the other ground-based radars. This project may be able to collaborate with other projects in terms of technology because similar techniques such as calibration methods, signal processing methods, and interference rejection methods are required in each project.
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 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 solar wind observation system is in progress. This project can contribute to understand the coupling processes in solar-terrestrial system through the improvement of the accuracy of IPS observations. 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. A small scall array system is under construction as a phase-I project. Dipole antennas or Yagi antennas were considered as candidates for the antenna elements of the array, and their prototypes were developed. Sixteen antenna elements are combined in an analog system, and the combined signal is digitized by an ADC. The digital signals are transmitted by optical fibers to a signal processing system composed of FPGAs. This system synthesizes 8 beams simultaneously.
This project aims to understand the acceleration process of the solar wind, the global structure of the heliosphere and its variations, and to improve the accuracy of space weather forecasting through IPS observations. In addition, this project will greatly contribute to understanding the coupling processes in solar-terrestrial system by cooperating with various projects for the magnetosphere, ionosphere, and atmosphere observations. Moreover, the phased array technique is common to the other ground-based radars. This project may be able to collaborate with other projects in terms of technology because similar techniques such as calibration methods, signal processing methods, and interference rejection methods are required in each project.