2020 Activity Report for Mission 5-3:
Space-Atmosphere-Ground Interaction in Daily Life

更新日: 2021/04/28

Research 1: Monitoring of the atmospheric environment with GNSS signals

Principal Investigator (PI): Masanori Yabuki (RISH, Kyoto University)
Research collaborator(s): Toshitaka Tsuda,
Hiroyuki Hashiguch (RISH, Kyoto University)

The radio waves transmitted from a global navigation satellite system (GNSS) such as global positioning system (GPS) are delayed and refracted by the Earths atmosphere. Measurement of the propagation phase delay of GNSS radio waves enables us to estimate atmospheric temperature and humidity, which are key parameters for understanding localized torrential rainfall and climate change. In FY2020, we have analyzed the GNSS-derived precipitable water vapor (PWV) by use of the dense-GNSS network and the water vapor Raman lidar in Shiga areas. The GNSS observation using the Quasi-Zenith Satellite System (QZSS) has started at Equatorial Atmosphere Radar (EAR) site.

Figure: Horizontal distributions of GNSS-derived precipitable water vapor (PWV) before and after heavy rainfall around Shigaraki MU observatory at 16:0016:40 JST on July 2, 2018.


Publications, etc.

  1. Yabuki, M. et al., A Raman Lidar with a Deep Ultraviolet Laser for Continuous Water Vapor Profiling in the Atmospheric Boundary Layer, EPJ Web of Conferences 237, 03001, 2020. doi:10.1051/epjconf/202023703001
  2. Fujita, Y. et al., Ground-based calibration of rotational Raman lidar for profiling atmospheric temperature, AGU fall meeting 2020, December 1-17, 2020.

Research 2: Ionospheric 3D tomography with GPS

Principal Investigator (PI): Mamoru Yamamoto (RISH, Kyoto University)
Research collaborator(s): Akinori Saito (Graduate School of Science, Kyoto University), Susumu Saito (Electrical Navigation Research Institute))

GPS (Global Positioning System) is a global navigation service operated by the United States of America. Such satellite navigation systems are now operated by other countries. Examples are GLONAS, Galileo, and BeiDou. The general name of these is Global Navigation Satellite System (GNSS). With GPS (or GNSS), we can measure Total Electron Consistent (TEC) in the ionosphere from the difference in the propagation of two radio waves at different frequencies. Geographical Survey Institute of Japan holds GEONET, the network of electronic reference points that are more than 1300 over the nation. The TEC data from GEONET (hereafter referred to as GNSS-TEC) are widely used for studies of the ionosphere. We have been conducting three-dimensional (3D) tomographic analysis of the GNSS-TEC to monitor the regional 3D distribution of ionospheric plasma density. This study aims to promote the GNSS-TEC tomography jointly with the Graduate School of Science and the Electronic Navigation Research Institute.
Using every-second data from GEONET, we developed a real-time 3D tomography analysis system that runs every 15 minutes. We started the real-time 3D tomography in March 1996, and the results are open at Utilizing Advanced Kyoto-daigaku Denpa-kagaku Keisanki-jikken (A-KDK) computer, we analyzed past data, too. In 2020, we developed a new GPS 3D tomography that incorporates the data from ionosondes. The results are much better than the original. We could demonstrate the reasonable 3D variation of the ionospheric during the geomagnetic storm time. Recently, very low-cost multi-constellation and multi-frequency GNSS receivers have become available. We are now developing a TEC measurement system based on such a low-cost GNSS receiver board.

Figures: (left) Concept of the GPS-TEC tomography, (right) Example of the real-time 3D tomograph

Publications, etc.

  1. Ssessanga, N., M., Yamamoto, S., Saito, A., Saito, M., Nishioka, Complementing regional ground GNSS-STEC computerized ionospheric tomography (CIT) with ionosonde data assimilation, GPS solutions, 25:93, 2021, doi:10.1007/s10291-021-01133-y.
  2. Ssessanga, N. M., M. Yamamoto, S. Saito, Assessing the performance of a Northeast Asia Japan-cantered 3-D ionosphere specification technique during the 2015 St. Patrick’s day solar storm, EPS, Submitted, 2021.
  3. Yamamoto, M., S. Saito, Development of Satellite-Ground Total Electron Content Observations (in Japanese), 148th SGEPSS Fall Meeting, November 1-4, 2020.

Research 3: Development of simulation model of geomagnetically induced current flowing in Japanese power grid

Principal Investigator (PI): Yusuke Ebihara (RISH, Kyoto University)
Research collaborator(s): Yoshiharu Omura (RISH, Kyoto University), Tadanori Goto (Kyoto University), Satoko Nakamura (RISH, Kyoto University), Shinichi Watari (NICT), Takashi Kikuchi (Nagoya University), Takashi Tanaka (Kyushu University), Shigeru Fujita (Meteorological College)

When a coronal mass ejection (CME) hits the Earth, a magnetic storm can occur. Large-scale electric current starts flowing in the magnetosphere and the ionosphere, which induces electric current in power grid. This is called a geomagnetically induced current (GIC). The amplitude of GIC was observed to exceed 100 A in Japan. This observational fact suggests that the Japanese power grid is probably not safe. To develop the GIC flowing in the Japanese power grid, we solved the geomagnetically induced electric field (GIE) by the finite-difference time-domain (FDTD) method. Using a power grid model for voltage equal to, or larger than 187 kV in Japan, we calculated the GICs flowing at 602 substations/power plants as a function of the direction of the geoelectric field. We also analyzed data obtained from substations near Tokyo, and evaluated the response to geomagnetic disturbances known as storm sudden commencement (SSC), sudden impulse (SI), magnetic storms, and solar flare effect (SFE) (Watari et al., 2021).


Watari, S., S. Nakamura, and Y. Ebihara, Measurement of geomagnetically induced current (GIC) around Tokyo, Japan, Earth, Planets and Space, in press, 2021.

Research 4: Simultaneous observations of atmospheric turbulence with MU (Middle and Upper atmosphere) radar, and small unmanned aerial vehicles (UAV)

Principal Investigator (PI): Hiroyuki Hashiguchi (RISH, Kyoto University)
Research collaborator(s): Mamoru Yamamoto, Masanori Yabuki (RISH, Kyoto University), Lakshmi Kantha, Dale Lawrence (University of Colorado, USA), Hubert Luce (Toulon-Var Univ., France), and Richard Wilson (LATMOS, CNRS, France)

Turbulence mixing is an important process that contributes to the vertical transport of heat and substances, but it is difficult to observe because its scale is very small. In a research collaboration between Japan, the United States, and France, the ShUREX (Shigaraki, UAV-Radar Experiment) campaign has been carried out using simultaneously small UAVs developed by the University of Colorado and the MU radar. The campaign demonstrated the validity and utility of the radar range imaging technique in obtaining very high vertical resolution (~20 m) images of echo power in the atmospheric column. Figure shows the frequency spectrum of the temperature obtained when the UAV flew horizontally in strong turbulence. The spectrum obeyed the -5/3 power law, and the wind spectrum also followed the -5/3 power law.

Frequency spectrum of the temperature obtained by UAV level flight. The red line indicates the slope of -5/3. [Luce et al., 2019]

Publications, etc.  

Luce, H., L. Kantha, H. Hashiguchi, A. Doddi, D. Lawrence, and M. Yabuki, On the relationship between TKE dissipation rate and temperature structure function parameter in the convective boundary layer, J. Atmos. Sci., 77, 2311-2326, doi:10.1175/JAS-D-19-0274.1, 2020.

Research 5: Monitoring of the atmospheric environment from space

Principal Investigator (PI):Masato Shiotani (RISH, Kyoto University)
Research collaborator(s): Akinori Saito (Graduate School of Science, Kyoto University)

Global satellite observation of the earth’s atmosphere from space is one of the most important information sources for understanding the change in atmospheric environment. On the basis of social and scientific requirements we propose a next-generation satellite mission to observe temperature and wind fields, and distributions of atmospheric trace gases from the middle atmosphere (stratosphere and mesosphere) to the upper atmosphere (thermosphere and ionosphere) where we can see clear signs from the lower atmosphere as a result of human activities. In 2009- 2010 the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the International Space Station demonstrated a 4 K mechanical cooler for high-sensitivity submillimeter limb-emission sounding of atmospheric observations. Based on the SMILES heritage, we investigate new observation concepts for the atmospheric environmental observations for the next era.

Research 6: Impact of high-energy particle precipitations from space on Earth’s upper atmosphere

Principal Investigator (PI):Satoshi Kurita (RISH, Kyoto University)
Research collaborator(s): Hirotsugu Kojima (RISH, Kyoto University), Yoshizumi Miyoshi (ISEE, Nagoya University), Shinji Saito (NICT)

Electromagnetic waves are naturally generated in the Earth’s magnetosphere. High-energy particles trapped in the magnetosphere are precipitated into the Earth’s upper atmosphere through interaction with these waves. The precipitations cause ionization and heating of the upper atmosphere, which results in enhanced chemical reactions in the upper atmosphere. This process might significantly contribute to change in composition of the upper atmosphere. To understand the process, we aim to evaluate amount of high-energy particle precipitations from the satellite observation.
We statistically clarified the propagation characteristics of whistler-mode chorus waves based on the Japanese “Arase” satellite. We also demonstrated that the chorus waves can cause simultaneous electron precipitations in the energy range from a few keV to ~MeV based on the computer simulation.


  1. Kurita, S. et al., Propagation characteristics of whistler mode chorus in the outer radiation belt deduced from the Arase observation, International Radio Science Union (URSI) GASS 2020.
  2. Miyoshi, Y., et al., Relativistic electron microbursts as high-energy tail of pulsating aurora electrons, Geophys. Res. Lett., 47, e2020GL090360, 2020. doi:10.1029/2020GL090360.

2019 Activity Report

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