Nishida Prize

Tatsuhiro Yokoyama


Study on ionospheric disturbances by various observations and numerical simulations

A list of five major papers

  • Yokoyama, T., and C. Stolle, Low and midlatitude ionospheric plasma density irregularities and their effects on geomagnetic field, Space Sci. Rev., 206, 495-519, doi:10.1007/s11214-016-0295-7, 2017.[10]
  • Yokoyama, T., H. Shinagawa, and H. Jin, Nonlinear growth, bifurcation and pinching of equatorial plasma bubble simulated by three-dimensional high-resolution bubble model, J. Geophys. Res. Space Physics, 119, 10,474-10,482, doi:10.1002/2014JA020708, 2014.[34]
  • Yokoyama, T., R. F. Pfaff, P. A. Roddy, M. Yamamoto, and Y. Otsuka, On post-midnight low-latitude ionospheric irregularities during solar minimum: 2. C/NOFS observations and comparison with Equatorial Atmosphere Radar, J. Geophys. Res., 116, A11326, doi:10.1029/2011JA016798, 2011 (9 pages).[20]
  • Yokoyama, T., D. L. Hysell, Y. Otsuka, and M. Yamamoto, Three-dimensional simulation of the coupled Perkins and Es layer instabilities in the nighttime midlatitude ionosphere, J. Geophys. Res., 114, A03308, doi:10.1029/2008JA013789, 2009 (16 pages).[106]
  • Yokoyama, T., S. Fukao, and M. Yamamoto, Relationship of the onset of equatorial F-region irregularities with the sunset terminator observed with the Equatorial Atmosphere Radar, Geophys. Res. Lett., 31, L24804, doi:10.1029/2004GL021529, 2004 (4 pages).[61]

Major achievements

Tatsuhiro Yokoyama has been studying ionospheric disturbances in the equatorial to middle latitudes using a numerical simulation model developed by himself. The characteristic of Yokoyama’s method is that it is a fluid simulation which deals with the motion of a neutral atmosphere and a weakly ionized plasma containing several kinds of ions in a three-dimensional model considering the shape of magnetic field lines. He proposed a model of wave structure generation mechanism of middle latitude ionosphere instability phenomenon found in the MU radar observation by this technique. He succeeded in simulating the observation fact on the nonlinear growth of the plasma bubble by applying original three-dimensional ionosphere simulation in the magnetic equator region. On the other hand, analysis of various observation data such as radar, artificial satellite, sounding rocket was also carried out, and results such as space structure and time development of equatorial spread F phenomenon (plasma bubble) were clarified separately were obtained. He has been highly evaluated, receiving various awards in Japan and overseas for his research results.


Mamoru Yamamoto