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Major achievements so far

  • Completion of a whole atmosphere-ionosphere coupled model


    Systematically coupled atmospheric, ionospheric and electrodynamics models to successfully develop the world’s first numerical model capable of handling the entire global atmospheric region, ranging from the troposphere through the ionosphere. The model was named GAIA for short (acronym meaning Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy).
  • Reproduction of ionospheric longitudinal variation and understanding vertical coupling processes in the Earth’s atmosphere


    It was proved that the persistent wavenumber-4 structure in the ionospheric longitudinal variation as recently observed by artificial satellites can be reproduced by the atmosphere-ionosphere coupled simulation. Moreover, the simulation found that certain atmospheric tidal components, which constitute a basis of the wavenumber-4 structure, are excited by convective activities in the troposphere and then propagate to the thermosphere, thereby influencing the ionosphere through electrodynamic dynamo action (Figure 1). The simulation also indicates that meteorological activity in the lower atmosphere is one important cause of daily ionospheric variations [Jin et al., 2011].
    Figure 1:Vertical atmospheric coupling reproduced by the GAIA model [Jin et al., 2011]
  • Reproduction of the "equatorial anomaly" in thermospheric distribution and understanding the causes thereof


    The peak electron density of the ionospheric F-region is known to appear at geomagnetic latitude of ±10 to 15 degrees, but not at the equator where sunlight intensity is the highest (so-called "equatorial ionization anomaly"). Recent observations by artificial satellites have also clarified the presence of an "equatorial anomaly” structure in thermospheric distribution similar to that in the ionosphere, raising ongoing discussions about what causes the structure to form. We conducted an atmosphere-ionosphere coupled simulation and found that the model also reproduced the equatorial anomaly not only in the ionosphere but also in the thermosphere (Figure 2). Detailed analyses then revealed something new for us to consider: in addition to the effects from interaction between the neutral atmosphere and ionospheric plasma, atmospheric tides directly propagating from the lower atmosphere to the upper thermosphere are attributed to the formation of the thermospheric equatorial anomaly. Furthermore, the wavenumber-4 longitudinal structure was also found to appear not only in the ionosphere but also in the upper thermosphere, suggesting that the lower atmosphere significantly influences the upper atmosphere [Miyoshi et al., 2011].
    Figure 2: Equatorial anomaly in thermosphere:(Upper) Observation by CHAMP satellite [Liu et al., 2010]. (Lower) Simulation by GAIA model [Miyoshi et al., 2011].
  • Reproduction of upper atmospheric phenomena through high-resolution simulations


    A high spatial resolution version of atmospheric model has been developed, which was found to have ability to reproduce gravity waves with their wavelength of several hundreds to thousands of km, along with their excitation in the troposphere and propagation to the thermosphere. Miyoshi and Fujiwara [2009] studied the features of gravity waves in the thermosphere by using the model, and then clarified the relation of gravity waves with longitudinally dependent convective activities in the lower atmosphere. Jin et al. [2011] incorporated the results from the high-resolution atmospheric model into the highly resolved electrodynamics model, and showed that the effects of gravitational waves in the thermosphere are apparent in the distribution of ionospheric electric fields.
    Shinagawa et al. [2009] developed a high resolution version of ionospheric model and conducted simulations on the ionosphere at the time of the total solar eclipse on July 22, 2009, thereby clarifying the influence of a solar eclipse on the ionosphere (including displacement of the region with reduced electron density due to displacement of the moon’s shadow) from both the model and observations of TEC (total electron content) above the Japanese archipelago.
  • Comparison of observations with atmosphere-ionosphere coupled simulations into which meteorological reanalysis data is assimilated


    A method has been developed to assimilate meteorological reanalysis data into the tropospheric and stratospheric portion of GAIA. With regard to daily variation of solar radiation, the F10.7 index actually observed is adopted in the model. As a result, a realistic modeling of the upper atmosphere has been realized, including influences from the actual lower atmosphere. This model was being used to conduct long-term simulations (several months so far), and compared with global satellite observations for validation. Jin et al. [2010, 2011] reported the initial results, indicating that the GAIA model offers good reproducibility regarding location of the equatorial anomaly and north-south asymmetry.

Publications

Shinagawa, H., C. Tao, H. Jin, Y. Miyoshi, and H. Fujiwara, Numerical prediction of sporadic E layer occurrence using GAIA, Earth Planets Space, accepted.
Liu, H., C. Tao, H. Jin, and T. Abe (2021), Examining geomagnetic activity effects on CO2-driven trend in the thermosphere and ionosphere using ideal model experiments with GAIA, J. Geophys. Res.: Space Phys., 126, 1, https://doi.org/10.1029/2020JA028607.
Tao, C., H. Jin, Y. Miyoshi, H. Shinagawa, H. Fujiwara, M. Nishioka, and M. Ishiim (2020), Numerical forecast of the upper atmosphere and ionosphere using GAIA, Earth Planets Space, 72:178, https://doi.org/10.1186/s40623-020-01307-x.
Miyoshi, Y. and Y. Yamazaki (2020), Excitation mechanism of ionospheric 6‐day oscillation during the 2019 September sudden stratospheric warming event, J. Geophys. Res.: Space Phys., 125, 9, https://doi.org/10.1029/2020JA028283.
Liu, H., C. Tao, H. Jin, and Y. Nakamozo (2020), Circulation and Tides in a Cooler Upper Atmosphere: Dynamical Effects of CO2 Doubling, Geophys. Res. Lett., 47, e2020GL087413, doi.org:10.1029/2020GL087413.
Sun, Y.-Y., H. Liu, Y. Miyoshi, L. C. Chang, and L. Liu (2019), Nino-Southern Oscillation effect on ionospheric tidal/SPW amplitude in 2007-2015 FORMOSAT-3/COSMIC observations, Earth, Planets and Space, 71:35, doi:10.1186/s40623-019-1009-7.
Yasui, R., K. Sato, and Y. Miyoshi (2018), The momentum budget in the stratosphere, mesosphere, and lower thermosphere. Part II: The in situ generation of gravity waves, J. Atmos. Sci., 3635–3651, https://doi.org/10.1175/JAS-D-17-0337.1.
Yamamoto, M., Y. Otsuka, H. Jin, and Y. Miyoshi (2018), Relationship between day-to-day variability of equatorial plasma bubble activity from GPS scintillation and atmospheric properties from Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy (GAIA) assimilation, Progress in Earth and Planetary Science, 5:26, doi:10.1186/s40645-018-0184-7 (11page).
Shinagawa, H., H. Jin, Y. Miyoshi, H. Fujiwara, T. Yokoyama, and Y. Otsuka (2018), Daily and seasonal variations in the linear growth rate of the Rayleigh-Taylor instability in the ionosphere obtained with GAIA, Progress in Earth and Planetary Science, 5:16, doi:10.1186/s40645-018-0175-8, doi:10.1186/s40645-018-0175-8 (14page). ->Research introduction at PSTEP website is here
Ishii, M., M. Den, H. Jin, Y. Kubo, Y. Kubota, A. Nakamizo, H. Shinagawa, D. Shiota, T. Tanaka, C. Tao, S. Watari, and T. Yokoyama (2018), Physics-Based Modeling Activity from the Solar Surface to the Earth's Atmosphere Including Magnetosphere and Ionosphere at NICT, Space Weather of the Heliosphere: Processes and Forecasts, Proceedings of the International Astronomical Union, IAU Symposium, Volume 335, 284-287, doi:10.1017/S1743921317011668.
Yamazaki, Y., C. Stolle, J. Matzka, H. Liu, and C. Tao (2018), Interannual Variability of the Daytime Equatorial Ionospheric Electric Field, J. Geophys. Res.: Space Physics, 123, 5, 4241-4256, doi:10.1029/2017JA025165.
Sun, Y.-Y., H. Liu, Y. Miyoshi, L. Liu, and L. C. Chang (2018), El Niño-Southern Oscillation effect on quasi-biennial oscillations of temperature diurnal tides in the mesosphere and lower thermosphere, Earth, Planets and Space, 70:85 (10page).
Miyoshi Y., Jin, H., Fujiwara, H., and H. Shinagawa (2018), Numerical Study of Traveling Ionospheric Disturbances Generated by an Upward Propagating Gravity Wave, J. Geophys. Res.: Space Physics, 123, 2141-2155, doi:10.1002/2017ja025110.
Tao, C., H. Jin, H. Shinagawa, H. Fujiwara, and Y. Miyoshi, Effect of intrinsic magnetic field decrease on the low- to middle-latitude upper atmosphere dynamics simulated by GAIA, J. Geophys. Res. Space Physics, 122, 9751-9762, doi:10.1002/2017JA024278, 2017.
Liu, H., Y.-Y. Sun, Y. Miyoshi, and H. Jin, ENSO effects on MLT diurnal tides: A 21 year reanalysis data-driven GAIA model simulation, J. Geophys. Res. Space Physics, 122, 5539–5549, doi:10.1002/2017JA024011, 2017.
Miyoshi, Y., D. Pancheva, P. Mukhtarov, H. Jin, H. Fujiwara and H. Shinagawa, Excitation mechanism of non-migrating tides, Journal of Atmospheric and Solar–Terrestrial Physics, 156, 24–36, doi:10.1016/j.jastp.2017.02.012, 2017.
Shinagawa, H., Y. Miyoshi, H. Jin, and H. Fujiwara, Global distribution of neutral wind shear associated with sporadic E layers derived from GAIA, J. Geophys. Res. Space Physics, 122, doi:10.1002/2016JA023778, 2017.
Yamazaki, Y., H. Liu, Y.-Y. Sun, Y. Miyoshi, M. J. Kosch, and M. G. Mlynczak, Quasi-biennial oscillation of the ionospheric wind dynamo, J. Geophys. Res. Space Physics, 122, doi:10.1002/2016JA023684, 2017.
Pedatella, N. M., T.-W. Fang, H. Jin, F. Sassi, H. Schmidt, J. L. Chau, T. A. Siddiqui, and L. Goncharenko (2016), Multimodel comparison of the ionosphere variability during the 2009 sudden stratosphere warming, J. Geophys. Res. Space Physics, 121, 7204–7225, doi:10.1002/2016JA022859.
Miyoshi, Y., H. Fujiwara, H. Jin, and H. Shinagawa, Impacts of sudden stratospheric warming on general circulation of the thermosphere, J. Geophys. Res. Space Physics, 120, 10,897–10,912, doi:10.1002/2015JA021894, 2015.
Chang, L. C., Liu, H., Miyoshi, Y., Chen, C., Chang, F., Lin, C., Liu, J. and Sun, Y., Structure and origins of the Weddell Sea Anomaly from tidal and planetary wave signatures in FORMOSAT-3/COSMIC observations and GAIA GCM simulations. J. Geophys. Res. Space Physics, 120: 1325–1340. doi: 10.1002/2014JA020752, 2015.
Liu, H., Y. Miyoshi, S. Miyahara, H. Jin, H. Fujiwara, and H. Shinagawa, Thermal and dynamical changes of the zonal mean state of the thermosphere during the 2009 SSW: GAIA simulations, J. Geophys. Res. Space Physics, 119, 6784–6791, doi:10.1002/2014JA020222, 2014.
Miyoshi, Y., H. Fujiwara, H. Jin, and H. Shinagawa, A global view of gravity waves in the thermosphere simulated by a general circulation model, J. Geophys. Res. Space Physics, 119, 5807–5820, doi:10.1002/2014JA019848, 2014.
Pedatella, N. M., T. Fuller-Rowell, H. Wang, H. Jin, Yasunobu Miyoshi, H. Fujiwara, H. Shinagawa, H.-L. Liu, F. Sassi, H. Schmidt, V.Matthias, L. Goncharenko, The neutral dynamics during the 2009 sudden stratosphere warming simulated by different whole atmosphere models, J. Geophys. Res. Space Physics, 119, 1306–1324, doi:10.1002/2013JA019421, 2014.
Liu, H. , H. Jin, Y. Miyoshi, H. Fujiwara, and H. Shinagawa, Upper atmosphere response to stratosphere sudden warming: Local time and height dependence simulated by GAIA model, Geophys. Res. Lett., 40, 635–640, doi:10.1002/grl.50146, 2013.
Jin, H., Y. Miyoshi, D. Pancheva, P. Mukhtarov, H. Fujiwara, and H. Shinagawa, Response of migrating tides to the stratospheric sudden warming in 2009 and their effects on the ionosphere studied by a whole atmosphere-ionosphere model GAIA with COSMIC and TIMED/SABER observations, J. Geophys. Res., 117, A10323, doi:10.1029/2012JA017650, 2012.
Pancheva, D., Y. Miyoshi, P. Mukhtarov, H. Jin, H. Shinagawa, and H. Fujiwara, Global response of the ionosphere to atmospheric tides forced from below: Comparison between COSMIC measurements and simulations by atmosphere-ionosphere coupled model GAIA, J. Geophys. Res., 117, A07319, doi:10.1029/2011JA017452, 2012.
Fujiwara, H., S. Nozawa, S. Maeda, Y. Ogawa, Y. Miyoshi, H. Jin, H. Shinagawa, K. Terada, Polar cap thermosphere and ionosphere during the solar minimum period: EISCAT Svalbard radar observations and GCM simulations, Earth, Planet and Space, 64, 6, 2012.
Miyoshi, Y., H. Jin, H. Fujiwara, H. Shinagawa and H. Liu, Wave-4 structure of the neutral density in the thermosphere and its relation to atmospheric tide, J. Sol.-Terr. Phys., 2012.
Miyoshi, Y., H. Fujiwara, H. Jin, H. Shinagawa, and H. Liu, Numerical simulation of the equatorial wind jet in the thermosphere, J. Geophys. Res., 117, A03309, doi:10.1029/2011JA017373, 2012.
Miyoshi, Y., H. Fujiwara, H. Jin, H. Shinagawa, H. Liu, and K. Terada, Numerical Simulation of the Equatorial Mass Density Anomaly, Journal of Geophysical Research, 116, A05322, doi:10.1029/2010JA016315, 2011.
Fujiwara, H., Y. Miyoshi, H. Jin, H. Shinagawa, and K. Terada, Characteristics of temperature and density structures in the equatorial thermosphere simulated by a whole atmosphere GCM, Aeronomy of the Earth's atmosphere and ionosphere, Division II IAGA book, edited by Abdu, Pancheva, and Bhattacharya, Volume 2, Part 4, pp.329-337, doi:10.1007/978-94-007-0326-1_24, 2011
Venkateswara Rao, N., T. Tsuda, S. Gurubaran, Y. Miyoshi, and H. Fujiwara, On the occurrence and variability of the terdiurnal tide in the equatorial Mesosphere and Lower Thermosphere and its comparison with the Kyushu-GCM, Journal of Geophysical Research, 116, D02117, 2011.
Jin, H., Y. Miyoshi, H. Fujiwara, H. Shinagawa, K. Terada, N. Terada, M. Ishii, Y. Otsuka, and A. Saito, Vertical Connection from the Tropospheric Activities to the Ionospheric Longitudinal Structure Simulated by a New Earth's Whole Atmosphere-Ionosphere Coupled Model, J. Geophys. Res. , 116, A01316, doi:10.1029/2010JA015925, 2011.
Fujiwara, H., and Y. Miyoshi, Morphological features and variations of temperature in the upper thermosphere simulated by a whole atmosphere GCM, Annales Geophysicae, 25, 427-437, 2010
Shinagawa, H., Ionosphere simulation, J. Natl. Inst. Inf. Comm. Technol., 56, 1-4, 199-207, 2009.
Miyoshi, Y., and H. Fujiwara, Gravity waves in the equatorial thermosphere and their relation to the lower atmospheric variability, Earth Planets Space, 61, 471-478, 2009.
Fujiwara, H., and Y. Miyoshi, Global structure of large-scale disturbances in the thermosphere produced by effects from the upper and lower regions: simulations by a whole atmosphere GCM, Earth Planets Space, 61, 463-470, 2009
Miyoshi, Y., and H. Fujiwara, J. M. Forbes, S. L. Bruinsma, The solar terminator wave and its relation to the atmospheric tide, Journal of Geophysical Re-search, 114, A07303, doi:10.1029/2009JA014110, 2009.
Jin, H., Y. Miyoshi, H. Fujiwara, and H. Shinagawa, Electrodynamics of the formation of ionospheric wave number 4 longitudinal structure, J. Geophys. Res., 113, A09307, doi:10.1029/2008JA013301, 2008.
Miyoshi, Y., and H. Fujiwara, Gravity waves in the thermosphere simulated by a general circulation model, J. Geophys. Res., 113, D01101, doi:10.1029/2007JD008874, 2008.
Shinagawa, H., T. Iyemori, S. Saito, and T. Maruyama, A numerical simulation of ionospheric and atmospheric variations associated with the Sumatra earthquake on December 26, 2004, Earth Planets Space, 59, 1015-1026, 2007.
Shinagawa, H., and S. Ohyama, A two-dimensional simulation of thermospheric vertical winds in the vicinity of an auroral arc, Earth Planets Space, 58, 1173-1181, 2006.
Fujiwara, H., and Y. Miyoshi, Characteristics of the large-scale traveling atmospheric disturbances during geomagnetically quiet and disturbed periods simulated by a whole atmosphere general circulation model, Geophys. Res. Lett., 33, L20108, doi:10.1029/2006GL027103, 2006.
Miyoshi, Y., Temporal variation of nonmigrating diurnal tide and its relation with the moist convective activity, Geophys. Res. Lett., 33, L11815, doi:10.1029/2006GL026072, 2006.
Miyoshi, Y., and H. Fujiwara, Excitation mechanism of intraseasonal oscillation in the equatorial mesosphere and lower thermosphere, J. Geophys. Res., 111, D14108, doi:10.1029/2005JD006993, 2006.
Miyoshi, Y., and H. Fujiwara, Day-to-day variations of migrating diurnal tide simulated by a GCM from the ground surface to the exobase, Geophys. Res. Lett., 30(15), 1789, doi:10.1029/2003GL017695, 2003.