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interaction, as well as through satellite data analysis. By using global MHD simulation codes for ionosphere-magnetosphere coupling processes, geomagnetic phenomena such as DP2, SC, and Pi2 pulsations have been studied, obtaining reasonable agreement with ground magnetic observations. Advances in the study of the upper atmosphere of non-magnetized planets and its escape have also been made through computer simulations.

1.3. Upper atmosphere Equatorial Atmosphere Radar (EAR), all-sky airglow imagers, coherent radars, MF and meteor radars, the meridional ionosonde chain, Rayleigh and Sodium lidars, and TEC observations with GPS were deployed in Indonesia, Thailand, and near-by countries. Data from these observations were utilized for studies of the equatorial and low-latitude ionosphere. Advances in the studies of the equatorial Spread-F (ESF), in particular its time-spatial structures, have been made. Evidence was found for the existence of coupling between the ESF occurrence and variations in the lower atmosphere. Dynamical coupling of the ionosphere and the lower atmosphere was extensively studied on the basis of large disturbances of the ionosphere associated with the North Sumatra earthquake of December 24, 2004. In Japan, the detection of the propagation direction of HF and VHF radio signals from low latitudes or from the southern hemisphere was used to examine large-scale patterns and motions of the ESF. The airglow network in Japan revealed cases where the ESF extends to the latitudes of Japan.

For the mid-latitude ionosphere, an important finding was the hemispheric symmetry of the middle-scale traveling ionospheric disturbance (MS-TID), seen in airglow imagers at Sata, Japan and

Darwin, Australia.

Simultaneous experiment between the MU radar and a portable radar in Sakata

showed clear evidence of electromagnetic coupling between F- and E-region ionospheric irregularities. GEONET, the network of over 1000 GPS receivers in Japan, provided a TEC database (GPS-TEC) useful for these studies. The development of the tomography from the GPS-TEC data has recently reached a level at which 3D spatial structures of the ionospheric plasma density over Japan can be discussed.

As for the polar region, the EISCAT Svalbard radar and the EISCAT UHF radar in Tromso were both

used for the study of the ion drag force in the lower thermospheric wind.

In August 2005, a small

scientific satellite “REIMEI” was launched. The observing precipitation of high-energy particles and

satellite captured 2D images of the aurora while the outflow of ions from the Earth. A Fabri-Perot

Doppler imaging system, a riometer, and an all-sky camera have been deployed in Alaska and Canada by

Japanese teams for the study of neutral winds and waves in the thermosphere.

By using a general circulation model of the atmosphere, simulation studies were conducted for tidal variations in the troposphere and thermosphere, as well as for the generation and propagation of large-scale traveling atmospheric disturbances. In addition, a real-time ionosphere/thermosphere model has been developed using real-time ionospheric parameters given by a global magnetospheric MHD model for space weather forecasts.

A unique instrument, ISUAL (Imager of Sprites and Upper Atmospheric Lightnings), was launched as a scientific payload of the FORMOSAT-2 satellite of Taiwan. The science team found a unexpected number of transient luminous events (TLEs), such as sprits and elves, over the whole globe, determining their physical parameters quantitatively.

  • 2.

    Earth and Planetary Interior

    • 2.1

      Geomagnetism and Paleomagnetism

Rapid progress in research on the Earth and planetary dynamos has been made for the last four years. This is partly owing to the development of high-performance computer systems, in particular the

supercomputers such as “Earth Simulator” and “TSUBAME.” geomagnetic field were performed.

Simulations of a quasi-Taylor state

Paleomagnetic and rock-magnetic studies were carried out for rocks and sediments of different ages from various places. Among them, using marine sediment cores, studies of the relative paleointensity


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