Report on the Activity of Commission G

(July 16, 2004)


1. Current status of facilities for ionospheric observation

Ionosonde stations near the magnetic equator

An FM/CW ionosonde was installed at Chiang Mai, northern Thailand in April. This is the 3rd station of the Southeast Asia Equatorial Ionospheric Network (SEALION). The three ionosonde stations are in the same magnetic meridian: two of them are at the magnetically conjugated points and the other is near the magnetic equator. The network is intended to investigate ionospheric dynamics related to onsets of severe ionospheric scintillations.


2. Observation Campaigns

CPEA First International Observation Campaign in March-May 2004

"Coupling Processes in the Equatorial Atmosphere (CPEA)" is a research program funded by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) as a Grant-in-Aid for Scientific Research on Priority Areas in the period from September 2001 to March 2007. CPEA studies dynamical coupling processes in the equatorial atmosphere by conducting various observations.

The first international observation campaign of CPEA was conducted from March to May 2004. In the campaign we operated the following facilities:

l         Radars: EAR, boundary layer radar, X-band meteorological radar, meteor radar, and FM-CW ionosonde (by NICT) at the EAR site, X-band Doppler radar near Bukittinggi, two MF radars at Pontianak and Pameungpeuk.

l         Lidars: Rayleigh/Mie lidar at the EAR site.

l         Balloon experiment: GPS radiosondes launched from four locations in Indonesia, and from three more locations in Malaysia and Singapore.

l         Other instruments: RASS, airglow imager and airglow temperature photometer at the EAR site, GPS receivers at the EAR site and Padang.

l         Meteorological instruments: Radiometer, rain gauge, disdrometer, etc., at the EAR site.

The period of the first international observation campaign was divided into two parts. During March 10 to April 3, 2004, we conducted collaborative experiments targeting the middle to upper atmosphere. Interaction between the equatorial Spread-F and the neutral atmosphere was a specific topic in the period. During April 10 to May 9, 2004, we concentrated on experiments of the lower to middle atmosphere. An X-band Doppler radar was operated throughout the period from a site approximately 20 km southeast of the EAR. RASS experiments were conducted with the EAR to measure fine structures of temperature and humidity. Radiosondes were launched from seven locations.

During the first half of the campaign, we could observe echoes from 3-m scale ionospheric irregularities associated with plasma bubbles for about half the nights. On March 25, 2004, the EAR, the FM-CW ionosonde, the airglow imager, and GPS receivers could simultaneously observe plasma bubble events.

The CPEA campaign is endorsed by CAWSES (Climate and Weather of the Sun-Earth System) under SCOSTEP (The Scientific Committee On Solar-TErrestrial Physics).

For more information visit at

FERIX (F- and E-Region Ionosphere Coupling Study)

A coordinated observational campaign is going on to clarify the coupling process between the F-region and E-region ionosphere at midlatitudes from June to August 2004 in northern part of Japan. The MU radar observes F-region field-aligned irregularities and LTPR, a VHF radar, observes E-region irregularities on the same magnetic field line that the MU radar observes. The ionospheric electric field is expected to map along the magnetic field line, and to affect the occurrence of irregularities in the both regions. Such electrical coupling between the F-region and the E-region can be clarified by this coordinated observation. Besides the VHF radars, three ionosondes and an all-sky airglow camera are deployed to detect the two-dimensional structure of the F-region and the E-region ionosphere in a wide area over Japan. These instruments compensated the gap of the permanent observational network, such as ionosondes, all-sky cameras, and GPS receivers. The neutral wind is an essential driver of the ionospheric dynamics. Two Fabry-Perot interferometers monitor the thermospheric neutral wind and its horizontal gradient to reveal the physical processes of the generation of field-aligned irregularities in the nighttime midlatitude ionosphere.


3. Coming Workshops

(1) XIth IAGA Workshop on Geomagnetic Observatory Instruments, Data Acquisition and Processing (November 9-17, 2004 in Kakioka and Tsukuba, Japan)

The workshop is organized by International Association of Geomagnetism and Aeronomy (IAGA), Japanese National Committee for Geomagnetism and Aeronomy, the Science Council of Japan, Society of Geomagnetism and Earth, Planetary and Space Sciences, and Kakioka Magnetic Observatory.

(2) International Workshop on Seismo Electromagnetics (March 15-17, 2005 in Chofu, Tokyo, Japan)

The workshop is organized by University of Electro-Communications, Society of Atmospheric Electricity of Japan, Chiba University, URSI Commission E, Institute of Electrical Engineers of Japan. For more information visit at



 (Prepared by T. Maruyama and M. Yamamoto)