Report on the Activity of Commission G

(November 13, 2003)

 

1. Outstanding ionospheric phenomena and observations

Solar-Terrestrial Environment Laboratory (STEL), Nagoya University observed mid-latitude red aurorae 4 times during severe magnetosphere-ionosphere disturbances in December.  The first red aurora appeared associated with a magnetic impulse event on October 24, 2003 at Rikubetsu (44 deg. N, northern part of Japan).   The rest aurorae appeared during the two severe magnetic storms of October 29-31 at Rikubetsu, Moshiri (44 deg. N, northern part of Japan), and Shigaraki (35 deg. N, middle part of Japan).

 

The Radio Science Center for Space and Atmosphere (RASC), Kyoto University conducted special IS observation by the Middle and Upper atmosphere (MU) radar at Shigaraki to catch ionospheric disturbances associated with the large solar flare event on October 30, 2003. The MU radar continues regular IS experiment at the rate of nine 4-day observations in a year to measure density, drift velocity and electron/ion temperature of the F-region ionosphere.

 

FRONT-3 (F-region Radio and Optical measurement of Nighttime TID) campaign was carried out in Japan and Australia to study the medium-scale traveling ionospheric disturbances (MSTIDs) at midlatitudes in May and June 2003. Scientists from Nagoya University, Kyoto University, and Communication Research Laboratory participated in this campaign. All-sky airglow imagers were operated at two pairs of the geomagnetic conjugate points, Sata-Darwin and Shigaraki-Renner Springs during the campaign period.

 

2. Current status of facilities for ionospheric observation

MU radar is now under renovation. The new system will consist of 29 channels of digital receivers associated with 25 antenna sub-arrays and 4 analog signal-combiners. A part of antenna elements and cables will be renewed to reduce signal losses. With the new system completed in 2004, more radio-interferometer observations will be available.

 

The Communications Research Laboratory (CRL) developed new FM/CW portable ionosonde with transmitter/receiver weight less than 35 kg. The ionosonde will be installed in the Southeast Asian countries to construct a magnetic conjugated observation network.

 

3. Planned Observation Campaigns

Japanese scientists involving with the SuperDARN program, a global HF radar network, focus their attention on the ionospheric response to the forthcoming solar eclipse on 23 November 2003. The total eclipse zone appears mainly in Antarctica, i.e., on the east-south-west of Syowa Station (69.0 deg. S, 39.6 deg. E), Japan’s Antarctica Base. At Syowa, the eclipse starts at 22:14.4 UT, has a maximum (97%) at 23:02.5 UT, and ends at 23:51 UT on 23rd. The total and partial eclipse zones can be probed with the two Syowa SuperDARN radars and also from Kerguelen. The partial eclipse zone can be probed from Halley and Sanae. Thus, the eclipse gives an excellent and rare opportunity to study large-scale ionospheric responses triggered by a solar eclipse in Antarctica. It may be anticipated that the responses in the Southern Hemisphere are more or less transferred, via the geomagnetic field, into the ionosphere in the Northern Hemisphere, so that they request to operate simultaneously the Northern SuperDARN radars. During the period from 22 to 24 November 2003, the ionosonde at Syowa Station is also planed to operate in a rapid-run mode with a five-minute interval.

 

During March-May period in 2004, an international observation campaign of the equatorial atmosphere from the tropopause up to the ionosphere is planed with core facility of Equatorial Atmosphere Radar (EAR) in Koto Tabang (100.32 deg. E, 0.20 deg. S), West Sumatra, Indonesia. EAR is owned by Kyoto University and operated by RASC, Kyoto University and National Institute of Aeronautics and Space of Indonesia (LAPAN). The pulse-to-pulse beam steerability of EAR makes it possible to investigate spatial structure and motion of the irregularities with several hundreds of kilometer scale. Other participating instruments are Lidar, spaced GPS receivers, VHF radar, meteor radar, ionosonde and so on. Also CRL plans to operate an ionosonde at the magnetic conjugated point of EAR site, Chiang Mai in Thailand. This campaign is related to the research project CPEA (Coupling Processes in the Equatorial Atmosphere) and endorsed by CAWSES.

 

4. Related Meetings

International symposium on GPS/GNSS will be held on 15-18 November, 2003, in Tokyo. The symposium include Atmospheric Effects and Timing session, in which ionospheric effects on the GPS radio waves will be discussed.

 

Second Ionospheric Effect Symposium will be held on 17 and 18 December, 2003 at CRL, Tokyo organized by CRL and URSI national commission G. The major topics will be ionospheric total electron content, ionospheric storms, anomalous radio propagation via sporadic E and plasma bubbles, and so on.

 

(Prepared by T. Maruyama and M. Yamamoto)