CAWSES (Climate And Weather of the Sun-Earth System) Space Weather Database in Japan Observation (CAWSESDB-J-OB0052) Version 1.0 March 2006 (CAWSES SPACE-W Database in Japan) Two-Dimensional Plots of Total Electron Content Perturbations over Japan 2005

OB0052

This CD-ROM contains two-dimensional plots of perturbation components of Total Electron Content (TEC) over Japan in 2005. The TEC data are derived from Global Positioning System (GPS) observation by GPS Earth Observation Network (GEONET) of Geographical Survey Institute, Japan.

1. Data

GEONET consists of about 1,200 dual-frequency GPS receivers. The dual frequency radio signals of the GPS allow measurements of the total number of electrons along ray paths from GPS satellites to receivers. TEC data are obtained in every 30 seconds for all of the satellite-receiver paths of GEONET [Saito et al., 1998].

To derive perturbation component of TEC, one-hour running average is subtracted from the original TEC for each satellite-receiver pair. The perturbations of slant TEC is converted to that of vertical TEC, by multiplying a slant factor on an assumption of thin ionospheric layer. The spatial resolution of the two-dimensional TEC data of GEONET is 0.15 x 0.15 degrees in latitude and longitude, and temporal resolution is 30 seconds.

The TEC data are daily processed and stored by GPS-TEC database of Kyoto University. This GPS-TEC database has been developed in collaboration with Drs. Yuichi Otsuka and Takuya Tsugawa of the Solar-Terrestrial Environment Laboratory, Nagoya University.

2. Plots

In this CD, perturbation components of vertical TEC detected by GEONET are displayed in two-dimensional maps. The spatial resolution of the TEC maps is 0.15 x 0.15 degrees in latitude and longitude.

The maps were drawn for every 30 minutes. The maps are snap-shots of the TEC perturbations at the instant, not the average for 30 minutes, though the data are derived in every 30 seconds. In some cases, TEC perturbations caused by traveling ionospheric disturbances (TID) can be seen in the map [Saito et al., 1998; Tsugawa et al., 2003].

There is an "index.html" file in the top directory/folder of CD. You can open it with any WWW browser. You can browse the GPS-TEC plots by clicking hyper-links in "index.html". The plots are saved in JPEG format.

Recent plots are available on the homepage of GPS-TEC database of Kyoto University. Its URL address is "http://stegps.kugi.kyoto-u.ac.jp/".

3. Notes

All the plotted data are just for browsing purpose and are not fully calibrated. Please do not use the plots at any presentations and publications without contacting the principal investigator, Akinori Saito (saitoua[AT]kugi.kyoto-u.ac.jp). Digital data are available on request.

Please contact the Principal Investigator to use the data and plots.

4. Contact address

Dr. Akinori Saito
Department of Geophysics, Graduate School of Science
Kyoto University
Kyoto 606-8502, Japan
TEL: +81-75-753-3954 FAX: +81-75-722-7884
E-mail: saitoua[AT]kugi.kyoto-u.ac.jp

5. Acknowledgments

We acknowledge Geographical Survey Institute, Japan for providing the GEONET data. GPS-TEC database of Kyoto University is supported by Japan Society of the Promotion of Science(JSPS) with a grant-in-aid for publication of scientific research results.

6. References

Saito, A., S. Fukao, and S. Miyazaki,
High resolution mapping of TEC perturbations with the GSI GPS network over Japan, Geophys. Res. Let., vol. 25, 3079-3082, 1998.

Tsugawa, T., A. Saito, Y. Otsuka, M. Yamamoto, Damping of large-scale traveling ionospheric disturbances detected with GPS networks during the geomagnetic storm, J. Geophys. Res., vol. 108, 1127, doi:10.1029/2002JA009433, 2003.