HR: 1340h
AN: SA13A-1061    [Abstracts]
TI: GPS Ionospheric Tomography over Japan with Constrained Least-squares Method
AU: * Saito, A
EM: saitoua@kugi.kyoto-u.ac.jp
AF: Department of Geophysics, Kyoto University, Kyoto University, Graduate School of Science 4th BLDG, Sakyo-Ku, Kyoto, 606-8502, Japan
AU: Teraishi, S
EM: teraishi@kugi.kyoto-u.ac.jp
AF: Department of Geophysics, Kyoto University, Kyoto University, Graduate School of Science 4th BLDG, Sakyo-Ku, Kyoto, 606-8502, Japan
AU: Ueno, G
EM: gen@ism.ac.jp
AF: The Institute of Statistical Mathematics, 4-6-7 Minami-Azabu, Minato-ku, Tokyo, 106-8569, Japan
AU: Fujita, N
EM: nobuyuki@kugi.kyoto-u.ac.jp
AF: Department of Geophysics, Kyoto University, Kyoto University, Graduate School of Science 4th BLDG, Sakyo-Ku, Kyoto, 606-8502, Japan
AU: Tsugawa, T
EM: tsugawa@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
AB: An ionospheric tomography method was developed for the GPS total electron data observed by a dense GPS receiver network in Japan. GEONET is a GPS network operated by Geographical Survey Institute, Japan, and consists of about 1,200 receivers. Its high-density distribution of the receivers, and wide coverage provide a suitable data set to reconstruct the electron density distribution in the ionosphere with high spatial resolution. The newly developed GPS ionospheric tomography (GPS-IT) model is based on the constrained least-squares method (CLM). The three dimensional distribution of the ionospheric electron is derived at every data sampling time, 30 seconds. A priori information requested for the GPS-IT is the intensity of restriction for the spatial gradient of the electron density. The vertical gradient of the electron density is restricted to be low above 800km altitude. The vertical boundary condition at bottom-side is based on the IRI model and at topside is based on the plasmaspheric model. The horizontal boundary condition is that the gradient of the electron density is nearly zero. The derived electron density distribution shows a good agreement with the electron density measured by the IS observation of the MU radar, and ionosondes. This GPS-IT can also include the data from the MU radar, ionosondes, and in-situ density measurements. This flexibility and robustness is an advantage of this GPS-IT model with CLM. The introduction of the algorithm, and the electron density distribution obtained in the quiet and disturbed days will be presented.
DE: 2435 Ionospheric disturbances
DE: 2443 Midlatitude ionosphere
DE: 2494 Instruments and techniques
DE: 6929 Ionospheric physics (1240, 2400)
DE: 6982 Tomography and imaging (7270, 8180)
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting