HR: 0800h
AN: G31A-0791    [Abstracts]
TI: How VLBI Can Contribute To Ionospheric Research
AU: * Hobiger, T
EM: hobiger@nict.go.jp
AF: Kashima Space Research Center, National Institute of Information and Communications Technology, 893-1 Hirai, Kashima, Ibaraki, 314 Japan
AU: * Hobiger, T
EM: hobiger@nict.go.jp
AF: Advanced Geodesy, Inst. of Geodesy and Geophysics, Vienna Univ. of Technology, Gusshausstrasse 27-29, Vienna, 1040 Austria
AU: Kondo, T
EM: kondo@nict.go.jp
AF: Kashima Space Research Center, National Institute of Information and Communications Technology, 893-1 Hirai, Kashima, Ibaraki, 314 Japan
AU: Schuh, H
EM: harald.schuh@tuwien.ac.at
AF: Advanced Geodesy, Inst. of Geodesy and Geophysics, Vienna Univ. of Technology, Gusshausstrasse 27-29, Vienna, 1040 Austria
AB: Like other space geodetic techniques VLBI observations are carried out at two distinct frequencies in order to determine ionospheric delay corrections. Each ionospheric delay corresponds to the total electron content (TEC) along the ray path through the ionosphere. Because VLBI is a differential technique the observed ionospheric delays represent the differences of the behaviour of the propagation media above each two stations. Additionally an instrumental offset, independent of azimuth and elevation in which the antennas point, is contained in the measurements. Due to the sparse geographical distribution of VLBI stations and the fact that this technique is not observing every day it is suggested to derive station-specific TEC values only. These results can be used to validate the TEC values derived by other space geodetic techniques or they can be incorporated into long-term studies of the ionosphere because already now VLBI observations cover more than two complete solar cycles. A combination with GPS should improve the models, because both techniques are almost always co-located. Finally a combined long-term model of the ionosphere that uses VLBI, GPS, and satellite altimetry data back to the date of implementation of each technique will be derived. This model should be able to predict the ionosphere on longer timescales, i.e. at least over months.
DE: 6954 Radio astronomy
DE: 6964 Radio wave propagation
DE: 2400 IONOSPHERE
DE: 2447 Modeling and forecasting
DE: 1243 Space geodetic surveys
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting