What is it about?
With a long integration time and sensitivity to ionosphere effects, the fully polarimetric GEO-SAR data could be utilized for estimation with high accuracy for both the time-variant TEC and the time interval. We have shown for the first time that time-variant TEC detection with Faraday rotation angle estimation at each azimuth time using full polarimetric SAR data. As shown by simulations with backscattering coefficients from AIRSAR and measured time-variant TEC from USTEC, the proposed method is very effective and enjoys high estimation accuracy for time-variant TEC.
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Why is it important?
On one hand, the ionospheric effects (including dispersion, scintillation and Faraday rotation) on GEO-SAR and low-frequency SAR systems can be accurately compensated with proposed time-variant TEC estimation method, which also solves the problem of lock-lose and positioning error in GNSS caused by ionosphere. On the other hand, the accurate measurements of time-variant TEC can be used for the Earth’s atmospheric science, weather forecast as well as planetary atmospheric sounding.
Perspectives
It is the first time to use GEO-SAR system to realize time-variant TEC real-time measurements with high accuracy, which has not been involved so far in previous studies. Compared with existing ionospheric sounding methods (mainly include ground-based observation, inversion with GPS occultation and topside with spaceborne radar), TEC measurements with GEO-SAR could break the limitation of detecting coverage, accuracy and instantaneity due to limited base station layout and demand of specific detection device as payload. The process of proposed method is much simpler and enjoys higher measuring accuracy than conventional methods and no professional atmospheric sounding equipment is needed. Moreover, with accurate measurements of time-variant TEC, ionospheric effects can be better compensated than traditional autofocusing-based processing, which will give a huge boost to the application performance of real-time global observations for GEO-SAR and low-frequency SAR systems.
Wei Guo
Beihang University
Read the Original
This page is a summary of: Time-Variant TEC Estimation with Fully Polarimetric GEO-SAR Data , Electronics Letters, October 2017, the Institution of Engineering and Technology (the IET),
DOI: 10.1049/el.2017.3297.
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