On the importance of accurately ray-traced troposphere corrections for Interferometric SAR data |
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| Authors: | Thomas Hobiger Youhei Kinoshita Shingo Shimizu Ryuichi Ichikawa Masato Furuya Tetsuro Kondo Yasuhiro Koyama |
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| Institution: | (1) Department of Navigation and Positioning, Finnish Geodetic Institute, Geodeetinrinne 2, Masala, Finland |
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| Abstract: | Numerical weather models offer the possibility to compute corrections for a variety of space geodetic applications, including
remote sensing techniques like interferometric SAR. Due to the computational complexity, exact ray-tracing is avoided in many
cases and mapping approaches are applied to transform vertically integrated delay corrections into slant direction. Such an
approach works well as long as lateral atmospheric gradients are small enough to be neglected. But since such an approximation
holds only for very rare cases it is investigated how horizontal gradients of different atmospheric constituents can evoke
errors caused by the mapping strategy. Moreover, it is discussed how sudden changes of wet refractivity can easily lead to
millimeter order biases when simplified methods are applied instead of ray-tracing. By an example, based on real InSAR data,
the differences of the various troposphere correction schemes are evaluated and it is shown how the interpretation of the
geophysical signals can be affected. In addition, it is studied to which extend troposphere noise can be reduced by applying
the exact ray-tracing solution. |
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