Geoscience Reference
In-Depth Information
Fig. 17
Simulation results
of tomographic reconstruc-
tion of the refractivity field.
The
upper plot
shows the
result obtained when the
simulated refractivity field
was 20 mm/km in the fifth
layer and zero elsewhere. In
the
lower plot
the simulated
refractivity field is 20 mm/km
only in the middle voxel of the
fifth layer, and zero elsewhere.
These results are from Nilsson
(
2007
)
8
Simulated
Estimated
7
6
5
4
3
2
1
0
−5
5
15
25
Refractivity [mm/km]
8
Simulated
Estimated
7
6
5
4
3
2
1
0
−5
5
15
25
Refractivity [mm/km]
in the lowest layer is however correctly estimated to zero. Here the sensitivity is
higher since the stations are at slightly different altitudes. In the lower plot of Fig.
17
the simulated refractivity field is non-zero just in one voxel: the middle voxel (of
25) of the layer between 3 and 4 km. In this case the tomographic reconstruction is
working better. This demonstrates that GNSS tomography can have a good sensitivity
to horizontal fluctuations in the refractivity field, and is even able to determine at
which height these fluctuations are occurring. For more details about the simulation
setup and other results from similar simulations, see Nilsson (
2007
).
Acknowledgments
First of all we would like to thank the reviewer, Gunnar Elgered, for providing
very valuable suggestions to improve the quality of this part of the topic. We are grateful for the
financial support from the German Science Foundation (DFG, SCHU 1103/3-2), and from the
Austrian Science Fund (FWF, P20902-N10).
