International GNSS Service (IGS) stations to estimate 7-parameter
Helmert transformations. Previous experience with mapping local
networks in SE Asia (e.g. Wilson et al., 1998; Simons et al., 1999) into
ITRF has shown that if only regional IGS stations are selected the
mapping may not always be optimal, and position and velocity errors
may occur. Moreover, some stations may have been affected by
nearby earthquakes, and hence they do not always fit the linear
velocity trend given by ITRF2005. To avoid the above-mentioned
mapping problems, up to 31 IGS stations were included in the data
processing. This was done to establish an un-deformed reference
solution, which is not affected by episodic jumps in the time series of
some of the IGS stations. In total, IGS data from up to 31 stations were
retrieved for each campaign period from the IGS databases. Typically,
10–20 IGS stations were used in the mapping of each weekly averaged
solution. They were selected (when available) on basis of best
performance in the weekly-combination repeatability test (Simons
et al., 2007). The root mean square (RMS) values obtained from the
mapping process were found to be of the order of 1–3 mmand 10 mm
respectively for the horizontal and vertical components
International GNSS Service (IGS) stations to estimate 7-parameter
Helmert transformations. Previous experience with mapping local
networks in SE Asia (e.g. Wilson et al., 1998; Simons et al., 1999) into
ITRF has shown that if only regional IGS stations are selected the
mapping may not always be optimal, and position and velocity errors
may occur. Moreover, some stations may have been affected by
nearby earthquakes, and hence they do not always fit the linear
velocity trend given by ITRF2005. To avoid the above-mentioned
mapping problems, up to 31 IGS stations were included in the data
processing. This was done to establish an un-deformed reference
solution, which is not affected by episodic jumps in the time series of
some of the IGS stations. In total, IGS data from up to 31 stations were
retrieved for each campaign period from the IGS databases. Typically,
10–20 IGS stations were used in the mapping of each weekly averaged
solution. They were selected (when available) on basis of best
performance in the weekly-combination repeatability test (Simons
et al., 2007). The root mean square (RMS) values obtained from the
mapping process were found to be of the order of 1–3 mmand 10 mm
respectively for the horizontal and vertical components
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