Geoscience Reference
In-Depth Information
Table 7.1 The networks in the combined adjustment of ITRF91 and their transformation param-
eters (translation parameters
X
0
,
Y
0
,
Z
0
, Euler angles
0
X
,
0
Y
,
0
Z
, and scale factor
m
0
)
Δ
Δ
Δ
ʵ
ʵ
ʵ
Δ
X
0
Y
0
Z
0
(cm)
m
0
(10
8
)
X
0
(0.001
00
)
Y
0
(0.001
00
)
Z
0
(0.001
00
)
Δ
(cm)
Δ
(cm)
Δ
Δ
ʵ
ʵ
ʵ
No. Network
1
SSC(GSFC)92R03
0.3
1.2
2.8
0.05
1.1
1.2
2.5
2
SSC(NOAA)92R01
2.1
0.4
2.2
0.08
4.6
9.9
0.2
3
SSC(USNO)92R01
1.9
4.4
0.8
0.42
0.4
0.2
0.2
4
SSC(NAOMZ)92R01
3.3
2.9
4.8
0.06
1.3
1.0
0.5
5
SSC(JPL)92R01
1.9
1.1
1.7
0.50
2.5
1.1
0.7
6
SSC(CSR)92L01
0.0
0.0
0.0
0.00
0.4
0.4
0.9
7
SSC(GSFC)92L01
2.9
1.4
0.3
0.31
0.3
5.7
7.3
8
SSC(DGFII)92L01
0.7
3.0
0.0
0.37
284.4
44.5
5.7
9
SSC(DUT)92L01
0.1
0.6
3.8
0.65
0.8
1.7
4.6
10
SSC(GFZ)92L01
0.1
0.2
3.0
0.06
0.1
0.1
0.2
11
SSC(GAOUA)92L01
1.4
0.4
7.2
0.52
0.3
0.4
1.4
12
SSC(NAL)92L01
0.4
0.6
3.5
0.08
1.0
1.6
0.6
13
SSC(UTXMO)92M01
0.1
3.5
17.6
3.20
6.5
0.8
38.5
14
SSC(JPL)92M01
6.5
1.2
4.7
1.97
1.0
1.4
44.7
15
SSC(SHA)92M01
6.8
0.5
1.9
2.75
0.3
0.1
3.2
16
SSC(JPL)01P01
6.7
14.8
17.0
0.14
0.4
0.7
61.5
Table 7.2 Transformation parameters (translation parameters ΔX
0
, ΔY
0
, ΔZ
0
, Euler angles
ʵ
x
, ʵ
y
, ʵ
z
, and scale factor Δm) between ITRF91A and ITRF90
ΔX (cm)
Δm (10
8
)
ΔY (cm)
ΔZ (cm)
ʵ
X
(0.001
00
)
ʵ
Y
(0.001
00
)
ʵ
Z
(0.001
00
)
0.1
0.4
1.5
0.02
0.4
0.4
0.9
2002a, b, 2007, 2011). It can be seen from the table that the origin and scale of ITRF
have been defined by the average of the chosen SLR, GPS, and VLBI solutions
since BTS87 (where BTS is the reference system established by BIH). The orien-
tation of ITRF was aligned to the BIH EOP (Earth Orientation Parameter) series,
while the orientation of ITRF93 was aligned to the IERS EOP series. For the
orientation time evolution, no global velocity field was estimated prior to
ITRF90, so the AMO-2 plate motion model was recommended. Starting with
ITRF91, the orientation time evolution satisfies the NNR condition with respect
to (represented by “wrt” in Table
7.3
) the previous ITRF series or the
NNR-NUVEL1, NNR-NUVEL1A plate motion models. However, the orientation
time evolution of ITRF93 was aligned to the IERS EOP series.
CTRF is four-dimensional or dynamic. Its dynamic feature lies in that CTRF is
composed of coordinates and velocities at a reference epoch. Temporal variation
(dynamism) is the innate property of CTRF. On the one hand, the plate motion,
crustal deformation, and geodynamic factors as such will cause the instantaneous
position of the point on the surface of the solid Earth to change constantly, and the
station coordinates and station velocities should be provided. On the other hand, the
new observational data are continually updated and new observation sites are ever
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