ARLA
33710S001
ARMA
3370S002
JoG: ARLA
should not be used for ITRF2005, too few data
IDS: ARLA
should not be used for ITRF2005, too few data
Preliminary
computations:
No ARLA
data available after 1993.0
Geodetic
local tie from SIMB is
ARMA 33710S002
ARLA 33710S001 1362.690 2163.732 -4825.937 0.010
In
ITRF2005, ARMA is
ARMA 2000.0
5991269.312 773728.625 2040688.550 -8.98 20.75 16.01
So , we
could derive
ARLA 2000.0
5992632.002 775892.357 2035862.613 -8.98 20.75 16.01
We first
need to verify the ARMA position and velocity as the formal error in the
velocity is quite large and could introduce errors on the long term
Using
weekly DORIS solutions (ign07d02) expressed in ITRF2005 and fixing the velocity
to the above ITRF2005 value, we obtain:
2000.0 ARMA
5991269.3261 773728.6203 2040688.5422 -8.98 20.75 16.01
statistics
ARMA XYZ 0.0024 0.0036 0.0021 209
so this is
in good agreement with the ITRF2005 values. As this station is not transmitting
any more the fact that the velocity is not totally know is not a problem for
DPOD2005 investigation, as there wonÕt be any extrapolation period for POD.
Reprocessing
old DORIS data (1990 and 1992), using weekly solutions and fixing the velocity
to be above value, we obatin :
2000.0 ARLA
5992632.0656 775892.3492 2035862.5945 -8.98 20.75 16.01
statistics
ARLA XYZ 0.0119 0.0192 0.0218 30
Y and Z are
rather close to the ITRF2005 prediction. However, the X-component is a bit
apart. As the formal error of the geodetic local is rather large and as the
difference could also be explained by some imprecsion in the X-velocity, I
suggest to use the DORIS-derived
solution as the weekly solution are rather consistent from one week to another
and that a 5 cm error would be detected. This would insure that the posiiton ate
the epoch of measurements for ARLA (1990.0-1993.0) will be good.
Recommendation:
For ARMLA, fix velocity to ARLA/ITRF2005 and use DORIS data
to estimate position in 2000.0
2000.0 ARLA
5992632.0656 775892.3492 2035862.5945 -8.98 20.75 16.01