Technical description of the SINEX solution opa2015a
1. Origin of input data: databases from IVS data center, version 4 or more.
2. Authentic processing steps after data retrieval: re-calc with Calc 11.0,
transform to superfile and treat with BATCH Solve.
3. Origin of meteorological data: use database content.
4. Use numerical weather model: ECMWF for computing VMF1.
5. Setting of mapping functions: VMF1.
6. Origin of cable cal data: use database content.
7. Application of cable cal flags: use database settings.
8. Selection/settings of geophysical models: replace database settings.
8.1. Nutation/precession: IAU 2000A nutation and IAU 2006 precession.
8.2. Short-period tidal variations in x, y, UT1: IERS 2010.
8.3. Troposphere mapping functions: VMF1.
8.4. A priori mean gradients: from VLBI data or DAO weather model.
8.5. Solid Earth tide: IERS 2010.
8.6. Ocean loading displacements: FES 2004.
8.7. Atmospheric loading displacements: APLO.
8.8. Permanent tide correction: applied.
8.9. Thermal expansion: Nothnagel (2008).
8.10. A priori station positions and velocities: opa2015a or database
content for new stations.
8.11. A priori source coordinates: opa2015a or database content for new
sources.
9. Parameterization
9.1. Clock: quadratic + continuous piece-wise linear with 60-mn interval.
9.2. Atmosphere: continuous piece-wise linear 20-mn interval.
9.3. Gradients: estimated at 6-hr interval at all sites.
9.4. Earth orientation: polar motion and rate, UT1 and rate, nutation
offsets.
9.5. Station positions: estimated.
9.6. Station velocities: not estimated.
9.7. Source coordinates: estimated.
9.8. Antenna axis offsets: fixed.
10. Outlier elimination: use database settings.
11. Constraints (only of interest for direct EOP estimates)
11.1. Sources: loose no-net rotation is uniformly applied to all sources
that were determined in the global solution opa2015a except the 39
'special handling' sources.
11.2. Stations: loose no-net rotation/translation is uniformly applied to
all stations that were determined in the global solution opa2015a
except those affected by earthquakes or nonlinear motions.
12. Generation of pre-reduced datum-free normal equations: yes.
13. Further details
13.1. Data type: group delays.
13.2. Data editing: 5 degree elevation cutoff.
13.3. Data weighting: weights are defined as follows: 1/sqrt(f**2+a**2)
where "f" is the formal uncertainty of the ionosphere free linear
combination of group delays at X- and S-band obtained by fringe fitting
on the base of achieved signal to noise ratio. Station-dependent
parameter "a" was computed for each session by an iterative procedure
such that the ratio of the sum of squares of the weighted residuals to
the estimate of their mathematical expectation is about unity.
13.4. Standard errors reported: all errors are derived from least-squares
estimation propagated from the data weights and the constraints applied
to the troposphere, clock and EOP parameters.
13.5. Software: Calc 11.0, Solve revision date 2014.02.21.
13.6. Other informations about the solution are reported at
http://ivsopar.obspm.fr.