Calc91

Abstract.

F-Solve has been upgraded to digest Calc 9.1 databases. A set of 50 VLBI experiments for 1995 years has been processed by Calc8.2+Solve and Calc9.1+Solve. The dataset contains primarily from NEOS data. Differences in EOP are presented.

Procedure.

Decalcing. 118 lcodes has been removed from each database.

Calcing. Databases has been processed by using this C-shell program . A priori site and station coordinates, ocean loading, EOP were supplied in external file .

Superfiling. New superfiles have been created by liptn. Special CORFIL has been supplied to SDBH in the process of creating superfiles.

Solving Independent solution with estimation EOP have been done using two set of superfiles for the same experiments. Control file for Calc 8.2 set of databases and for Calc 9.1 used mapped site coordinates and velocities, source coordinates and EOP. They used the same weight files (only version number has been updated). The difference was in $CONTRIBUTIONS section: Control file for calc 8.2 used
```
$CONTRIBUTIONS
 Ocean Pol_Tide EarthTid K1_Plus Love+Rad 3rd_Tide Cons.Rel Equ_Eqnx WobXCont  WobYCont Axis_2
```
while the control file for calc 9.1 used
```
$CONTRIBUTIONS
 Pol_Tide WobXCont WobYCont EarthTid Ocean    PTideOld Axis_2  
```
Despooling Series of 6 Earth orientation parameters from spool files were extracted by GETPAR.

Plotting differences. Differences in estimates of EOP from Calc 9.1 and Calc 8.2 databases has been obtained (9.1 minus 8.2) and plotted. Formal uncertainty from Calc 9.1 solution is ascribed to the differences. Mean value of the difference and rate of change (unit: 1/year) have been computed.

Results

X pole coordinates
Y pole coordinates
UT1 angle
UT1 rate
Nutation PSI
Nutation EPS

Discussion

I don't care about X pole and Y pole differences: they look normally. I am not so concerned about nutation angles: procedure of estimation of nutation is not well defined at the limit 0.1-0.2 mas. But I cannot reconcile with shift and drift in UT1. Something is wrong here. I was trygin to use calibrations with plays back to CACL 8.2:

 Pol_Tide WobXCont WobYCont EarthTid Ocean    PTideOld Axis_2  Wahr_Nut C82ETide

Results changed slightly, but the differences in UT1 remained. We have to explain this difference.

Correction in contr-bug UT1S-rate-AUG97 in ../cutil/flyby_map.f has been done next day. Contributions setup was changed in according with recommendations of Dave Gordon:
For Calc8.2 databases:

$CONTRIBUTIONS
 Pol_Tide  WobXCont  WobYCont EarthTid  3rd_Tide  Ocean  Cons.Rel Equ_Eqnx

For Calc9.1 databases:

$CONTRIBUTIONS
 Pol_Tide  WobXCont  WobYCont EarthTid  3rd_Tide  Ocean  Cons.Rel Equ_Eqnx

And solutions have been obtained once more.
Results are:

X pole coordinates
Y pole coordinates
UT1 angle
UT1 rate
Nutation PSI
Nutation EPS

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Last update: 15-NOV-99 16:58:44