# Presentation: 704584

## Global VLBI Solution IGG05R01

- 1 Institute of Geodesy and Geophysics (IGG), Vienna, Austria
- 2 German Geodetic Research Institute (DGFI), Munich, Germany

- Robert Heinkelmann1, Johannes Boehm1, Harald Schuh1, and Volker Tesmer2

## Motivation

**general** **aim**: contributions to future realizations of IVS and IERS combined products-  TRF-  CRF-  EOP time series
**special** **aim**: investigations of dependencies between the long-term characteristics of -  met data in VLBI Analysis-  tropospheric parameters
- 	-  station positions and velocities-  scale factor and scale rate

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## IGG05R01 – General characteristics

- unconstrained simultaneous estimation of - source positions (VieCRF)- station positions and velocities (VieTRF) - Earth orientation parameters (VieEOP)
- using OCCAM 6.1 (LSM) VLBI software
- 	and DOGS-CS for handling the normal equations1
- geodetic datum definitions: - VieCRF: NNR w.r.t. ICRF-Ext.1 using 199 stable sources- VieTRF: NNR+NNT w.r.t. ITRF2000 using 15 stations
- 1 the DOGS-CS software was developed at DGFI, Munich; thank you for provision

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## IGG05R01 – General characteristics

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- 3,414,325 observations
- 1450 globally estimated parameters
- 2702 sessions in NGS-format
- 1984-01-04 till 2005-11-28

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## Criteria for the solution

- session criteria
- minimal duration: 18h (no intensive sessions)
- minimum of 3 stations
- no sessions unreliable for the determination of EOP  (http://vlbi.geod.uni-bonn.de/IVS-AC/data/exclude.html)
- rms < 2 cm, fraction of outliers < 3.5 %
- station criteria
- 50 VLBI stations (of 136 out of ITRF2000)
- no mobile stations (but TIGOCONC)
- source criteria
- 552 radio sources (of 667 out of ICRF-Ext. 1)
- minimum of 3 observations per session
- minimum of 3 sessions for global estimation of source position

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## Estimated parameters with OCCAM

- CRF: right ascension α, declination 
- TRF: positions X, Y, Z
- EOP: nutation , , and 	   ERP: Xp, Ẋp, Yp, Ẏp, dUT1, dUṪ1
- tropospheric zenith delays: offset, 	PWLF with 1 hour interval, 	rates constrained with 10 mm/h
- tropospheric gradients: offset constrained with 0.5 mm
- clock parameters: offset, rate, and squared rate w.r.t. 	reference station + clock breaks (if necessary), 	PWLF with 1 hour interval, 	rates constrained with 30 mm/h

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## Estimated parameters with DOGS-CS

- CRF: right ascension α, declination 
- TRF: positions X, Y, Z, and velocities Ẋ, Ẏ, Żdiscontinuities:	GILCREEK	| 02-11-03 	| earthquake				TSUKUB32	| 99-04-01	| rail repair			DSS65		| 97-04-15	| rail repair			EFLSBERG	| 96-10-01	| rail repair
- 				MEDICINA	| 96-06-01	| rail repair				DSS15		| 92-06-27	| earthquake
- 				MOJAVE12 	| 92-06-27 	| earthquake
- 				NRAO85 3 	| 90-12-01	| unknown
- EOP
- tropospheric zenith delays
- tropospheric gradients
- clock parameters

- reduced

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## Analysis settings and geophysical models

- outlier elimination: data snooping with threshold of 3.5
- mapping function: VMF
- cutoff elevation angle : 5°
- a-priori zenith delays from homogenized pressure records
- axis offsets: taken from the Analysis Coordinator webpage (http://giub.geod.uni-bonn.de/vlbi/IVS-AC/data/axis-offsets.html)
- model of relativity: ‘consensus model’
- ephemerides: DE405/LE405
- model of nutation: MHB 2000 (without FCN)
- solid earth tides: IERS Conv. 2003
- ocean loading: GOT00p2 (provided by H.G. Scherneck)
- no a-priori tropospheric gradients
- no atmospheric loading, snow loading, ...
- no antenna thermal deformation

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## VieCRF* w.r.t. ICRF-Ext.1

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- [hour]

- [hour]

- [deg]

- [deg]

- [mas]

- *cos() [mas]

-  1.1 %>3 mas

-  0.8 %>3 mas

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- * sources with >3 sessions

## VieEOP w.r.t. IERS-C04

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- MHB2000 model was used without free core nutation part!
- :
- signal with period ~ 430 d(free core nutation)
- shift: - 0.012 mas
- rate: +0.019 mas/y
- :
- signal with period ~ 430 d
- (free core nutation)
- shift: -0.036 mas
- rate: -0.010 mas/y

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## VieEOP w.r.t. IERS-C04

- ITRF2000, ICRF-Ext.1 and EOP-C04 are from different solutions!
- dXp:
- shift: -0.212 mas
- rate: -0.005 mas/y
- dYp:
- shift: 0.108 mas
- rate: 0.037 mas/y
- dUT1:
- shift: 0.776 s
- rate: 0.158 s/y

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## 12

- IGG05R01

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##  Vertical component w.r.t. ITRF2000

-  Vertical component w.r.t. ITRF2000

- VieTRF
- VTRF2003
- VTRF2005
- DGFI-TRF

- The 15datumstations

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## Helmert parameters from VieTRF into ITRF2000

- 12 regularly used stations (*IVS 2005*)

| epoch | 2000 | 2010 |
| --- | --- | --- |
| [as] | -37.4 ± 151 | 112 ± 240 |
| [as] | -66.6 ± 155 | -238 ± 247 |
| [as] | -51.4 ± 148 | -82.4 ± 236 |
| X    [mm] | 1.5 ± 4.0 | -2.1 ± 6.3 |
| Y    [mm] | -2.6 ± 3.9 | -1.5 ± 6.2 |
| Z    [mm] | 1.0 ± 3.8 | -0.9 ± 6.0 |
| scale [ppb] | 0.81 ± 0.59 | 0.84 ± 0.94 |
| scale [mm]* | 5.2 | 5.4 |

- ALGOPARK
- FORTLEZA
- GILCREEK
- HARTRAO
- HOBART26
- KOKEE
- MATERA
- NYALES20
- SESHAN25
- TSUKUB32
- WESTFORD
- WETTZELL

- scale rate is 0.0029 ppb/y, 0.02 mm*/y	    * at Earth radius

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## Earthquake near Concepción, 2004-05-03

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- Earthquake near Concepción, 2004-05-03

- superconducting gravity meter jump of +26Gal
-  (free-air gradient ≈  -0.3086 mgal/m)
- => up=  ̶  84 mm

- model 2: constant rate => up=  ̶  7.7 mm

- model 1: two rates=> up=  +0.5 mm

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- no comparable jump in up component!

- instrumental effect?!

## Summary and outlook

- IGG05R01, the Vienna global solution, is already of acceptable quality
- it can be improved by
- using met data from NWM
- extending the number of stations
- extending the number of sources (outside the ICRF-Ext.1)
- adding sub-sets of 24h type of sessions, in particular the large VLBA sessions
- applying atmospheric loading corrections
- applying corrections for the thermal deformation of telescopes
- applying a-priori atmospheric gradients
- applying new mapping functions VM1 (instead of VMF)
- optimizing soft + hard constraints

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##    Thank you for your attention!

- rob@mars.hg.tuwien.ac.at

-    Thank you for your attention!

- end

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- The coauthors are greatly acknowledgedfor their scientific advice.Project 16992 is funded by