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Robert Heinkelmann 1 , Johannes Boehm 1 , Harald Schuh 1 , and Volker Tesmer 2. Global VLBI Solution IGG05R01. 1 Institute of Geodesy and Geophysics (IGG), Vienna, Austria 2 German Geodetic Research Institute (DGFI), Munich, Germany. Motivation.

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slide1

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

Global VLBI Solution IGG05R01

1 Institute of Geodesy and Geophysics (IGG), Vienna, Austria

2 German Geodetic Research Institute (DGFI), Munich, Germany

motivation
Motivation
  • generalaim: contributions to future realizations of IVS and IERS combined products- TRF- CRF- EOP time series
  • specialaim: 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

total number ofsessions availablein NGS-format

4490

2702

IGG05R01

  • 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 homogenizedpressure 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

Dd[mas]

a[hour]

d[deg]

1.1 %>3 mas

Da*cos(d) [mas]

a[hour]

d[deg]

0.8 %>3 mas

* sources with >3 sessions

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VieEOP w.r.t. IERS-C04

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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slide12

VTRF2005

VieTRF

IGG05R01

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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)

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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slide15

Earthquake near Concepción, 2004-05-03

superconducting gravity meter jump of +26Gal

(free-air gradient ≈ -0.3086 mgal/m)

=> up= ̶ 84 mm

model 1: two rates=> up= +0.5 mm

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

instrumental effect?!

no comparable jump in up component!

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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!

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

contacts: R. Heinkelmann

[email protected]

end

4th IVS General Meeting

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