SLR-Beobachtungen zu LAGEOS und GNSS-Satelliten und die ... · Geomatik-Seminar der ETH Zürich,...

Geomatik-Seminar der ETH Zürich, 24. November 2010

SLR-Beobachtungen zuLAGEOS und GNSS-Satelliten

und die gemeinsame Auswertungmit GNSS-Beobachtungen

Daniela ThallerAstronomisches Institut, Universität Bern (AIUB)


Gliederung

1. Prozessierung der LAGEOS-Daten am AIUB

2. Allgemeine Aspekte der Kombination von GNSS und SLR- Stationen als Kolokation- Satelliten als Kolokation

3. SLR-Tracking der GNSS-Satelliten(GPS und GLONASS)

4. Resultateder kombinierten GNSS-SLR-Auswertung - Stationskoordinaten / TRF- GNSS satellite antenna offsets- Biases zwischen GNSS und SLR

5. Zusammenfassungund Ausblick


Prozessierung von LAGEOS am AIUB

Bernese GPS Software (BSW)wurde erweitert:→ Orbit-Modellierung für Kugelsatelliten→ Handling von SLR-Beobachtungen

Zusammenarbeit mit Bundesamt für Kartographie und Geodäsie (BKG):→ ILRS Analysis Center→ BKG-Beiträge basierend auf BSWseit Juli 2010

Analyse der LAGEOS-Daten am AIUB :

→ 2 Satelliten: LAGEOS-1 / -2

→ Wochenlösungen für2006 – 2010


−180 −120 −60 0 60 120 180−90

−60

−30

0

30

60

90SLR network for 2007 − 2009 (Lageos tracking)

SLR tracking of LAGEOS

→ Geographical distribution is not ideal!→ Total for 2006 – 2009: 35 stations; 11 stations for datum definition→ Number of stations per week: 12 – 26(datum definition: 7 – 11)


SLR tracking of LAGEOS

Total number of observations (normal points) per week for both satellites: ~ 3000

2006 2006.5 2007 2007.5 2008 2008.5 2009 2009.5 2010 2010.5 20110

1000

2000

3000

4000

5000

6000

7000

Year

# N

P p

er w

eek

Number of NP per week: LAGEOS−1 + LAGEOS−2


Weekly LAGEOS solutions

Estimated parameters for weekly ILRS solution:

→ Station coordinates

→ Satellite orbits: 1 arc per week→ 6 osculating elements→ Dynamic orbit parameters:

- Constant acceleration in along-track- Once-per-rev in along-track- Once-per-rev in cross-track

→ Earth rotation :→ Polar motion (constant per day)→ Length of Day (LOD)

→ Range biasesfor selected sites (1 – 3 stations per week)

⇓

~ 120 – 140parametersper week



Residualsfor LAGEOS-1after least squares adjustment:→ Yarragadee→ Zimmerwald

1 2 3 4 5 6 7 8 9 10 11 12−120

−100

−80

−60

−40

−20

0

20

40

60

80

100

120SLR residuals for station 7090 50107M001, satellite L51

Month of 2009

Res

idua

l [m

m]

#residuals = 11406, Mean = −0.1mm, RMS = 13.1mm

1 2 3 4 5 6 7 8 9 10 11 12−120

−100

−80

−60

−40

−20

0

20

40

60

80

100

120SLR residuals for station 7810 14001S007, satellite L51

Month of 2009

Res

idua

l [m

m]

#residuals = 9661, Mean = 0.9mm, RMS = 10.3mm



Weekly RMS after least squares adjustment for Zimmerwald

2009 2009.2 2009.4 2009.6 2009.8 20100

2

4

6

8

10

12

14

16

Time

Wee

kly

RM

S [m

m]

Weekly RMS of residuals for station 7810

LAGEOS−1: mean = 9.3 mmLAGEOS−2: mean = 8.4 mm

2009 2009.2 2009.4 2009.6 2009.8 20100

100

200

300

400

500

600

Time

# N

P p

er w

eek

Number of NP per week: Station 7810

LAGEOS−1: mean = 206LAGEOS−2: mean = 160


Co-locations for GNSS and SLR

Co-location at stations (e.g., for actual ITRF computation):→ Application of known local tie values→ GNSS observations of ground network; SLR observations to Lageos etc.

→ Independent ofsatellite tracked→ Local ties from terrestrial measurements


Co-locations for GNSS and SLR→ bad global distribution of co-location sites→ only few co-locations (37)→ questions concerning accuracy, transformation local measurements → global

from ITRF2008-D solution (provided by M. Seitz, DGFI)


Co-locations for GNSS and SLRCo-location at GNSS satellites = Common orbit parameters from GNSS

microwave and SLR range data

→ Vectorsof GNSS and SLR reference points w.r.t. satellite CoM needed

Space Tie =

1. GNSS Satellite Antenna Offsets (SAO) w.r.t. CoM

2. GNSS Phase Center Variations (PCV)

3. Offsets for Laser Retroreflector Array (LRA ) w.r.t. CoM


Expectation from combined analysis

For a few sites only

Decorrelated if different elevation

angles

-Range biases

↔↔↔↔ Scale

-independentProblems in phase center modelling

GNSS satellite antenna phase center

↔↔↔↔ Scale

RPR well modelled

Problems in RPR modelling

Problems in RPR modelling

Radiation pressure

↔↔↔↔ Geocenter

SLR @LageosSLR @GNSSGNSS @GNSS

SLR @GNSS:

⇒ Geocenteris affected as well ⇒ LAGEOS needed

⇒ Scaleis transferred to GNSS⇒ LAGEOS helps for decorrelation


SLR tracking of GNSS satellites→ Only 2 GPS satellitesare equipped with retro-reflector arrays (G05, G06)

→ All GLONASS satellitesare equipped with retro-reflector arrays

→ SLR tracking for selected GNSS satellites:

2 GPS →→→→ 2009: 13 GLONASS →→→→ 2010: 6


SLR tracking of GNSS satellites

8 sites with > 1000 NP5 sites with > 500 NP6 sites with > 100 NP6 sites with < 100 NP

Altogether (2008):25 SLR sites31855 normal points (NP)

Northern hemisphere:16804 NP

Southern hemisphere:15051 NP

−180 −120 −60 0 60 120 180−90

−60

−30

0

30

60

90

Satellites tracked in 2008:

GPS: G05G06

GLONASS:R15R24R07R11


07/03 01/04 07/04 01/05 07/05 01/06 07/06 01/07 07/07 01/08 07/08 01/09 07/09 01/100

20

40

60

80

Month / Year

# S

LR o

bs. /

Day

G05

Number of SLR observations per day

07/03 01/04 07/04 01/05 07/05 01/06 07/06 01/07 07/07 01/08 07/08 01/09 07/09 01/100

10

20

30

40

50

60

70

Month / Year

# S

LR o

bs. /

Day

G06


07/07 01/08 07/08 01/09 07/09 01/100

20

40

60

80

100

120

140

Month / Year

# S

LR o

bs. /

Day

R15

07/03 01/04 07/04 01/05 07/05 01/06 07/06 01/07 07/07 01/080

20

40

60

80

100

120

140

Month / Year

# S

LR o

bs. /

Day

R03

Number of SLR observations per day

07/03 01/04 07/04 01/05 07/05 01/06 07/06 01/07 07/07 01/080

20

40

60

80

100

120

140

Month / Year

# S

LR o

bs. /

Day

R22

07/03 01/04 07/04 01/05 07/05 01/060

20

40

60

80

100

120

140

Month / Year

# S

LR o

bs. /

Day

R24


−60

−40

−20

0

20

40

60

7090

7832

7810

7406

7839

7825

7840

8834

7405

7845

7080

7110

7308

7237

7941

7210

7358

7105

7249

7841

7501

7355

7821

7838

Bia

s [m

m]

Satellite− / site−specific bias

G05 G06

SLR residuals: Mean bias

Mean bias for all stationsfor 2003 – 2009 [mm]:

G05 G06-24.0 -26.4

Stations

R03 R07 R11 R15 R22 R24a R24b-13.5 -8.6 -19.5 -2.6 -14.1 -17.9 -16.0


Combined analysis of GNSS and SLRProblems and Questions:

Are satellite co-locations (space ties) strong enough or are co-locations on ground (local ties) needed additionally?

Biases between GNSS and SLRare seen in SLR range residuals to given microwave-based orbits→ Several possible error sources ...

Correlations between parameters (offsets, range biases) and scale→ Common estimation possible?

Only few SLR observationsto GNSS satellites (10 – 20 per day)→ Weak estimation of parameters→ Daily solutions not possible


Systematic effects between SLR and GNSS

2004 2005 2006 2007 2008 2009 2010−100

−50

0

50SLR residuals for station 7839 11001S002, satellite G06

Year

Res

idua

l [m

m]

Residuals: RMS = 13.1mmEpoch−diff. of residuals: RMS = 3.2mm

07/05 01/06 07/06 01/07 07/07 01/08 07/08−200

−150

−100

−50

0

50

100

150

200SLR residuals for station 7839 11001S002, satellite R07

Month/Year

Res

idua

l [m

m]

Residuals: RMS = 35.7mmEpoch−diff. of residuals: RMS = 8.5mm

1) Biases in SLR range residuals (cm-level)2) Epoch-differences of SLR range residuals have a much smaller RMS

⇒ systematic effects


Systematic effects between SLR and GNSS

Possible reasons for systematic effects in SLR range residuals:

SLR station coordinates (fixed to SLRF2005)

TRF (scale, geocenter)

Offset for GNSS satellite antenna (SAO from igs05.atx)

Offset for laser reflector array (LRA from ILRS web site)

SLR range biases (unknown for GNSS satellites)

GNSS orbit modelling (solar radiation pressure)

⇒⇒⇒⇒ Must be handled in combined solution: - use known / better values- Estimation


Combined analysis of GNSS and SLR

SLR station coordinates→ estimate + inclusion of LAGEOS

TRF scale (and geocenter)→ use from SLR

Offset for GNSS satellite antenna (SAO from igs05.atx)→ estimate

Offset for laser reflector array (LRA from ILRS web site)→ estimate

SLR range biases (unknown for GNSS satellites)→ estimate + inclusion of LAGEOS

⇒⇒⇒⇒ GNSS-microwave + SLR@GNSS + SLR@LAGEOS for 2006-2009

GNSS has rank-deficiency w.r.t. scale if SAO areestimated

Estimation of 1 bias parameter per station / per GNSS satellite


Combined analysis of GNSS and SLR

→ GNSS-only NEQs (daily):- Combined GPS+GLONASS analysis performed at CODE- Re-analysis for 2003 – 2008, routine IGS analysis for 2009

→ SLR-only NEQs for SLR@GNSS (daily):- SLR data to GPS and GLONASS satellites- Parameterization identical to GNSS analysis (orbits, ERP, geocenter)- Range biases for all sites

→ Combination of daily NEQs

→ SLR-NEQs for Lageos (weekly):- Range biases only for selected sites

→ Combination of NEQs and accumulation to long-term solution:- Use of “Space ties” only; Local ties are not applied!


SLR station coordinates

SLR station network- Not included in the datum definition (no-net-rotation, no-net-translation)- No local ties applied→ Only appended via the „space ties“ (common orbit parameters)

→ Agreement is at the cm-level if only SLR@GNSS is used→ Inclusion of Lageosimproves the coordinate estimates→ Connection by using space ties only is feasible

Validation of SLR station coordinates: Helmert transformation

SLRF2005 Lageos-onlyComb: SLR@GNSS 54.40 54.22 [mm]Comb: + Lageos 6.70 2.95 [mm]Lageos-only 7.49 [mm]

RMS


SLR station coordinates

SLR station network:- Not included in the datum definition (no-net-rotation, no-net-translation)- No local ties applied→ Only appended via the „space ties“ (common orbit parameters)

→ Scale of SLR is defined well→ Inclusion of Lageosimproves the coordinate estimates

Validation of SLR station coordinates: Helmert transformation

SLRF2005 Lageos-onlyComb: SLR@GNSS 1.06+- 2.76 2.34 +- 2.75 [ppb]Comb: + Lageos 1.02 +- 0.34 0.25 +- 0.15 [ppb]Lageos-only 1.28 +- 0.38 [ppb]

Scale


0

10

20

30

40

50

60

70

80

90M

DO

1−70

80Y

AR

2−70

90Y

AR

R−

7090

GO

DZ

−71

05M

ON

P−

7110

MA

UI−

7119

TH

TI−

7124

BJF

S−

7249

KG

NI−

7308

AR

EQ

−74

03C

ON

Z−

7405

HA

RB

−75

01H

RA

O−

7501

ZIM

M−

7810

ZIM

T−

7810

BO

R1−

7811

SF

ER

−78

24S

TR

1−78

25S

TR

2−78

25G

RA

Z−

7839

HE

RS

−78

40H

ER

T−

7840

PO

TS

−78

41G

RA

S−

7845

MA

T1−

7941

MA

TE

−79

41W

TZ

J−88

34W

TZ

L−88

34W

TZ

R−

8834

WT

ZZ

−88

34

AB

S(d

iscr

epan

cy w

.r.t.

LT

) [m

m]

Coordinate differences w.r.t. local ties: Absolute value of discrepancy

IGS−ILRS for ITRF2008AIUB: SAO fixed to igs05.atxAIUB: SAO estimated

Comparison with co-located GNSS sites1. Estimated SLR and GNSS station coordinates ⇒ ∆∆∆∆CRD_estimate2. Local tie between SLR and GNSS reference points: ∆∆∆∆CRD_LT

⇒ ∆∆∆∆CRD_estimate -∆∆∆∆CRD_LT

from ITRF2008-D solution (provided by M. Seitz, DGFI)


Comparison with local ties1. Estimated SLR and GNSS station coordinates ⇒ ∆∆∆∆CRD_estimate2. Local tie between SLR and GNSS reference points: ∆∆∆∆CRD_LT

⇒ ∆∆∆∆CRD_estimate -∆∆∆∆CRD_LT: Height component ⇒ Agreement between GNSS and SLR sites better if GNSS SAO are estimated

(i.e. using the SLR scale)

−40

−30

−20

−10

0

10

20

30

40

MD

O1−

7080

YA

R2−

7090

YA

RR

−70

90

GO

DZ

−71

05

MO

NP

−71

10

MA

UI−

7119

TH

TI−

7124

BJF

S−

7249

KG

NI−

7308

AR

EQ

−74

03

CO

NZ

−74

05

HA

RB

−75

01

HR

AO

−75

01

ZIM

M−

7810

ZIM

T−

7810

BO

R1−

7811

SF

ER

−78

24

ST

R1−

7825

ST

R2−

7825

GR

AZ

−78

39

HE

RS

−78

40

HE

RT

−78

40

PO

TS

−78

41

GR

AS

−78

45

MA

T1−

7941

MA

TE

−79

41

WT

ZJ−

8834

WT

ZL−

8834

WT

ZR

−88

34

WT

ZZ

−88

34

height component [mm]

SAO fixed to igs05SAO estimated

SAO fixed to igs05.atxSAO estimated


01/07 07/07 01/08 07/08 01/09 07/09 01/10−200

−150

−100

−50

0

50SLR range biases from weekly solutions: Station 7090

Ran

ge b

ias

[mm

]

Month / Year

GNSS sat. only: Mean = −41.7 mm, RMS = 29.8 mmGNSS+Lageos: Mean = −41.2 mm, RMS = 12.8 mm

→ Weekly estimation from SLR@GNSSdata only: not possible→ Inclusion of Lageosdata improves weekly solutions→ Yearly (or multi-year) solutions needed for reliable values

SLR-GNSS biases


5

10

1530

210

60

240

90270

120

300

150

330

180

0

5

10

1530

210

60

240

90270

120

300

150

330

180

0

SLR-GNSS biases and GNSS SAOEffect of range bias:

identical effect for all directions of the observationEffect of SAO:

different size for different directions of the observation

⇒ Correlation can be reduced by homogeneous distributionof observations (regarding nadir / azimuth angle at the satellite)

G05 R15


SLR-GNSS biases and GNSS SAO

Impact of GNSS-SAO estimation on SLR-GNSS „range“ biases:

< 5 mm

−50

−40

−30

−20

−10

0

10

20

30

40

50

Ran

ge b

ias

[mm

]

7810

7090

7406

7405

7105

7839

7110

7237

7825

7941

8834

7845

7308

7840

7080

7824

SLR range biases for satellite G06

GNSS SAO fixedGNSS SAO estimated

−50

−40

−30

−20

−10

0

10

20

30

40

50

Ran

ge b

ias

[mm

]

7810

7090

7406

7405

7105

7839

7110

7237

7825

7941

8834

7845

7308

7840

7080

7824

SLR range biases for satellite R15

GNSS SAO fixedGNSS SAO estimated



No general shift of SAO estimates⇒ Scale of SLR is transferred properly

to GNSS

Mean ∆∆∆∆Z for GPS:76.4 mm

Mean ∆∆∆∆Z for GLONASS:-47.7 mm

0 10 20 30 40 50 60 70−200

−100

0

100

200

300

Satellite number

∆ S

AO

Z [m

m]

Satellite Antenna Offset correction: Z component

GPS GLONASS (+40)




to GNSS


≈≈≈≈ 0.59 ppb


0 10 20 30 40 50 60 70−200

−100

0

100

200

300

Satellite number

∆ S

AO

Z [m

m]


GPS GLONASS (+40)

∆∆∆∆scale[ppb] ≈≈≈≈ -7.8• ∆∆∆∆SAO[m]




to GNSS


≈≈≈≈ 0.59 ppb


∆∆∆∆Scalefor GNSS network:0.59 ppb

∆∆∆∆Scalefor SLR network:0.00 ppb

0 10 20 30 40 50 60 70−200

−100

0

100

200

300

Satellite number

∆ S

AO

Z [m

m]


GPS GLONASS (+40)

∆∆∆∆scale[ppb] ≈≈≈≈ -7.8• ∆∆∆∆SAO[m]


Zusammenfassung und Ausblick -1-

- LAGEOS-Prozessierung mit BSW ist auf einem guten Stand

- In Zusammenarbeit mit BKG werden täglich Lösungen an den ILRSgeliefert (seit Juli 2010)

- Re-Prozessierungam AIUB bisher für 2006 – 2010

- Weitergehende Re-Prozessierung im Rahmen eines gemeinsamen Projektes zusammen mit ETH Zürich, TU München und TU Dresden

- Erweiterung für ETALON ist momentan in der Testphase

- Verbesserung der Orbitmodellierung (Albedo-Modell)

- Weitere Parameter, z.B. Schwerefeld


Zusammenfassung und Ausblick -2-

- Gemeinsame Auswertung von SLR- und Mikrowellen -Beobachtungenzu GNSS-Satellitenerfolgreich

- LAGEOS Beobachtungen stabilisieren die kombinierte Lösung

- SLR-Massstabwird über Satelliten-Kolokationen direkt ins GNSS-Netzübertragen→ ermöglicht Schätzung der GNSS SAOohne Fixieren des apriori

Massstabs

- GNSS SAO aus igs05.atxund SLR Massstabsind inkonsistent (0.59 ppb)

- SLR-GNSS-Kombination via „Space Ties“ ist möglich (ohne Local Ties)→ Genaue Tiesals Voraussetzung (Stationen und Satelliten)

- Trennung von SLR Range Biases und LRA Offsets noch nötig


AIUBRolf Dach, Krzysztof Sosnica, Gerhard Beutler

BKGMaria Mareyen, Bernd Richter

DGFI Manuela Seitz


Danke für die Aufmerksamkeit !



Station coordinates: 7-parameter Helmert transformation w.r.t. SLRF2005RMS of transformation (weighting not considered!)

01/08 04/08 07/08 10/08 01/09 04/09 07/09 10/09 01/10 04/100

5

10

15

20

25

30

35

40

Month/Year

RM

S tr

ansf

orm

atio

n [m

m]

RMS of 7−parameter transformation to SLRF2005

Median = 12.0 mm



Station coordinates: 7-parameter Helmert transformation w.r.t. SLRF2005

01/08 04/08 07/08 10/08 01/09 04/09 07/09 10/09 01/10 04/10−4

−3

−2

−1

0

1

2

3

4

5

6

Month/Year

Sca

le w

.r.t.

SLR

F20

05 [p

pb]

Scale w.r.t. SLRF2005

Median = 1.55 ppb



Orbit comparison with other ILRS analysis centers

01/08 04/08 07/08 10/08 01/09 04/09 07/09 10/09 01/100

5

10

15

20

25

30Compare orbits: RMS of residuals

RM

S o

f res

idua

ls [m

m]

Month/Year

AIUB vs. BKGAIUB vs. ASIBKG vs. ASI


Kombination von GNSS und SLR

SrelAAionAMWtrop tctc δδρδδρδρ ⋅−+⋅+++ ,),(=S

AL )( SAAt τ−− Sr⋅EOPR

SA

mult

phas

SAN

εδρδρλ

+

+

+⋅+)( AtAr

GNSS

⋅EOPR )(opttropδρ+=⋅⋅ SAc τ

2

1)( StSr− S

ACoMbiasrel εδρδρδρ ++++)( StAr

SLR


Kombination von GNSS und SLR

SrelAAionAMWtrop tctc δδρδδρδρ ⋅−+⋅+++ ,),(=S

AL )( SAAt τ−− Sr⋅EOPR

SA

mult

phas

SAN

εδρδρλ

+

+

+⋅+)( AtAr

GNSS

⋅EOPR )(opttropδρ+=⋅⋅ SAc τ

2

1)( StSr− S

ACoMbiasrel εδρδρδρ ++++)( StAr

SLR

EOP:Pol, UT, Nutation

TRF Satellite orbit

SLR-Beobachtungen zu LAGEOS und GNSS-Satelliten und die ... · Geomatik-Seminar der ETH Zürich,...

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