analysis of newly-released goce egg nom 1b data fileinstitutfürerdmessung analysis of...

Institut für Erdmessung

Analysis of Newly-Released GOCEEGG_NOM_1B Data

Geodetic Week, Hannover

October 9, 2012

Hu Wu, Phillip Brieden, Jürgen Müller

[email protected]


Leibniz Universität Hannover


Outline

1 Background

2 Motivation

3 Analysis of EGG_NOM_1B Data

4 Conclusions

Hu Wu, Phillip Brieden, Jürgen Müller | Geodetic Week, Hannover | October 2012 Slide 2


Introduction of GOCE Mission

GOCE Mission

• first core mission• SGG and SST-hl• high accuracy and resolution

EGG_NOM_1B Data

• Gravity Gradients• CM (Common Mode) Accelerations• DM (Differential Mode) Accelerations• GAR (Gradiometer Angular Rates)• . . .

GOCE satellite



Introduction of GOCE Mission

GOCE Mission

• first core mission• SGG and SST-hl• high accuracy and resolution

EGG_NOM_1B Data

• Gravity Gradients• CM (Common Mode) Accelerations• DM (Differential Mode) Accelerations• GAR (Gradiometer Angular Rates)• . . . Gravity gradiometer



Motivation

November, 2011: an update version of EGG processor was adopted• angular rates reconstruction (Kalman → Wiener)• interpolation of calibration matrix• . . .

July, 2012: reprocessed GOCE data released

the differences of the old and new EGG_NOM_1B data have been explored . . .

Version Number: “old”—04.04; “new”—05.06;



Gravity Gradients

recover the medium and short wavelength part of the gravity field

time series of gradients

psd of gradients

spatial analysis of gradients



Gravity Gradients



psd of gradients


−830

−810

−790

Vxx

[E

]

−2780

−2760

−2740

−2720

−2700

Vyy

[E

]

0 5 10 15 20 252480

2500

2520

Time [day]

Vzz

[E

]

slope = −0.0963

slope = 0.0266

slope = 1.6103

−1800

−1700

−1600

−1500

Vxy

[E

]

−60

−40

−20

Vxz

[E

]

0 5 10 15 20 25−28800

−28400

−28000

Time [day]

Vyz

[E

]

slope = −4.1835

slope = 0.0020

slope = −1.0868

Time series of gravity gradients (November, 2009)



Gravity Gradients



psd of gradients


2460

2480

2500

2520

Vzz

[E

]

V1

V2

6600

6650

6700

Rad

ius

[km

]

941087922 941102922 941117922 941132922 941147922

−5000

0

5000

GPST [s]

Z [

km]

Time series of Vzz and its orbitparameters (November 1, 2009)

∆V [E] MEAN STD∆Vxx 0.2656 0.5854∆Vyy -1.3792 0.1930∆Vzz 1.8313 0.6745∆Vxy -2.1497 0.3040∆Vxz -0.0302 0.0999∆Vyz -14.8581 0.5043

∆Vi j = V 2i j − V

1i j i , j = x, y , z



Gravity Gradients



psd of gradients


10−4

10−3

10−2

10−1

100

10−2

100

102

104

106

Frequency [Hz]

PS

D1/

2 [m

E/(

Hz1/

2 )]

TraceV

xx

Vyy

Vzz

10−4

10−3

10−2

10−1

100

10−2

100

102

104

106

Frequency [Hz]

PS

D1/

2 [m

E/(

Hz1/

2 )]

Vxx

Vyy

Vzz

Power spectral densities of gravity gradients(Left: original gradients; Right: simulated gradients from EGM2008, d/o 720)



Gravity Gradients



psd of gradients


10−4

10−3

10−2

10−1

100

10−1

100

101

102

103

104

105

106

Frequency [Hz]

PS

D1/

2 [m

E/(

Hz1/

2 )]

Vtrace1

Vtrace2

Power spectral densities of the trace of gravity gradients



Gravity Gradients



psd of gradients


Spatial distribution of filtered Vzz(Left: filtered Vzz ; Right: difference of filtered Vzz between original and simulated ones)



Common Mode Accelerations

non-conservative accelerations of the satellite

time series of CM accelerations

psd of CM accelerations

P14 P25 P36

X U U UY L U LZ U L U

U: Ultra-Sensitive

L: Less-Sensitive

Gravity gradiometer







−1

0

1x 10

−5

a y [m

/s2 ]

P14

P25

P36

2468

x 10−7

941087922 941102922 941117922 941132922 941147922

−5

0

5x 10

−9

GPST [s]

∆ay [

m/s

2 ]

P14

P25

P36

0

2

4x 10

−10

10−4

10−3

10−2

10−1

100

10−12

10−11

10−10

10−9

10−8

10−7

10−6

10−5

Frequency [Hz]

PS

D1/

2 [m

⋅s−2

/(H

z1/2 )]

ay14

ay25

ay36

Time series (November 1, 2009) and power spectral densities of ay







10−4

10−3

10−2

10−1

100

10−12

10−11

10−10

10−9

10−8

10−7

10−6

10−5

Frequency [Hz]

PS

D1/

2 [m

⋅s−2

/(H

z1/2 )]

ax141 ax

142 ay

251 ay

252 az

361 az

362

Power spectral densities of ax , ay , az



Angular Rates

used for gravity gradients determination

time series of angular rates

psd of angular rates



Angular Rates




−0.0002

0.0000

0.0002

ωx [

rad

⋅s−1

]

−0.0014

−0.0012

−0.0010

ωy [

rad

⋅s−1

]

941087922 941107922 941127922 941147922 941167922−0.0002

0.0000

0.0002

GPST [s]

ωz [

rad

⋅s−1

]

Time series of angular rates (November 1, 2009)

ω[rad/s] MEAN STD

ωx 5.68e-6 6.27e-5ωy -1.17e-3 4.87e-6ωz -3.94e-6 6.31e-5



Angular Rates




10−4

10−3

10−2

10−1

100

10−12

10−10

10−8

10−6

10−4

10−2

Frequency [Hz]

PS

D1/

2 [ra

d⋅s

−1/(

Hz1/

2 )]

ωx

ωy

ωz

10−4

10−3

10−2

10−1

100

10−12

10−10

10−8

10−6

10−4

10−2

Frequency [Hz]

PS

D1/

2 [ra

d⋅s

−1/(

Hz1/

2 )]

ωx1

ωx2

Power spectral densities of angular rates



GGT, DM and GAR

relationship between GGs, DM accelerations and Gradiometer Angular Rates

Vxx = −2axd,14

Lx− ω2

z − ω2y

Vyy = −2ayd,25

Ly− ω2

z − ω2x

Vzz = −2azd,36

Lz− ω2

x − ω2y



GGT, DM and GAR


−145

−140

−135

a x×109

680

685

690

a y×109

0 5 10 15−970

−965

−960

a z×109

Time [day]

0

5

10

ωx2 ×1

09

1355

1360

1365

ωy2 ×1

09

0 5 10 150

5

10

ωz2 ×1

09

Time [day]

Left: time series of DM accelerations; Right: square of angular rates(from November 1 to November 15, 2009)



GGT, DM and GAR


10−4

10−3

10−2

10−1

100

10−14

10−12

10−10

10−8

10−6

Frequency [Hz]

PS

D1/

2

Vxx2ax

d ,14

Lx

ω2y + ω

2z

10−4

10−3

10−2

10−1

100

10−14

10−12

10−10

10−8

10−6

Frequency [Hz]

PS

D1/

2

Vxx2ax

d ,14

Lx

ω2y + ω

2z

Power spectral densities of GGs, terms of DM accelerations and GAR



Conclusions

Gravity Gradients• improvement of trace of gradients in the lower frequency part• original gradients have more energy above 0.02 Hz• typical geographical features are visible in the high frequency part

CM Accelerations• calibration matrix interpolation has a significant influence on ax

Angular Rates• higher rotational instability in flight and radial directions• the update processor cuts off the angular rates above 0.2 Hz

GGs, DM accelerations and Angular Rates• the DM accelerations are dominant in the high frequency part of the gradients, andangular rates affect more in the lower frequency part


analysis of newly-released goce egg nom 1b data fileinstitutfürerdmessung analysis of...

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