semmering, 2002-10-17 h. sünkelsag-bgÖ 2002 h. sünkel institut für geodäsie technische...
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Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
H. Sünkel
Institut für GeodäsieTechnische Universität Graz
undInstitut für Weltraumforschung
Österreichische Akademie der Wissenschaften
Die Satellitenmission GOCE der ESADie Satellitenmission GOCE der ESAEine Herausforderung an
Mathematik, Numerik und Informatik
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Galilei - Newton - Einstein
Mass
Gravitation Space-time
Gravity = Gravitation + Rotation
„Mass tells space-time how to curve
and space-time tells masshow to move“.
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Gravity in control of our daily life
• Shape of the Earth‘s surface• Distribution of land and water on Earth• Speed of processes inside, on and outside the Earth• Density and constitution of the Earth‘s atmosphere• Biological processes• Growth of plants• Anatomy and physiology of men and animals• Motion of living organism• Architecture of buildings• Mechanical design and structure of machines and vehicles
Gravity scales life in space and time2...81.9 ms 2...81.9 ms
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
A primitive Earth model
Core
Lower mantle
Upper mantle
Crust Radial-symmetric,not rotating, staticmass distribution
Radial-symmetric,static gravity field
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Mantle convection
Mantle convection
CouplingMantle - Core
CouplingMantle - Core
RheologyRheology
Tectonic processes(Lithosphere)
Tectonic processes(Lithosphere)
Gravity anomalies due to mass anomalies
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Post-glacialrebound
Post-glacialrebound
Ocean circulation& heat transport
Ocean circulation& heat transport
Ice SheetMelting
Ice SheetMelting
Sea level changeSea level change
VolcanicactivitiesVolcanicactivities
108 - 106 yr Time Scales 102 - 100 yr108 - 106 yr Time Scales 102 - 100 yr
The dual role of the gravity field
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Turning inside out
massmass
shapeshape
Geoid Geoid
Earth
dvlGV 1Earth
dvlGV 1
Gravitational potential
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
mSmCPr
R
R
GMV lmlm
llm
ll
m
sincos)(cos2
1
0
The gravitational potential
Properties of the gravitational potential:
0 VT1. is harmonic outside the Earth:V
Consequence: is represented by a linear combination of harmonic functions (= solutions of )
3. belongs to an infinite dimensional spaceV
2. decreases to zero towards infinityV
V0 VT
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The gravity potential
0.)( WconstPW Unique „global horizontal“ surface of constant gravity potential ( )at „mean“ sea level: geoidGlobal reference surface for „orthometricheight“
0W
)(PV Gravitational potential ( ) Rotational potential ( )Gravity potential ( )
V
)(P)(PW 2/)( 22
PhP W
)(PW Unique „local vertical“Reference direction for „local-horizontalreference system“
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
gravdensBGI.gifgravdensBGI.gif
Surface gravity: incomplete data coverage
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
POD for gravity field recovery
Mass distributionMass distribution Gravitational field
Gravitational field
Satellite orbit
Satellite orbit
The idea:
0 Vr
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
POD for gravity field recovery
Equation of motion, defined in a space-fixedgeocentric reference systemfree fall (around the Earth)Vr Satellite motion due to surface forces F
=F
),;;,( 00 lmlm SCtrrrr Satellite orbit as a function of gravitational field parameters lmlm SC ,
),( 0000lmlm SCVV Reference gravitational field controlled by
parameters 00 , lmlm SC
),;;,( 0000
00
00lmlm SCtrrrr Reference satellite orbit as a function of
gravitational field parameters 00 , lmlm SC
0
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
POD for gravity field recovery
),( 0000lmlm SCrr
Principle:
Real orbit from satellite tracking
Reference orbit based on a priori gravitational field
),(0lmlm SCrrrr
),( lmlm SCrr
0
0
lmlmlm
lmlmlm
SSS
CCC
Residual harmonic coefficientsunknowns
Functional relation
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
lmlm SC ˆ,ˆ
Harmonic coefficient(parameter) residuals
Observation residualsLSALSA
lmlmiiiT
i SCfzyxr ,,, Pseudo-observations
POD for gravity field recovery
lmlm
iii
SC
zyxA
,
,,Design matrix from partials
iii zyx ,,
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
• JGM3 lmax = 70
• OSU91a lmax = 360
• EGM96 lmax = 360
2 0
1
1l
l
mlmlmlm
l
)msin(S)mcos(C)(cosPr
R
R
MG),,r(V
lmax
l m
0 0 0. 0.1 0 0. 0.1 1 0. 0.2 0 -0.48417e-03 0.2 1 0.85718e-12 0.28961e-112 2 0.24382e-05 -0.13999e-053 0 0.95714e-06 0.3 1 0.20297e-05 0.24943e-063 2 0.90465e-06 -0.62044e-063 3 0.72030e-06 0.14147e-05... ... ... ...
lmC lmS
The Earth’s gravitational field: models
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
• Solid Earth Physics anomalous density structure of lithosphere and upper mantle• Oceanography quasi-stationary dynamic ocean topography• Sea Level Change • Glaciology ice sheet balance• Geodesy unification of height systems, levelling by GPS, inertial navigation, orbit prediction
Open problems
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Gravity field: current knowledge
The geoid: a surface of constant gravity potential at zero level
+ 100 m
- 100 m
0 m
Offset fromreferenceellipsoid:
m1
cm1
Accuracy
Now:
Required:
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
3 Mission scenarios:
1. Satellite-to-Satellite Tracking in high-low mode
SST - hl
2. Satellite-to-Satellite Tracking in low-low mode
SST - ll
3. Satellite Gravity Gradiometry
SGG
Gravity field exploration from space
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
CHAMP (2000)
GRACE (2002)
GOCE (2006)
Love affairs with body Earth(... “move your body close to mine”)
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
CHAllenging
Minisatellite
Payload
The CHAMP mission: spacecraft
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
GPS - satellites
Earthmassanomaly
3-D accelerometer
sst_hl.epssst_hl.eps
SST - hl
)msin(S)mcos(C
)(cosPr
R
R
MG),,r(V
nmnm
2n
n
0mnm
1n
)x(VV k
ii
i VVx
a
The CHAMP Mission: SST - hl
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Earth‘s gravity field
and its temporal variations
Gravity Field Model „Eigen 1S“ Geostrophic currents
The CHAMP mission: objectives
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Earth‘s magnetic field
and its temporal variations
The CHAMP mission: objectives
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Earth‘s atmosphere and ionosphere
and temporal variations
The CHAMP mission: objectives
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
• Electrostatic STAR Accelerometer• GPS Receiver TRSR-2• Laser Retro Reflector• Fluxgate Magnetometer• Overhauser Magnetometer• Advanced Stellar Compass • Digital Ion Drift Meter
STAR accelerometer
FluxgateMagnetometer
OverhauserMagnetometer
Laser retro-reflector
The CHAMP mission: payload
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
front side view
rear side view
The CHAMP mission:spacecraft
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
• Launch: July 15, 2000, Cosmodrome Plesetsk• almost circular orbit: e = 0.004• near polar orbit: i = 87°• initial altitude: 454 km• satellite lifetime: 5 years
COSMOS launch vehicle
The CHAMP mission: launch & orbit
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The CHAMP mission: altitude
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The GRACE Mission
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
SST - hl
GPS - satellites
Earthmassanomaly
sst_ll.epssst_ll.eps
SST - ll
)(i)(
i
)(i VV
xa 1
11
)(i)(
i
)(i VV
xa 2
22
j
i)(
j)(
j
)(i
)(i
x
V
xx
VV
12
12
The GRACE Mission: SST-hl and SST-ll combined
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
• Two satellites following each other on the same orbital track
• Position and velocity of the satellites are measured using onboard GPS antennae
• Interconnected by a K-band microwave link• S-band radio frequencies used for communication
with ground stations
The GRACE Mission: constellation
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The GRACE Mission: constellation
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
• K-Band Ranging System (KBR) • Accelerometer (ACC) • GPS Space Receiver (GPS) • Laser Retro-Reflector (LRR) • Star Camera Assembly (SCA) • Coarse Earth and Sun Sensor (CES) • Ultra Stable Oscillator (USO) • Center of Mass Trim Assembly (CMT)
The GRACE Mission: payload
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The GRACE Mission: spacecraft structure
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
• Launch: March 17, 2002, Cosmodrome Plesetsk• almost circular orbit: e < 0.005• near polar orbit: i = 89°• initial altitude: 485 - 500 km• satellite system lifetime: 5 years
The GRACE Mission: launch & orbit
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The CHAMP mission: altitude
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Gravity Field and Steady-state
Ocean
Circulation
Explorer
The GOCE Mission
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The GOCE mission: team structure
GOCE Project Team GOCE Industry Team
GOCE - MAGProject scientist (ESA) and
members
European GOCE GravityConsortium (EGG-C)
Team leaderand Task leaders
Science Data Use:Solid Earth
Science Data Use:Solid Earth
Science Data Use:Oceanography
Science Data Use:Oceanography
Science Data Use:Ice
Science Data Use:Ice
Science Data Use:Geodesy
Science Data Use:Geodesy
Science Data Use:Sea Level
Science Data Use:Sea Level
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
SGG
Earthmassanomaly
GPS - satellites
gradiometry.epsgradiometry.eps
SST - hl
ijji
)(j
)(j
)(i
)(i
xV
xx
V
xx
VVlim
j
2
12
12
0
The GOCE Mission: SST-hl and SGG combined
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
• Launch: Feb. 2006, Cosmodrome Plesetsk (62.7° N, 40.3° E)• Total satellite mass: 800 kg• Orbit inclination: i = 97°• Injection altitude: 270 km• Passive descent from 270 km to 250 km• Altitude controlled by ion thrusters• Satellite lifetime: 2 years
The GOCE mission: launch & orbit
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Mission duration: 20 months– Commission phase: 3 months
– Phase 1: 6 months– Hibernation phase: 5 months – Phase 2: 6 months
Design orbit altitude:– Phase 1: 250 km– Phase 2: 240 km
Orbit characteristics:– Dawn-dusk sun-synchronous, Inclination: 96.5°– Injection eccentricity: 0.000– phase 1: two months repeat, phase 2: eventually drifting ground track– Maximum air drag during gradiometer operation: 0.3 mGal / in mbwHz
GOCE: mission parameters
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
2 5 0 k m
2 4 0 k m
T 0 T 0 + 3 m o n th s T 0 + 9 m o n th s T 0 + 1 4 m o n th s T 0 + 2 0 m o n th s
2 6 0 k m
2 7 0 k m
O rb itA ltitud e
E clip seD ura tio n
5 m in .
1 0 m in .
1 5 m in .
4 3 d 3 5 d3 5 d 1 3 5 d
S pacecra ftC o m m issio n ing
G rad io m ete rC a lib ra tio n
1 .5 1 .5 6 m on th s 4 .5 m o n th s .5 6 m on th s
G rad io m ete rS e t-up andC alib ra tio n
M easu rem en tIn te rrup tio n
F irs t M easu rem en tP hase
S eco nd M easu rem en tP hase
3 0 m in .
2 5 m in .
2 0 m in .
The GOCE mission: timeline
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Scientific payload:• 3-axis gravity gradiometer• GPS receiver• SLR retroreflector• Star tracker
Auxiliary equipment:• Ion thrusters• FEEPS• Solar panels (8 m²) • On board computer• Telemetry
S 44
The GOCE mission: spacecraft design
center of mass
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Gravity gradiometer:
• 3-axis• mbw: 5 - 100 mHz• Precision: < 1 mE
XY
Z
The GOCE mission: gravity gradiometer
1 mE: curvature radius of equipotential surface of 10 Mill. km !
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
3 mE / Hz
specified
(Predicted per-
formance curve
derived from a
combination of
analysis and test)
5 mHz 100 mHzmbw
Specified noise psd
Predicted noise psd
The GOCE mission: gradiometer noise
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
dragfx)]2(V[Ladragfx)]2(V[Ra
Accelerometer equations:
Common mode:
dragLR f
2
aa
x)](V[
2
aa 2LR
Differential mode:
V ... gravitational tensorV ... gravitational tensor
The GOCE mission: gravity gradiometry
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Attitude:
d)()t()t(
)(2
1
t
ot
o
T
Gravitational tensor:
x2
aa LR
Measurement tensor:
2T )(2
1V
The GOCE mission: gravity gradiometry
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Ion thruster(for drag compensation)
Micro thruster(for attitude control)
Gas: Xenonthrust level: 1 - 20 mN thrust level: 0.0001 - 0.1 mN
The GOCE mission: attitude & drag control
Field emission electric propulsion system (FEEPS)
Gas: Indium (Austrian system)Caesium (Italian system)
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The GOCE mission: observation sensitivities
22
22
222
2
2
1
12
1
1
1
123
1
n
lk
n
n
lik
Rr
R
z
y
x l
21
1
11 22
2
2
3
ll
lk
lk
Rr
R
V
V
V l
zz
yy
xx
Orbit perturbations Gradiometer dataSST (hi-lo): SGG:
Sat. alt. smoother Sat. alt. smoother
SST amplifier SGG amplifier
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
jiij xx
PVPV
)(
)(2
]sincos[
)(cos)(2
1
0
PlmPlm
L
lPlm
l
P
l
m
mSmC
Pr
R
R
GMPV
Gravitational potential as a function of position P:)(PV
The GOCE mission: data processing
Gravity gradiometer observations:
LSALSA100 000 000 observations
100 000parameters
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
vik.bw.epsvik.bw.eps
yyV
xyVxxV xzV
yzV
zzV
100 000 000 observations
100 000 parameters
The GOCE mission: gravity field recovery
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
SpacewiseSpacewiseTimewiseTimewise
OtherwiseOtherwise
SpacewiseSpacewiseTimewiseTimewise
OtherwiseOtherwise
The GOCE mission: processing methods
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The Real Life: Distributed Non-approximative Adjustment (DNA)
Strict solution of the normal equation system
Flexible, but enormous computation requirements
The GOCE mission: processing methods
The Runner: Semi-Analytic approach (SA)
Approximative, iterative algorithm: works partially in the frequency domain (FFT) and uses the dominant block-diagonal structure of the normal equations
The Progressive Worker: Parallel pcgma package
Approximative algorithm, using a block-diagonal preconditioner as a first guess (initialization step) and applying iteratively a conjugate gradient method
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
SGG observations regarded as a function of space position P
)P(Vij
]msinSmcosC[
)(cosPr
R
R
GM)P(V
PlmPlm
L
2lPlm
1l
P
l
0m
]msinSmcosC[
)(cosPr
R
R
GM)P(V
PlmPlm
L
2lPlm
1l
P
l
0m
Potential regarded as a function of space position P)P(V
The GOCE mission: spacewise processing
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
lmlm S,C
Harmonic coeff.SGG observ.LSALSA
)P(Vij
Iterative Direct
serial parallel serial parallel
The GOCE mission: spacewise processing
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Preconditioned Conjugated Gradient Method (PCGM)
• Iterative solution• Preconditioning by appropriate representative matrix• Inclusion of prior information possible• Extended by frequency selective filters to account for coloured noise SGG data• Serial and parallel versions operational • Successfully tested up to degree 300 on different platforms (DEC-Alpha, SGI Origin, CRAY T3E, Graz Beowulf Cluster)
The GOCE mission: spacewise processing
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Distributed Non-approximative Adjustment (DNA)
• Direct solution• Inclusion of prior information possible• Inclusion of non-gravitational parameters (non-conservative force model, calibration parameters, ...)• Extended by frequency selective filters to account for coloured noise SGG data• Parallel versions successfully tested up to degree 180 on the Graz Beowulf Cluster
The GOCE mission: spacewise processing
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
SGG observations regarded as a function of time)t(Vij
even:ml
odd:mllm
lmL
]2min[ll
klm
1l
km
L
Lkkmkmkmkm
L
0m
S
C)I(F
r
RA
)]t(sinB)t(cosA[R
GM)t(V
Potential regarded as a function of time t)t(V
The GOCE mission: timewise processing
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
lmlm S,Ckmkm B,A
Harmonic coeff. Lumped coeff.Sensitivity coeff.Sensitivity coeff.
In case of a periodic SGG time series: • Lumped coefficients = Fourier coefficients of SGG time series• Lumped coefficients considered as pseudo observations in LSA for the estimation of the harmonic coefficients• Ideally the normal matrix has block diagonal structure• In reality it is (strongly) block diagonally dominant• Iteration required due to sun-synchronous orbit and varying orbit parameters
The GOCE mission: timewise processing
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
mSmCPr
R
R
GMV lmlm
L
llm
ll
m
sincos)(cos2
1
0
The gravitational potentialand derived quantities
mSmCPRN lmlm
L
llm
l
m
sincos)(cos2 0
mSmCPlg lmlm
L
llm
l
m
sincos)(cos12 0
Geoid:Resolution: 100 kmAccuracy: 1 cm
Gravity anomaly:Resolution: 100 kmAccuracy: 1 mGal
100 km resolution requires L = 20000 km / 100 km = 200
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
simulated GOCE performance
spatial resolution D(half wavelength)
maximum degree L(corresponds to D)
geoid height[mm]
gravity anomaly[mGal]
1000 km 20 0.4 0.0006
400 km 50 0.5 0.001
200 km 100 0.6 0.03
100 km 200 2.5 0.08
65 km 300 ~ 45 ~ 2
< 10 mm < 1 mGal
Goal:
The GOCE mission: performance( cumulative error )
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Slm order Clm
EGM spherical harmonic error spectrum
The GOCE mission: error spectrum
Closed loop simulation Gravity fieldGravity field
Gradiometersignal
Gradiometersignal
Harmonicanalysis
Harmonicanalysis
Harmonic coeff.Harmonic coeff.
Colourednoise
Colourednoise
FilteringFilteringObservationsObservations
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
“Delft data-set”:• 29 days repeat orbit• ~ 1.5 million observations (SGG diagonal components)
• lmax = 180
• Size of full normal equation matrix 4.1 GByte
Very different time behaviour of the three methods
The GOCE mission: closed loop simulation
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
0
500
1000
1500
2000
2500
min
utes
0 2 4 6 8 10 12 14 16
Iterations
DEC-Alpha CRAY (25 PEs)CRAY (50 PEs) CRAY (75 PEs)
Near linear speed-up
with additional processing
elements (PE)
Near linear speed-up
with additional processing
elements (PE)
The GOCE mission: solution time
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
method # PEs iteration timepcgma 25 10 12h20min
SA 25 5 20min
DNA 49 - 14.5d
338h / 10h
The GOCE mission: test performance
Solution time:
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
• March 2001: TU Graz started to build up a Beowulf cluster
• 24 Dual-Pentium (866 MHz) PC’s (computing nodes)• 1GB RAM / 18 GB local HD• 1 Master server PC• 1.5 GB RAM• 5*73 GB RAID 5• Linux (Redhat, Kernel 2.4.19) , MPICH, ...• TU Graz cluster outperforms Columbus / Ohio cluster by a
factor of 2• Same performance as the CRAY T3E in Columbus / Ohio
The TU Graz clusterComponents and performance
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
• 10 ES45 Alphaserver• 4 CPUs each / 1.25 GHz• 2 ES45 with 32 GB RAM
• 8 ES45 with 16 GB RAM• 120 GB local hard disks• connected via 16 ports
Quadrics switch
• 10 ES45 Alphaserver• 4 CPUs each / 1.25 GHz• 2 ES45 with 32 GB RAM
• 8 ES45 with 16 GB RAM• 120 GB local hard disks• connected via 16 ports
Quadrics switch
HP SC-45 cluster
Realization: October 2002
The TU Graz cluster: future plans (1/2)
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
• System based on Linux• connection between the
nodes via Myrinet (Cluster 1)• connection between the
nodes via GigaBit Ethernet (Cluster 2)
• 24 nodes (Cluster 1)36 nodes (Cluster 2)
• Intel / 2.6 GHz CPUs• 0.5 GB RAM per CPU• 5*73 GB SCSI RAID5
• System based on Linux• connection between the
nodes via Myrinet (Cluster 1)• connection between the
nodes via GigaBit Ethernet (Cluster 2)
• 24 nodes (Cluster 1)36 nodes (Cluster 2)
• Intel / 2.6 GHz CPUs• 0.5 GB RAM per CPU• 5*73 GB SCSI RAID5
Realization: January 2003
The TU Graz cluster: future plans (2/2)
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Gravity satellite missions: comparison
2 years5 years5 yearsduration
250 km~450 km454 kmaltitude
96.5°89.0°87.3°inclination
SST-hl/SGGSST-hl / llSST-hlmode
200620022000start
GOCEGRACECHAMP
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
70 km250 km650 kmresolution(half wavelength)
< 1 cm~ 1 cm~ 1 cmaccuracy
GOCEGRACECHAMP
3008030Harmonic degree
Gravity satellite missions: comparisonAccuracy and resolution
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
SST - hlSST - hl
SST - llSST - ll
KaulaKaula
SGGSGG
Gravity satellite missionsAccuracy and resolution
EGM 96EGM 96
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The GOCE missionOcean topography
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
x
Hgvf
y
Hguf
s
s
Steady - state flow:
H ... Sea surface height (SSH) relative to geoidx, y ... Local cartesian coordinates (W-E, S-N)u, v ... Surface velocity (W-E, S-N)g ... Gravityf ... Coriolis term
0vu
The GOCE missionDynamic ocean topography
Navier-Stokes equation
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Signal l = 20
Range: -75 to +75 cm
l = 80 l = 200
Gravity satellite missionsOcean topography signal
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The GOCE missionMean dynamic ocean topography
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The GOCE missionGeostrophic current
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Problem: conversion velocity density
Propagation of seismic waves
The GOCE mission: geotomography
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
RiftingRifting
OrogenyOrogeny
Volcanoes,Hot Spots
Volcanoes,Hot Spots
SpreadingSpreading
SubductionSubduction
The GOCE mission: solid Earth
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The GOCE mission: surveying
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
CHAMPmagnetic field determinationtemporal variations of the gravity field
GRACEimproved knowledge of the geoidestimates of time variable components
GOCEhighly precise static geoid determination
Gravity satellite missions: summary
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
Oceanography:• Absolute ocean circulation• Sea level changes• Ice mass balance
Solid Earth Physics:• Geotomography• Processes in the deep Earth‘s interior• Earthquake prediction
Geodesy:• Unified height datum• GPS levelling• Orbit prediction• Inertial navigation
Gravity satellite missions: benefits
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
GOCE will cover Theme 1 of ESA‘s Living Planet Programme (with the exception of the magnetic field part)
Geodesy
Solid Earth Physics
Absolute OceanCirculation
Sea Level Change Studies
Ice Sheet Mass Balance
Gravity satellite missionsBenefits for geosciences
Semmering, 2002-10-17 H. SünkelSAG-BGÖ 2002
The End
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