Terrestrial, Airborne and Satellite Gravimetryissge.ir/uploads/files/Taft/Hatam.pdf · - GPS...
Transcript of Terrestrial, Airborne and Satellite Gravimetryissge.ir/uploads/files/Taft/Hatam.pdf · - GPS...
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Terrestrial, Airborne and Satellite
GravimetryY. HatamY. Hatam
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- Terrestrial Gravimetry:
Absolute Gravimetry: FG-5, A10
National Absolute Gravity Network of Iran (NAGNI09)
Relative Gravimetry: CG-3/M, CG-5,
Multi-purpose Network (MPGGNI10),
National Gravity Calibration line (NGCLI10)
Damavand Gravimetry Profile
Digital Zenith Camera (DIADEM)
- Airborne (shipborne) Gravimetry: S124b L&R
- Satellite Gravimetry: CHAMP, GRACE, GOCE
New Gravimetric Geoid of Iran (IRGeoid10)
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Spatial Resolution: Different G. Systems
Micro-g FG-5
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Developping Gravimeters
(precision modification)
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National Absolute Gravity Network of Iran
NAGNI09
Objectives:
Reference four other more densed gravity networks
(1st, 2nd , 3rd orders)
Opportunity of studying the variations inter-annuals at two sites
(Tehran et Alborz)
Specifications: Station distribution 300 km
Precision better than 5 µGal
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Astara
Birjand
Chalous
Cheshmeh-shur
Esfahan
Kalaleh
Kandovan
Kermanshah
Lahijan
Low shan
Mashhad
Tabas
Tabriz
Teheran Abali
Yazd
35° N
40° N
2000
2500
3000
3500
m
Distribution of Absolute Gravity stations (NAGNI09)
Topogrphical Map
of Iran
Ahvaz
Bandar Abbas
Bushehr
Chabahar
Kerman
Laar
Shiraz
Yazd
Zahedan
45 ° E 50° E 55° E 60
° E
25° N
30° N
0
500
1000
1500To transfer FG-5
24 Measuring Stations
Approximately 40 Measurements
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Measuring Absolute Gravity by FG-5
Measuring the couples ’’position - time’’ of an object in free-fall
Calculating the acceleration of the object =>
Gravity
FG5 228
2 23 40 0 0
0 0 0 0
( )1 1, .
2 2 6 24
i i ii i i i i
g t x t x xx x v t v t g t t t
c
γγ γ
−= + + + + + = −
% %% % % %
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Measurement procedure
One fall
-5
0
5
10
15
20Cumulative Mean: 979095237.12 µGal +/- 0.71 µGal
µG
al
One hourly Measurement:
120 Falling of the object
Dispersion: 5.56 µGal
-20
-15
-10
15:00Sat 7 Oct 2006
18:00 21:00 Sun 8 3:00Time
16 hours of measurements
⇒16 * 120 fallings
Final Dispersion: 0.71 µGal
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 250
1
2
3
4
5
Station Number of Absolute Gravity points
Set
Scatt
er(
µG
al)
a)
Precision of the Absolute G. Network NAGNI09
Uncertainty of the
measurement
Noise of
the wavesSite in
altitude
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 254.25
4.3
4.35
4.4
4.45
4.5
Station Number of Absolute Gravity points
Tota
l U
ncert
ain
ty(µ
Gal)
b)
Total Uncertainty
Systematical
Error
Set up ErrorMeasurement and Total
Uncertainties of the
NAGNI09 network
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Interannual variation of the Gravity in Iran: at
Tehran (NCC)
NCC
Significant Inter-annual
Decreasing of absolute gravity
Regional Hydrological Component (GLDAS et ECMWF, cf. J. P. Boy)
Inter-annual Decreasing : -0.4 µGal/anGPS height variation
Decreasing not explained by GPS or
Regional hydrological Models
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Inter-annual Variations of the gravity in Iran
Tehran (NCC)
Estimated Porosity by the gravity measurements: between 2 and
12 %
Estimated Porosity by the pomping: App. 10 % (Engalenc, 1968)
Good Correlation with the height of water
level of the wellsPlate Effect / porosity
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Inter-annual Variations of the gravity in Iran
Abali (Alborz Chain)
Decreasing -0.76 ±±±±0.30 µGal/an
ABALI
Regional Hydrological Variations
0.28 à -0.35 µGal/an (GLDAS et ECMWF)
Decreasing not
explained by Regional
hydrological Models
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Residual Slopes:
-0.99 ±31 µGal/an (GLDAS)-0.30 ±38 µGal/an (ECMWF)� Vertical Movement
� With tectonic origin
Inter-annual Variations of the gravity in Iran
Abali (Alborz Chain)
Vertical Speed:
The continental lithosphere
���� Elastic Plate
ECMWF: between 1 ±1.26 mm/an and 1.6 ±2.00 mm/an
GLDAS: between 3.3 ±1.03 mm/an and 5.2 ± 1.63 mm/an
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Multi-purpose Physical Geodesy and Geodynamic
Network of Iran (2005-8) (MPGGNI10)
Objectives
– Densification of the absolute gravity network (0 order) by the 1-st
order gravity network
calculating locally the geoidal undulation
Specifications:Specifications:
- Measuring relative gravities each 55 km, with a precision of the order
of 10 µGal
- GPS geodetic height determination with a precision of the order of 1-3
cm
- Precise levelling Height determination with a precision of the order of
Opportunity
– Study of the Geodynamics and Crustal structure of Iran
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30° N
35° N
40° N
Region of study
Old g in land
g at 1 st levelling
g at Sea
data5
data6
Land boundary
Sea boundary
Pre-existed gravimetric measurements
45 ° E 50° E 55
° E 60
° E
25° N
Distribution of the pre-existed gravities BGI)
• Land gravity (Green Points)
• At Levelling BMs (Yellow points)
• Sea gravity (red points)
Complete Bouguer Anomaly map (1984)
Completed based on 10 000 gravity data
(Green points)
Not enough measurements for calculation of a
precise geoid
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Multi-purpose Network ’’MPGGNI10’’• 600 sites
• 1600 gravimetric
observations
• 1600 working days at
field by 6 gravimètres
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Relative Gravimetry ( ) ( )j jij i it St
f S S S j i j iC m m V g g D t t− + = − + −
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Ahvaz
Astara
Birjand
Bushehr
Chalous
Cheshmeh-shur
Esfahan
Kalaleh
Kandovan
Kerman
Kermanshah
Lahijan
Low shan
Mashhad
Shiraz
Tabas
Tabriz
Teheran Abali
Yazd
Zahedan
30° N
35° N
40° N
1500
2000
2500
3000
3500
4000
4500
5000
m
Astara
Chalous
Kandovan
Lahijan
Low shan
Teheran-NCCAbali
Tochal1Tochal2
Tochal5Tochal7
Caspian Sea
36° N
37° N
38° N
1500
2000
2500
3000
3500
4000
4500
5000
m
National Gravity Calibration Lines of Iran
Bandar Abbas
Chabahar
Laar
45 ° E 50° E 55
° E 60
° E
25° N
0
500
1000Cheshmeh-shur
48° E 49
° E 50
° E 51
° E 52
° E 53
° E
35° N
0
500
1000
Old Line
851 mGal
New Line
1154 mGal
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Profile of Damavand gravimetry
6- Damavand Summit St.
5610 m
5- Permanent icefall St.
5100 m
4- Climbing house St.4- Climbing house St.
4200 m
3- Goosfandsara St.
3000 m
2- Iraa St.
1700 m
1- ABALI Absolute Gravity st.
3160 m
Polour Permanent GPS Station
2280 m ■
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Objectives of Damavand gravimetry
- To obtain minimum gravity value in Alborz mountain
- To extend and modify national gravity calibration line
- To modify the gravity prediction models
- To study the isostasy situation of the highest mountain of Iran
- To modify and control the existed numerical density models- To modify and control the existed numerical density models
- To modify the quality of Geoid
- To establish the control points for the future airborne gravimetry
- To study the geodynamical phenomena (Earthquake, Volcano, …)
- To obtain the correct elevation value of Damavand Summit
( Before= 5671 m , Now= ?)
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Damavand Gravimetry Profile + NGCLI10
979,400
979,500
979,600
979,700
979,800
979,900
980,000
980,100
980,200Damavand Summit Gravimetry and Extending the new National Gravity Calibration Line of Iran (TC/L NGCLI2005)
All
Gra
vit
y V
alu
es
in
Ira
n (
mG
al)
Gravity Values (Blue)
Gravity Station (Red)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16978,200
978,300
978,400
978,500
978,600
978,700
978,800
978,900
979,000
979,100
979,200
979,300
Damavand Abshar PanahGah Gosfand Ira Abali TochalS Tochal7 Tochal5 Tochal2 Tochal1 NCC Lowshan Lahijan Astara
Summit Yakhi Sara
All
Gra
vit
y V
alu
es
in
Ira
n (
mG
al)
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Misclosure Errors of the triangular gravity loops
Error < 50 µµµµGal
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40
60
80
100
120
40
60
80
100
120
Uncertainties of the relative gravity measurements
and of the gravity values
-0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.040
20
mGal0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.02 0.0220
20
mGal
Histogram of the residuals of the relativegravity measurements
Histogram of the precisions of the gravities
Errors at measurements and at gravity of
the MPGGNI10, of the order of 10 µµµµgal
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Permanent GPS Network + IGS
Precision for the GPS height : 1 cm
National GPS and Precise Levelling Networks
1st order
2nd order
Precision for the GPS height : 1 cm
GPS Measurements at 55 km Network (duration 24h)
Precision for the GPS height GPS: 1-3 cm (treated GAMIT)
National Precise Levelling Networks
Precision of the levelling: 3mm km
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Transportable Zenith Cameras
(TZK1 , TZK2 , TZK3)
1976, 2000, 1986
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Digital
Zenith
Camera
TZK2-D
(DIADEM)
20062006
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Airborne
Gravimetry
(Shipborne G.)
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GRACE (Gravity Recovery and Climate Experiment)
16 Mars 2002 – for 5 years NASA + DLR
2 Satellite, 200 km distance,
Polar orbit: 480 km
Precision N: 1 cm for 300-400 km, Monthly N
CHAMP (CHAllenging Minisatellite Payloadfor geoscience and application)
15 July 2000
Polar orbit
Altitude: 400 km
Constantly positioned by GPS
Perturbation analyses:
Precision N: 10 cm for wavelength 485 km
CHAMP
Precision N: 1 cm for 300-400 km, Monthly N
1-st Model: GGM02S, Deg. 160, Resolutin:
125 km (Tapley et al., 2005)
GRACE
GOCE
GOCE (Gravity field and steady state Ocean Circulation Explorer mission) ---- 17 Mars 2009 (ESA)
Orbit heliosyncronizd, Altitude: 250 km
Measure Accelerations by 6 accelerometers, 50 cm apart,
Tensor of the gradients (9 elements) and 6 are independent
Precision: 1 cm for wavelength 100 km
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Geoid computation
Objective :
Calculation of a new gravimetric geoid model with high
precision - resolution
Method:
Remove - restore + Helmert Condensation
1-D FFT (Haagmans, 1993)
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Reference surfaces and heights
N=R
4πγ∆gS(ψ)dσ
σ∫∫
N(Geoid) = h(ellipsoidal) – H(orthometric)
Earth Surface
Geoid
Ellipsoid
Ellipsoidal height
Geoidal Height
Orthometric Height
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SRTM topographical Data over Iran
Distribution of gravity data over Iran
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Free air Anomaly
∆gFGeopotential Model
∆gGGMDTM
∆gRTM
∆gres = ∆gF - ∆gGGM - ∆gRTMAtpoin
ts
Gravimetric Geoid Computation by remove-restore + Helmert C.
Interpolation
N = Nres + NGGM + NI
∆ggeoidres NresStokes
At
gri
d
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Free air Anomaly
∆gFGeopotential Model
∆gGGMDTM
∆gRTM
∆gres = ∆gF - ∆gGGM - ∆gRTMAtpoin
ts
Gravimetric Geoid Computation by remove-restore + Helmert C.
Interpolation
N = Nres + NGGM + NI
∆ggeoidres NresStokes
At
gri
d
-
Free air Anomaly
∆gF
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Gravimetric Geoid Computation by remove-restore + Helmert C.
Free air Anomaly
∆gFGeopotential Model
∆gGGMDTM
∆gRTM
∆gres = ∆gF - ∆gGGM - ∆gRTMAtpoin
ts
Interpolation
N = Nres + NGGM + NI
∆ggeoidres NresStokes
At
gri
d
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Statistics of different Global Geopotential Models (GGMs)
At the points GPS / nivelés
Geopotential Model
∆gGGM
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Geopotential Model
∆gGGM
Calculated by using the model GOCO01SEGM08(360)
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Free air Anomaly
∆gFGeopotential Model
∆gGGMDTM
∆gRTM
∆gres = ∆gF - ∆gGGM - ∆gRTMAtpoin
ts
Gravimetric Geoid Computation by remove-restore + Helmert C.
Interpolation
N = Nres + NGGM + NI
∆ggeoidres NresStokes
At
gri
d
-
45 ° E ° 25° N
30° N
35° N
40° N
-100
-50
0
50
100
150
mGal
40° N
35
mGal
DTM
∆gRTM
45 ° E 50° E 55° E 60
° E
25 N -100
45 ° E 50° E 55° E 60
° E
25° N
30° N
35° N
0
5
10
15
20
25
30
The principal term of the
Residual Terrain Model RTM
Terrain Correction TC
∆∆∆∆gRTM = 2ΠΠΠΠkρρρρ(h - href) - TC
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Free air Anomaly
∆gFGeopotential Model
∆gGGMDTM
∆gRTM
∆gres = ∆gF - ∆gGGM - ∆gRTMAtpoin
ts
Gravimetric Geoid Computation by remove-restore + Helmert C.
Interpolation
N = Nres + NGGM + NI
∆ggeoidres NresStokes
At
gri
d
-
35° N
40° N
20
40
60
80
100
mGal
∆gres = ∆gF - ∆gGGM - ∆gRTM
45 ° E 50° E 55° E 60
° E
25° N
30° N
-100
-80
-60
-40
-20
0
Map of the residual free-air gravity anomaly
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Free air Anomaly
∆gFGeopotential Model
∆gGGMDTM
∆gRTM
∆gres = ∆gF - ∆gGGM - ∆gRTMAtpoin
ts
Gravimetric Geoid Computation by remove-restore + Helmert C.
Interpolation
N = Nres + NGGM + NI
∆ggeoidres NresStokes
At
gri
d
-
35° N
40° N
50
100
150
200
250mGal
∆ggeoidres
45° E 50° E 55° E 60
° E
25° N
30° N
-150
-100
-50
0
Residual free-air gravity anomaly at geoid surface
-
Free air Anomaly
∆gFGeopotential Model
∆gGGMDTM
∆gRTM
∆gres = ∆gF - ∆gGGM - ∆gRTMAtpoin
ts
Gravimetric Geoid Computation by remove-restore + Helmert C.
Interpolation
N = Nres + NGGM + NI
∆ggeoidres NresStokes
At
gri
d
-
35° N
40° N
-0.5
0
0.5
1
1.5
m
Nres
45° E 50° E 55° E 60° E
25° N
30° N
-2
-1.5
-1
-0.5
Residual Geoid undulation
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Free air Anomaly
∆gFGeopotential Model
∆gGGMDTM
∆gRTM
∆gres = ∆gF - ∆gGGM - ∆gRTMAtpoin
ts
Gravimetric Geoid Computation by remove-restore + Helmert C.
Interpolation
N = Nres + NGGM + NI
∆ggeoidres NresStokes
At
gri
d
-
-35
-33-31-2
9
-27
-25-23
-21 -21
-21
-19
-19-19
-17
-17
-17
-15
-15
-13
-13
-11
-11
-9
-7
-7
-5
-3
-3-1
1
1
3
3
5
5
5
7
7
7
9
9
11
11
13
13
15
15
17
19
2123
35° N
40° N
0
10
20m
The new Gravimetric
Geoid Mode
IRGeoid10
Precision
• Absolute : 0.26 m
N = Nres + NGGM + NI
-33
-33
-31-3
1
-29
-29
-29
-27
-27
-27
-27
-25
-25-23
-23 -23
-23
-21
-21
-21
-21
-21
-21
-19
-19
-19
-19
-17
-17
-17
-17
-15
-15
-15
-15
-13
-13
-13
-13
-13
-11
-11
-11
-11
-9
-9
-9
-9
-7-7
-7
-7
-7
-5-5
-5
-5
-5
-3
-3
-3
-3
-1-1
-1 1
1
3
3 5
5
9
45 ° E 50° E 55° E 60
° E
25° N
30° N
35 N
-30
-20
-10
0• Absolute : 0.26 m
• Relative : 2.8 ppm
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Gravimetric Geoids SD ou RMS (m) Nomber of
GPS/Lev. points
IRGeoid88 (Weber and Zomorrodian, 1988)
IRGeoid01 (Ardalan et al, 2001)
1.40 (RMS)
1.26 (RMS)
----
258
Precision of the gravimetric geoids
Comparison of the models at GPS/Levelling points
IRGeoid01 (Ardalan et al, 2001)
IRGeoid05a (Safari et al, )
IRGeoid05b (Nahavandchi et Soltanpour, 2005)
IRGeoid06 (Kiamehr, 2006)
IRGeoid10 (Hatam et al, 2010)
1.26 (RMS)
1.068 (SD)
0.672 (SD)
0.58 (RMS)
0.26 (SD)
258
51
200
260
819
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Thank you for your attention