introduction to geomatics engineering -...
Post on 09-Mar-2020
44 Views
Preview:
TRANSCRIPT
Introduction to Geomatics Engineering
GEODESY « a branch of applied mathematics concerned with the determination of the
size and shape of the earth and the exact positions of points on its surface and
with the description of variations of its gravity field »
1
Three pillars of Geodesy
2
Geodynamical Geodesy Geodetic techniques are used
to study geodynamic processes, such as plate tectonic
motions, postglacial rebound (now called glacial
isostatic adjustment) or variations in Earth rotation and orientation.
Physical Geodesy: the observation and use of gravity
measurements (from ground, air and space) to
determine the figure of the Earth, notably the geoid,
which involves the formulation and solution of boundary-value problems
Geometrical/Mathematical Geodesy: computations,
usually on the reference ellipsoid, to yield accurate
positions from geodetic measurements, including map
projections, which involves aspects from differential
geometry.
Satellite/Space Geodesy: determination of the orbits of
satellites (hence inferring the gravity field) or for
determining positions on or near the Earth’s surface
from ranging measurements to navigation satellites.
Four branches of Geodesy
Geokinematics
3
Global horizontal velocity vectors
4
Station motion: Post glacial rebound
5
Station motion: Solid Earth Tides
6
Station motion: Tidal Ocean Loading
7
International Terrestrial Reference Frame (ITRF)
8
International Celestial Reference Frame (ICRF)
9
Time Systems (Scales)
Siederal Time Scales Atomic Time Scales Dynamical Time Scales
GMST : Greenwich Mean Siederal Time
TAI : Temps Atomique International (Atomic time)
ET : Ephemeris Time
GAST : Greenwich Apparent Siederal Time
UTC : Universal Time Coordinated
TDT : Terrestrial DynamicalTime
LMST : Local MeanSiederal Time
GPST : GPS Time BDT : Barycentric Dynamical Time
LAST : Local Apparent Siederal Time
TCB : Barycentric Coordinate Time
UT1 : Universal Time 1 TCG : Geocentric CoordinateTime
TT : Terrestrial Time
10
Siederal Time Scales
1 mean siederal day = 1 mean solar day – 3m 55.909s
11
Atomic Time Scales
TAI – UT1 = 0s (The epoch of TAI agreed with the epoch of UT1 on 1st of January 1958)TAI – UT1 = 6.1s on 1st of January 1968TAI – UT1 = 16.4s on 1st of January 1978
12
Earth rotation
• Why do we care?– Dynamical equations
expressed in a non-rotating frame (e.g. spacecraft tracking)
– Sensitive to mass transport in the earth (e.g. winds, ocean currents, etc)
– Sensitive to the deep internal structure of the earth
13
Earth rotation
POLAR MOTION NUTATION
14
Transformation schemebetween ITRF and ICRF
Pole of ICRS
TCP=CIP
R(t)Q(t)
W(t)
Pole of ITRS = Conventional Terrestrial Pole
CTP
„Top View“
CRS)t(Q)t(R)t(WTRS
W(t) ... Polar motion matrixR(t) ... Earth rotation matrixQ(t) ... Precession and Nutation Matrix
15
Gravity field of the Earth and the Geoid
Combination Gravity Field Model EIGEN-CG01C (CHAMP-GRACE-TERR.)
GOCE global gravite ve jeoid belirleme uydusu (Mart 2009 , yükseklik: 250 km )
16
Uydu İzleme
Uydu Altimetre
CHAMP (2000) GRACE (2002)
GOCE (2009)
max
0 0
)(sinsincos),,(N
n
n
m
nmnmnm
n
PmSmCr
R
r
GMrT
Gravity field of the Earth and the Geoid
17
A-10FG-5 CG-5
Gravity field of the Earth and the Geoid
18
Gravity field of the Earth and the Geoidg ≈ 9.8 m/s2 ≈ 980 Gal ≈ 980000 mGal
g = 9 8 0 7 2 4.6 7 3 1…. mGal
Yer basıklığı ve dönmesi (merkezkaç kuvveti)
Geniş su rezervuarları
Atmosferik basınç, okyanus topografyası, kutup hareketi
Dağlar, okyanus sırtları
Yer içerisindeki yoğunluk düzensizlikleri
Yer ve okyanus gelgitleri
Hidroloji, yer altı suları,
Kü
tle/
Yoğ
un
luk
Dü
zen
sizl
ikle
ri
Kü
tle
Değ
işim
leri
(za
ma
nsa
l değ
.)
Yer’
in ş
ekli
ve d
ön
üşü
19
Yer’in Şekli
Fiziksel Yüzey (Topografya)
(Dağlar, Ovalar, Vadiler vb.)
Matematiksel Yüzey (Model)(JEOİT)
Elipsoit, Küre, Düzlem
+8,000 m (Everest),
−11,000 m (Mariana Çukuru)
Gravity field of the Earth and the Geoid
20
dgSR
N )(4
Gravity field of the Earth and the Geoid
21
Gravite – Yükseklik
Elipsoit Yük.
h
W0 : JeoitFiz Yük.
H
Jeoit Yük.
N
g
Q
P
PQQP gdHCCC
dgSR
N )(4
Ort.Deniz Sev.
Gravite Vektörü
JeoitFiziksel Yeryüzü Elipsoit
Gravity field of the Earth and the Geoid
22
GRS80-WGS84
CLARKE 1866
GEOID
Earth Mass
Center
Approximately
236 meters
Local vs. Global
Reference Ellipsoid
Datum
• A datum defines the
position of the ellipsoid
relative to the center of
the earth 23
Datum
Ellipsoid vs. Geoid
Ellipsoid
– Simple Mathematical Definition– Described by Two Parameters– Cannot Be 'Sensed' by Instruments
Geoid
– Complicated Physical Definition– Described by Infinite Number of
Parameters– Can Be 'Sensed' by Instruments
24
Space/satellite Geodesy
25
Sensitivity of the space geodetic techniques to geodetic parameters
Parameter Type VLBI GPS/GLON.
DORIS/PRARE
SLR LLR Alti-metry
Quasar Coord. (ICRF) X
Nutation X (X) X
Polar Motion
XUT1
XLength of Day (LOD)
X X X X
Coord.+Veloc.(ITRF) X X X X X (X)
Geocenter X X X XGravity Field X X X (X) X
Orbits X X X X XLEO Orbits X X X X
Ionosphere X X X XTroposphere X X X X
Time/Freq.; Clocks X X (X)
(X)
ICR
FITR
F
Earth R
otatio
nG
ravity Field
Atm
osp
here
X
X X X X
Markus Rothacher, 9-13 Ocak 2006. The Global Geodetic Observing System and the IVS Service, Fourth
IVS General Meeting, Concepcion, Şili. 26
Very Long Baseline Interferometry
x
y
z TRF
b
b b
b
cos cos
cos sin
sin
x
y
z CRF
k
k k
k
27
VLBI observes quasars at radiowavelengths of which frequencies are at S and X bands
This research has made use of the United States Naval Observatory(USNO) Radio Reference Frame Image Database (RRFID).
S-band X-band
28
Global Navigation and Satellite Systems
( ) ( ) ( )S
R R r S t R S
S S
R trop ion R
L x t x t c t t
N
29
Satellite/Lunar Laser Ranging (SLR/LLR)
30
Satellite Altimetry
31
International Association of Geodesy IAG
http://www.iag-aig.org/
• International Gravimetric Bureau
• Time Section of the International Bureau of Weights and Measures
• International Altimetry Service
• International Center for Earth Tides
• ICGEM (International Centre for Global Earth Models)
• International DEM Service
• International Doris Service
• International Earth Rotation and Reference Systems Service
• International Geoid Service
• International Gravity Field Service
• International GNSS Service
• International Laser Ranging Service
• International VLBI Service
• Permanent Service for Mean Sea Level32
Thanks for your attention !
33
top related