200910

GNSS GPS Glonass GalileoTopex, JasonHY-II Icesat InSar CHAMP, GRACE GOCE

GPSSLRVLBISASGAG

VLBI25VLBI

VLBI NETWORK

SLRLageos-1

SLR NETWORK

GPS GPS

GPS , , , , :: 2420000km. , 4, 55, , 11h58m: : , (), , 4, 4.t, x, y, z, , >4, .

GPS Satellite

( ) , L1 1575.42MHz L2 1227.6MHz L P C/A D ()L1 P, C/A, D L2 PDP, 10mC/A, 30m (SA100m)

, () , ,

(), , . ., , .(), :h

GEOSAT1985-3-12

ERS-1 1991-7-17

Topex/Poseidon1992-8-10

ERS-21995-4-21

GFO(Geosat-Follow-On) 1998-2-10

JASON(T/P-follow-on) 2000-5-18

ENVISAT2000-5

Sea Surface Topography observed from Topex/Poseidon

M2

When La Nia 98 takes over El Nio 97

An altimetric view of the seafloor

(October 1992)Wind speed (October 1992) (October 1992)

T/PTide Gauge

1.2.

16th Century17th18th19th20th21stEarths Gravity MeasurementHistory

Satellite Gravity MeasurementPrinciple

CHAMPGOCEGRACEInternational Satellite Gravity Missions

SSTSGG 1969 SST 1979 GRM 1980 1985 Geosat 1987 , 1990-91 AristotelesGradio 1992 Topex/PoseidonGPS 1995 CHAMP 1996 GRACE GOCE 1997 1998 22IUGG IAG2NASAESAGRACE GOCE 2000.7.15 CHAMP 2002.3.19 GRACE 2009.3 GOCE

Launch: July 2000

SST - hlGPS SatellitesEarthMassanomaly3-D accelerometerCHAMP ConceptH = 470 - 300 km,polar, circular orbitT = 5 years,High-Low-SST(d = 20 000 km) + accelerometryd

Launch: March 20021cm-geoid with a spatial resolution of 200 km and temporal variations

May 3, 2003Gravity anomaly and intersatellite range changes when GRACE flying the Qinghai-Tibet Platean

SST - hlGPS SatellitesEarthMassanomalySST - llGRACE ConceptH = 470 - 300 km,polar, circular orbitT = 5 years,Low-low-SST(d = 250 km, sd=10 mm) + accelerometryd

H = 240 kmdrag-freesun-synchronouslaunch: 2006T = 20 monthsgradiometry1cm-geoid with a spatial resolution of 100 km

SGGEarthMassanomalyGPS SatellitesSST - hlGOCE ConceptGradiometry: differential accelerometry within the satellited = 30 cmsa = 8 mEd1 E = 1 Etvs = 10-9 s-2

Main points of satellite technique Low orbit (400km) Near polar orbit GPS space borne receiver (cm accuracy) 3D accelerometer to measure and substract the non-conservation forces Satellite-satellite range and range-rate measurement Gravity gradiometer

CHAMP GRACE GOCE GFZ NASA DLR ESA 2000.7.15 2002.3.17 2009.3 (y)5 ~ 105 ~ 102 (km)454 ~ 300500 ~ 300250 ~ 240 (o)878996.5 < 0.004 < 0.004 < 0.001 (km) 22050 SST-HL SST-HL/LL SST-HL/SGG

CHAMP GRACE GOCE GPS (cm) 1031 (m/s2 )310-9 310-10 K (m/s) 10-6 (/s2) 310-12

CHAMP, GRACE, GOCE

Cumulative Geoid Height Errors (10-2 m)

Degree(L)EIGEN-CHAMP03SCHAMP(Energy)EIGEN-GRACE02SGRACE(Energy)GRACE(Semi-analytic)GOCE(SGG)200.4560.3730.0760.0450.0660.625504.0854.2260.2280.2110.1991.18670 18.419 17.2730.8130.8120.8061.7131005.7564.8855.5032.228120 18.938 17.316 18.3952.4312004.6822509.055

Before satellite gravity (20 years data)Advances in Earths Gravitational FieldGRACE mission(111 days measurements)GRACE mission(13 months measurements

Static satellite gravity field

OutlineGRACE data span now >6 yrsSeveral Science Data System (SDS) centers (e.g. CSR, GFZ, JPL, CNES)

post-processing improvement (Spectrum interference )Mass changes detection (Three Gorges region, Sumatra earthquake, sea level changes, etc) stripe

Cumulative Geoid Error CurvesError curves provided by GFZ Potsdam

Inversion of gravity modelDynamic orbit integration methodEnergy conservation method

Gravity models GGM01C (CSR MODEL) EIGENGRACE02 (GFZ MODEL)

IGG MODELGRACE data:Level 1B data products, including K-band range and range rate, orbit , accelerometer and star camera assembly data et al.Dynamic models Plantetary Ephmerides:DE-200 Background static gravity field:GGM01C Solid tidal corrections:Wahr(1981) Ocean tidal corrections:CSR3.0 Polar motion:IERSC04 Uniform time system: all change to UTC

1 Problems with GRACE L2 data

Stokes

22)

22

2005321.63 mGal 2.92 mGal0.69 mGal2.0 mGal1.0-2.0 mGal

228000 222.9 mGal3-5mGal

ETOPO5 Obtained from altimetric graivty anomaly

A Shaded-relift image of the bathymetry over the East China Sea

183mETOPO5252m

Tectonic setting

mGal

ABCD1795231917922125-5.3-4.8-6.9-7.95.24.42.16.70.9-0.4-2.0-0.51.81.72.12.92.01.72.92.9

The interrelation of gravity, gravity variation, mass transports and mass anomalies

Science, Wahr, 2006

GRACE(without PGR)PGR model Mass changes over AntarcticaPGR correction applied, Paulson et al. 2007 (a) East Antarctica Ice Sheet;b West Antarctica Ice Sheet;cLarsen Ice Sheet (Point C)GRACE(with PGR)GRACE

MODISICESat, GRACE2003-2008GRACEICEsat2

The Greenland ice sheet is the 2nd largest ice cap on Earth, and contains ~ 2.5 million cubic kilometers or 10% of total global ice mass. The glacial complex in southeast Greenland is among the most active glaciers.Science, Chen, 2006

IAG, Ramillien, 2006

+++--5

Water Storage Changes over China landNorth Niemeng region (-), North China(-), Lower Reaches of Yangtze river (-), Middle and Upper Reaches of Yangtze river (+), Tian mountain snowfield (-), Himalayas Icefield (-).Tian mountain snowfield Himalayas IcefieldNorth NiemengNorth ChinaLower Reaches of Yangtze riverMiddle and Upper Reaches of Yangtze riverWenchuan Earthquake??

(400).

GRACEGRACE23.29/.,,! 77.80,33.20.

GRACE- 19.32/48/42/197640/

GRACE- 17.82/,

,GRACE15.3/.80.60,42.1081.50,42.4082.30,42.80

,5~10,11~4,

,,.

IPCC WG1 Fourth Assessment Report,2006 192021

10 40

SLVtotal = SLVsteric + SLVmass + GRACE

Seasonal Variations Removed60-Day SmoothingGIA Correction AppliedRate = +3.3 0.4 mm/year(GIA Correction Applied)http://sealevel.colorado.edu

22 1mm/600km

2.60.4 mm/yr2.8 mm/yr ICE-4G)()C.K. Shum, 2007,IUGGIB correction (ECMWF) applied

GRACE1.4 mm/yrBouhours)

GIA: -0.3mm/yr GIA: +1.4mm/yr2003-2006GRACE

+3.2 0.6 mm/yrGRACE : ocean mass variations from GSMAltimetry SLA minus GRACE : steric height variationsTotal Sea level variation budgetSteric Component (by combining altimetry and gravimetry data) : ~ 1.9 0.3 mm/yr Ishii: steric component+1.9 0.1mm/yr (Willis)Before 2003, not afterAltimetry SLA

CMONOC ,

GRACE Observed Gravity Change (15 gal)Seismic Model Predicted Gravity ChangeGalGal2005Nature, Han & Shum, 2006

ABSumatra-earthquake regionSumatra-earthquake region

122 20073210633 35.681.6 7.3 ----1 2008-05-12 14:28 31.0, 103.4 8.0 7-------7

GRACE show that a rising rate is 12.1 mm/y.An notable change: water storage or solid mass redistribution? (2008.5.12,M7.9,N30.99,E103,36,Depth 19.0km)Wenchuan Earthquake

globalDynamicSteric4-D3-DRegionalSpaceGroundGlobal changes:Sea level change, Ice balanceocean currents and water storage etc.

Disaster monitoring:Earthquake, volcano, ionosphere etc.National defence:Spaceflight technology improvement.ApplicationsPowerful geodesy

Thank you!

******Slide to introduce the sea level change time series from altimetry (note that this has some animations - modify this if you dont like it).Point out the change in MSL during the 1997-98 ENSO event.**